Hip Arthritis in the Athlete

History

Hip arthritis in the young and active patient can often be a challenging entity with regard to selecting appropriate treatment options. Making an accurate diagnosis is the first step in providing suitable treatment options for the patient. Burnett et al. reported that a mean of 3.3 providers were seen prior to a definitive diagnosis being made. This process can often lead to frustration. A structured history and physical exam can simplify the treating provider's approach to this sometimes complex problem.

Initial patient history should include a detailed description of the patient's current symptoms, including their time of onset, duration, and any inciting trauma or injury. Patients with arthritis often describe a gradual onset of pain, though some may remain asymptomatic until the later stages of disease and experience onset of pain after a particular injury or activity. Aggravating factors such as specific activities or positions should be noted, as should alleviating factors including any already attempted treatments. Patients typically report worsened pain with increased activity such as walking, standing, running, or playing a sport, and improved pain with rest. Sitting with the hip flexed, such as during an extended car or plane ride, or entering or exiting a low vehicle may also aggravate symptoms. The pain often worsens as the day progresses, and can persist as an aching pain at night. The physician's initial task should be to determine whether the patient's pain is indeed intra-articular in origin, as opposed to extra-articular. The location of pain is quite useful in beginning this differentiation. Intra-articular hip pain is often localized to the deep anterior groin. Patients often use the “C” sign when describing the location of their symptoms. Though intra-articular pathologies can sometimes present as posterior hip pain, this is much less common. Posterior pain is worthy of considering musculotendinous strains, deep gluteal space syndrome, sacroiliac joint pathology, or lumbar spine pathology. Pain localized to the lateral hip is often the result of greater trochanteric pain syndrome (GTPS). The term GTPS was coined as a less specific but often more precise description for the etiology of lateral hip pain. It encompasses trochanteric bursitis, gluteus medius and minimus tendinopathy or tearing, and snapping iliotibial band or iliotibial band friction syndrome. Anterior hip pain may also represent musculotendinous injuries, including to the hip flexor musculature, core muscle injuries (including injury to the rectus abdominis insertion and adductor longus origin), or pubic symphysis pathology such as osteitis pubis. In the athlete, consideration should also be given to pelvic or proximal femoral stress fractures.

Patients with hip arthritis often report associated stiffness. Substantial limitations in motion may be a sign of later stages of arthritis. Mechanical symptoms such as catching, clicking, or locking may be experienced, and may represent the presence of loose bodies or chondral injuries, or alternatively snapping of musculotendinous structures.

Physical Exam

Examination begins with evaluation of the patient's gait. An antalgic gait is noted in patients with various hip pathologies, including intra-articular issues such as hip arthritis. The antalgic gait is hallmarked by a decrease in the duration of the stance phase of the ipsilateral hip. This effectively decreases the amount of time the patient is applying his weight through the affected hip. Another common gait abnormality is the Trendelenburg gait. This is seen in patients with abductor injuries, including those to the gluteus medius and gluteus minimus tendons. During the stance phase of the affected hip, the contralateral hemipelvis is noted to drop. A compensatory thoracolumbar lurch is noted toward the affected hip to maintain coronal balance. In patients with hip arthritis, a decreased stride length may also be noted secondary to diminished range of motion (ROM) of the hip. Gait parameters have been shown to correlate highly with radiographic femoroacetabular impingement (FAI) morphology as well. General observation of the patient may also offer some insight into the underlying cause of pain. The overweight or obese patient may understandably be predisposed to earlier arthritis in the hip due to increases in joint reactive forces, and this factor should be included in the overall assessment and treatment of the patient. The patient's sitting posture often reveals avoidance of deep hip flexion both in cases of nonarthritic intra-articular pain such as femoroacetabular impingement, or cases of hip arthritis.

Examination of the hip then begins with assessment of any skin lesions such as contusions or scars from previous surgical procedures. The log roll test is performed with the patient in the supine position. This simple maneuver consists of rolling the limb gently back and forth between internal and external rotation, avoiding drastic end range motions. This maneuver avoids stressing the musculotendinous structures that surround the hip, instead simply rotating the femoral head within the acetabulum. The test is not very sensitive, though it is specific for pain from intra-articular pathologies. Basic ROM measurements should then be performed. A standardized approach to this is important and leads to reproducible more measurements. Measurements can be performed in the supine position. Flexion, extension, internal rotation, and external rotation are noted. Internal and external rotation measurements are typically made with the hip flexed 90 degrees. It is important to ensure that the patient's lumbar spine remains flat on the table, and that the pelvis is not rotating throughout this testing, as this can alter measurements obtained. Comparing ROM measurements to the contralateral side is valuable, as each patient has a unique normal baseline ROM. Patients with intra-articular pathology may show globally decreased ROM. Patients with femoroacetabular impingement tend to have decreased internal rotation. More specifically, individuals with cam morphology of the femoral head-neck junction have more limited ROM than those without cam morphology.

