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Hip Pain in the Young Adult and Hip Preservation Surgery


It has long been known that significant hip deformity resulting from childhood conditions such as developmental dysplasia of the hip and Legg-Calvé-Perthes disease can lead to secondary hip osteoarthritis in adult life. Over the past two decades, more subtle deformity of the hip has been implicated in the development of osteoarthritis in patients who previously were thought to have “primary osteoarthritis” of the hip. Primary or idiopathic osteoarthritis of the hip attributes arthritic progression to the effect of age-related chemical and mechanical deterioration of hip articular cartilage present in a subset of individuals for unknown reasons. Many patients who would formerly have been thought to fall within this primary group are now believed to have had hip impingement leading to osteoarthritis over time.

As early as 1965, Murray described the subtle “tilt deformity” of the proximal femur that he believed would lead to osteoarthritis. This theory that small deformities of the hip from childhood would inevitably lead to osteoarthritis was again stated in 1975 by Stulberg et al., who coined the term “pistol grip” deformity of the proximal femur ( Fig. 6.1 ). In the mid-1990s, Ganz et al. refined the description of hip impingement caused by femoral and acetabular deformity and ushered in a new era of hip-preserving surgery in symptomatic young adult patients by describing techniques to correct these deformities.

FIGURE 6.1
Pistol-grip deformity of proximal femur leading to secondary osteoarthritis.

Periacetabular osteotomy (PAO), with or without femoral osteotomy, for treatment of painful hip dysplasia in young adults appears to be effective in delaying prosthetic hip reconstruction when the surgical intervention occurs while the arthritic progression is fairly mild. The results of PAO in patients with more advanced arthritis have been less favorable. More recently, the disease patterns of hip impingement have been elucidated, and surgical procedures aimed at hip preservation for this condition have been applied. Similar to hip dysplasia, it appears that the articular damage resulting from hip impingement can occur while symptoms remain relatively mild and intermittent. These facts argue for early intervention in both hip dysplasia and hip impingement before the onset of irreversible arthritis. The goal of hip preservation surgery in both dysplasia and impingement is to alter the hip joint morphology to allow more unhindered physiologic range of motion while optimizing hip joint mechanics to delay or halt the progression of hip osteoarthritis.

Other sources of hip pain in young adults, including osteonecrosis of the femoral head and transient osteoporosis of the hip, are discussed in this chapter. Extraarticular sources of groin, buttock, and lateral hip pain must be differentiated from articular sources. Some of these are discussed, including sports hernias, peritrochanteric pain, and osteitis pubis.

Evaluation and History

Patient History

The patient history can focus the physician on probable sources of hip pain, thus directing further evaluation. The onset and duration of pain can be helpful, with conditions such as osteonecrosis and stress fracture having fairly acute onsets, whereas dysplasia and hip impingement tend to have insidious onsets often described as a recurrent groin pull that occurs with certain activities. Stress fractures are common in runners, particularly amenorrheic women with lowered bone densities. Pain onset after a twisting injury is common in sports such as soccer, ice hockey, and tennis and suggests a labral injury and may also be associated with bony morphologies that predispose a patient to labral injury. Patients with labral pathology frequently describe a catching, sharp pain when twisting on a weight-bearing hip or when simultaneously flexing and internally rotating their hip, as when entering a car. Psoas tendonitis usually is described as groin pain that is made worse with active hip flexion and frequently is associated with an audible snapping of the hip.

The localization of pain also is helpful. Posterior pain along the posterosuperior iliac spine and buttock frequently is referred pain from the lumbar spine and possibly the sacroiliac joint. The radiation of this pain down the posterior thigh and past the knee is highly suggestive of a radicular origin, particularly when associated with other neurologic symptoms. Lateral hip pain is frequently peritrochanteric in origin and can radiate down the lateral thigh as in iliotibial band tendinitis. Intraarticular pathology usually presents as some amount of groin or deep, more ill-defined pain. Byrd described the frequent “C sign” suggestive of intraarticular pathology in which the patient places his hand about the affected hip with the thumb in the groin crease and the fingers on the buttock surrounding the hip with the hand in the shape of a C ( Fig. 6.2 ). However, intraarticular pathology can present as primarily lateral or posterior pain that must be differentiated from extraarticular sources by physical examination combined with imaging studies and occasionally diagnostic injections.

FIGURE 6.2, The “C sign” is suggestive of intraarticular hip pathology.

Pain that occurs with sitting for prolonged times but is minimal with standing and walking suggests hip impingement, although it also can be spine related. Weight-bearing pain that is relieved by sitting or lying is more nonspecific, with possibilities including osteoarthritis, osteonecrosis, stress fracture, dysplasia, and inflammatory arthritis. Pain associated with a popping or a snapping sensation can be caused by a labral tear or snapping psoas tendon or iliotibial band.

Physical Examination

Physical examination of the hip begins with observation of the patient’s gait. An antalgic gait is described as having a decreased stance phase on the affected limb. A painful hip, however, often causes the patient to walk with an abductor lurch, in which he or she lurches toward the affected side during the stance phase of gait in an effort to reduce the joint reactive forces on the hip. This same type of gait is seen with weakness of the hip abductor. Weakness of the hip abductor is tested with the Trendelenburg test. The Trendelenburg test is positive for hip abductor weakness when the pelvis sags more than 2 cm during single-leg stance on the limb tested ( Fig. 6.3 ).

FIGURE 6.3, Trendelenburg sign is positive when affected hemipelvis sags during one-legged stance.

With a fixed or painful hip flexion contracture, a patient will stand with compensatory hyperextension of the lumbar spine. During gait, extension of the hip is accomplished by further extension of the lumbar spine. With a flexion contracture the pelvis also may rotate toward the affected side during extension of the hip because of the inability of the patient to extend the hip adequately. This asymmetric external rotation of the pelvis during extension of a hip with a flexion contracture is known as a pelvic wink.

Some patients experience a snapping sensation during gait or with specific standing maneuvers. The examiner may have the patient reproduce the snapping while palpating the lateral side of the hip. A snapping iliotibial band frequently can be palpated or visualized as it catches while sliding over the lateral border of the greater trochanter during gait. Many patients with a snapping iliotibial band, also known as an external snapping hip, can reproduce the snapping by bearing weight on the leg while flexing and extending the hip.

Palpation of the pelvis may identify tenderness at the pubic symphysis typical of osteitis pubis. Tenderness along the inguinal canal may represent a classic inguinal hernia or deficiency of the abdominal wall known as a sports hernia. The muscular origins of the rectus femoris and adductor longus can be tender with strains or avulsion injuries. Tenderness over the greater trochanter and abductor tendon will be present with trochanteric bursitis and partial tears of the gluteus medius or minimus.

The examination continues with the patient supine with both hips examined for symmetry of motion. Flexion, extension, abduction, and adduction, as well as internal and external rotation, are noted. Rotation is tested in both extension and 90 degrees of flexion. Rotation of the hip in extension can most reliably be tested with the patient prone on the examination table. The presence of a flexion contracture is determined by the Thomas test. With the patient supine, both hips are flexed maximally, thus flattening any lumbar lordosis. The legs are then alternatively brought into extension with any residual flexion contracture noted while the pelvis and lumbar spine are held stationary by keeping the contralateral hip flexed ( Fig. 6.4 ). The presence of reproducible popping or clicking during hip range of motion testing should be noted because it may be suggestive of a labral tear.

FIGURE 6.4, Thomas test detects hip flexion contracture by extending affected hip while contralateral hip is held flexed, flattening and immobilizing lumbar spine.

A hip with synovitis from any cause can be painful when the hip is rotated passively to the extremes of motion allowable. The range of motion in all planes may be decreased, with internal rotation and abduction tending to be most affected. When the hip is quite irritable, even log-rolling the patient’s hip on the examination table can be painful. A hip that is irritable with log-rolling should make the examiner consider diagnoses such as inflammatory arthritis, sepsis, stress fracture, acute onset of osteonecrosis, or advanced degenerative arthritis.

An active straight leg raise performed by the patient produces a force of approximately two times body weight because of the joint reactive force produced by the hip flexors. Pain with an active straight-leg raise can be helpful because this force is reproducible in a given patient and can be used as a gauge of disease severity. Pain with resisted hip flexion past 30 to 45 degrees is known as a positive Stinchfield test and can detect even more subtle degrees of intraarticular hip pathology than is detected by straight leg raise alone.

The anterior impingement test or FADIR (flexion adduction internal rotation) test is performed by flexing the hip to 90 degrees, adducting across the midline, and maximally internally rotating the hip ( Fig. 6.5 ). Hips with symptomatic anterior impingement are limited in internal rotation and are painful with this maneuver. Contralateral comparison of internal rotation is particularly helpful because this value will vary greatly between individuals. With anterior impingement, patients have distinctly more pain with the FADIR test than with other extremes of rotation. With lateral or posterior impingement, however, as in patients with a protrusio deformity, pain may be produced by pure abduction or with the FABER (flexion abduction external rotation) test ( Fig. 6.6 ). The FABER test also may elicit posterior pelvic pain with disorders of the sacroiliac joint or lumbosacral junction.

FIGURE 6.5, FADIR test: f lexion, ad duction, and i nternal r otation of hip.

FIGURE 6.6, FABER test: f lexion, ab duction, and e xternal r otation of hip.

