Introduction and Objectives: We compared the clinical and radiographic results of patients with JRA and primary arthritis using a non-cemented THR with an alumina-alumina THA.

Materials and Methods: We studied 29 THR (Cerafit cup and Multicone stem) implanted in 19 patients with JRA in group 1 and 135 with primary arthritis in group 2. Mean follow-up was 59.0 months. It was seen that 13 hips in group 1 had moderate-severe acetabular protrusion and allograft was used in 12 hips. The center of rotation was determined pre and postoperatively in group 1 according to Ranawat.

Results: In group 1 age (p< 0.001), weight (p< 0.001), and level of activity (p< 0.001) were less. Type A acetabulum (p=0.014) and a cylindrical femur (p< 0.01), according to Dorr, were more frequent in group 1. There was no noise or alumina breakage. There were two intraoperative femur fractures in group 1. There was a revision of 1 cup in group 1 and infection of 1 stem in group 2. In most of the group 1 cases anatomical position was recovered (p< 0.001). The preoperative center of rotation of the hip with acetabular protrusion was 23.2 mm and in the postoperative X-ray 5.6 mm.

Discussion and Conclusions: In spite of the differences, THR with alumina-alumina allows similar results to be obtained in the medium term in patients with JRA. The use of an allograft in those patients with severe acetabular protrusion makes it possible to reconstruct the center of rotation of the hip.

Introduction and Objectives: We compared the clinical and radiological results in patients under and over 40 years of age who had received a non-cemented alumina-alumina hip replacement.

Materials and Methods: We studied 337 Cerafit acetabular cups implanted in 4 hospitals in association with Multicone-Hydroxyapatite stems with alumina-alumina bearing surfaces. Group 1 consisted of 63 patients under 40 years of age and group 2 of 274 patients over 40 years of age. Mean follow-up was 59.0 months. Demographic data and clinical and radiological results of both groups were compared.

Results: There were no cases of primary arthritis in group 1, however severe hip dysplasia and juvenile rheumatoid arthritis were frequent (p< 0.001). Weight (p< 0.001) and degree of activity (p=0.003) were greater in group 2. Preoperative function (p=0.03) and mobility (p< 0.001) were worse in group 1. There were 3 cup revisions in group 1 and 4 (including an alumina breakage) in group 2. Survival with no revision due to any cause was 91.4+5.1% in group 1 and 97.0+ 1.1 in group 2 (p=0.4007). There were no noises. Clinical and radiological results were similar in both groups.

Discussion and Conclusions: Diagnoses were different in both groups, the younger patients were in worse conditions. In spite of these differences, the alumina-alumina prosthesis showed similar results in both groups in the medium term. Long-term follow-ups are necessary to confirm these results.

We reviewed 111 hemispherical Duraloc series-500 acetabular components with a minimum follow-up of 12 years. The mean clinical and radiological follow-up was 13.4 years (12 to 15). A Profile hydroxyapatite-coated anatomical femoral component was used in each case. Six patients had a late dislocation, for whom the polyethylene liner was exchanged. Each acetabular component was well fixed and all femoral components showed signs of bone ingrowth. The mean rate of femoral head penetration was 0.10 mm/year (0.021 to 0.481). The probability of not developing femoral cortical hypertrophy and proximal osteopenia by 12 years was 80.2% (95% confidence interval, 72.7 to 87.6) and 77.5% (95% confidence interval, 69.7 to 85.2), respectively. Despite these good clinical results, further follow-up is needed to determine whether these prostheses will loosen with time.

Ultra-high-molecular-weight polyethylene sterilised in the absence of air and highly cross-linked polyethylene have been used to avoid osteolysis and loosening in total hip replacement. Our prospective randomised study has assessed the results using two different polyethylenes associated with the same prosthetic design. We assessed 45 Allofit acetabular components with a Sulene-polyethylene liner of conventional polyethylene gamma sterilised with nitrogen and 45 Allofit acetabular components with a Durasul-polyethylene liner sterilised in ethylene oxide, both matched with an Alloclassic stem with a 28 mm modular femoral head. The prostheses were implanted between May 1999 and December 2001. The mean follow-up was for 66.3 months (60 to 92). The linear penetration of the femoral head was estimated at 6 weeks, at 6 and 12 months and annually thereafter from standardised digitised radiographs using image-analysis software.

There was no loosening of any prosthetic component. There were no radiolucent lines or osteolysis. The mean rate of penetration calculated from regression analysis during the first five years was 38 μm/year (sd 2) for the Sulene group and 6 μm/year (sd 1) for the Durasul group (p = 0.00002). The rate of penetration of the Durasul group was 15.7% of that of the Sulene group.

Aim: We assessed prospectively clinical and radiographic results of two different polyethylenes (PE) associated with the same prosthetic design (Zimmer-Centerpulse).

