Spontaneous osteonecrosis of the femoral condyle: causal treatment by early core decompression.

In 16 patients with an average age of 64.6 +/- 9.8 years and sudden onset of severe knee pain, the initial stage of Ahlbäck disease (spontaneous osteonecrosis of a femoral condyle) was verified by magnetic resonance imaging (MRI) and subsequent histology. The first radiological sign of osteonecrosis (flattening of the affected femoral condyle) was present in only one case. All patients were treated surgically by extra-articular drilling into the affected femoral condyle to achieve core decompression. The knee pain disappeared immediately after surgery in all patients. Successful healing was confirmed by normalization of the bone marrow signal on MRI (on average, 35.8 months follow-up). Core decompression by extra-articular drilling into the femoral condyle can be recommended as an effective treatment in initial osteonecrosis of the knee (still radiologically invisible). However, if radiologically a flattening of the affected femoral condyle becomes apparent, progression of this disease cannot be avoided.