We have examined the outcome of 400 consecutive patients who underwent total knee replacement with the Low Contact Stress mobile-bearing system between 1993 and 1994 and were followed up for a minimum of ten years. All operations were performed by surgeons in Christchurch, New Zealand, who used no other knee prosthesis during the study time.

At ten years after operation 238 patients (244 knees) remained for independent clinical and radiological assessment. There was a significant improvement (p < 0.001) in the postoperative knee scores at one, three, seven and ten years, although a slight deterioration in the score occurred between seven and ten years which did not reach statistical significance. The survival for polyethylene wear or loosening was 97% (95% CI 96 to 98) and survival using reoperation for any cause was 92% (95% CI 90 to 94) at 12 years. Polyethylene wear was more common in the meniscal-bearing component, with five knees requiring revision and a further eight demonstrating early wear. Osteolysis was not seen in the rotating platform component, but was present in three of the meniscal-bearing knees.

There was no association between the radiological alignment at one year and those knees that subsequently required revision. However, there was an association between the overall limb alignment and the Western Ontario McMasters University score (p < 0.001).

The Low Contact Stress mobile-bearing total knee replacement has proved to be a reliable implant at ten years when used in primary knee replacement irrespective of the deformity and diagnosis.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26).

At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision.

Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

We report the clinical and radiological outcome at ten years of 104 primary total hip replacements (100 patients) using the Metasul metal-on-metal bearing. Of these, 52 had a cemented Stuehmer-Weber polyethylene acetabular component with a Metasul bearing and 52 had an uncemented Allofit acetabular component with a Metasul liner. A total of 15 patients (16 hips) died before their follow-up at ten years and three were lost to follow-up. The study group therefore comprised 82 patients (85 hips).

The mean Oxford score at ten years was 20.7 (12 to 42). Six of 85 hips required revision surgery. One was performed because of infection, one for aseptic loosening of the acetabular component and four because of unexplained pain. Histological examination showed an aseptic lymphocytic vasculitis associated lesion-type tissue response in two of these. Continued follow-up is advocated in order to monitor the long-term performance of the Metasul bearing and tissue responses to metal debris.

Our aim was to determine the success rate of repeated debridement and two-stage cementless revision arthroplasty according to the type of infected total hip replacement (THR). We enrolled 294 patients (294 hips) with an infected THR in the study. There were 222 men and 72 women with a mean age of 55.1 years (24.0 to 78.0). The rate of control of infection after the initial treatment and after repeated debridement and two-stage revisions was determined. The clinical (Harris hip score) and radiological results were evaluated. The mean follow-up was 10.4 years (5.0 to 14.0).

The eventual rate of control of infection was 100.0% for early superficial post-operative infection, 98.4% for early deep post-operative infection, 98.5% for late chronic infection and 91.0% for acute haematogenous infection. Overall, 288 patients (98%) maintained a functioning THR at the latest follow-up. All the allografts appeared to be united and there were no failures.

These techniques effectively controlled infection and maintained a functional THR with firm fixation in most patients. Repeated debridement and two-stage or repeated two-stage revisions further improved the rate of control of infection after the initial treatment and increased the likelihood of maintaining a functional THR.

This prospective study describes the outcome of the first 1000 phase 3 Oxford medial unicompartmental knee replacements (UKRs) implanted using a minimally invasive surgical approach for the recommended indications by two surgeons and followed up independently. The mean follow-up was 5.6 years (1 to 11) with 547 knees having a minimum follow-up of five years. At five years their mean Oxford knee score was 41.3 (sd 7.2), the mean American Knee Society Objective Score 86.4 (sd 13.4), mean American Knee Society Functional Score 86.1 (sd 16.6), mean Tegner activity score 2.8 (sd 1.1). For the entire cohort, the mean maximum flexion was 130° at the time of final review.

The incidence of implant-related re-operations was 2.9%; of these 29 re-operations two were revisions requiring revision knee replacement components with stems and wedges, 17 were conversions to a primary total knee replacement, six were open reductions for dislocation of the bearing, three were secondary lateral UKRs and one was revision of a tibial component. The most common reason for further surgical intervention was progression of arthritis in the lateral compartment (0.9%), followed by dislocation of the bearing (0.6%) and revision for unexplained pain (0.6%). If all implant-related re-operations are considered failures, the ten-year survival rate was 96% (95% confidence interval, 92.5 to 99.5). If only revisions requiring revision components are considered failures the ten-year survival rate is 99.8% (confidence interval 99 to 100).