Material and Methods: We assessed 56 Allofit cups with Sulene-PE liner (sterilized in nitrogen) and 45 with Durasul-PE liner (highly cross-linked) associated with an Alloclassic stem (28-mm femoral head) implanted between 1999–2002. The mean follow-up was 29.4 months for the Sulene-PE and 25.3 for Durasul-PE. The radiologic study according to Johnston et al. and the PE wear estimated according to a software package (AutoCAD R14), were analysed at 6 weeks (zero position), at 6 and 12 months and annually thereafter.

Results: There were 3 dislocations which were excluded from the follow-up study. There were no infections. All assessed hips had good clinical and radiographic results. There was no loosening of any prosthetic component. There were no radiolucent lines, osteolysis, cortical hypertrophy, or femoral osteopenia. The distances between the acetabular shell and the femoral head centres taken in the early postoperative radiographs (zero position or bedding-in) were 0.30+0.094 mm for the Sulene-PE group and 0.20+0.074 for the Durasul-PE (p=0.029). The mean wear related with the zero position was 0.1035+0.0686 and 0.0819+0.078 (p=0.108) respectively.

Conclusions: Despite the measurement error of PE wear being higher in the Allofit cup, a higher zero position (bedding-in) was found in the Sulene-PE group than in the Durasul-PE. Although the mean wear was higher in the Sulene-PE than in the Durasul-PE, with the number of hips available, differences were not significant after 3 years

Introduction. Plain radiograph underestimates the lysis extent while bone defect determines acetabular revision. We determine the multislice computed tomography (CT) efficacy with metal-artifact minimization to calculate the volume, extent and location of lytic lesions around a loose acetabular cup.

Patients and Methods. 48 hips with a loose acetabular cup were evaluated before cup revision. Multislice CT scans with metal-artifact minimization (Toshiba-MEC CT) were done. Scans were taken at 135 kV and 250 mA to maximize the resolution and bone contrast. CT slice thickness was 3 mm and reconstruction index 1.5 mm. Evidence of osteolytic lesion on these scans was compared with plain radiographs and with intraoperative findings. Bone defects were classified according to Paprosky.

Results. Acetabular lysis were found in the radiographs of 18 hips and in the CT scans of 36 hips. The most frequent locations of osteolysis were medial (32 hips) and posterior walls (23 hips). Radiographs underestimated the extent of the lysis: there were 28 hips with radiographic type 1 defects and 16 hips with CT defects; 6 and 11 with type 2; 8 and 10 with type 3A; and 6 and 11 with type 3B respectively (Wilcoxon test, p< 0.001). The mean volumetric bone loss was 35.4 cm3 . Intraoperative findings confirmed CT findings.

Conclusions. Multislice CT scans with metal-artifact minimization is more sensitive for identifying and quantifying osteolysis around the cup than are plain radiographs. Since CT scans allow us to show the extent and location of the osteolysis, they are useful to plan cup revision.

Introduction and purpose: This study analyses the long-term results and the polyethylene wear rate of a first-generation hemispherical porous shell.

Materials and methods: 40 Tri-Lock shells were analyzed associated to an ACS (DePuy) PE insert implanted between 1988 and 1992. The PE had been gamma sterilized in air. The mean follow-up until revision or last control was 9.3 years (range: 3.1–15.0). PE wear was assessed by means of image digitalization with an Auto-CAD 14R software after 6 weeks (position zero), 6 and 12 months and, then, once a year. All cases were associated to a Profile stem.

Results: All shells showed themselves to be radiographically osseointegrated. 7 cases had acetabular osteolysis (Kaplan-Meier survival: 74.1% at 13 years). The appearance of osteolysis was related to a higher average wear rate (p=0.0021) and a higher wear rate at the end of follow-up (p=0.0147). 11 cases showed a breakage of the PE (Kaplan-Meier survival: 61.69+29.9% at 13 years). These breakages appeared on average after 60.1 months. The distance between the axis of the femoral head and that of the shell on the initial radiograph (position zero or initial settling) was 0.6018 in cases with breakage and 0.2338 in cases with no breakage (p=0.009). PE breakage was related to a higher mean wear rate (p< 0.0001) and the verticalization of the shell (p=0.0016).

Conclusions: Although all Tri-Lock cups were osseoin-tegrated, the breakage of the ACS insert was an usual finding, which was related with a higher initial settling of the PE, a higher mean wear rate and the verticalization of the shell.

We have analysedin the results of 24 femoral lengthenings in 23 patients operated on between 1993 and 2000, using a gradual elongation intramedullary nail (Albizzia). Of the 23 patients, 22 had femoral deficiency and one was of short stature. Their mean age was 16.9 years. Technical difficulties encountered during the procedure were mild or moderate in 18 femora and severe in six femora. Distraction was obtained by 15 ratchetings per day (1 mm/day).

There were 18 excellent results although in two patients this was achieved after the development of a pseudarthrosis which required further surgery. There were four good and two fair results in which the lengthening obtained was at least 3 cm less than had been projected. The consolidation index was 35.2 days/cm. No patient had associated long-term stiffness of the knee.

Femoral lengthening using an elongation nail gives good results and is a comfortable procedure.