The anterior apprehension test is performed with the patient supine on the edge of the examination table. The hip is extended and externally rotated ( Fig. 6.7 ). Patients with hip dysplasia, including deficient anterior coverage, will experience groin discomfort or a sense of apprehension with this maneuver. This maneuver also may elicit posterior or lateral pain in a patient with posterior impingement.

FIGURE 6.7, Apprehension test.

The test for internal snapping of the hip or a snapping iliopsoas tendon is performed by passively flexing the hip to 90 degrees in a slightly abducted and externally rotated position, and then asking the patient to extend the hip to the examination table while keeping the foot suspended. A snapping psoas tendon frequently is audible as a distinctive, low-pitched “thunk” as it crosses from lateral to medial over the iliopectineal eminence during extension of the hip. This finding is common as a normal variant in individuals with no hip pain.

The area about the greater trochanter and gluteal muscles is more easily assessed with the patient in a lateral position. Pain with resisted abduction or against gravity may be present in patients with gluteus medius or minimus tendinitis or partial tears. The Ober test is performed with the patient in the lateral position by abducting the patient’s hip with the knee flexed and then letting the hip fall into adduction. A delay in adduction caused by gravity is a positive Ober test. With the hip extended past neutral, a positive Ober test signifies tightness of the iliotibial band, whereas a positive Ober test with the hip in neutral flexion/extension is indicative of a gluteus medius contracture or tendinopathy. In the lateral position, snapping of the iliotibial band over the greater trochanter can be reproduced in patients with external snapping hip syndrome by flexing and extending the hip while tensioning the iliotibial band similar to the Ober test. In thin patients, a thickened portion of the iliotibial band may produce visible snapping with this maneuver.

The use of a diagnostic intraarticular hip injection with local anesthetic can be used as a means of identifying patients with an intraarticular pathologic process when physical examination and radiographic studies are equivocal. This test can be particularly helpful when encountering a patient with an atypical pain pattern or when trying to differentiate pain from intraarticular pathology from referred pain generated from another source. Examining the patient within a couple of hours of the injection can be helpful, with the patient asked to reproduce the activities that previously elicited hip pain. Definite improvement in the patient’s symptoms has been noted by Byrd to predict the presence of an intraarticular pathologic process with 90% accuracy.

Radiographic Assessment

Assessment of the painful hip begins with plain radiography and a standing anteroposterior pelvic view. The radiographic signs on an anteroposterior pelvic radiograph are highly sensitive to rotation and tilt of the pelvis. A satisfactory anteroposterior pelvic view displays symmetry of the iliac wings and obturator foramina with the tip of the coccyx 1 to 3 cm above the pubic symphysis ( Fig. 6.8 ). A true anteroposterior view of the pelvis is particularly necessary when evaluating acetabular version and coverage.

FIGURE 6.8, Satisfactory anteroposterior pelvic radiograph shows coccyx centered 1 to 3 cm above the symphysis with symmetric obturator foramina.

The lateral center edge (LCE) angle of Wiberg ( Fig. 6.9 ) is measured on the anteroposterior pelvic radiograph by first drawing a horizontal reference line by connecting the centers of the femoral heads or the base of the radiographic teardrops. A line perpendicular to this horizontal reference line is drawn through the center of the femoral head and dome of the acetabulum. Another line is drawn from the center of the femoral head to the lateral edge of the sourcil or dense subchondral bone forming the dome of the acetabulum. Bone that extends lateral to the sourcil is not included in the measurement because it does not contribute to the weight-bearing support of the femoral head. The angle between these lines is the LCE angle. An LCE angle of less than 20 degrees is indicative of hip dysplasia with inadequate coverage of the femoral head by the lateral dome of the acetabulum. Hips with LCE angles in the range of 20 to 24 degrees have borderline dysplasia, and hips with an LCE angle of more than 40 degrees display overcoverage.

FIGURE 6.9, Lateral center edge (LCE) angle of Wiberg measures arc of superolateral acetabular coverage beyond vertical line drawn through center of femoral head. Tönnis angle measures inclination of radiographic sourcil compared with interteardrop line.

The version of the acetabulum is evaluated on the anteroposterior pelvic radiograph by tracing the rim of the anterior and posterior walls. In a normal hip, the anterior and posterior walls converge at the superior lateral margin of the acetabulum. The crossover sign is present when the anterior wall outline crosses over the posterior wall below the superior lateral margin of the acetabulum ( Fig. 6.10 ). The crossover sign is indicative of either isolated anterior overcoverage of the hip or retroversion of the entire acetabulum with deficient posterior coverage. The position of the posterior wall relative to the center of the femoral head is noted. A positive posterior wall sign exists when the posterior wall lies medial to the femoral head center and indicates deficient posterior wall coverage ( Fig. 6.11 ). When combined with a crossover sign, a positive posterior wall sign indicates relative retroversion of the acetabulum. Another sign of acetabular retroversion is ipsilateral prominence of the ischial spine in an otherwise properly rotated and positioned anteroposterior pelvic radiograph. The distinction between isolated anterior overcoverage and retroversion of the entire acetabulum is crucial because the surgical treatment is different for these two conditions. Of note, a crossover sign also may be caused by variations in the morphology of the AIIS in the presence of normal acetabular version.

FIGURE 6.10, Crossover sign is indicative of acetabular retroversion with anterior overcoverage of femoral head.

FIGURE 6.11, Posterior wall sign is present when center of femoral head lies lateral to lateral margin of posterior wall on anteroposterior pelvic radiograph.

The inclination of the acetabulum is measured on the anteroposterior pelvic view with the Tönnis angle, which is determined by first drawing a line from the most medial aspect of the radiographic sourcil to its most lateral aspect. A second line is drawn parallel to the interteardrop line with the apex of the angle at the medial sourcil (see Fig. 6.9 ). This angle normally is between 0 and 10 degrees. Angles of more than 10 degrees are present with hip dysplasia, whereas an angle of less than 0 degrees can indicate overcoverage.

The presence of coxa profunda is seen on the anteroposterior pelvic radiograph when the medial aspect of the acetabular fossa extends medial to the ilioischial line ( Fig. 6.12 ). Coxa profunda may be present in patients with acetabular overcoverage, though it can also be a normal variant, particularly in women. Protrusio acetabuli exists when the medial aspect of the femoral head is projected crossing the ilioischial line and usually indicates excessive acetabular depth and possible acetabular overcoverage with pincer impingement morphology. Protrusio acetabuli frequently is associated with inflammatory arthropathy or Marfan syndrome, but can be isolated and idiopathic.

FIGURE 6.12, Coxa profunda is present when the acetabular fossa extends medial to the ilioischial line and indicates excessive acetabular depth sometimes associated with pincer type impingement.

The anterior center edge (ACE) angle of Lequesne is generated on the false profile view of the pelvis to assess the anterior coverage of the hip. The false profile view is made with the patient standing with the affected side of the pelvis externally rotated 65 degrees from the anteroposterior projection ( Fig. 6.13 ). The ACE angle is determined by first drawing a vertical line from the center of the femoral head through the dome of the acetabulum. A second line is drawn from the center of the femoral head to the anterior edge of the subchondral bone of the acetabulum, ignoring bone anterior to the sclerotic subchondral edge because this bone does not provide anterior support for the femoral head. The normal ACE angle is approximately 20 degrees, with lesser values indicative of undercoverage.

FIGURE 6.13, Anterior center edge angle of Lequesne is measured on false profile view and is indicative of anterior coverage of hip.

Other views typically obtained in younger patients with hip pain include a frog-leg lateral, a cross-table lateral, and a 45-degree modified Dunn view of the hip. The modified Dunn view is obtained with the patient supine with the hip in 45 degrees of flexion, 20 degrees of abduction, and neutral rotation ( Fig. 6.14 ). With the use of these three views in addition to the anteroposterior pelvic view, the femoral head-neck junction is evaluated at different degrees of femoral rotation for the presence of head-neck offset abnormality and anterolateral prominence of the femoral neck that can cause cam impingement. The cam deformity was described by Murray as a “tilt” deformity of the femoral head and later by Stulberg et al. as a “pistol grip” deformity with flattening of the lateral head-neck junction seen on an anteroposterior view of the hip. The cam deformity appears to predispose individuals to secondary osteoarthritis. This anterolateral cam deformity is better seen on the lateral and modified Dunn views and is quantitated by the alpha angle and head-neck offset ratio.

FIGURE 6.14, Modified Dunn view displays anterosuperior head-neck junction, which frequently is involved with cam impingement.

The alpha angle is used to assess the femoral head-neck junction on AP, lateral, and modified Dunn views. The angle is formed by a line drawn from the center of the femoral neck to the center of the femoral head and a second line drawn from the center of the femoral head to the point on the anterior head-neck junction where the contour of the femoral head diverges from the spherical contour determined more medially on the head ( Fig. 6.15 ). Nötzli et al. described the normal value for the alpha angle to be 42 degrees in asymptomatic hips. An alpha angle of more than 50 to 55 degrees is generally considered consistent with a cam deformity of the femoral head-neck junction.

FIGURE 6.15, Alpha angle measures angle between axis of femoral neck and junction of spherical portion of femoral head with more prominent head-neck junction.

The anterior head-neck offset ratio is determined from the cross-table lateral view with the hip in 10 degrees of internal rotation ( Fig. 6.16 ). The offset of the femoral head is determined by measuring the distance between two lines drawn parallel to the axis of the femoral neck. The first line is drawn through the most anterior portion of the femoral neck, and the second line is drawn through the most anterior portion of the femoral head. The ratio is determined by dividing this distance by the diameter of the femoral head. According to Beaulé et al., a value of less than 0.15 has a 95% positive predictive value of diagnosing femoroacetabular impingement.

