Osteosynthesis with the hook-pin in slipped capital femoral epiphysis

Osteosynthetic materials, such as metallic nails, screws, pins, and bone pegs, used in the surgical treatment of slipped capital femoral epiphysis, have caused peroperative problems because of increased displacement of the femoral head and postoperative problems because of bone resorption and growth of the femoral neck, resulting in loosening of the osteosynthetic material and reslipping of the femoral head. Premature closure of the growth plate and shortening of the femoral neck have also been registered. In order to avoid these problems, a hook-pin was developed. This device has now been in use for a period of 6 years and has been applied in 38 cases, the pin being placed in a drilled channel with the hook in the femoral head. The operation has been performed on the slipped side with or without reduction of displacement and on the asymptomatic side. Seventy-five hips have been operated on. The advantages of the hook-pin and of the operative technique are presented. No avascular necrosis has been noted in 74 hips pinned in situ or after closed reduction. Avascular necrosis occurred in one hip after femoral neck osteotomy. All 28 asymptomatic hips and 27 out of 37 hips with slipped epiphyses showed no tendency toward premature closure during a postoperative observation period of 1--6 years. The growth in length of the femoral neck was found to be up to 15 mm, almost the same on the slipped side as on the asymptomatic side. Only one of the 75 hips required reoperation because of resorption around the hook-pin. After the end of the growth period the hook-pin was extracted in 19 hips without problems.