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Do I need an operation to correct Osteonecrosis?
There are several treatment choices, determined by the extent of involvement of the femoral head. Non-operative management consists of protective weight-bearing (e.g., partial weight-bearing with crutches) for six weeks then re-evaluation. However, historical reviews of the natural progression in non-surgically managed cases document an 85-92% risk of progression. In one series of 55 such hips, 84% required total hip replacement, usually within 3 yrs. of diagnosis. Even in the most favorable early stages (e.g., FICAT 1,2), 69% required total hip replacement.
What is core decompression?
Core decompression is a procedure which entails drilling into the femoral neck, up into the necrotic area of the femoral head, to get the bone to heal faster. Theoretically, removing this central core of bone will lower the intraosseous pressure, which is thought to be one of the etiologies of the disease. When properly done, this procedure has minimal morbidity. Patients must remain non-weight bearing on crutches for 6 weeks following the procedure in order to prevent a small but real risk of fracture.
In reviewing the literature there is clearly a disparity of results in the use of core decompression regardless of the Ficat stage. In selected patients, core decompression may be indicated for stages 1 and 2. However, for more advanced stages (e.g. 3 and 4) the results are much less predictable. This procedure appears to be best suited for the stage 1 and early stage 2 hips in which pain relief and preservation of the femoral head are relatively predictable (>70%).
Are there other choices?
Besides non-operative management and core decompression, there are several other treatment modalities, which include osteotomies, bone grafting, and total hip arthroplasty.
Bone Grafting: This procedure involves taking a segment of bone from the fibula on the same side, and placing it along with cancellous bone graft from the fibula or greater trochanter into the core which is made in the same manner as described in core decompression. Bone grafting can either be of the non-vascularized or vascularized types. In the latter the blood vessels of the fibular graft are preserved and transferred along with the graft and subsequently reattached to the blood vessels of the hip. Data has shown encouraging results. Disadvantages of this procedure include a longer recovery period, less complete relief of pain than after total hip arthroplasty., two scars and the potential for nerve injury in the calf related to obtaining the bone graft.
Osteotomies: There are several types which are described in the literature (e.g., rotational, angulation). No matter what type they all have the same goal, which is to preserve the femoral head by altering the pattern of stress transfer. A varus osteotomy attempts to shift the most involved portion of the head medially. A valgus osteotomy attempts to shift the superolateral lesion more lateral. Often varus and valgus osteotomies are performed in conjunction with a flexion osteotomy. Rotational osteotomies by design attempt to shift the diseased head medially, inferiorly and posteriorly. Theoretically it is a structurally more appropriate treatment for this disease, but it is technically difficult. For all of the osteotomies, there have been excellent short-term results. For angulation osteotomies with small to medium size lesions initial results are good to excellent in 60-75% of patients at 3-5yrs. Rotational osteotomies have had anywhere from 20-100% success depending on how much intact area of femoral head was the weight bearing surface after transposition. The better results correlating with greater intact weight bearing surface areas. |