FIGURE 6.16, Anterior head-neck offset ratio (see text for description).

The beta angle, originally described by Wyss et al. using an open MRI, determines the angle between the pathologic head-neck junction, the center of the femoral head, and the acetabular rim with the hip in 90 degrees of flexion. Brünner et al. described the measurement of the beta angle on plain radiographs. The radiograph is obtained with the patient seated and the hip held in 90 degrees of flexion, 20 degrees of abduction, and neutral rotation. The beam is angled 15 degrees from the anteroposterior projection to be tangential to the acetabular plane and centered on the femoral shaft approximately 6 cm lateral to the anterior-superior iliac spine. The beta angle is measured from the point where the contour of the femoral head-neck junction departs from the spherical contour of the femoral head to the center of the femoral head and then to the superior lateral bony margin of the acetabulum ( Fig. 6.17 ). According to Brünner et al., a beta angle of less than 30 degrees is indicative of impingement morphology, including cam, pincer, and mixed types.

FIGURE 6.17, A , “Beta view” for measurement of the beta angle with the hip in 90 degrees of flexion, 20 degrees of abduction, and 0 degrees of rotation. X-ray beam is angled 15 degrees to the anteroposterior direction so that it is tangential to the acetabular plane. Beta-view radiographs showing ( B ) cam-type femoroacetabular impingement with a reduced beta angle of 8.5 degrees and ( C ) a healthy control subject with a more normal beta angle of 55.2 degrees.

The Tönnis grading system is commonly used to describe the presence of osteoarthritis in hips being considered for hip preservation surgery:

  • Grade 0: no signs of osteoarthritis

  • Grade 1: sclerosis of the joint with minimal joint space narrowing and osteophyte formation

  • Grade 2: small cysts in the femoral head or acetabulum with moderate joint space narrowing

  • Grade 3: advanced arthritis with large cysts in the femoral head or acetabulum, joint space obliteration, and severe deformity of the femoral head.

The prognosis of any hip preservation surgery is improved when it is done in patients with lower Tönnis grades.

Small impingement cysts or sclerosis at the anterolateral femoral head-neck junction are radiographic evidence of femoroacetabular impingement and are present in approximately one third of symptomatic patients ( Figs. 6.18 and 6.19 ). A calcified labrum may worsen pincer-type impingement by producing secondary overcoverage. The sphericity of the femoral head and the congruence of the femoral head with the acetabulum are evaluated on all views. Posterior cartilage space narrowing occasionally can be discerned on the false profile view, whereas the other views remain relatively normal.

FIGURE 6.18, Sclerosis seen at femoral head-neck junction is indicative of impingement.

FIGURE 6.19, Impingement cyst is seen at anterolateral head-neck junction in patient with combined cam and pincer impingement.

CT of the pelvis with three-dimensional reconstruction is frequently used to offer guidance with bony resection in cam- and pincer-type deformities ( Fig. 6.20 ).

FIGURE 6.20, Computed tomography scan of pelvis with three-dimensional reconstruction shows acetabular overcoverage and direct surgical correction.

MR arthrography (MRA) of the hip has been the gold standard in detection of labral pathology, improving the sensitivity of demonstrating labral tears from around 60% to more than 90% when compared with traditional MRI of the hip performed without administration of a contrast agent ( Fig. 6.21 ). The status of the articular cartilage is more difficult to ascertain on MRA . Occasionally, contrast medium can be seen tracking beneath the articular cartilage adjacent to the labrum because of delamination in cam-type impingement. With the evolution of MRI technology, higher resolution 3Tesla scans with various sequencing have been shown to reliably demonstrate labral and articular cartilage pathology. These scans may eventually obviate the benefit of injecting intraarticular contrast at the time of the study. Edema in the anterior femoral neck and the anterosuperior acetabulum also can be seen with impingement. Small cysts within the anterior femoral neck have been described as anatomical variants or “herniation pits.” These cysts, as well as sclerosis of the femoral head-neck junction, are thought to be caused by the repetitive trauma of hip impingement. Thinning of the articular cartilage on MRA is indicative of more advanced disease, as is the presence of acetabular subchondral cysts. The alpha angle described earlier used with plain radiographs also has been applied to radial MRA and CT images of the hip for planning bony resection of both cam and pincer deformities.

FIGURE 6.21, Magnetic resonance arthrogram shows gadolinium tracking into labral chondral junction, indicating a labral tear.

Labral tears seen on MRA may occur secondary to injury alone, although they are uncommon without underlying bony deformity. Labral tears are more likely to be the result of abnormal hip mechanics with secondary injury of the labrum and adjacent acetabular rim. These abnormal mechanics may be exacerbated by physical activity as is seen in certain sports such as hockey, soccer, and tennis.

Femoroacetabular Impingement

Femoroacetabular impingement (FAI) occurs when anatomic variation of the hip causes impingement between the femoral head-neck junction and the acetabular rim during functional range of motion. The presence of symptomatic hip impingement in adolescence and young adulthood is believed to be one of the primary causes of osteoarthritis in patients younger than the age of 50 years. In a study of patients under 50 years of age undergoing total hip replacement, Clohisy et al. found that in patients with osteoarthritis, after excluding those with developmental dysplasia of the hip, slipped capital femoral epiphysis, and Perthes disease, 97% had radiographic signs of cam, pincer, or mixed type impingement. Early recognition of hip impingement and intervention to correct the underlying pathology has been championed in an attempt to modify the natural history of the condition. Multiple approaches to hip-preserving surgery have evolved based in part on the varied pathologic processes involved as well as varied surgical philosophies and skills.

Two basic types of impingement have been described. Cam impingement occurs when the anterosuperior femoral head-neck junction is prominent or the femoral neck has a diminished offset from the adjacent femoral head ( Fig. 6.22 ). With flexion and particularly flexion combined with internal rotation, the nonspherical portion of the femoral head-neck junction rotates into the acetabulum. A typical injury pattern with cam impingement is a tear at the base of the labrum at the labral-chondral junction. The adjacent articular cartilage then becomes injured because of compression from the femoral head with its relatively larger radius of curvature rotating into the acetabulum. Frequently, the articular cartilage delaminates from the underlying subchondral bone, progressing from the acetabular rim ( Fig. 6.23 ). In this process, the acetabular labrum is relatively spared, with more injury incurred within the adjacent articular cartilage. Cam morphology is more common in young athletic males. Kapron et al. found 72% of collegiate football players to have an alpha angle of more than 50 degrees. The etiology of the deformity is unknown, although some authors have postulated that it may be a mild variant of slipped capital femoral epiphysis, whereas more commonly others have postulated a developmental abnormality of the lateral femoral physis, possibly related to activity level. In a cross-sectional MRI study of adolescents, abnormal alpha angles were not found in any hips with open physes, but 14% of hips with closed physes had cam deformities. The daily activity levels for patients with cam deformities were significantly higher than for those with no deformity.

FIGURE 6.22, Cam impingement occurs when prominent head-neck junction contacts acetabular rim during hip flexion.

FIGURE 6.23, Delamination of articular cartilage secondary to impingement injury.

There is an increasing body of evidence that cam impingement can predispose a hip to osteoarthritis. A large, prospective, cross-sectional, population-based study found 6% of men and 2% of women to have cam deformities, whereas 42% of those who had hip replacements had evidence of a cam deformity. In a longitudinal, prospective study, a cam deformity with an alpha angle of more than 60 degrees had an adjusted odds ratio of 3.67 for development of end-stage osteoarthritis, whereas an alpha angle of more than 83 degrees had an adjusted odds ratio of 9.66. In a 20-year longitudinal study of 1003 women, each degree increase in the alpha angle over 65 degrees was associated with a 5% increase in the risk of developing osteoarthritis.

Pincer impingement occurs when the acetabular rim has an area of overcoverage causing impingement against the femoral neck with functional motion ( Fig. 6.24 ). The area of overcoverage can be global, as with protrusio acetabuli, or can be localized to the anterior acetabulum as with acetabular retroversion. Acetabular retroversion can also be global or isolated. In true global retroversion of the acetabulum, the posterior coverage of the acetabulum is deficient, with the entire acetabulum rotated or retroverted about the longitudinal axis. In isolated retroversion of the acetabulum the anterosuperior rim of the acetabulum extends farther around the femoral head whereas the remainder of the acetabulum has more normal morphology.

FIGURE 6.24, Pincer impingement occurs when acetabulum has localized or global overcoverage leading to contact of acetabular rim with femoral head-neck junction during normal hip motion.

The injury pattern with pincer impingement is created by the femoral neck abutting the acetabular rim and labrum during the extremes of motion. The labrum is pinched between the bony surfaces and subsequently suffers more damage than the adjacent articular cartilage, which is relatively spared. Pincer impingement may worsen with time as the result of reactive bone growth at the acetabular rim or calcification of the labrum, effectively increasing the arc of overcoverage of the acetabulum ( Fig. 6.25 ). A “contrecoup” injury frequently is seen on the posterior femoral head and posteroinferior acetabulum owing to levering of the femoral neck on the acetabular rim with subsequent increased pressure on the posterior hip cartilage. Pincer morphology is more commonly encountered in women.

FIGURE 6.25, Calcified labrum contributing to pincer-type impingement.