This is the largest published series of UKRs implanted through a minimally invasive surgical approach and with ten-year survival data. The survival rates are similar to those obtained with a standard open approach whereas the function is better. This demonstrates the effectiveness and safety of a minimally invasive surgical approach for implanting the Oxford UKR.

We present the clinical and radiographic outcome of 68 consecutive primary total hip replacements performed in 54 patients under the age of 55 years using a hydroxyapatite-coated femoral component and threaded cup with a modular ceramic head (JRI-Furlong). We reviewed 62 (91%) hips at a median follow-up of 8.8 years (5 to 13.8) after implantation; six (9%) were lost to follow-up. At review there had been four (6%) revisions but only one for aseptic loosening (acetabulum). Radiographic review of the remaining hips did not identify any evidence of femoral or acetabular loosening. The median Harris and Merle d’Aubigné and Postel hip scores were 95.9 (42.7 to 100) and 17 (3 to 18) respectively. The JRI-Furlong hip gives promising functional and radiographic results in young patients in the medium term.

In a prospective study, 93 unselected consecutive uncemented hip arthroplasties were performed in 80 patients using the titanium-coated RM acetabular component and the CLS femoral component. The mean age of the patients at operation was 52 years (28 to 81). None were lost to follow-up. In the 23 patients who had died (26 hips) only one acetabular component had been revised. In the 57 living patients (67 hips), 13 such revisions had been performed. Of the 14 revisions, seven were for osteolysis, five for loosening and two for infection.

Survival analysis of this implant showed a total probability of survival of 83% (95% confidence interval 73 to 90), with all revisions as the endpoint, and a probability of 94% (95% confidence interval 87 to 98) with revision for aseptic loosening as the endpoint, indicating reliable long-term fixation of the titanium-coated RM acetabular component.

This article considers some of the problems of the interpretation of information from other national arthroplasty registers when setting up a new register. In order for the most useful information to be available from registers much international co-operation is required between all those responsible for the design of registers as well as those who gather, assess and publish the data.

Our aim in this pilot study was to evaluate the fixation of, the bone remodelling around, and the clinical outcome after surgery of a new, uncemented, fully hydroxyapatite-coated, collared and tapered femoral component, designed specifically for elderly patients with a fracture of the femoral neck.

We enrolled 50 patients, of at least 70 years of age, with an acute displaced fracture of the femoral neck in this prospective single-series study. They received a total hip replacement using the new component and were followed up regularly for two years.

Fixation was evaluated by radiostereometric analysis and bone remodelling by dual-energy x-ray absorptiometry. Hip function and the health-related quality of life were assessed using the Harris hip score and the EuroQol-5D.

Up to six weeks post-operatively there was a mean subsidence of 0.2 mm (−2.1 to +0.5) and a retroversion of a mean of 1.2° (−8.2° to +1.5°). No component migrated after three months. The patients had a continuous loss of peri-prosthetic bone which amounted to a mean of 16% (−49% to +10%) at two years. The mean Harris hip score was 82 (51 to 100) after two years.

The two-year results from this pilot study indicate that this new, uncemented femoral component can be used for elderly patients with osteoporotic fractures of the femoral neck.

Total shoulder replacement is a successful procedure for degenerative or some inflammatory diseases of the shoulder. However, fixation of the glenoid seems to be the main weakness with a high rate of loosening. The results using all-polyethylene components have been better than those using metal-backed components. We describe our experience with 35 consecutive total shoulder replacements using a new metal-backed glenoid component with a mean follow-up of 75.4 months (48 to 154).

Our implant differs from others because of its mechanism of fixation. It has a convex metal-backed bone interface and the main stabilising factor is a large hollow central peg. The patients were evaulated with standard radiographs and with the Constant Score, the Simple Shoulder Test and a visual analogue scale. All the scores improved and there was no loosening, no polyethylene-glenoid disassembly and no other implant-related complications.

We conclude that a metal-backed glenoid component is a good option in total shoulder replacement with no worse results than of those using a cemented all-polyethylene prosthesis.

Our aim in this prospective study was to evaluate the outcome of total shoulder replacement in the treatment of young and middle-aged active patients with primary glenohumeral osteoarthritis. We reviewed 21 patients (21 shoulders) with a mean age of 55 years (37 to 60). The mean follow-up was seven years (5 to 9). The same anatomical, third-generation, cemented implant had been used in all patients. All the patients were evaluated radiologically and clinically using the Constant and Murley score.

