Approach Considerations
Surgery is the mainstay of treatment for osteonecrosis. Obvious disorders aside (eg, severe systemic disease, systemic sepsis), these patients often are young and have few surgical contraindications. Numerous procedures are available, indicating that no single procedure is distinctly advantageous.
Nonsurgical treatment of osteonecrosis is limited. Observation and protected weight bearing are options. Certain cases of early-stage disease (eg, Ficat stage 1) can be treated successfully with this option. However, most studies indicate that the risk of disease progression is greater with nonsurgical treatment than with surgical intervention.
Cell-based therapies for the treatment of osteonecrosis of the femoral head have been reported to be safe and suggest improved clinical outcomes with lower disease progression rate, particularly when employed at early disease stages. [22, 23, 24, 25, 26, 27, 28] However, there has been substantial heterogeneity in the cell-based therapies used and studies vary widely with respect to cell sourcing, cell characterization, adjuvant therapies, and assessment of outcomes. Specific clinical indications and cell-therapy standardization have not yet been determined. [29]
Medical Care
Nonsteroidal anti-inflammatory drugs (NSAIDs) can be used to reduce pain and inflammation in patients who cannot have surgery for medical or other reasons or for patients who are undergoing surgical treatment. Physical therapy can be helpful to restore motion and improve gait. Electrical stimulation has been used in several centers. In some studies, it has been helpful in treatment prior to femoral head collapse.
Pharmacotherapy that addresses the pathophysiology of the disease has had mixed results. Examples include gemfibrozil (Lopid) for hyperlipidemias and nifedipine for vascular disorders. Alendronate has been suggested as an option to avoid or delay progression of the disease clinically and radiographically. However, one randomized study showed no significant difference in radiographic and MRI data between the alendronate and control groups. [30] Short-term follow-up (about 24 months) of patients in alendronate studies have demonstrated delayed femoral head collapse. [31]
Extracorporeal shockwave treatment has shown some promise in treating early disease by promoting angiogenesis and bone remodeling. [32, 33]
Surgical Care
The choice of procedure is based on preoperative staging. Core decompression and cancellous and cortical bone grafting procedures usually are indicated in Ficat stage IIa or earlier stages. The trapdoor procedure and allograft procedures are indicated for stage IIb or stage III lesions. Osteotomies are used for stage II and stage III disease. Arthrodesis and arthroplasty are utilized primarily for stages III and IV but occasionally are used for stages I and II. Limited femoral resurfacing for young patients with intact acetabular cartilage and a collapsed femoral head is a valuable alternative to total hip replacement.
The growth factors Op-1 (osteogenic protein-1) and rhBMP-2 (recombinant human bone morphogenetic protein-2) may be useful bone grafting adjuncts. [34] Platelet-rich plasma therapy is also used as an adjunctive treatment. [35, 36]
Core decompression and bone grafting
The objective in core decompression is to stimulate revascularization and decrease pressure within the femoral head. The patient is placed supine on a fracture table. Using image intensification through a lateral incision above the trochanteric ridge, a 10-mm core of bone is removed from the femoral necrotic lesion. Other techniques include multiple drilling into the lesion
For cancellous bone grafting, the defect is filled with cancellous bone graft material, usually iliac crest or allograft. Cancellous iliac crest graft is placed in a channel in the infracted region and covered by a graft with the quadratus femoris muscle attached. Following surgery, non-weightbearing ambulation for 6-12 weeks, then gradual resumption of normal activities as tolerated.
With cortical bone grafting, a strut graft is placed in the defect under the weightbearing surface of the femoral head. Iliac crest or fibula has been used. Strut grafting with a tantalum implant, a highly porous metallic cylinder placed in a channel to support subchondral bone, is also an option. [37, 38] Following surgery, no weight bearing for 6 weeks, with progressive weight bearing to 6 months. Recent retrieval studies have shown little bone ingrowth, insufficient mechanical support of subchondral bone, and a significant rate of femoral head collapse. [15]
Use of a vascularized free fibular graft harvested from the ipsilateral leg with a vascular pedicle inserted into the proximal femoral defect and anastomosed with the lateral circumflex artery has become popular. The procedure is technically difficult with increased morbidity and has questionable benefit compared with core decompression.