Pincer impingement morphology also has been implicated in the development of osteoarthritis, though not as strongly as cam impingement morphology. In a comparison of radiographs of hips that had total hip arthroplasty (THA) for osteoarthritis to radiographs of nonarthritic hips, 20% of the arthritic hips had evidence of acetabular retroversion, although only 5% of the asymptomatic hips showed signs of retroversion. In the Copenhagen Osteoarthritis Study, deep acetabular sockets had an adjusted risk ratio of 2.4 for the development of osteoarthritis.

Combined mechanism hip impingement occurs when cam and pincer morphology coexist in the same hip ( Fig. 6.26 ). Associated pincer deformities have been reported in variable percentages of patients being operated on for cam-type impingement, though according to some authors, most hips treated for FAI have combined morphology. Interestingly, Bardakos and Villar described a positive posterior wall sign as a risk factor for arthritis progression when observing patients with cam deformities and Tönnis grade 1 or 2 arthritic staging over a 10-year time interval. Some of these patients are likely to have had associated acetabular retroversion, whereas others may have had a dysplastic variant.

FIGURE 6.26, Combined cam and pincer femoroacetabular impingement.

Surgical Indications

As FAI has become better defined, the number of surgical procedures performed for FAI has increased dramatically, particularly hip arthroscopic procedures. Surgical indications are being refined as the short-term and midterm outcomes of open, arthroscopic, and combined procedures are reported.

Accurate diagnosis of the source of pain in young adults or adolescents is crucial in obtaining optimal surgical outcomes with FAI surgery. The diagnosis of FAI is primarily made clinically from the patient’s history and physical examination and then correlated with the radiographic findings. Occasionally, a diagnostic hip injection is done at the time of MRA. A study by Hack et al. corroborates the need for a compelling clinical picture of FAI as an indication for surgery. Of 200 asymptomatic volunteers who had MRI of the hips, 14% had cam morphology of at least one proximal femur (alpha angle of more than 50.5 degrees), including 25% of the men and 5% of the women. With symptomatic individuals excluded from the study and with an estimated lifetime radiographic incidence of osteoarthritis of the hip of 8%, the radiographic appearance of a cam deformity as currently defined does not appear to always lead to osteoarthritis. The authors stated that concurrent pincer-type deformity and other environmental factors may have a role in the development of osteoarthritis.

Hanke et al. identified MRA findings that correlated with failure of FAI surgery within 10 years of surgery, including the presence of an acetabular rim cyst, involvement of 60 degrees of the articular cartilage, and the presence of a sabertooth (central acetabular) osteophyte ( Fig. 6.27 ). They recommended routine MRA with radial cuts to search specifically for these signs of early osteoarthritis that portend a poorer outcome with FAI surgery.

FIGURE 6.27, A “sabertooth” osteophyte seen on MRA and depicted in drawing.

The exclusion criteria for arthroscopic intervention have tended to focus on the residual hip cartilage thickness. A residual joint space of over 2 mm frequently is cited as being associated with a good result after FAI surgery. Skendzel et al. found that, at 5 years after arthroscopic FAI surgery, of those with a preoperative cartilage space measuring 2 mm or less 86% had been converted to THA, while only 16% of those with preserved cartilage spaces had been converted to THA. Byrd et al. stated that with 2-year follow-up even Tönnis grade 2 hips had meaningful improvement of patient-reported outcomes (mHHS). Outcomes with longer follow-up of Tönnis grade 2 hips have been less favorable.

Osteochondroplasty of the femoral head-neck junction is the surgical treatment for symptomatic cam impingement. This is usually accomplished arthroscopically, though it can be done through a limited open anterior approach or open surgical dislocation. The technique is determined by the extent of the pathologic process, associated pathology, and the surgeon’s familiarity with a given approach.

The radiographic parameters defining pincer morphology are studied to determine the extent and regions of overcoverage or deficiency. An LCE angle of more than 40 degrees is indicative of lateral overcoverage and may be associated with a coxa profunda or protrusio acetabuli deformity with global overcoverage. Three-dimensional CT images may be helpful in determining the location and extent of acetabular overcoverage. In patients with pincer impingement caused by isolated retroversion of the anterosuperior rim of the acetabulum, the crossover sign may be the only plain radiographic finding. This type of pincer impingement can be treated arthroscopically with labral reflection, rim trimming, and labral reattachment (see Chapter 51 ). Limited anterior approaches have been used to treat this lesion, as well as open surgical dislocation. Larger deformities on the acetabular side of the joint involving the posterior-superior and posterior acetabular rim usually are treated with open surgical dislocation with acetabular rim trimming and labral reattachment when possible.

A crossover sign associated with a posterior wall sign and a prominent ischial spine indicates retroversion of the entire acetabulum with deficient posterior coverage. These patients have true retroversion of their entire acetabulum and are candidates for PAO. Some of these patients have a component of dysplasia with deficient lateral coverage. Some surgeons advocate arthroscopy alone for treating global acetabular retroversion, with anterior rim trimming reported to improve patient-reported outcomes 2 years postoperatively while avoiding the greater surgical intervention of a PAO. However, predominant thought is that treating these patients with acetabular rim trimming may predispose them to symptoms of instability. Performing a PAO allows the surgeon to antevert the acetabulum, with or without changing lateral coverage, as needed to optimize the position of the acetabulum from the predetermined radiographic parameters.

There is a subset of patients with borderline hip dysplasia (LCE angle of 20 to 25 degrees) with coexistent cam deformity. This is a difficult patient group because the pain may be primarily from impingement or dysplasia. Careful history and physical examination must be relied upon to determine the appropriate treatment of these patients because purely positional pain not associated with weight-bearing activity may be primarily due to impingement. Some of these patients experience pain because of instability and are appropriately treated with a PAO to correct the borderline dysplasia with combined osteochondroplasty of the femoral cam deformity and open labral repair through an anterior capsulotomy at the time of PAO or with arthroscopy.

Surgical Dislocation of the Hip

Surgical dislocation of the hip was described by Ganz et al. for the treatment of FAI. The surgery is designed to allow full access to the acetabulum and the femoral head-neck junction while preserving the blood supply to the femoral head. The approach protects the deep branch of the medial circumflex artery as it supplies the posterolateral retinacular vessels to the femoral head. The major advantage of the approach is its extensile nature with full access to the acetabular rim, the labrum, and the femoral head-neck junction without the limitations of arthroscopy and limited anterior approaches. Surgical dislocation of the hip also has been used for open treatment of slipped capital femoral epiphysis, the deformities of residual Perthes disease and Pipkin fractures of the femoral head. The shortcoming of the approach also relates to its extensile nature, which requires trochanteric osteotomy with a more prolonged recovery compared with more limited exposures.

Surgical Dislocation Of The Hip

Technique 6.1

(Ganz et al.)

  • ▪

    With the patient in the lateral decubitus position, make a Kocher-Langenbeck incision ( Chapter 1 ) and split the fascia lata accordingly. Alternatively, make a Gibson approach ( Chapter 1 ) and retract the gluteus maximus posteriorly.

  • ▪

    Internally rotate the leg and identify the posterior border of the gluteus medius. Do not mobilize the gluteus medius or attempt to expose the piriformis tendon.

  • ▪

    Make an incision from the posterosuperior edge of the greater trochanter extending distally to the posterior border of the ridge of the vastus lateralis.

  • ▪

    Use an oscillating saw to make a trochanteric osteotomy with a maximal thickness of 1.5 cm along this line. At its proximal limit, the osteotomy should exit just anterior to the most posterior insertion of the gluteus medius ( Fig. 6.28A ). This preserves and protects the profundus branch of the medial femoral circumflex artery.

    FIGURE 6.28, A, Trochanteric osteotomy exits proximally just anterior to most posterior attachment of gluteus medius, preserving capsular branch of medial femoral circumflex artery. B, Hip capsule is exposed above level of piriformis by dissecting gluteus minimus off capsule while displacing trochanteric fragment anteriorly. C, Z-shaped capsulotomy is performed. D, Hip is dislocated anteriorly while placing leg in sterile drape pouch over anterior side of operating table and cutting ligamentum teres. E, Labrum is reflected off overhanging acetabulum. F, Excessive bone is trimmed with osteotome or burr, and intact labrum is reattached with suture anchors if possible. G, Labrum is reattached with suture anchors. H, Burr is used to recontour head-neck junction. I, Clear plastic spherometer can be used to judge point where femoral head becomes aspherical and to guide extent of osteochondroplasty. SEE TECHNIQUE 6.1.

  • ▪

    Release the greater trochanteric fragment along its posterior border to about the middle of the tendon of the gluteus maximus and mobilize it anteriorly with its attached vastus lateralis.

  • ▪

    Release the most posterior fibers of the gluteus medius from the remaining trochanteric base. The osteotomy is correct when only part of the fibers of the tendon of the piriformis have to be released from the trochanteric fragment for further mobilization.

  • ▪

    With the patient’s leg flexed and slightly rotated externally, elevate the vastus lateralis and intermedius from the lateral and anterior aspects of the proximal femur.

  • ▪

    Carefully retract the posterior border of the gluteus medius anterosuperiorly to expose the piriformis tendon.

  • ▪

    Separate the inferior border of the gluteus minimus from the relaxed piriformis and the underlying capsule. Take care to avoid injury to the sciatic nerve, which passes inferior to the piriformis muscle into the pelvis.