No patients required revision. In one a tear of the supraspinatus tendon occurred. Overall, 20 patients (95%) were either very satisfied (n = 18) or satisfied (n = 2) with the outcome. Significant differences (p < 0.0001) were found for all categories of the Constant and Murley score pre- and post-operatively. The mean Constant and Murley score increased from 24.1 points (10 to 45) to 64.5 points (39 to 93), and the relative score from 30.4% (11% to 50%) to 83% (54% to 116%). No clinical or radiological signs of loosening of the implant were seen.

For young and middle-aged patients with osteoarthritis, third-generation total shoulder replacement is a viable method of treatment with a low rate of complications and excellent results in the mid-term.

Up to 20% of patients are not satisfied with the outcome following total knee replacement (TKR). This study investigated the pre- and post-operative predictors of dissatisfaction in a large cohort of patients undergoing TKR. We assessed 1217 consecutive patients between 2006 and 2008 both before operation and six months after, using the Short-form (SF)-12 health questionnaire and the Oxford Knee Score. Detailed information concerning comorbidity was also gathered. Satisfaction was measured at one year when 18.6% (226 of 1217) of patients were unsure or dissatisfied with their replacement and 81.4% (911 of 1217) were satisfied or very satisfied. Multivariate regression analysis was performed to identify independent predictors of dissatisfaction. Significant (p < 0.001) predictors at one year included the pre-operative SF-12 mental component score, depression and pain in other joints, the six-month SF-12 score and poorer improvement in the pain element of the Oxford Knee Score.

Patient expectations were highly correlated with satisfaction. Satisfaction following TKR is multifactorial. Managing the expectations and mental health of the patients may reduce dissatisfaction. However, the most significant predictor of dissatisfaction is a painful total knee replacement.

We report the findings of an independent review of 230 consecutive Birmingham hip resurfacings (BHRs) in 213 patients (230 hips) at a mean follow-up of 10.4 years (9.6 to 11.7). A total of 11 hips underwent revision; six patients (six hips) died from unrelated causes; and 13 patients (16 hips) were lost to follow-up. The survival rate for the whole cohort was 94.5% (95% confidence interval (CI) 90.1 to 96.9). The survival rate in women was 89.1% (95% CI 79.2 to 94.4) and in men was 97.5% (95% CI 92.4 to 99.2). Women were 1.4 times more likely to suffer failure than men. For each millimetre increase in component size there was a 19% lower chance of a failure. The mean Oxford hip score was 45.0 (median 47.0, 28 to 48); mean University of California, Los Angeles activity score was 7.4 (median 8.0, 3 to 9); mean patient satisfaction score was 1.4 (median 1.0, 0 to 9). A total of eight hips had lysis in the femoral neck and two hips had acetabular lysis. One hip had progressive radiological changes around the peg of the femoral component. There was no evidence of progressive neck narrowing between five and ten years.

Our results confirm that BHR provides good functional outcome and durability for men, at a mean follow-up of ten years. We are now reluctant to undertake hip resurfacing in women with this implant.

Pseudotumours are a rare complication of hip resurfacing. They are thought to be a response to metal debris which may be caused by edge loading due to poor orientation of the acetabular component. Our aim was to determine the optimal acetabular orientation to minimise the risk of pseudotumour formation.

We matched 31 hip resurfacings revised for pseudotumour formation with 58 controls who had a satisfactory outcome from this procedure. The radiographic inclination and anteversion angles of the acetabular component were measured on anteroposterior radiographs of the pelvis using Einzel-Bild-Roentgen-Analyse software. The mean inclination angle (47°, 10° to 81°) and anteversion angle (14°, 4° to 34°) of the pseudotumour cases were the same (p = 0.8, p = 0.2) as the controls, 46° (29° to 60°) and 16° (4° to 30°) respectively, but the variation was greater. Assuming an accuracy of implantation of ± 10° about a target position, the optimal radiographic position was found to be approximately 45° of inclination and 20° of anteversion. The incidence of pseudotumours inside the zone was four times lower (p = 0.007) than outside the zone.

In order to minimise the risk of pseudotumour formation we recommend that surgeons implant the acetabular component at an inclination of 45° (± 10) and anteversion of 20° (± 10) on post-operative radiographs. Because of differences between the radiographic and the operative angles, this may be best achieved by aiming for an inclination of 40° and an anteversion of 25°.

