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Concern about polyethylene wear and related osteolysis after knee arthroplasty has developed in the last years. Mobile-bearing knee prostheses were designed in order to reduce the influence of this critical factor on long-term success of total knee replacement. We present a prospective study comparing clinical and radiological results with a mobile-bearing (Ceragyr) and a fixed-bearing knee prosthesis (posterior stabilized Hermes). Clinical results did not show any significant differences in Knee Society scores. We found better results in the mobile-bearing group for pain scores and subjective preference, but the difference did not reach statistical significance. Within the time limits of this study, radiological analysis showed no osteolysis in either group, but longer follow-up will be needed to confirm this.

Serum C-Reactive Protein was measured serially in 45 patients treated with uncomplicated primary total hip and knee arthroplasty (24 THR y 21 TKR). Blood specimens were obtained before surgery, on surgery day and on the 2nd, 3rd, 5th, 13th, 42nd and 150th postoperative days. In both groups serum CRP levels increased rapidly after surgery, with maximum levels on second postoperative day, higher in the TKR group and decreased gradually to preoperative levels on day 150, but still high on 42nd day. Levels returned to normal after surgery at the same time in both groups and no significant differences were found. Rising CRP levels after the third postoperative day may suggest a surgery complication such as infection.

Ossifying fibroma (osteofibrous dysplasia) is a rare fibro-osseous lesion made up of fibrous tissue with woven bone formation. It is most commonly found in the tibia and fibula of children ten years of age or younger. The most important differential diagnosis is monostotic fibrous dysplasia, which is radiologically similar but without woven bone rimmed by active osteoblasts like ossifying fibroma on histological examination. No epitheloid cells are found as in adamantinoma. We report the case of a 45-year-old woman who had a 12-month history of pain and slight swelling. Radiographs showed a multilocular radiolucent lesion with sclerotic rim in the proximal tibia. The lesion was curetted and the defect was packed with bone graft and acrylic cement. Microscopic examination showed active osteoblasts rimming the irregulary woven bone. One-year follow-up showed good functional recovery without recurrence of the lesion.