Palpation of bony landmarks and soft tissue structures about the hip and pelvis is a simple and useful part of the physical exam to help identify extra-articular sources of pain. A structured approach to this is simple and efficient and plays an important role in guiding treatment. Although both the patient and treating physician's focus often is directed at underlying joint disorders, including arthritis, identification, and improvement of associated soft tissue symptoms can be useful. The adductor longus origin is palpated in the groin with the patient in the supine position with the hip flexed to approximately 45 degrees, and externally rotated. Asking the patient to adduct the thigh against resist, thus contracting the adductor musculature, can increase the sensitivity of this test. Pain may be indicative of adductor longus tendinopathy, or sometimes adductor tendon partial or complete tearing. The pubic symphysis and pubic rami may also be palpated, and specific tenderness here may indicate osteitis pubis. With the patient still in the supine position, the rectus abdominis near its insertion at the superior pubic rami is palpated while the patient is asked to perform a resisted sit up. Tenderness elicited here may represent a core muscle injury. In the setting of hip arthritis, with limited motion of the joint, increased strain may be placed on the rectus abdominis–adductor aponeurosis as the patients unknowingly compensate for limited joint motion with increased lumbopelvic and abdominal rotation. The proximal anterior thigh hip is palpated to screen for hip flexor strains. The patient is then asked to move to lateral decubitus position. The greater trochanter is palpated. Tenderness here is common and may represent isolated peritrochanteric symptoms or secondary symptoms often seen with intra-articular disorders. The patient's sacroiliac joint and lumbar spine is then palpated. If posterior pain is reported, palpation of the ischial tuberosity and hamstring origin can help narrow the differential diagnosis. Posterior hip pain presents a diagnostic dilemma, though more recent descriptions of deep gluteal syndrome, a nondiscogenic, extrapelvic entrapment of the sciatic nerve, has offered some guidance to the assessment of this group of patients.

Strength testing is then performed. While in the supine position, hip flexion and adduction strength is tested. In the lateral decubitus position with the knee slightly flexed to relax the iliotibial band, abduction strength is tested. Muscle strength is graded using the traditional five-point scale. Patients with chronic hip joint pain have been reported to have reduced hip muscle strength in all muscle groups or the ipsilateral hip and to a lesser degree the contralateral hip.

Multiple special tests exist that are helpful in identifying the etiology of pain about the hip. The “Impingement Test,” performed by placing the hip in flexion, adduction, and internal rotation (FADIR), has been used to screen for femoroacetabular impingement. The motion brings the anterosuperior femoral-head junction in close proximity to the anterosuperior acetabular rim. In patients with pincer and/or cam morphology, or those with anterosuperior labral pathology, conflict between the acetabulum and femoral head-neck causes pain. The maneuver is not specific and may cause with a number of intra-articular hip pathologies, including hip arthritis. The contralateral side should also be examined, as an aggressive maneuver may cause some degree of discomfort in even a normal, asymptomatic hip. The FABER (flexion, abduction, external rotation) maneuver is the performed. The ipsilateral ankle may be rested on the contralateral knee while in the supine position, and gentle downward pressure applied to the ipsilateral knee. The maneuver may elicit symptoms in various regions, including the ipsilateral hip joint, ipsilateral posterolateral hip soft tissues, and the contralateral sacroiliac joint. Ipsilateral hip joint pathology typically causes deep anterior pain with this maneuver. It is important to note location of pain, as opposed to simply its presence. The posterior impingement test is performed by abducting, extending, and externally rotating the hip. Unlike the FADIR maneuver, it brings the posterolateral femoral head-neck junction in conflict with the posterior acetabular rim, potentially causing pain. It may also cause pain in a hip with limited ROM, or one with adhesive capsulitis. Patients with arthritis often have globally diminished ROM, and this maneuver may be painful.

The Stinchfield test, a resisted straight leg raise performed at approximately 30 degrees of hip flexion with the patient supine, may cause deep anterior hip pain in patients with intra-articular pathology. However, this is not a specific test, as those with hip flexor strains or other musculotendinous injury will likely also have pain with it.

In summary, physical examination of the hip with arthritis can be expected to show globally diminished ROM; the patient may commonly have sites of tenderness to the extra-articular musculotendinous structures of the hip and pelvis; the log roll, FADIR, FABER, Stinchfield, and posterior impingement tests may elicit pain. The patient may present with an antalgic gait pattern.