  • ▪

    Retract the entire flap, including the gluteus minimus, anteriorly and superiorly to expose the superior capsule ( Fig. 6.28B ). Further flexion and external rotation of the hip makes this step easier.

  • ▪

    Incise the capsule anterolaterally along the long axis of the femoral neck; this avoids injury to the deep branch of the medial femoral circumflex artery ( Fig. 6.28C ).

  • ▪

    Make an anteroinferior capsular incision, taking care to keep the capsulotomy anterior to the lesser trochanter to avoid damage to the main branch of the medial femoral circumflex artery, which lies just superior and posterior to the lesser trochanter.

  • ▪

    Elevate the anteroinferior flap to expose the labrum.

  • ▪

    Extend the first capsular incision toward the acetabular rim and then turn it sharply posteriorly parallel to the labrum, reaching the retracted piriformis tendon. Take care not to damage the labrum.

  • ▪

    Dislocate the hip by flexing and externally rotating the leg; bring the leg over the front of the operating table and place it in a sterile bag ( Fig. 6.28D ). Most of the acetabulum can now be inspected.

  • ▪

    Manipulation of the leg allows a 360-degree access to the acetabulum and nearly 360-degree access to the femoral head.

  • ▪

    After exposure of the acetabulum, reflect the labrum from the portion of the acetabular rim that displays overcoverage ( Fig. 6.28E ) and trim excessive bone with an osteotome or burr ( Fig. 6.28F ).

  • ▪

    If possible, reattach the labrum at the margin of the articular surface with suture anchors, recreating the seal effect of the labrum ( Fig. 6.28G ).

  • ▪

    For osteochondroplasty, outline the femoral head-neck junction with a surgical marker and then cut the articular cartilage at the proximal edge of the resection with a scalpel to avoid inadvertent extension into the normal femoral head.

  • ▪

    Carefully perform the resection with small osteotomes, using a burr to complete the recontouring of the head-neck junction ( Fig. 6.28H ). Cadaver studies have shown that up to 30% of the diameter of the femoral neck can be removed from the anterolateral quadrant of the head-neck junction without substantially altering the strength of the femoral neck to axial load. A typical resection, however, is much less than 30% and is tailored to the specific anatomy encountered.

  • ▪

    Check the contour of the femoral head with a plastic template or spherometer to gauge the proximal extent of the osteochondroplasty where the femoral head becomes aspherical ( Fig. 6.28I ).

  • ▪

    Coat the exposed cancellous bone with bone wax. Reduce the hip and reproduce the position of impingement, evaluating range of motion directly and with fluoroscopy.

  • ▪

    Repair the capsule anatomically with nonabsorbable sutures.

  • ▪

    Reattach the greater trochanter with two 4.5-mm cortical screws aimed medially and distally in the region of the lesser trochanter.

Postoperative Care

Postoperatively, the patient is mobilized with touch-down weight bearing for 6 weeks with avoidance of active abduction and extreme flexion or rotation of the hip. After 3 weeks, pool exercises are begun, and at 6 weeks weight bearing is allowed with progressive abductor strengthening. Low-molecular-weight heparin is used for deep venous thrombosis prophylaxis for 2 weeks, followed by aspirin 325 mg per day for another 4 weeks.

Results

In follow-up studies ranging from 2 to 10 years, the rate of good to excellent results has ranged from 68% to 94%. Hip scores improved an average 2 to 5 points as measured by the Merle d’Aubigné Score and in one study by 30 points as measured by the modified Harris Hip Score ( Fig. 6.29 ). Conversion to total hip replacement occurred in 0% to 30% of patients. Factors that negatively impacted results included preoperative evidence of arthritis (Tönnis grade 2), intraoperative evidence of cartilage delamination, and increasing age. In a study by Anwander et al., refixation of the labrum improved the good to excellent percentage from 48% to 83% at 10 years when compared with labral debridement, although radiographic progression of osteoarthritis and conversion to THA was not significantly affected. In a separate report from the same group, Steppacher et al. reported a 10-year survivorship free of arthritic progression for 80% of FAI patients treated with surgical dislocation including labral reattachment . Heterotopic ossification and painful trochanteric hardware requiring removal were rarely reported complications.

FIGURE 6.29, A and B, Preoperative anteroposterior and lateral pelvic radiographs of 32-year-old woman with combined cam and pincer impingement after treatment of femoral neck fracture. C and D, After surgical dislocation with acetabular rim trimming and femoral osteochondroplasty.

Combined Hip Arthroscopy and Limited Open Osteochondroplasty

This approach described by Clohisy et al., Laude et al., and others has been used for patients with cam impingement. After hip arthroscopy for intraarticular or central compartment labral debridement or repair, the anterior aspect of the hip is approached through a limited Smith-Petersen approach or Hueter approach (through the sheath of the tensor fascia lata). The osteochondroplasty of the femoral head-neck junction is performed under direct vision. With traction, the anterior rim of the acetabulum can be resected with reflection of the labrum and reattachment with suture anchors although the extent of rim exposure and resection is limited. The advantage of this approach is primarily avoiding the morbidity of surgical dislocation with a larger exposure including trochanteric osteotomy. This approach allows direct vision of a typical cam deformity on the femoral head-neck junction. The limitation of this approach is that only the anterior aspect of the femoral head and neck and acetabular rim can be accessed. The lateral femoral cutaneous nerve may be injured in this approach as well. Placing the incision several centimeters lateral to the anterosuperior iliac spine and approaching the anterior hip through the fascial sheath of the tensor fascia lata may lessen the risk of injury to the nerve.

Combined Hip Arthroscopy And Limited Open Osteochondroplasty

Technique 6.2

(Clohisy and Mcclure)

  • ▪

    With the patient supine, perform a standard arthroscopic examination of the hip ( Chapter 51 ) for inspection of the articular cartilage of the femoral head, acetabulum, and acetabular labrum. Debride any unstable flaps of acetabular labrum and associated articular cartilage flaps.

  • ▪

    After arthroscopic debridement is completed, irrigate the joint, remove the arthroscopic instruments, and release the traction.

  • ▪

    Obtain a cross-table lateral or frog-leg lateral fluoroscopy view ( Fig. 6.30A ) to ensure excellent visualization of the proximal femur, specifically the femoral head-neck junction.

    FIGURE 6.30, A, Frog-leg lateral fluoroscopic view shows femoral head-neck junction. B, Incision incorporates anterior arthroscopy portal slightly lateral to anterosuperior iliac spine to avoid lateral femoral cutaneous nerve. C, Tensor fascia lata muscle is retracted laterally, and rectus and iliocapsularis are reflected to access anterior hip capsule. D, Frog-leg lateral fluoroscopic view verifying adequate resection. SEE TECHNIQUE 6.2.

  • ▪

    Make an 8- to 10-cm incision, starting just inferior to the anterosuperior iliac spine and incorporating the anterior arthroscopy portal incision ( Fig. 6.30B ).

  • ▪

    Carry the dissection through the subcutaneous tissue laterally directly onto the fascia of the tensor fascia lata muscle.

  • ▪

    Incise the fascia and retract the muscle belly laterally and the fascia medially. Protect the femoral cutaneous nerve by placing the fascial incision lateral to the tensor-sartorius interval.

  • ▪

    Develop the interval between the tensor and sartorius, identify the rectus origin, and release the direct and reflected heads.

  • ▪

    Reflect the rectus distally, and dissect the adipose tissue and iliocapsularis muscle fibers off the anterior hip capsule ( Fig. 6.30C ).

  • ▪

    Make an I-shaped or T-shaped capsulotomy to provide adequate exposure of the anterolateral femoral head-neck junction.

  • ▪

    Using the normal head-neck offset anteromedially as a reference point for resection of the abnormal osteochondral lesion along the anterolateral head-neck junction, use a 0.5-inch curved osteotome to perform an osteoplasty at the head-neck junction.

  • ▪

    Direct the osteotome distally and posteriorly to make a beveled resection to prevent delamination of the retained femoral head articular head cartilage.

  • ▪

    After the anterolateral head-neck offset has been established, confirm accuracy of the resection with fluoroscopy using frog-leg lateral or cross-table lateral views in neutral and varying degrees of internal rotation ( Fig. 6.30D ).

  • ▪

    Examine the hip for impingement in flexion and for combined flexion and internal rotation, while palpating the anterior hip to test for residual impingement.

  • ▪

    If the anterior acetabular rim is overgrown secondary to labral calcification or osteophyte formation, carefully debride until adequate clearance is obtained.

  • ▪

    Hip motion should improve at least 5 to 15 degrees in flexion and 5 to 20 degrees in internal rotation.

  • ▪

    The goal of osteoplasty is to remove all prominent anterolateral osteochondral tissue that contributes to an aspherical shape of the femoral head ( Fig. 6.31 ). If sphericity has not been achieved, perform additional resection of the femoral head-neck junction.

    FIGURE 6.31, After limited open osteochondroplasty of femoral head-neck junction. SEE TECHNIQUE 6.2.

  • ▪

    Control bleeding with bone wax, irrigate the joint, and close the longitudinal and superior transverse arms of the arthrotomy with nonabsorbable suture. Close the remainder of the wound in standard fashion.

