From 1970 to 1980 cemented metal-on-plastic total hip replacement was performed on 799 hips with primary osteoarthritis using one surgical technique. At the 10- to 20-year follow-up there had been 97 revisions for mechanical loosening. Univariate survivorship analysis showed that an increased risk of revision was associated with male gender, young age at primary THR, the Brunswik and Lubinus snap-fit prostheses with large femoral heads (as compared with the Charnley prosthesis), and varying experience of the surgeon. Multivariate statistical analysis showed a three-fold increased risk of revision for men (p < 0.0001), an increase in relative risk of 1.8 per 10 years younger at surgery (p < 0.0001), a fivefold increase in risk for the Brunswik prosthesis (p < 0.0001) and a twofold increase for the Lubinus prosthesis (p = 0.0067). Inexperience of the surgeon, however, was not validated as a risk factor. The study shows that the true risk factors for revision can be identified accurately by combining univariate survivorship and multivariate statistical analyses

Survivorship analysis is a useful way of expressing the long-term results of joint replacement: it provides a means of comparing the life span of one type of prosthesis with another. However, such studies should include a full life-table and the confidence intervals for the survival rates at given times. At least 40 surviving prostheses are required to provide reliable results

Aims. The aim of this study was to assess the influence of obesity on the clinical outcomes and survivorship ten years postoperatively in patients who underwent a fixed-bearing unicompartmental knee arthroplasty (UKA). Patients and Methods. We prospectively followed 184 patients who underwent UKA between 2003 and 2007 for a minimum of ten years. A total of 142 patients with preoperative body mass index (BMI) of < 30 kg/m. 2. were in the control group (32 male, 110 female) and 42 patients with BMI of ≥ 30 kg/m. 2. were in the obese group (five male, 37 female). Pre- and postoperative range of movement (ROM), Knee Society Score (KSS), Oxford Knee Score (OKS), 36-Item Short-Form Health Survey (SF-36), and survivorship were analyzed. Results. Patients in the obese group underwent UKA at a significantly younger mean age (56.5 years (. sd. 6.4)) than those in the control group (62.4 years (. sd. 7.8); p < 0.001). There was no significant difference in preoperative functional scores. However, those in the obese group had a significantly lower ROM (116° (. sd. 15°) vs 123° (. sd. 17°); p = 0.003). Both groups achieved significant improvement in outcome scores regardless of BMI, ten years postoperatively. All patients achieved the minimal clinically important difference (MCID) for OKS and KSS. Both groups also had high rates of satisfaction (96.3% in the control group and 97.5% in the obese group) and the fulfilment of expectations (94.9% in the control group and 95.0% in the obese group). Multiple linear regression showed a clear association between obesity and a lower OKS two years postoperatively and Knee Society Function Score (KSFS) ten years postoperatively. After applying propensity matching, obese patients had a significantly lower KSFS, OKS, and physical component score (PCS) ten years postoperatively. Seven patients underwent revision to total knee arthroplasty (TKA), two in the control group and five in the obese group, resulting in a mean rate of survival at ten years of 98.6% and 88.1%, respectively (p = 0.012). Conclusion. Both groups had significant improvements in functional and quality-of-life scores postoperatively. However, obesity was a significant predictor of poorer improvement in clinical outcome and an increased rate of revision ten years postoperatively

Aims

The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution.

This editorial considers the shortcomings of assessing outcome after joint replacement only by the survival of the implant.

