We operated on five men and seven women, aged 17 to 48 years, for avascular necrosis of the femoral head. Eleven had subchondral collapse and one Calvé-Legg Perthes’ disease. The hip was dislocated through an anterolateral approach. The cartilage over the necrotic area was elevated as a flap with the base towards fovea capitis femoris. The necrotic/cystic area was debrided and channels were drilled into well-perfused bone. Autologous bone from the iliac crest was transplanted, slightly overcorrecting the defect. The cartilage flap was sutured back and the hip relocated.

Postoperatively patients were limited to 15 kg of weight-bearing for 12 weeks and then gradually resumed full weight-bearing over six weeks. Follow-up ranged from three months to three years. No patients have been operated on again and no major complication has occurred. Preoperatively the mean joint space was 4.3 mm (3 to 5 mm); at the last follow-up, it was 3.9 mm (2.3 to 5 mm). The roundness of the femoral head was judged better postoperatively than preoperatively. No patient has so far been scheduled for arthroplasty, but two patients have had relapses of more severe pain.

The Trap Door procedure may postpone the need for arthroplasty in patients with avascular necrosis of the femoral head. Our initial results have been encouraging, but further follow-up is required.

Over 13 months we prospectively monitored C-Reactive Protein (CRP) to assess surgical site infection (SSI) in 148 patients undergoing hip arthroplasty, including 34 hemiprostheses for femoral neck fracture, 35 hemiprostheses for osteosynthesis failure, 17 primary total hip arthroplasties (THAs) and 62 revisions of hemi-arthroplasty or THA. Ten patients who had probably had interaction with CRP were included.

In four out of seven patients with SSI, CRP values peaked three days after the operation, compared to eight out of 131 without SSI (p =0.0001). This gives a 60% sensitivity for detecting SSI by the CRP curve, with a specificity of 94%. The positive predictive value was 33%, and the negative predictive value 98%.

Previous studies have established the normal CRP curve after major joint replacement surgery. This study shows that a peak in CRP after day three may indicate SSI, or point to other deep infections such as pneumonia.

This paper investigates the association between risk factors recorded prospectively before primary total hip arthroplasty (THA) and the risk for later revision surgery. The National Health Screening Service in Norway invited 56 818 people born between 1925 and 1942 to participate in an investigation of risk factors for cardiovascular disease and 92% participated. Matching these screening data with data from the Norwegian Arthroplasty Register about primary THA and revision THA, we identified 504 men and 834 women who had undergone primary THA at a mean age of 62 years. Of these, 75 and 94 were revised during follow-up. The mean age at screening was 49 years and the mean age at censoring was 68 years. The mean age of those who underwent revision THA was 57 years. Men had a 1.9 times higher risk of undergoing hip revision during follow-up (95% CI). For each year’s increase in age at primary THA, the risk of revision THA during follow-up decreased by 14% for men and 17% for women. Men who at screening had the highest level of physical leisure activities had 5.5 times the risk of later revision than those with the lowest level of physical activity (95% CI).

Men have a higher risk for revision THA. The older the patient, the lower the risk for revision. Men with intense physical activity in middle age are at increased risk of undergoing revision THA before they reach 70.

The purpose of this study was to compare old and new techniques in hemiprosthesis for primary femoral neck fractures. We implemented a new technique for inserting the Charnley stem via the Hardinge approach. This included a distal centraliser, broaches and specific entry into the femoral canal via the piriformis fossa. We then compared stem alignment and cement mantle quality in old and new techniques. The sample comprised 42 patients (34 women) who had been operated on with the old technique and 49 patients (39 women) exposed to the modern technique.

Postoperative anteroposterior and true lateral radiographs were taken and evaluated for cementing quality, mantle thickness in the 14 Gruen zones and alignment of the femoral stem in both planes. On the Barrack classification there were nine grade-A with the new technique, compared to none with the old. There was one Grade-B with the old technique. With the new technique, cement mantle thickness and uniformity was better in Gruen zones 1 to 3, 5 to 10, and 12. Alignment as measured in the lateral plane by the mean antero-posterior angle was 5.2° with the old technique and 2.2° with the new (p =0.0001). In the frontal plane there was no difference.

