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In tibial shaft fractures in the rabbit, the early stage of bone healing after metal-plate fixation was compared with that after treatment with a long or short plaster cast. The animals were killed after 6 weeks. The plate-fixed bones healed more rapidly, with less periosteal callus and less angulation of the fragments, than those treated with a cast. The results indicated that function of the muscles and joints of the injured limb, including weight bearing, promotes bony union, whereas the degree of fixation stiffness is relatively unimportant.

Unilateral midshaft tibial osteotomies in rabbits were fixed with 6-hole steel plates. In half the animals, no additional fixation was used, whereas in the other half, a plaster bandage from the toes to the midthigh was applied. At 6 weeks all the osteotomies had healed radiographically with little or no periosteal callus. The median strength of bones without plaster was 107 per cent of the normal value compared with 55 per cent in the plaster group. The results indicated a severely adverse effect of plaster immobilization on the healing of plate-fixed osteotomies.

The anteversion angle (AV-angle) of the femur was measured according to the method of Rippstein in a series of 50 patients with "primary" osteoarthritis of the hip, and in a control group of 30 individuals of the same age without hip disease. The median AV-angle of the hips in osteoarthritic patients was 17.5 degrees, and in the control group 13 degrees. Osteoarthritic patients had a significantly increased AV-angle in relation to the control group (P = 0.0028). The greatest AV-angle in the hips of the control group was 25 degrees. In 18 hips of osteoarthritic patients an AV-angle greater than 25 degrees was found. Osteoarthritis was found in 15 of these hips; there was no osteoarthritis in the remaining 3 hips. Our results lead to the conclusion that increased femoral anteversion is a predisposing factor for hip osteoarthritis. This implies that derotational osteotomy in children can be a prophylactic procedure.

During the period 1978-1984, 38 patients aged 23-55 years were treated for patellofemoral pain by the Maquet procedure. The mean postoperative observation time was 5(3-9) years. Thirty-three of the 38 patients were available for follow-up including functional and activity scoring, clinical examination, and Cybex II dynamometer muscle-strength measurement. Ten patients improved, 17 were unchanged, and 6 were worse. Characteristic for the improved group was Grades III and IV chondromalacia - mainly involving the lateral facet - whereas the group with no improvement or deterioration exhibited a low-grade chondromalacia, chiefly affecting the medial patellar facet.

If resection followed by end-to-end anastomosis is not possible in obstructive lesions of the trachea other methods of reconstruction must be used. The ability of a periosteal graft to induce bone or cartilage formation when transplanted to cover a tracheal defect was confirmed in a previous experimental study. In this study free tibial periosteal grafts were used for repair of tracheal defects created in rabbits. The graft was placed circumferentially around the trachea. It is concluded that there is a high risk of development of severe osseous tracheal stenosis when periosteal grafts are placed circumferentially around the trachea.