Fresh osteochondral allografts were used to repair post-traumatic osteoarticular defects in 92 knees. At the time of grafting, varus or valgus deformities were corrected by upper tibial or supracondylar femoral osteotomies. A survivorship analysis was performed in which failure was defined as the need for a revision operation or the persistence of the pre-operative symptoms. There was a 75% success rate at five years, 64% at ten years and 63% at 14 years. The failure rate was higher for bipolar grafts than for unipolar and the results in patients over the age of 60 years were poor. The outcome did not depend on the sex of the patient and the results of allografts in the medial and lateral compartments of the knee were similar. Careful patient selection, correction of joint malalignment by osteotomy, and rigid fixation of the graft are all mandatory requirements for success. We recommend this method for the treatment of post-traumatic osteochondral defects in the knees of relatively young and active patients

A consecutive series of patients with a hydroxyapatite-coated uncemented total knee replacement (TKR) performed by a single surgeon between 1992 and 1995 was analysed. All patients were invited for clinical review and radiological assessment. Revision for aseptic loosening was the primary outcome. Assessment was based on the Knee Society clinical score (KSS) and an independent radiological analysis. Of 471 TKRs performed in 356 patients, 432 TKRs in 325 patients were followed for a mean of 16.4 years (15 to 18). The 39 TKRs in 31 patients lost to follow-up had a mean KSS of 176 (148 to 198) at a mean of ten years. There were revisions in 26 TKRs (5.5%), of which 11 (2.3%) were for aseptic loosening. Other further surgery was carried out on 49 TKRs (10.4%) including patellar resurfacing in 20, arthrolysis in 19, manipulation under anaesthetic in nine and extensor mechanism reconstruction in one. Survivorship at up to 18 years without aseptic loosening was 96% (95% confidence interval 91.9 to 98.1), at which point the mean KSS was 176 (134 to 200). Of 110 knees that underwent radiological evaluation, osteolysis was observed in five (4.5%), one of which was revised. These data indicate that uncemented hydroxyapatite-coated TKR can achieve favourable long-term survivorship, at least as good as that of cemented designs

Aims

The aim of this study was to establish the results of isolated exchange of the tibial polyethylene insert in revision total knee arthroplasty (RTKA) in patients with well-fixed femoral or tibial components. We report on a series of RTKAs where only the polyethylene was replaced, and the patients were followed for a mean of 13.2 years (10.0 to 19.1).

Aims

The aim of this study was to evaluate the survival of a collarless, straight, hydroxyapatite-coated femoral stem in total hip arthroplasty (THA) at a minimum follow-up of 20 years.

Aims

The outcomes of patients with unexpected positive cultures (UPCs) during revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) remain unknown. The objectives of this study were to establish the prevalence and infection-free implant survival in UPCs during presumed aseptic single-stage revision THA and TKA at mid-term follow-up.

Aims

There are limited long-term studies reporting on outcomes of the Zimmer Modular Revision (ZMR) stem, and concerns remain regarding failure. Our primary aim was to determine long-term survival free from all-cause revision and stem-related failure for this modular revision stem in revision total hip arthroplasty (THA). Secondary aims included evaluating radiological and functional outcomes.

Between 1971 and 1991 we performed Charnley low-friction arthroplasty (LFA) on 116 patients (186 hips) with juvenile chronic arthritis (JCA). We have now carried out a survival study, taking endpoints as revision, death or the end of the year 1993.

Overall survival was 91.9% at ten years and 83.0% at 15 years. That of the femoral component was 95.6% at ten years and 91.9% at 15 years and of the acetabulum 95.0% and 87.8%, respectively. Only the use of steroids significantly impaired the survival.

We therefore recommend the use of Charnley LFA for young patients with JCA requiring total hip replacement.

We studied prospectively the long-term results of the Charnley Elite-Plus femoral stem in 184 consecutive young patients (194 hips). There were 130 men and 54 women with a mean age of 49.1 years (21 to 60). The predominant diagnosis was osteonecrosis of the femoral head (63.6%, 117 patients). Clinical and radiological evaluation was undertaken at each follow-up. The mean follow-up was 11.2 years (10 to 12).

The mean pre-operative Harris hip score was 43.4 (12 to 49) which improved to 91 (59 to 100) at the final follow-up. The survival of the femoral stem at 12 years was 99% with revision as the end-point. The mean annual linear wear of the polyethylene liner was 0.17 mm (0.13 to 0.22). The prevalence of acetabular osteolysis was 10.8% (21 hips) and osteolysis of the calcar femorale 12.9% (25 hips).

