The wear rate of modern ceramic wear couples with hip simulators is extremely low (0.001mm/year, 0.5mg/year), but there are only few data concerning the in-vivo wear rate. We have performed a retrieval analysis of two ceramic couples. The ceramic heads and the cup inserts were retrieved after 24 months of in-vivo function. There were no scratches and no sign of third body wear. The articulating surfaces were still in a polished state. The wear rate was below detection limit.

We followed prospectively 27 patients with severe acetabular bone-stock deficiencies due to developmental dysplasia of the hip. Mean preoperative patient age was 56 (34-78) years, mean Harris hip score was 31 (16-66) points and pre-operative mean acetabular angle of Sharp was 47 degrees (34 degrees - 61 degrees). Operative acetabular reconstruction was performed in 28 hips using reinforcement ring with a hook placed in the true acetabulum and autologous bone grafting. A 2-year clinical and radiological follow-up was available in 27 hips. Mean Harris hip score improved to 91 (70-100) points. There were no clinical or radiological signs of aseptic loosening in 25 hips, and the bone graft was radiologically incorporated in all hips. In 24 hips, a radiostereometric analysis showed low rates of non-progressive translation and rotation in 21 reinforcement rings. Three rings showed progressive translation and/or rotation at the 2-year follow-up and were rated probably loose.

Objective: Brachymetatarsia is defined as the pathological shortening of a metatarsal bone, which can cause cosmetic problems and pain in the forefoot. The main surgical treatment options are: extension osteotomy, interposition of a bone graft, and callus distraction. Usually, a bone graft from the iliac crest is used for the interposition osteotomy. The operative technique of graft extraction from the fibula has not been described in the literature yet. Methods: Eight feet with brachymetatarsia in 5 patients were evaluated retrospectively. The minimum follow-up period was 2 years. Via a dorsal V/Y skin incision, a central osteotomy on the metatarsal bone was done. A graft was obtained from the anterior fibula. The graft was inserted and fixed by a locking plate. Additional soft tissue procedures were done. Results: We had bony consolidation in all cases. The mean extension was 9.01 mm (5.49 to 12.54 mm). This corresponded to a mean 20.3% extension of the entire metatarsal. High patient satisfaction as well as high satisfaction regarding the cosmetic results were achieved. There were no postoperative complications. The range of motion of the metatarsal-phalangeal joint IV was 20% less preoperative in terms of plantar flexion. Standing up on tiptoes was possible in all patients postoperatively. One patient reported mild symptoms after sports activities. Conclusions: Because of its anatomy the graft adapts to the metatarsal IV bone. As our study showed, harvesting from the distal fibula causes no functional restriction. In terms of wound and bone healing as well as pain symptoms, this method should be considered as an alternative to the standard iliac graft.

The purpose of the present study was to assess the in-vivo migration of a press-fit acetabular component in total hip arthroplasty using alumina or polyethylene liners. The measurements were performed using radiostereometric analysis (RSA). Fifty patients (50 hips) with degenerative hip osteoarthritis were randomized in two groups. All received a modular press-fit cup and an alumina head. In 27 cases we used a polyethylene, in 23 an alumina liner. RSA was performed for a followup of 2 years after surgery. The mean preoperative Harris hip score was rated 48.9 points in the alumina, and 47.7 points in the polyethylene group. The mean Harris hip score after one year of the alumina group was rated 94.1 points, 93.7 points in the polyethylene group. There were no clinical and radiological signs of aseptic loosening at follow-up. Radiostereoanalysis of the alumina group of cups showed a median axial migration of 0.034 mm (max. 0.382mm). The median axial migration of the polyethylene group was 0.094 mm. The median rotational displacement was 0.03° in the alumina group, -0.07° in the polyethylene group. Overall rotational displacement ranged between -5.59° to 1.72°. Median tilting of the cup was 0.06° in the alumina group, and 0.43° in the polyethylene group. At an average of one year postoperatively, the cups inserted with an alumina liner showed limited displacement, and results did not contrast with those achieved using the same implant with a polyethylene liner.

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