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Arthrodesis of the Hip
Arthrodesis of the hip is an infrequently performed procedure with few indications. Advances in total hip arthroplasty, which have greatly improved functional scores and patient satisfaction, have made hip fusion a much less desirable option for most patients. Good intermediate outcomes have been reported after total hip arthroplasty in patients as young as adolescence. Nevertheless, a number of recent literature reviews agree that hip arthrodesis still has a role in the treatment of carefully selected patients. In the past, a good candidate for hip fusion was a young, healthy laborer with a stiff and painful arthritic hip. In developing countries, where resources are limited or unavailable, fusion still represents a major treatment option for patients with painful hip arthritis. Internal fixation to achieve hip fusion was introduced by Watson-Jones and others in the 1930s and improved by Charnley; however, these early methods of internal fixation were associated with high rates of incomplete union and prolonged external immobilization. To gain more stability of the arthrodesis, Müller described a double compression plating technique that did not require postoperative casting. Schneider later developed a cobra-head plate that also does not require postoperative immobilization. Other internal fixation modalities, such as hip compression screws or cancellous screws alone, have been described for certain situations and can be useful alternatives as the clinical situation and available resources dictate.
Indications and Results
Arthrodesis of the hip still may be considered an alternative in patients younger than 40 years of age with severe, usually posttraumatic, arthritis and normal function of the lumbar spine, contralateral hip, and ipsilateral knee. Fusion could also be considered as primary treatment for severe trauma of the acetabulum or femoral head in select patients. Hip arthrodesis has been shown to be successful in treating painful spastic subluxed or dislocated hips in ambulatory adolescents with cerebral palsy. Before arthrodesis is considered, nonoperative treatment of arthritis, such as the use of walking aids and antiinflammatory medication, should be tried, as should less invasive and potentially less debilitating operative procedures. Hip arthrodesis can provide a functional and durable alternative to total hip replacement in properly selected younger patients. This has been confirmed by several reviews, including those by Stover et al. and Schafroth et al. Both noted that a properly performed arthrodesis can lead to years of pain relief and reasonable function.
An absolute contraindication to arthrodesis is active sepsis of the hip; the infection should be eradicated and inactive for 3 to 6 months before arthrodesis is undertaken. Relative contraindications include severe degenerative changes in the lumbosacral spine, contralateral hip, or ipsilateral knee. Poor bone stock from osteoporosis or iatrogenic causes, such as proximal femoral resection for tumor, also is associated with lower success rates and increased disability.
Good or excellent functional results have been reported with hip arthrodesis, but low back pain, limited ambulation, and sexual dysfunction have been noted. The importance of careful patient selection cannot be overemphasized. Hip fusion increases stress in the lumbar spine, contralateral hip, and ipsilateral knee and requires greater energy expenditure for ambulation; hip fusion probably should be done only in young, otherwise healthy patients. Properly selected patients generally are satisfied with the results of hip fusion; several long-term follow-up studies have documented patient satisfaction of approximately 70% at 30 years, despite evidence of degenerative changes in the lumbar spine and adjacent joints of the lower extremities.
Degenerative changes in nearby joints typically begin to become symptomatic in 15 to 25 years after arthrodesis. A review of such patients confirmed that the average time from fusion to onset of back and joint pain was 24 years. Pain most commonly affected the back (75%), then the ipsilateral knee (54%), with fewer complaining about the contralateral knee or hip. It appears such pain symptoms are ultimately quite common but usually quite delayed in onset, especially with an optimally positioned fusion. Although ipsilateral knee pain and contralateral hip pain occur less frequently than back pain, they more often require operative intervention, such as total knee or hip arthroplasty.
Late onset of pain in patients previously asymptomatic for many years after hip arthrodesis has been reported by Wong et al. The pain in their two patients was found to be caused by implant protrusion and was resolved by implant removal.
Other less common complications can occur after hip fusion. Proximal femoral fractures, perhaps made more likely by the increased stresses in the vicinity of an immobile joint, have been reported as long as 53 years after arthrodesis. Wong et al. reported femoral shaft fractures, distal to plate hardware, treated successfully by retrograde nailing.