Postoperative Care

Physical therapy is instituted for toe-touch weight bearing with crutches to minimize the risk of femoral neck stress fracture. A pillow is used under the thigh to protect the rectus repair, and active flexion is avoided for 6 weeks. Abductor strengthening is begun immediately and is continued with a home exercise program. Crutches are discontinued at 6 weeks, and activities are resumed gradually as tolerated. Impact activities, such as running, are not encouraged for at least 6 months. Aspirin, 325 mg, is taken as a thromboembolic prophylaxis, and indomethacin, 75 mg sustained release, is used for heterotopic ossification prophylaxis; therapy with both is continued for 6 weeks.

Results

Clohisy et al. reported an average improvement in the modified Harris hip score from 64 to 87 with normalization of the alpha angle at 2-year follow-up after arthroscopic labral debridement and limited open osteochondroplasty. Two of 36 patients showed radiographic progression of arthritis from Tönnis grade 0 to grade 1. Laude et al. showed at average 58-month follow-up an increase in the nonarthritic hip score of 29 points. There was an 11% failure rate with conversion to total hip replacement, with better results obtained in patients younger than 40 years of age and patients having Tönnis grade 0 arthritis preoperatively.

Mini-Open Direct Anterior Approach

Similar to the limited open osteochondroplasty described above, the mini-open direct anterior approach described by Ribas et al. uses the Smith-Petersen interval to access the anterior hip, but the procedure is done on a standard operating table with distraction of the hip accomplished by extension of the hip and a T-shaped anterior hip capsulotomy. No muscle is detached from the pelvis. Specialized retractors with attached fiber-optic illumination are recommended. A 70-degree arthroscope can be used through the capsulotomy to inspect the articular surface of the acetabulum. The acetabular rim can be treated in the region of the most common pathology, and cam lesions of the head-neck junction can be directly visualized and corrected. The labrum can be repaired with suture anchors. Cohen et al. reported the use of this approach in athletes and found similar activity score improvements and return to sport compared with arthroscopic and surgical dislocation techniques.

Technique 6.3

(Ribas et al.)

Positioning and Approach

  • ▪

    With the patient supine on an extension table, make an incision beginning 1 cm below and 1 cm lateral to the anterosuperior iliac spine and continuing 4 to 8 cm distally toward the fibular head.

  • ▪

    Open the crural fascia and the tensor fascia latae approximately 1 cm posterior to the first fibers of the tensor fascia latae and identify the interval between the sartorius and the tensor fascia latae muscles. This maneuver protects the posterior branches of the lateral femorocutaneous nerve by making a “double fascial pocket” ( Fig. 6.32A ).

    FIGURE 6.32, Mini-open direct anterior approach for osteochondroplasty. A , Development of “double fascial pocket” to protect lateral femoral cutaneous nerve and its posterior branches. B , Inspection and treatment of the internal compartment using a 70-degree arthroscope. C , Appearance of the cam deformity after labral suture. D , After completion of the femoral osteoplasty. SEE TECHNIQUE 6.3.

  • ▪

    Detach the reflected portion of the rectus femoris muscle.

  • ▪

    Place a curved blunt Hohmann retractor over the upper part of the capsule and a straight Hohmann retractor between the iliocapsularis muscle and the capsule with the hip in at least 30 degrees of flexion to avoid damage to the femoral nerve.

  • ▪

    Make a T-shaped capsulotomy from distal to proximal through the interval between the iliofemoral ligaments, taking care to identify the labrum by lifting the capsule as the dissection reaches the acetabulum.

  • ▪

    Place reference sutures in both sides of the capsule and place two blunt curved Hohmann retractors intraarticularly around the femoral neck.

Inspection of the Hip Joint

  • ▪

    Perform the impingement (FADIR) maneuver to observe the area of impingement.

  • ▪

    Apply an extension force for hip distraction. Once the hip is distracted about 10 mm, use an additional light source attached to the Hohmann retractor or a 70-degree arthroscope to inspect the joint for acetabular chondral and labral lesions in the six zones described by Ilizaliturri: zone 1, anterior inferior; zone 2, anterior superior; zone 3, middle superior; zone 4, posterior superior; zone 5, posterior inferior; and zone 6, middle inferior (cotyloid fossa) ( Fig. 6.32B ).

Acetabular Osteoplasty and Labral Repair

  • ▪

    Repair chondrolabral delamination by detachment of the labrum and trimming of the acetabular rim with 5-mm diamond burrs.

  • ▪

    Reattach the labrum with 3.1-mm resorbable transosseous anchors, and release extension of the hip ( Fig. 6.32C ).

Femoral Osteoplasty

  • ▪

    Use fluoroscopy to identify intraoperative landmarks according to preoperative planning.

  • ▪

    For cam-type impingement, excise the bony prominence with ultra-sharp curved osteotome and round burrs manipulated counter-clockwise to avoid excessive bone penetration.

  • ▪

    Start the bump resection at the posterosuperior head-neck junction with hyperextension, adduction, and internal rotation of the hip. Then flex, abduct, and externally rotate the hip to reach the posteroinferior head-neck junction and the acetabular rim ( Fig. 6.32D ). Use pulsed lavage throughout the procedure to prevent heterotopic ossification.

  • ▪

    When bone resection is complete, obtain a final fluoroscopic image and test the femoroacetabular clearance and range of motion, especially flexion and internal rotation.

Closure

  • ▪

    Close the wound in routine fashion. Close the hip capsule with the hip in full extension to avoid capsular overtightening.

  • ▪

    Take care to avoid injury to the branches of the lateral femoral cutaneous nerve during superficial closure.

Postoperative Care

Indomethacin protocol is used to prevent heterotopic ossification. Gastroprotective drugs and low-molecular-weight heparin also are administered.

Periacetabular Osteotomy

Periacetabular osteotomy developed primarily for the treatment of dysplasia also has been used for the treatment of pincer-type impingement caused by global acetabular retroversion ( Fig. 6.33 ) identified radiographically by a crossover sign with a corresponding posterior wall sign on the anteroposterior radiograph of the pelvis. Some of these patients also have deficient lateral coverage with a center edge angle of less than 20 degrees. According to the algorithm described by Peters et al., the articular cartilage of the anterior acetabulum should be judged to be intact by MR arthrogram before proceeding with a PAO because that cartilage is rotated into a more weight-bearing position with correction of the bony deformity.

FIGURE 6.33, A, Preoperative radiograph of patient with both crossover and posterior wall signs indicative of acetabular retroversion with deficient posterior coverage. B, After “reverse” periacetabular osteotomy to increase patient’s acetabular anteversion.

Surgical Technique

The technique of PAO is described in the section on hip dysplasia (Technique 6.4). The direction of rotation of the acetabular segment is individualized for each patient. Care must be taken not to overantevert the acetabular segment because posterior impingement can be created. In combined type deformity, an osteochondroplasty of the femoral head-neck junction can be done through the Smith-Petersen approach used for the PAO.

Results

Siebenrock et al. reported the use of PAO for impingement caused by acetabular retroversion in 29 hips, 24 of which had concurrent reshaping of the femoral head-neck junction. They strove for 30 degrees of internal rotation in 90 degrees of hip flexion. Seventy-one percent had good to excellent results with no evidence of osteoarthritis at an average 11-year follow-up. Predictors for poor outcome were the lack of femoral offset creation and overcorrection of the acetabular version resulting in excessive anteversion. The authors emphasized the intraoperative assessment of acetabular correction with anteroposterior pelvic images and assessment of range of motion. Peters et al. reported an improvement in the average Harris hip score from 72 to 91 in 30 hips at 4-year follow-up after PAO for acetabular retroversion with a positive posterior wall sign.

Hip Arthroscopy

Management of FAI with arthroscopic osteochondroplasty of the femoral head-neck junction and/or acetabular rim trimming with labral debridement or refixation has evolved quickly, with almost all FAI surgery in the United States now performed arthroscopically. Early results of hip arthroscopy reflected primarily labral debridement without correction of underlying bony pathology. Studies by McCarthy et al. and Byrd and Jones demonstrated subsequent conversion to THA in 44.1% and 22.6%, respectively, at 13- and 10-year follow-up. Studies representing more contemporary treatment that includes correction of underlying impingement morphology as well as labral refixation appear to obtain better outcomes . Menge et al., however, in their study of 10-year results of FAI surgery with labral debridement and labral repair, found that 34% of patients underwent THA within 10 years, regardless of the technique of labral treatment. Older patients, patients treated with microfracture, and those with a preoperative joint space of less than 2 mm were most at risk for subsequent THA.

Currently, almost all FAI surgery is being done arthroscopically. More rapid recovery following arthroscopy has been reported by multiple authors, while radiographic and clinical parameters of impingement are treated effectively. Although advanced techniques of arthroscopy have been developed, there do appear to be some general limitations to the arthroscopic technique and situations in which open techniques may be preferable. A cam deformity extending into the posterior-superior head-neck junction, behind the retinacular vessels, is more difficult to access arthroscopically. Similarly, a symptomatic pincer deformity that involves the posterior-superior and posterior wall may be better treated through open surgery. Significant deformity of the proximal femur, including excessive anteversion, coxa valga, or a residual deformity from childhood from slipped capital femoral epiphysis, Perthes disease, or previous open reduction for developmental dysplasia of the hip (DDH) are reasons for possible femoral osteotomy and open assessment with correction.

Care also should be taken with a cam deformity combined with a borderline dysplastic acetabulum because arthroscopic capsulotomy with rim trimming can lead to hip instability. Some authors cite reasonable 2-year outcomes with arthroscopic FAI treatment in patients with borderline dysplasia compared to those with normal LCE angles as long as capsular plication is done. Others state that this deformity is better treated with PAO combined with an open reshaping of the femoral head-neck junction and functional assessment of impingement.