A third-generation cementing technique, accurate alignment of the stem and the use of a 22 mm zirconia head were important factors in the prevention of aseptic loosening of the Elite Plus femoral stem in these high-risk young patients.

The Kinematic Stabilizer is a posterior-cruciate-substituting design of total knee replacement. We have reviewed 109 primary total knee replacements in 95 patients at a mean follow-up time of 12.7 years (10 to 14). We used survival analysis with failure defined as revision of the implant. This gave a cumulative survival rate of 95% (95% CI± 5%) at ten years and 87% (± 10%) at 13 years.

These results from an independent centre confirm the value of an established design of cemented total knee replacement and question the wisdom of the introduction of modifications and new designs without properly controlled trials.

Aims

The purpose of this study was to determine the lifetime risk of revision surgery for patients undergoing Charnley cemented total hip arthroplasty (THA), with 40-year follow up, using death as a competing risk.

We determined the cumulative survival rates, in arthroplasty of the knee, of three designs of tibial component, using a change of position on standard radiographs or revision for aseptic loosening as criteria of failure. The average migration of each of the three designs in the first postoperative year is known from roentgen stereophotogrammetric analysis reported by other authors. The ranking order of the components as judged by cumulative survival is the same as that determined by early migration. This finding supports the view that the measurement of early migration can predict late aseptic loosening and therefore that such measurements are clinically of value.

A retrospective study was conducted to investigate the changes in metal ion levels in a consecutive series of Birmingham Hip Resurfacings (BHRs) at a minimum ten-year follow-up. We reviewed 250 BHRs implanted in 232 patients between 1998 and 2001. Implant survival, clinical outcome (Harris hip score), radiographs and serum chromium (Cr) and cobalt (Co) ion levels were assessed.

Of 232 patients, 18 were dead (five bilateral BHRs), 15 lost to follow-up and ten had been revised. The remaining 202 BHRs in 190 patients (136 men and 54 women; mean age at surgery 50.5 years (17 to 76)) were evaluated at a minimum follow-up of ten years (mean 10.8 years (10 to 13.6)). The overall implant survival at 13.2 years was 92.4% (95% confidence interval 90.8 to 94.0). The mean Harris hip score was 97.7 (median 100; 65 to 100). Median and mean ion levels were low for unilateral resurfacings (Cr: median 1.3 µg/l, mean 1.95 µg/l (< 0.5 to 16.2); Co: median 1.0 µg/l, mean 1.62 µg/l (< 0.5 to 17.3)) and bilateral resurfacings (Cr: median 3.2 µg/l, mean 3.46 µg/l (< 0.5 to 10.0); Co: median 2.3 µg/l, mean 2.66 µg/l (< 0.5 to 9.5)). In 80 unilateral BHRs with sequential ion measurements, Cr and Co levels were found to decrease significantly (p < 0.001) from the initial assessment at a median of six years (4 to 8) to the last assessment at a median of 11 years (9 to 13), with a mean reduction of 1.24 µg/l for Cr and 0.88 µg/l for Co. Three female patients had a > 2.5 µg/l increase of Co ions, associated with head sizes ≤ 50 mm, clinical symptoms and osteolysis. Overall, there was no significant difference in change of ion levels between genders (Cr, p = 0.845; Co, p = 0.310) or component sizes (Cr, p = 0.505; Co, p = 0.370). Higher acetabular component inclination angles correlated with greater change in ion levels (Cr, p = 0.013; Co, p = 0.002). Patients with increased ion levels had lower Harris hip scores (p = 0.038).

In conclusion, in well-functioning BHRs the metal ion levels decreased significantly at ten years. An increase > 2.5 µg/l was associated with poor function.

Cite this article: Bone Joint J 2013;95-B:1332–8.