Aims: We wanted to investigate the association between risk factors recorded prospectively before primary hip replacement, and the risk for later revision hip surgery. Methods: During the years 1977–83 The National Health Screening Service in Norway conducted an investigation of risk factors for cardiovascular disease. 56,818 persons born 1925–42 were invited, and 92% participated. We matched these screening data with data from the Norwegian Arthroplasty Register concerning primary and revision hip arthroplasty. Results: We identified 504 men and 834 women who had received a primary total hip replacement after the screening. Of these 75 and 94 were revised during follow-up. Mean age at screening was 49 years; mean age at primary hip replacement was 62 years. Mean age at censoring was 68 years. Men vs women had a relative risk of 1.9 of undergoing hip revision during follow-up (95% CI 1.3–2.8). For each years increase in age at primary hip arthroplasty, the risk of revision surgery during follow-up decreased with 14% for men and 17% for women. Men who at screening had the highest level of physical activity during leisure had 5.5 times the risk of later revision, relative to those with the lowest level of physical activity (95% CI 1.0–31.9). Conclusions: Men have a higher risk for revision hip surgery. There is less risk of revision the older the patient is at primary hip arthroplasty. Men with intense physical activity at middle age are at increased risk of undergoing revision hip surgery before they are 70 years old.

The Trap Door procedure for avascular necrosis of the femoral head has been reported to give acceptable result (1). All patients reported here were clinically approaching indication for total hip replacement (THR), and short-term results may therefore be of interest.

Material and Method: Thirteen patients (5 men) age 14–48 were operated for avascular necrosis with subchondral collapse (n = 12) or sequel CalvŽ-Legg Perthes disease (n = 1). The hip was dislocated through the anterolateral. The cartilage over the necrotic area was elevated as a ßap with the base towards fovea capitis femoris. The necrotic area was debrided and channels were drilled into well-perfused bone. Autologue bone from the iliac crest was transplanted, overcorrecting the defect slightly. The cartilage ßap was sutured back and the hip relocated. Postoperatively the patients have loaded 15 kg 12 weeks, and then gradually resuming full weight bearing in additionally 6 weeks.

Results: Follow up ranges from 3 months to 3.3 years. Postoperative recovery was uneventful. No patient has been reoperated, but two patient are scheduled for THR 19 and 13 months postoperatively. Preoperatively the joint space was mean 4.3 mm (3–5,) at the last follow-up it was 3.9 mm (2,3 Ð 5). The roundness of the femoral head was judged as being better postoperatively than preoperatively Discussion: The TrapDoor procedure may delay or postpone the need for arthroplasty in patients with avascular necrosis of the femoral head. The two patients who will be converted to THR did both have pain and poor range of motion after the procedure, probably indicating that the cartilage/transplanted bone were degenerating.

Malalignment and cement mantle quality have been implicated in loosening of the Charnley stem [2]. We implemented a new technique for insertion of the Charnley stem (Hardinge approach) including a distal centralizer, broaches and speciþc entry into the femoral canal via the piriformis fossa, and compared it to the old technique for alignment of the stem and cement mantle quality.

Material and methods: Forty-two patients (old technique) were compared with forty-two patients operated with the modern technique. Residents operated all patients with primary hemiarthroplasty. Post-operative antero-posterior and true lateral radiographs were taken and evaluated for cementing quality [1], mantle thickness in the 14 Gruen zones, and alignment of the femoral stem.

Results: For the Barrack classiþcation there was 9 grade A with the new technique, compared to none with the old (p< 0.0001). The cement mantle was more uniform (p< 0.0001), and the mean thickness was higher with the new technique for zones 1–3, 5–10 and 12. Alignment in the lateral plane was 5.2û with the old technique, compared to 2.2û for the new technique (p=0.0001).

Discussion: A modern insertion technique for the Charnley stem gave a much better cementing quality, better cement mantle uniformity and a thicker mantle in the critical zones, and more neutral alignment of the stem. As poor alignment and thin or absent cement mantle has been implicated in loosening the results should hopefully confer into longer survival.