Asymptomatic osteonecrosis: should it be treated?

Currently, there is no consensus regarding the treatment of precollapse osteonecrosis, particularly for asymptomatic osteonecrosis. With approximately 10,000 to 20,000 new cases of osteonecrosis a year, no single surgeon or center has the kind of experience that is able to address the most important questions concerning this disease. The literature strongly documents that symptoms of osteonecrosis will progress. Although the literature also supports the progression of asymptomatic osteonecrosis to symptomatic osteonecrosis on to collapse, that support is less convincing. Progression is proportional to lesion size, with small lesions (< 15% of femoral head involvement by volume) unlikely to progress. Although the results of core decompression have been somewhat controversial, the weight of the literature supports both the efficacy and safety of the procedure. The decision to treat osteonecrosis with core decompression is primarily based upon lesion size and stage of disease and does not necessarily depend on whether the patient is symptomatic. As large lesions (> 30% of the femoral head) are less likely to be successfully treated by core decompression and small lesions (< 15% of the femoral head) are less likely to progress, asymptomatic lesions within these ranges can be observed. The literature supports the position that moderately sized lesions (15-30% of the femoral head) should be treated by core decompression (with or without bone grafting).