Twenty-six hips (19 patients) with osteonecrosis of the femoral head with stage I or II of the disease, according to the Ficat and Arlet classification, underwent core decompression. Osteonecrosis was confirmed histologically in all 26 hips. Of 19 patients, 7 had prognostic factors traditionally associated with poor outcome including collagen vascular disease and continued use of steroids. The follow-up period averaged 7 years 10 months (range: 2 years 5 months-13 years 8 months) for 17 patients with 24 hips. Two patients died secondary to systemic illness. Seventeen hips (65.4%) had very good or good results using the Ficat criteria. Eight hips (30.8%) needed further operation [total hip arthroplasty (THA) for 7 hips, osteotomy for 1 hip]. Of the 12 hips in patients who had used steroids, 6 hips (50%) were converted to THA. Four hips in patients with systemic lupus erythematosus (SLE) needed THA (100%). We conclude that core decompression provides an effective treatment for steroid-associated osteonecrosis other than in cases with SLE, as well as providing effective treatment for non-steroid-associated osteonecrosis in the early stages of the disease.

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We present the case of a 39-year-old man with bilateral piriformis syndrome 4 and 6 years after two cementless total hip arthroplasties, respectively. During surgical exploration, each sciatic nerve was found to be entrapped by a tense piriformis muscle and hypertrophic posterior hip capsule. The sciatic-type pain was relieved after sectioning each piriformis muscle with external neurolysis. This is the first reported case of piriformis syndrome after total hip arthroplasty.

We performed osteosynthesis with the use of a Mennen plate for six patients with femoral fractures in the vicinity of the stem, which occurred after ipsilateral hip arthroplasty. The fixation was so favorable that postoperative deformity was slight. At 4 months after surgery, bone fusion was obtained in all patients, and their hip joint functions recovered to the preinjury level. For femoral fractures in the vicinity of the stem after ipsilateral arthroplasty, there are no suitable fixation methods other than treatment with the Mennen plate. Therefore, this method is recommended.