The treatment of FAI with arthroscopic techniques is discussed in Chapter 51 .

Extraarticular Hip Impingement

There is a subgroup of patients who appear to have extraarticular bony impingement. The demographics, physical examination findings, and bony morphologies of these patients were characterized by Ricciardi et al. They tended to be younger women, 40% of whom had previously had a hip procedure for another diagnosis. Factors that increased clinical suspicion of extraarticular FAI included a history of lateral or posterior pain, decreased external rotation, decreased internal rotation with no evidence of a cam lesion, absence of major pelvic or acetabular deformity, a positive posterior impingement sign, incomplete response to intraarticular injection of a local anesthetic or corticosteroid, and continued impingement-type symptoms after arthroscopic treatment without a residual cam lesion.

The types of extraarticular impingement are characterized as anterior, posterior, and complex ( Fig. 6.34 ). In the anterior type, also known as subspinal impingement, the anterior greater trochanter or intertrochanteric line impinges on prominent bone just below the anterior inferior iliac spine or on the AIIS itself. On axial imaging, this type frequently is associated with femoral retrotorsion, defined as less than 5 to 10 degrees of femoral anteversion. On examination, these patients have diminished internal rotation in 90 degrees of hip flexion with increased hip external rotation in both flexion and extension. Failure to recognize subspinal FAI is thought to be a common cause of continued pain following adequate correction of intraarticular FAI. It can be difficult to diagnose significant extraarticular impingement when obvious coexistent intraarticular FAI is present. This underscores the value of examination on the operating table after intraarticular FAI has been corrected to search for restriction of internal rotation in flexion as evidence of extraarticular impingement.

FIGURE 6.34, Classification of extraarticular FAI described by Ricciardi et al. A , Anterior. B , Posterior. C , Complex. (See text).

Similar to cam impingement, subspinal impingement can be iatrogenically created during PAO when the acetabular fragment is rotated forward to create more anterior coverage, bringing the AIIS caudad into an impinging position. This can be demonstrated with intraoperative fluoroscopic examination and allow correction before concluding the operation ( Fig. 6.35 ).

FIGURE 6.35, Iatrogenic subspinal impingement created during periacetabular osteotomy was seen on fluoroscopy, prompting decompression.

Posterior type of extraarticular impingement occurs when the posterior greater trochanter and extraarticular femoral neck impinge against the ischium when the hip is flexed and externally rotated. These hips tend to have excessive femoral anteversion with limited external rotation clinically. Their internal rotation in flexion tends to be increased. If symptoms warrant, these patients can be treated with derotational osteotomy of the femur.

The complex type of extraarticular impingement occurs both anteriorly and posteriorly in femurs with diminished femoral offset and proximal femoral deformity secondary to Perthes disease with an enlarged greater trochanter and femoral head deformity. Rotation tends to be limited in both directions in flexion and limited in external rotation in extension. The surgical treatment of these patients is aimed at relieving the impinging areas by anterior or posterior trochanteric osteoplasty, relative lengthening of the femoral neck, osteochondroplasty of the femoral neck, and treatment of coexisting FAI deformities. Relative femoral neck lengthening ( Fig. 6.36 ) is done during open surgical dislocation with careful mobilization of the retinacular vessels and osteotomy and distalization of the greater trochanter. This correction not only relieves extraarticular impingement but also improves the hip abductor function by increasing the abductor moment arm. It also provides better access to the femoral canal for subsequent THA if later required.

FIGURE 6.36, A, Patient with a short femoral neck and high-riding greater trochanter from Perthes disease. B, After relative femoral neck lengthening.

Ischiofemoral extraarticular impingement in extension has been described in active patients with a diminished distance between the lesser trochanter and the ischium. Pain typically is described in the lower buttock, groin, and medial thigh, with worsening pain during pronounced extension of the hip. MRI may show edema within the quadratus femoris muscle ( Fig. 6.37 ). Small series have reported improvement with open or arthroscopic partial resection or distalization of the lesser trochanter.

FIGURE 6.37, MRI T2 sequence of a patient with ischiofemoral impingement of the left hip. Outlined arrow , quadratus femoris muscle belly edema; solid arrow , sciatic nerve.

Hip Dysplasia

Hip dysplasia in young adults results from residual childhood developmental dysplasia of the hip or, less frequently, Perthes disease ( Fig. 6.38 ). The treatment of these disorders in skeletally immature patients is discussed in Chapter 30 .

FIGURE 6.38, Twenty-year-old male with residual right hip deformity from Legg-Calvé-Perthes disease with an enlarged femoral head and shortened femoral neck. The acetabulum has secondary signs of dysplasia including an increased Tönnis angle and extrusion of the lateral portion of the head and undercoverage.

Radiographically, dysplasia of the hip is characterized by an LCE angle of less than 20 degrees, with hips in the 20- to 25-degree range having borderline dysplasia. Typically, the Tönnis angle is increased above 10 degrees. Dysplastic hips also display a lateralized hip center with a broadened radiographic teardrop. The femoral neck-shaft angle usually is increased, and the proximal femur is usually excessively anteverted. The femoral head may be small and have a flattened lateral contour. Many patients with hip dysplasia display an increased alpha angle and thus have a cam morphology. Studies of patients with symptomatic acetabular dysplasia have found cam morphology in 10% to 40%. Cam morphology may lead to symptomatic FAI after acetabular reorientation. Disruption of the Shenton line is present with superior and lateral positioning of the hip center and with true hip subluxation from the hip center ( Fig. 6.39 ).

FIGURE 6.39, In more severe dysplasia, the Shenton line is disrupted, indicating superior subluxation of the femoral head and hip center.

The natural history of untreated dysplasia has been studied by a number of investigators. Murphy et al. longitudinally observed hips in patients who had undergone total hip replacement for osteoarthritis. They found that the contralateral hips having a LCE angle less than 16 degrees routinely developed significant osteoarthritis by the age of 65. Jessel et al. used dGEMRIC (delayed gadolinium-enhanced magnetic resonance imaging of cartilage) indexing to quantitate the osteoarthritic state in a cohort of dysplastic hips and found that increasing age, severity of dysplasia as defined by both the lateral and ACE angles, and the presence of a labral tear on MRA all correlated with increasing osteoarthritis. Interestingly, a 20-year longitudinal study of women by Thomas et al. found that for each degree of reduction in the LCE angle below 28 degrees there was a 14% increase in the risk of developing secondary osteoarthritis, implying that our definition of dysplasia based on a LCE angle of 20 degrees may be too restrictive. Wyles et al. followed the contralateral hip in patients younger than 55 years of age who had a THA and found at 10-year follow-up that 1 of 33 Tönnis 1 dysplastic hips progressed to THA compared to 1 of 5 Tönnis 1 FAI morphology hips and Tönnis 1 normal morphology hips.

Typically, patients with hip dysplasia become symptomatic between their second and fifth decades of life. Initially, pain may occur only with high-stress activities or prolonged standing. Impingement or FADIR testing may become positive with injury to the labrum. Apprehension testing can be positive with insufficient anterior coverage and anterior cartilage injury.

The radiographic workup of these patients as outlined earlier includes an assessment of the acetabular coverage, depth, version, and lateralization. Sphericity of the femoral head is noted because rotational correction of the acetabulum may worsen congruence of the hip when the femoral head is aspherical. An anteroposterior view with the hip slightly flexed and abducted can be performed to simulate the congruence that would be attained with a PAO ( Fig. 6.40 ). Any evidence of arthritic change is noted and graded by the Tönnis scale. The false profile is evaluated for evidence of subluxation or posterior cartilage wear. Evaluation of the contour of the femoral head-neck junction is important, because rotating the acetabulum with a PAO may create anterior cam impingement requiring femoral osteochondroplasty. An MR arthrogram is performed to evaluate the status of the articular cartilage and labrum . A low-dose CT scan of the pelvis with a few slices through the epicondyles of the knee is useful to determine the pattern of acetabular dysplasia, the version of the acetabulum, and the version of the femoral neck.

FIGURE 6.40, A, Anteroposterior radiograph of dysplastic hip with questionable articular congruence. B, Same hip held in abduction and slight flexion to mimic congruence that would be attained with periacetabular osteotomy.

Periacetabular Osteotomy

PAO was described by Ganz and others in the 1980s as a method of stabilizing symptomatic dysplastic hips in skeletally mature patients and preventing arthritic deterioration. The osteotomy is done through a Smith-Petersen approach ( Chapter 1 ) with reproducible bony cuts and extensive rotational freedom for acetabular repositioning with little risk of osteonecrosis of the acetabular segment ( Fig. 6.41 ). The labrum and anterior femoral head-neck junction can be accessed through the distal end of the Smith-Petersen approach with a capsular arthrotomy. The rotated fragment can be stabilized with screw fixation, and the patient can be mobilized relatively quickly because the posterior column is left in continuity, leaving the ischium attached to the axial skeleton.

FIGURE 6.41, Bernese periacetabular osteotomy. A, Internal view of bony pelvis. B, External view of bony pelvis.

Surgical Indications

PAO is clearly indicated for symptomatic younger patients with spherically congruent dysplasia of the hip, an LCE angle of less than 20 degrees, and minimal or no secondary arthritic changes (Tönnis grade 0 or 1). Symptomatic patients with weight bearing, activity-related pain with center edge angles between 20 and 25 degrees, particularly women with coxa valga and excessive anteversion, may be reasonable surgical candidates. Adolescent patients with hip dysplasia who have fair congruity also may be considered because they tend to fare better than older patients and may be able to delay hip replacement for one to two decades.