Imaging

Imaging of the hip begins with plain radiographs. In cases where the clinical presentation and plain radiographs fit the diagnosis of arthritis, further imaging beyond plain radiographs is often unnecessary. Pain radiographs of the hip should begin with a well centered anteroposterior (AP) view of the pelvis. This is most commonly obtained in the supine position, but may also be obtained in the standing position to provide information about the patient's functional sagittal pelvic tilt. The coccyx and pubic symphysis should be in line, with the caudal tip of the coccyx between 2 and 3 cm from the pubic symphysis. The obturator foramen should be symmetric bilaterally ( Fig. 88.1 ). Variations in pelvic tilt, thus providing oblique views with characteristics of the inlet or outlet view, have been shown to skew interpretations of acetabular version. When the pelvis is tilted anteriorly, the acetabulum may appear falsely retroverted, and when the pelvis is tilted posteriorly, the acetabular may appear falsely anteverted. Rotation of the pelvis can similarly skew measurements of acetabular version as well as acetabular depth. On the anterosuperior measurement, general observation of any joint space narrowing should be assessed. The joint space should be measured, as the severity of joint narrowing has been inversely correlated with success after treatment with hip arthroscopy. Joint space of less than 2 mm has been reported as a lower limit, below which arthroscopy should be avoided for treatment. Measurements are routinely made in three locations: superomedially, superiorly, and superolaterally. The presence of subchondral sclerosis of the acetabulum or femoral head should be noted, as should the presence of osteophytes. Subchondral cyst formation in the acetabulum or femoral head, when visible on plain radiographs, typically indicates more advanced degenerative changes. Fig. 88.2 demonstrates a hip with these advanced arthritic findings. Degenerative changes are often classified using the Tönnis grading system ( Table 88.1 ). The Lateral Center Edge Angle of Wiberg is then measured ( Fig. 88.3 ). This provides a measurement of lateral acetabular coverage of the femoral head. A best fit circle of the femoral head is drawn, and an angle from its center with one limb directed superiorly and the other to the lateral margin of the acetabulum is drawn. Conventionally, acetabular dysplasia has been diagnosed when the lateral center edge angle is less than 25 degrees. More recently, a subcategory of “borderline” dysplasia has been described in patients with LCE measurements of 18 to 25 degrees. Acetabular dysplasia has important implications for treatment of hip pain, as patients with true dysplasia are typically not good candidates for hip arthroscopy, and may indeed require pelvic osteotomies to correct their underlying bony acetabular deficiency if substantial arthritis is not present.

The presence of an acetabular crossover sign is evaluated on the AP plain radiograph. The crossover sign is present when the anterior acetabular wall and posterior acetabular wall cross prior to their convergence at the lateral acetabular sourcil. This indicates some degree of retroversion of the acetabulum, sometimes a contributing factor in femoroacetabular impingement. The further distal/medial the point of crossover, the more substantial the retroversion. The crossover sign can be quantified as a ratio of the distance between the lateral margin of acetabular sourcil and the crossover point to the diameter of the acetabulum altogether. The posterior wall sign is present when a point marked at the center of the femoral head lies lateral to the posterior wall of the acetabulum on the AP radiograph, and may indicate undercoverage of the posterior acetabulum, which can exist as part of a retroverted acetabulum or in the setting of global acetabular undercoverage.

Various lateral views of the hip exist. Commonly used examples include the frog-leg lateral, the cross-table lateral, and the Dunn 45-degree or Dunn 90-degree views. Each view may offer a slightly different angle and view of the femoral head-neck junction. The frog-leg lateral is a technically simple and easily reproducible. In many hip arthroscopy and preservation clinics, the Dunn 45-degree lateral view is utilized, given that it has been shown to be most sensitive for the presence of CAM morphology. Regardless of which view is utilized, the presence or absence of CAM morphology should be noted, and when present it should be quantified. The CAM morphology can be quantified using the alpha angle. The alpha angle was classically described using axial magnetic resonance imaging (MRI) cuts, but can be extrapolated to lateral radiographic views. This is measured by first drawing a best fit circle on the femoral head. At the center of this circle, an angle with one limb directed parallel to the femoral neck and the other directed to the point where the femoral head-neck exits the best fit circle ( Fig. 88.4 ). Gosvig et al. classified alpha angle measurements as pathologic (>57 degrees), borderline (51 to 56 degrees), subtle (46 to 50 degrees), very subtle (43 to 45 degrees), or normal (≤42 degrees). Commonly alpha angle values greater than 50 degrees are generally regarded as abnormal, and represent CAM morphology. Another available method of quantifying CAM morphology is the femoral offset. Again using the center of the femoral head on the lateral view, a line is drawn in the axis of the femoral neck. Two other parallel lines are drawn—one at the femoral neck and the other at the anterior-most border of the femoral head. A decreased offset is seen in patients with cam morphology. As an alternative to reporting the true offset, the offset ratio may be obtained by dividing the offset by the diameter of the femoral head, and may offer a more standardized value.