Trapdoor procedure and allograft
Trapdoor is indicated more in stage III disease, in which above procedures are unsuccessful. The trapdoor procedure involves open excision of the necrotic bone by elevation of the cartilage and cancellous grafting. In an osteochondral allograft procedure the necrotic area is replaced with a nonvascularized free allograft. During recovery, the patient is 20% weight bearing for 6 weeks, 50% weight bearing to 10 weeks, then progresses to full weight bearing.
Osteotomy
Osteotomy is technically very difficult and complications include nonunion and malunion. Total hip replacement is technically more difficult following osteotomy thus it is used in cases in which total hip replacement is not advisable.
The concept in osteotomy is to rotate the diseased area of the femoral head away from the weightbearing surface. Several different techniques are available:
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Angular osteotomy: Varus or valgus flexion usually is performed intertrochanterically and fixed with a plate.
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Rotational osteotomy: The head is rotated transtrochanterically, moving the weightbearing surface away from the necrotic lesion.
Recovery requires protected weight bearing for 6 weeks with gradual progression to full weight bearing.
Arthrodesis and arthroplasty
Arthrodesis is fusion of the hip joint. The joint is denuded of articular cartilage, and the femoral head and acetabulum are fixed to create a solid interface. No weight bearing is allowed following the procedure, with full weight bearing initiated at 3 months.
In arthroplasty, conventional techniques are used with either cemented or cementless implants. Resection arthroplasty involves excision of the femoral head. Mold or cup arthroplasty involves resurfacing of the articular surface of the femoral head with a prosthetic device. Resurfacing arthroplasty involves a cup-type arthroplasty on the femoral side with a metal-on-metal acetabular component.
Unipolar prosthetic arthroplasty involves replacement of the femoral head with a nonmobile bearing head and bipolar arthroplasty involves replacing the femoral head with a mobile bearing component.
Total hip replacement is primarily with cementless devices, with metal-on-polyethylene, ceramic-on-polyethylene, or ceramic-on-ceramic bearings. Weight bearing is allowed as tolerated immediately following surgery, depending on surgeon preference.
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Osteonecrosis, hip. Anteroposterior radiograph showing Ficat stage III disease.
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MRI showing osteonecrosis of right hip, normal left hip.
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Bone scan showing osteonecrosis of right hip.
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Osteonecrosis, hip. Anteroposterior radiograph core biopsy.
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Osteonecrosis, hip. A radiograph of a limited femoral resurfacing performed for a collapsed femoral head with damaged femoral head cartilage and intact acetabular cartilage.
Tables
Stage |
Criteria |
0 |
Normal radiograph, bone scan, and magnetic resonance images |
I |
Normal radiograph. Abnormal bone scan and/or magnetic resonance images A: Mild (< 15 % of femoral head affected) B: Moderate (15–30 % of femoral head affected) C: Severe (>30 % of femoral head affected) |
II |
Cystic and sclerotic changes in femoral head A: Mild (< 15 % of femoral head affected) B: Moderate (15–30 % of femoral head affected) C: Severe (> 30 % of femoral head affected) |
III |
Subchondral collapse without flattening (crescent sign) A: Mild (< 15 % of femoral head affected) B: Moderate (15–30 % of femoral head affected) C: Severe (>30 % of femoral head affected) |
IV |
Flattening of femoral head A: Mild (< 15 % of surface and < 2 mm of depression) B: Moderate (15–30 % of surface and 2–4 mm of depression) C: Severe (>30 % of surface and > 4 mm of depression) |
V |
Joint narrowing or acetabular changes A: Mild B: Moderate C: Severe |
VI |
Advanced degenerative changes |
Stage |
Criteria |
0 |
Bone biopsy results consistent with osteonecrosis; other test results normal |
I |
Positive findings on bone scan, MRI, or both A: < 15% involvement of the femoral head (MRI) B: 15-30% involvement C: > 30% involvement |
II |
Mottled appearance of femoral head, osteosclerosis, cyst formation, and osteopenia on radiographs; no signs of collapse of femoral head on radiographic or CT study; positive findings on bone scan and MRI; no changes in acetabulum A: < 15% involvement of the femoral head (MRI) B: 15-30% involvement C: > 30% involvement |
III |
Presence of crescent sign lesions classified on basis of appearance on AP and lateral radiographs A: < 15% crescent sign or < 2-mm depression of femoral head B: 15-30% crescent sign or 2- to 4-mm depression C: > 30% crescent sign or > 4 mm depression |
IV |
Articular surface flattened; joint space shows narrowing; changes in acetabulum with evidence of osteosclerosis, cyst formation, and marginal osteophytes |