Preoperative age older than 35 and fair or poor joint congruence have been reported to be independent factors predictive of failure of PAO; when both factors occurred in a given patient, the chance of resultant severe pain or conversion to total hip replacement reached 95%. Others, however, have found that patients older than 50 years of age had radiographic and clinical 2-year results similar to those in patients younger than 50 years of age. In our practice, PAO can be indicated for patients older than the age of 40 with a spherical femoral head and minimal arthritic change as evaluated on the standard radiographic views and MRA. This decision, however, is always weighed against the option of symptomatic treatment with probable future THA. Pincer-type FAI with global acetabular retroversion is another indication for PAO discussed earlier.

Intertrochanteric osteotomy of the proximal femur occasionally is done as a simultaneous procedure. Varus derotational osteotomy is done to correct excessive valgus and anteversion of the proximal femur, although guidelines for this indication are not uniform ( Fig. 6.42 ). Valgus osteotomy can be done for coxa vara and aspherical Perthes type femoral head deformity to maintain articular congruence and to avoid impingement of the greater trochanter with the rotated acetabular rim ( Fig. 6.43 ). A relative neck lengthening with osteochondroplasty of the femoral neck through an open surgical dislocation in combination with a PAO has been reported to have good short-term benefits in patients with typical Perthes deformity.

FIGURE 6.42, Preoperative (A) and postoperative (B) radiographs of a patient with hip dysplasia associated with high femoral neck-shaft angle treated with periacetabular osteotomy and intertrochanteric varus osteotomy.

FIGURE 6.43, A , After periacetabular osteotomy for dysplasia, a patient with varus deformity of the proximal femur developed impingement symptoms relieved by valgus osteotomy of the proximal femur ( B ).

Surgical Technique

The original technique described by Ganz et al. involved exposure of both inner and outer tables of the ilium through the Smith-Petersen approach with stripping of the abductors to expose the posterior column of the acetabulum on the lateral surface of the pelvis. Murphy and Millis described a modified abductor-sparing variant of the Smith-Petersen approach for PAO, making the osteotomy from the internal surface of the pelvis with minimal lateral stripping. They also described a bikini-type skin incision that follows the inguinal crease medially ( Fig. 6.44 ). Although we use this bikini-type incision in thin females, access to the hip joint for labral repair and femoral osteochondroplasty is better through a standard Smith-Petersen incision, and we prefer to use it in most patients. We currently use an abductor-sparing approach as described by Matheney et al. However, in patients with no cam deformity of the proximal femur, no labral tear or articular defect on MRA, and no mechanical symptoms suggestive of labral pathology, we use a rectus-sparing approach as described by Novais et al. With this approach, an anterior arthrotomy of hip is not made, and the direct and indirect heads of the rectus femoris are not detached from the anterior-inferior iliac spine and acetabular rim. This is done in an attempt to minimize postoperative pain and possibly improve postoperative hip flexion strength.

FIGURE 6.44, Smith-Peters e n incision is preferred for most patients, with occasional use of more cosmetic bikini incision in thin patients. ASIS , Anterior superior iliac spine.

Bernese Periacetabular Osteotomy

Technique 6.4

(Matheney et al.)

  • ▪

    With the patient supine, prepare and drape the involved extremity free to the costal margin, medially to the umbilicus, and posteriorly to the posterior third of the ilium.

Superficial Dissection

  • ▪

    Make a direct anterior longitudinal Smith-Petersen incision or an anterior bikini-type incision just below the iliac crest extending a few centimeters medial to the anterior superior iliac spine ( Chapter 1 ).

  • ▪

    Identify the fascia over the external oblique and gluteus medius and incise it posterior to the anterior superior iliac spine.

  • ▪

    Develop the plane between the two muscles to expose the periosteum over the iliac crest. Divide this periosteum and subperiosteally dissect the inner table of the ilium.

  • ▪

    Enter the compartment of the tensor fasciae latae and bluntly dissect the muscle off the septum with the sartorius muscle; this is done to protect the lateral femoral cutaneous nerve.

  • ▪

    Identify the floor of this compartment and follow it proximally until the anterior aspect of the ilium is palpated.

  • ▪

    Predrill the anterosuperior iliac spine with a 2.5-mm drill and osteotomize the anterior portion (1 × 1 × 1 cm) to make dissection and later repair easier.

  • ▪

    Alternatively, detach the sartorius with a thin wafer of bone that will be repaired with suture at the end of the procedure.

  • ▪

    Continue subperiosteal dissection to the anteroinferior iliac spine.

Deep Dissection

  • ▪

    Flex and adduct the hip to take tension off the anterior musculature.

  • ▪

    Divide the reflected head of the rectus femoris at its junction with the direct head.

  • ▪

    Elevate the direct head of the rectus femoris and the underlying capsular portion of the iliacus as a unit and reflect them distally and medially from the underlying joint capsule.

  • ▪

    Reflect the iliacus, sartorius, and abdominal contents medially.

  • ▪

    Open the sheath of the psoas and retract its muscle and tendon medially. Alternatively, retract the psoas by subperiosteal release of its sheath from the pubic ramus and separate the sheath from the capsule. This allows exposure of the anterior portion of the superior pubic ramus medial to the iliopectineal eminence, an important landmark denoting the most medial extent of the osseous acetabulum.

  • ▪

    Create an interval between the medial joint capsule and the iliopsoas tendon and sequentially dilate with the tip of a long Mayo scissor and/or Lane retractor.

  • ▪

    Use the tips of the scissors and Lane retractors to palpate the anterior portion of the ischium at the infracotyloid groove; confirm proper placement of these instruments with fluoroscopy. The goal is to place them superior to the obturator externus tendon. If the joint capsule is accidentally entered, a second pass can be made by entering the floor of the psoas tendon sheath to develop a second, extraarticular path to reach the anterior portion of the ischium.

Osteotomy of the Anterior Portion of the Ischium

  • ▪

    Place the hip in 45 degrees of flexion and slight adduction.

  • ▪

    Insert a 30-degree forked, angled bone chisel (15- or 20-mm blade width) ( Fig. 6.45A ) through the previously created interval between the medial capsule and the psoas tendon to place its tip in contact with the superior portion of the infracotyloid groove of the anterior portion of the ischium, just superior to the obturator externus tendon. Staying proximal to the obturator externus helps prevent injury to the nearby medial femoral circumflex artery.

    FIGURE 6.45, A, 30-degree Ganz osteotome. B, Ischial osteotomy is performed through interval between psoas tendon and hip capsule with 30-degree osteotome. C, Osteotomy of pubis is performed just medial to iliopectineal eminence and radiographic teardrop. D, Initial iliac osteotomy is made with oscillating saw aiming toward top of sciatic notch. E, Posterior column osteotomy proceeds from tip of iliac osteotomy through pelvic brim then through medial cortex of quadrilateral plate. F, 30-degree Ganz osteotome is used carefully to complete posterior column osteotomy from medial to lateral under fluoroscopic control and to connect posterior column osteotomy to ischial osteotomy. G, Fixation of osteotomy can be solely through screws through iliac wing into rotated fragment or include a “home run” screw that goes from anteroinferior iliac spine directed into sciatic buttress. SEE TECHNIQUE 6.4.

  • ▪

    Gently palpate the medial and lateral aspects of the ischium with the chisel, confirming the position of the chisel with fluoroscopy in both the anteroposterior and iliac oblique projections. The chisel should be positioned approximately 1 cm below the inferior lip of the acetabulum with its tip aimed at the ischial spine or a point slightly above the ischial spine ( Fig. 6.45B ).

  • ▪

    Impact the chisel to a depth of 15 to 20 mm through both medial and lateral cortices of the ischium. Take care not to drive the chisel too deeply through the lateral cortex because of the proximity of the sciatic nerve, especially with the hip flexed and adducted.

Osteotomy of thse Superior Public Ramus

  • ▪

    With the hip still flexed and adducted, gently retract the psoas tendon and medial structures medially. Retraction can be aided by impacting either the tip of a spiked Hohmann retractor or a large-gauge Kirschner wire into the superior pubic ramus just beyond the most medial extent of the dissection.

  • ▪

    Incise the periosteum over the superior pubic ramus along its axis and perform careful circumferential subperiosteal dissection. This can be aided by making a transverse periosteal incision 1 to 2 cm medial to the iliopectineal eminence and working to continue the previous subperiosteal dissection of the inner iliac table into the lateral obturator foramen.

  • ▪

    Place Hohmann retractors, Rang retractors, or Lane bone retractors anteriorly and posteriorly around the superior pubic ramus into the obturator foramen to protect the obturator nerve and artery. Watch for spontaneous adduction of the limb, which is indicative of stretching or irritation of the obturator nerve.

  • ▪

    Osteotomize the superior pubic ramus perpendicular to its long axis when viewed from above and oblique from proximolateral to distomedial when viewed from the front. The osteotomy can be made by using a Satinsky vascular clamp to pass a Gigli saw around the ramus and sawing upward, away from the retractors, or by impacting a straight osteotome just medial to the iliopectineal eminence. The key to this osteotomy is to stay medial to the iliopectineal eminence to avoid creating an intraarticular osteotomy ( Fig. 6.45C ).

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