We studied the influence of soft-tissue releases and soft-tissue balance on the outcome of 526 total knee replacements one year after operation. The surgery had been performed by seven surgeons in five centres in the United Kingdom between October 1999 and December 2002. Balancing was carried out by five surgeons using spacers and trials and by two surgeons using a ‘balancer’ instrument. All the surgeons assessed the adequacy of their releases by taking measurements with the balancer after soft-tissue release before implanting the components. Independent observers collected the Oxford knee scores and applied the American Knee Society functional and knee scores as well as recording the range of movement of the replaced knee. These were compared with the pre-operative scores and the extent of the releases.

We found differences in outcomes between minimal and extensive releases and between balanced and imbalanced knees.

Knees requiring extensive soft-tissue releases showed greater change in the short-term clinical outcome without increased complications and achieved similar results at one year compared with those with less deformity pre-operatively which had required less soft-tissue release. Balancing an imbalanced knee improved the short-term knee outcome.

We reviewed the rate of revision of unicompartmental knee replacements (UKR) from the New Zealand Joint Registry between 1999 and 2008. There were 4284 UKRs, of which 236 required revision, 205 to a total knee replacement (U2T) and 31 to a further unicompartmental knee replacement (U2U). We used these data to establish whether the survival and functional outcome for revised UKRs were comparable with those of primary total knee replacement (TKR). The rate of revision for the U2T cohort was four times higher than that for a primary TKR (1.97 vs 0.48; p < 0.05). The mean Oxford Knee Score was also significantly worse in the U2T group than that of the primary TKR group (30.02 vs 37.16; p < 0.01). The rate of revision for conversion of a failed UKR to a further UKR (U2U cohort) was 13 times higher than that for a primary TKR. The poor outcome of a UKR converted to a primary TKR compared with a primary TKR should contra-indicate the use of a UKR as a more conservative procedure in the younger patient

We prospectively studied 217 patients who underwent 234 Elite Plus total hip arthroplasties. At a mean of 6.4 (SD 0.7) years post-operatively, 39 patients had died and 22 were either lost to follow-up or had no radiographs available. Clinical (Oxford hip score) and radiological assessments were performed on 156 patients (168 hip arthroplasties) who had a mean age of 67.7 (SD 9.7) years at operation. In the assessed group, 26 of 159 (16.4%) of femoral stems which had not already been revised and 19 of 159 (11.9%) of acetabular cups were definitely loose. In total, 52 of 168 (31%) of hips had either been revised or had definite evidence of loosening of a component. We could not establish any relationship between clinical and radiological outcomes. Despite the fact that the clinical outcome and rate of revision for the Elite Plus appeared to meet international standards, our findings give us cause for concern. We believe that joint registries should include radiological surveillance in order to provide reliable information about medium-term outcomes for hip prostheses

The survivorship of contemporary resurfacing arthroplasty of the hip using metal-on-metal bearings is better than that of first generation designs, but short-term failures still occur. The most common reasons for failure are fracture of the femoral neck, loosening of the component, osteonecrosis of the femoral head, reaction to metal debris and malpositioning of the component. In 2008 the Australian National Joint Registry reported an inverse relationship between the size of the head component and the risk of revision in resurfacing hip arthroplasty. Hips with a femoral component size of ≤ 44 mm have a fivefold increased risk of revision than those with femoral components of ≥ 55 mm irrespective of gender. We have reviewed the literature to explore this observation and to identify possible reasons including the design of the implant, loading of the femoral neck, the orientation of the component, the production of wear debris and the effects of metal ions, penetration of cement and vascularity of the femoral head. Our conclusion is that although multifactorial, the most important contributors to failure in resurfacing arthroplasty of the hip are likely to be the design and geometry of the component and the orientation of the acetabular component.

The cortical strains on the femoral neck and proximal femur were measured before and after implantation of a resurfacing femoral component in 13 femurs from human cadavers. These were loaded into a hip simulator for single-leg stance and stair-climbing. After resurfacing, the mean tensile strain increased by 15% (95% confidence interval (CI) 6 to 24, p = 0.003) on the lateral femoral neck and the mean compressive strain increased by 11% (95% CI 5 to 17, p = 0.002) on the medial femoral neck during stimulation of single-leg stance. On the proximal femur the deformation pattern remained similar to that of the unoperated femurs.

The small increase of strains in the neck area alone would probably not be sufficient to cause fracture of the neck However, with patient-related and surgical factors these strain changes may contribute to the risk of early periprosthetic fracture.

This article considers the establishment, purpose and conduct of knee arthroplasty registers using the Swedish register as an example. The methods of collection of appropriate data, the cost, and the ways in which this information may be used are considered.