It is hoped the advantages associated with this modern technique for inserting the Charnley stem will confer longer survival.

Malalignment and cement mantle quality have been implicated in loosening of the Charnley stem [2]. Several types of cemented prosthesis have adopted a modern insertion technique, which has not been available for the Charnley stem. We implemented a new technique for insertion of the Charnley stem via the Hardinge approach including a distal centralizer, broaches and specific entry into the femoral canal via the piriformisfossa, and compared it to the old technique for alignment of the stem and cement mantle quality.

Material and methods: Forty-two patients (34 women) operated with an old technique were compared with forty-nine patients (39 women) with the modern technique. All patients were operated through the Hardinge lateral approach, with primary hemiprosthesis by residents. Post-operative anteroposterior 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 in both planes.

Results: For the Barrack classification there was 9 grade A with the new technique, compared to none with the old (p< 0.0001, Table 1), and only 1 grade B with the old technique. The cement mantle thickness was more uniform (p< 0.0001), and the mean thickness was higher with the new technique for zones 1-3, 5-10 and 12 compared to the old technique. Alignment as measured in the lateral plane by the mean anteroposterior angle was 5.2° with the old technique, compared to 2.2° for the new technique (p=0.0001). In the frontal plane there was no difference.

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.

New prosthesis designs should be compared to a standard implant in randomized studies evaluated by radiostereometric analysis (RSA). The Unique customized prosthesis (UCP) is a newly developed concept for fitting uncemented prosthesis to the exact internal shape of the proximal femur [1]. We evaluated the new UCP design with the null hypothesis that this implant would be no more stable than a standard cemented implant.

Material and methods: 38 patients, mean age 51.6 years (31–65) were randomized to a UCP HA coated femoral stem or an Elite Plus (DePuy) cemented stem. All patients were implanted with a Duraloc (DePuy) uncemented cup except one patient with a protrusio who was primary impaction grafted with a cemented cup. Most patients received a Zirconium head, and all heads were 28 mm. The femoral stems were fitted with 3 tantalum balls and 4–10 tantalum balls were implanted in the femur during operation. RSA pictures were taken postoperatively, after 6 and 12 months.

Results: The Elite Plus stem rotated more into retroversion after 6 and 12 months (0.79° versus 0.31° after 12 months, P< 0.05). Nearly all of this rotation took place during the first 6 months. The Elite Plus stem migrated medially while the UCP migrated laterally (0.04 mm medially versus 0.03 mm laterally, P=0.06). The Elite Plus stem also migrated more distally than the UCP (0.17 mm versus −0.06 mm, P=0.055).

Discussion: Customized implants were more stable than the cemented Elite Plus prosthesis. Compared to other results with the Elite Plus rotations and migrations were small in this study [2]. Initially all patients had good clinical results, and only by long time follow up any clinical differences due to the small differences in stability as measured by RSA can be found.

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.

We performed isokinetic knee testing to assess thigh muscle function in ten patients (12 legs) before and after mid-shaft femoral shortening averaging 46 mm (27 to 70). Tests were at angular velocities of 60 degrees/sec and 180 degrees/sec, and were performed preoperatively and after 3, 6, 12 and 24 months. Isokinetic tests at two years showed a significant reduction in muscle function in both quadriceps and hamstrings, but recovery of function was significantly better for the hamstrings. There was a linear relationship with correlation of r2 = 0.31 to 0.86 between loss of muscle force at two years and the magnitude of shortening. Long-term loss of muscle force should be expected after a mid-shaft shortening of the femur of more than 10%.

We performed bilateral femoral shortening operations on 15 skeletally mature patients (11 women and four men). Their mean height pre-operatively was 193.5 cm and they were shortened by 5 to 9 cm. We used a subtrochanteric Z-osteotomy with an AO condylar plate in 11 patients, and mid-diaphyseal osteotomy with an intramedullary locking nail in four. After an average follow-up of 8.1 years, isokinetic muscle testing showed that muscle strength was reduced bilaterally in five patients. The strength ratio between hamstrings and quadriceps muscles was normal in all those treated by subtrochanteric shortening; in those shortened at the mid-shaft the quadriceps was relatively weaker. The result was rated as excellent by 11 patients, very good by three, and good by one.