The Wagner revision prosthesis consistently restores femoral bone structure.
(57/2055)
The short-term results are reported for 43 hip revision operations with the long-stemmed Wagner prosthesis. The patients were followed-up for an average of 25 months. The Charnley scores were; pain 5.2, movement 4.0 and walking 4.0. All patients except one showed abundant new bone formation. The stem subsided more than 20 mm in 5 patients and in 22 the subsidence was less than 5 mm. The major complication was dislocation, which occurred in 9 patients; 8 of these were reoperated and from then on remained stable. (+info)
Comparison of in vivo wear between polyethylene liners articulating with ceramic and cobalt-chrome femoral heads.
(58/2055)
At yearly intervals we compared the radiological wear characteristics of 81 alumina ceramic femoral heads with a well-matched group of 43 cobalt-chrome femoral heads. Using a computer-assisted measurement system we assessed two-dimensional penetration of the head into the polyethylene liner. We used linear regression analysis of temporal data of the penetration of the head to calculate the true rates of polyethylene wear for both groups. At a mean of seven years the true rate of wear of the ceramic group was slightly greater (0.09 mm/year, SD 0.07) than that of the cobalt-chrome group (0.07 mm/year, SD 0.04). Despite the numerous theoretical advantages of ceramic over cobalt-chrome femoral heads, the wear performance in vivo of these components was similar. (+info)
A conservative femoral replacement for total hip arthroplasty. A prospective study.
(59/2055)
Between 1985 and 1993, 146 patients (162 hips) had total hip replacement (THR) using a conservative uncemented femoral component. The mean age of the patients was 50.8 years and the mean follow-up was 6.2 years (2 to 13). One patient was lost to follow-up, one died within two years of surgery and one had a revision procedure after a fracture sustained in a road-traffic accident. For the remaining 159, Kaplan-Meier survival analysis was calculated for the incidence of revision because of mechanical loosening or osteolysis. Survival without mechanical loosening at both five and ten years was 98.2%. Survival without osteolysis was 99% at five and 91% at ten years. The Harris hip score improved from a mean of 66.3 before to 90.4 at follow-up. Of particular note is the lack of thigh pain in this group. Radiological analysis showed that 139 stems (88%) had no measurable subsidence, 8 (5%) had less than 2 mm and 12 (7%) had more than 2 mm. Two of the eight and one of the 12 were revised for mechanical loosening. Nine hips were revised for late loosening associated with osteolysis. No reaming of the femoral canal was associated with statistically significant less blood loss compared with a comparable control group of uncemented implants (p < 0.0001). Our study suggests that using a conservative femoral implant does not protect against wear debris but the reliable mechanical stability (98.2%) makes this an attractive design of implant particularly for young patients. (+info)
Precision of the measurements of periprosthetic bone mineral density in hips with a custom-made femoral stem.
(60/2055)
Our aim was to determine the precision of the measurements of bone mineral density (BMD) by dual-energy x-ray absorptiometry in the proximal femur before and after implantation of an uncemented implant, with particular regard to the significance of retro- and prospective studies. We examined 60 patients to determine the difference in preoperative BMD between osteoarthritic and healthy hips. The results showed a preoperative BMD of the affected hip which was lower by a mean of 4% and by a maximum of 9% compared with the opposite side. In addition, measurements were made in the operated hip before and at ten days after operation to determine the effect of the implantation of an uncemented custom-made femoral stem. The mean increase in the BMD was 8% and the maximum was 24%. Previous retrospective studies have reported a marked loss of BMD on the operated side. The precision of double measurements using a special foot jig showed a modified coefficient of variation of 0.6% for the non-operated side in 15 patients and of 0.6% for the operated femur in 20 patients. The effect of rotation on the precision of the measurements after implantation of an uncemented femoral stem was determined in ten explanted femora and for the operated side in ten patients at 10 degrees rotation and in 20 patients at 30 degrees rotation. Rotation within 30 degrees influenced the precision in studies in vivo and in vitro by a mean of 3% and in single cases in up to 60%. Precise prediction of the degree of loss of BMD is thus only possible in prospective cross-sectional measurements, since the effect of the difference in preoperative BMD, as well as the apparent increase in BMD after implantation of an uncemented stem, is not known from retrospective studies. The DEXA method is a reliable procedure for determining periprosthetic BMD when positioning and rotation are strictly controlled. (+info)
The effects of cementless femoral stem shape and proximal surface texture on 'fit-and-fill' characteristics and on bone remodeling.
(61/2055)
We measured the post-operative radiological "fit and fill" of two different femoral stem designs, one with a straight proximally porous-coated (Bi-Metric, n=50) and the other with a proximally anatomic, hydroxyapatite-coated and distally over-reamed stem (ABG, n=26). A comparison was then made between the clinical and radiological 5-year follow-up data of these two series and also of the bone remodeling changes around the stems. The observed differences in "fit and fill" parameters in the metaphyseal region were minute. However, in the diaphyseal bone the straight stem had substantially more cortical contact. The clinical results were excellent for both groups. Subsidence (>2 mm) was more frequent with the anatomical ABG stems, although the ABG stems had better bone ingrowth in the lower metaphyseal area. The present results indicate that the anatomical design may improve the fit and fill of a femoral stem in the metaphysis. On the other hand, a looser fill of the diaphyseal bone made the stems of this type more susceptible to subsidence. The straight stem with tight diaphyseal fit showed excellent stability, but the good bone ingrowth and remodeling around the distal part of the stem indicates stress transfer through this region and increased stress shielding of the proximal metaphyseal femur. (+info)
Surface analysis of a femoral stem after failed total hip replacement.
(62/2055)
We analysed the surface of a Ti alloy femoral stem in a cementless total hip replacement with early failure. A specific protocol consisting of non destructive and destructive tests was used in the evaluation of the retrieved stem. The tests confirmed that implant fretting due to bone abrasion constitutes an early phase of loosening. (+info)
Evaluation by explicit criteria of the use of total hip joint replacement.
(63/2055)
OBJECTIVE: To evaluate the appropriateness of the use of total hip replacement (THR) using explicit criteria developed by an expert panel. METHODS: Patients with a diagnosis of osteoarthritis who were undergoing THR in five public hospitals in Spain were included consecutively in the study during a 1-yr period. The appropriateness of the indication was judged by explicit criteria developed using a mutidisciplinary approach. Complications were measured 3 months after surgery. One year after discharge, pain, functional limitation and general health were measured. RESULTS: After evaluation of 583 patients, 82 (13.6%) were considered to have undergone inappropriate procedures, and for 279 (46.2%) patients indication for the procedure was considered uncertain. Differences were found in the rate of appropriateness among some centres. One year after discharge, the perception of general health was slightly better in those patients who had been judged to have undergone an appropriate procedure. CONCLUSIONS: The study identified a moderate percentage of inappropriately performed THR. When considered together with those cases that were judged to have uncertain indications, the results indicate that further studies should be done to identify patients who may have an inadequate benefit:risk ratio from this procedure. (+info)
Anti-TNF-alpha therapy as a clinical intervention for periprosthetic osteolysis.
(64/2055)
Aseptic loosening of total joint arthroplastics due to periprosthetic osteolysis is a frequent cause of implant failure. The absence of clinical interventions to arrest or prevent this complication limits the use of total joint replacement especially in younger patients. Here we review recent studies implicating tumor necrosis factor (TNF)-alpha in periprosthetic osteolysis and the rationale for clinical studies of anti-TNF therapy and other interventions for periprosthetic loosening. (+info)