Techniques
Successful arthrodesis of the hip can be achieved through a variety of methods. All techniques require removal of articular cartilage for preparation of the fusion site. Acetabular reamers and hip resurfacing (reverse) reamers have been shown to be helpful in the preparation of the acetabulum and femoral head. General principles of fracture fixation, such as rigid fixation and optimal biologic environment, are applicable. Regardless of the technique selected, the ideal fusion position is 20 to 30 degrees of flexion, 0 to 5 degrees of adduction, and 0 to 15 degrees of external rotation.
Arthrodesis With Cancellous Screw Fixation
Benaroch et al. described a simple method of hip arthro-desis for adolescent patients. Fusion was obtained in 11 of 13 patients (average age 15.6 years); two had mildly symptomatic nonunions. At an average 6.6-year follow-up, nine patients had no pain or slight pain, three had mild pain, and one had marked pain. According to a modified Harris hip scoring system, functional results were excellent in five patients, good in two, fair in five, and poor in one. The investigators noted a progressive drift into adduction averaging 7 degrees, most of which occurred within 2 years of surgery; because of this, they recommended fusion with the hip in 20 to 25 degrees of flexion and neutral or 1 to 2 degrees of abduction.
Technique 5.1
(BENAROCH ET AL.)
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With the patient in the lateral position, make an anterolateral approach and perform an anterior capsulotomy.
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Dislocate the femoral head and denude both sides of the joint of the articular cartilage and necrotic bone.
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Place the leg in the desired position, and insert one or two cancellous screws through the femoral head into the inner surface of the ilium.
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Before tightening the screws to compress the femoral head into the acetabulum, perform an intertrochanteric osteotomy to decompress the long lever arm of the femur.
Postoperative Care
A spica cast is worn for 8 to 12 weeks.
Arthrodesis With Anterior Fixation
Anterior plating through a modified Smith-Petersen approach is useful when there is loss of acetabular or proximal femoral bone stock. The plate is placed along the pelvic brim immediately lateral to the sacroiliac joint and posterior-superior iliac spine ( Fig. 5.1A ). A lag screw inserted from the trochanteric area through the center of the femoral head into the supra-acetabular bone provides additional compression because of a lateral tension-band effect ( Fig. 5.1B ). Matta et al. reported successful fusion in 10 of 12 patients with anterior plating.
Technique 5.2
(MATTA ET AL.)
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With the patient supine on a fracture table, expose the hip through a combined ilioinguinal/Smith-Peterson approach (Technique 1.64).
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Proximally expose the inner table of the ilium to the sacroiliac joint using the lateral window of the ilioinguinal approach.
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Distally expose the anterior hip capsule between the tensor fascia lata and the rectus femoris as per the Smith-Peterson approach.
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Expose the proximal femur by retracting the vastus lateralis medially.
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Excise the anterior hip capsule and dislocate the hip with traction and external rotation of the femur; a Steinmann pin in the proximal femur can assist with this maneuver.
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Denude the hip of articular cartilage.
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Relocate the hip and, using the fracture table, place the leg in the desired position of fusion.
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Through a percutaneous incision, place a 6.5- to 7.4-mm lag screw through the greater trochanter and femoral neck into the iliac bone superior to the acetabular dome.
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Contour a 12- to 14-hole, wide, 4.5-mm dynamic compression plate over the internal ilium, pelvic brim, femoral neck, and proximal femoral shaft. Place the proximal part of the plate just lateral to the sacroiliac joint ( Fig. 5.1 ).
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Secure the plate to the pelvis first. Use a tensioning device distally on the femur, and fill the distal screw holes.
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Pack bone graft from reaming or from the iliac crest over the fusion site as needed.
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Irrigate and close the wound in layers.
No postoperative immobilization is required; weight bearing is protected for 10 to 12 weeks.
Arthrodesis With Double-Plate Fixation
Double-plating may be useful in difficult situations such as an unreduced hip dislocation, avascularity of bony surfaces, multiply operated hips, and poor patient compliance. A significant (more than 4 cm) limb-length discrepancy may require correction before the fusion. Six to 8 weeks after intertrochanteric osteotomy, a broad lateral plate is contoured over the trochanteric bed and placed anterior to the greater sciatic notch and along the lateral aspect of the femur. After removal of the anterior inferior iliac spine, a narrow anterior plate is applied along the femoral shaft ( Fig. 5.2 ).
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