MRI is commonly used to aid in the evaluation of the athlete with hip pain. It can be obtained with or without intra-articular contrast (arthrogram). Magnetic resonance arthrogram (MRA) has excellent sensitivity in identifying labral tears at the chondrolabral transition zone. Debate exists on the necessity of arthrogram for assessment of chondrolabral structures of the hip. Improvements in MRI technology and the use of 3.0 T scanner have led to many hip preservation surgeons avoiding the routine use of the arthrogram. 3.0 T nonarthrogram MRI has shown excellent sensitivity and specificity in identifying arthroscopically proven labral tears. In addition to assessment of the labrum, MRI is a sensitive imaging modality able to identify early degenerative changes, including subchondral edema and subchondral cyst formation. Acetabular and femoral head chondral irregularities, thinning, or delamination can be evaluated. The clinical relevance of this often depends on the degree of arthritis. One must take care to avoid focusing on the presence or absence of labral pathology. Subchondral edema may indicate early stages of degenerative disease, and may be masked by the stark contrast created by intra-articular contrast, thus offering an additional reason to consider nonarthrogram studies. In a study of 208 hip patients over 50 years of age, MR arthrogram identified some degree of labral pathology in 93% of patients and true labral tearing in 73% of patients (with no statistical correlation between labral tearing and presence/degree of arthritis). Patients with diagnosed labral tears may be quite determined that repair of this structure will rid them of their symptoms. Treatment of a torn acetabular labrum in the arthritic hip is unlikely to provide substantial mid to long-term improvement, and should be avoided. The ligamentum teres is also visualized, with surrounding synovium in the cotyloid fossa. Damage to the ligamentum teres or synovitis in the cotyloid fossa and diffusely throughout the joint may be seen. Loose osteochondral bodies may also be present in the setting of arthritis, and may be responsible for some mechanical symptoms.

Evaluation of the periarticular soft tissues may also yield important information about other extra-articular sources of pain. Correlation to the physical examination is important, as sites of musculotendinous edema, or even low grade partial thickness tearing, may not always be clinically relevant, and are commonly noted around the degenerative joint. Pathology of the gluteus medius or gluteus minimus tendons at the respective insertions at the greater trochanter should be evaluated, along with adjacent greater trochanteric bursitis. Tears of these abductor tendons are clinically significant when the patient's pain can be localized to the lateral hip at the greater trochanter, and in these cases should be treated. Peritrochanteric pathology and intra-articular pathology may be compensatory to each other; thus thoughtful assessment and treatment of the underlying cause of pain as well as associated symptoms may yield the best results. Femoral neck and acetabular stress fractures should be ruled out on MRI, and are especially common among longer distance runners and other impact activities. These may not be visible on plain radiographs but easily noted on MRI. They may be present concurrently in a runner with arthritis, but may cause acute chronic pain in the athlete with known arthritis of the hip.

Computed tomography (CT) is not usually necessary for diagnostic purposes around the hip in the setting of FAI or osteoarthritis. It does have a role for preoperative planning in patients who have an established diagnosis and are indicated for surgery. Two-dimensional radiographs also do have some limitations, and the use of the measurements such as lateral center edge angle and anterior center edge angle may not tell the whole story as it relates to acetabular coverage. Similarly, femoral head-neck convexities and irregularities exist in variations that two-dimensional radiographs do not fully represent. Three-dimensional reconstruction of CT imaging is now possible, providing easily manipulated imaged that morphology aberrances such as CAM or pincer morphology, thus guiding surgical treatment. Various commercially available software options exist that allow motion assessments of the hip, indicating areas of bony conflict between the acetabulum and femoral head in FAI.

Decision-Making Principles

In keeping with the typical goals of treating the active patient, the treatment of athletic patients with hip arthritis aims at minimizing pain or discomfort while keeping the patient active. Unlike many other conditions diagnosed and treated by sports medicine specialists, arthritis carries certain weight and implications for the patient. Many patients view it as an end to their ability to either compete in their sport or enjoy it recreationally. In general, regardless of the severity of arthritis on imaging, treatments should be begin with noninvasive to minimally invasive measures, directed at reducing pain and limiting the progression of degenerative changes.

Treatment Options