The Rise in Single-Mother Families and Children's Cognitive Development: Evidence From Three British Birth Cohorts.

This article assessed changes in the association between single motherhood and children's verbal cognitive ability at age-11 using data from three cohorts of British children, born in 1958 (n = 10,675), 1970 (n = 8,933) and 2000 (n = 9,989), and mediation analysis. Consistent with previous studies, direct effects were small and insignificant. For those born in 1958 and 1970 indirect effects, operating through reduced economic and parental resources, were associated with -.107-SD to -.156-SD lower attainment. Differences between the two cohorts, and by children's age when parents separated, were insignificant. For the 2000 cohort, effect sizes for children born to single mothers did not change significantly (-.112-SD) but attenuated for children whose parents separated in early childhood (-.076-SD) or while of school age (-.054-SD).

EARLY, LATE OR NEVER? WHEN DOES PARENTAL EDUCATION IMPACT CHILD OUTCOMES?

We estimate the causal effect of parents' education on their children's education and examine the timing of the impact. We identify the causal effect by exploiting the exogenous shift in (parents') education levels induced by the 1972 minimum school leaving age reform in England. Increasing parental education has a positive causal effect on children's outcomes that is evident in preschool assessments at age 4 and continues to be visible up to and including high-stakes examinations taken at age 16. Children of parents affected by the reform attain results around 0.1 standard deviations higher than those whose parents were not impacted.

Implant Optimisation for Primary Hip Replacement in Patients over 60 Years with Osteoarthritis: A Cohort Study of Clinical Outcomes and Implant Costs Using Data from England and Wales.

BACKGROUND: Hip replacement is one of the most commonly performed surgical procedures worldwide; hundreds of implant configurations provide options for femoral head size, joint surface material and fixation method with dramatically varying costs. Robust comparative evidence to inform the choice of implant is needed. This retrospective cohort study uses linked national databases from England and Wales to determine the optimal type of replacement for patients over 60 years undergoing hip replacement for osteoarthritis. METHODS AND FINDINGS: Implants included were the commonest brand from each of the four types of replacement (cemented, cementless, hybrid and resurfacing); the reference prosthesis was the cemented hip procedure. Patient reported outcome scores (PROMs), costs and risk of repeat (revision) surgery were examined. Multivariable analyses included analysis of covariance to assess improvement in PROMs (Oxford hip score, OHS, and EQ5D index) (9159 linked episodes) and competing risks modelling of implant survival (79,775 procedures). Cost of implants and ancillary equipment were obtained from National Health Service procurement data. RESULTS: EQ5D score improvements (at 6 months) were similar for all hip replacement types. In females, revision risk was significantly higher in cementless hip prostheses (hazard ratio, HR = 2.22, p<0.001), when compared to the reference hip. Although improvement in OHS was statistically higher (22.1 versus 20.5, p<0.001) for cementless implants, this small difference is unlikely to be clinically important. In males, revision risk was significantly higher in cementless (HR = 1.95, p = 0.003) and resurfacing implants, HR = 3.46, p<0.001), with no differences in OHS. Material costs were lowest with the reference implant (cemented, range £1103 to £1524) and highest with cementless implants (£1928 to £4285). Limitations include the design of the study, which is intrinsically vulnerable to omitted variables, a paucity of long-term implant survival data (reflecting the duration of data collection), the possibility of revision under-reporting, response bias within PROMs data, and issues associated with current outcome scoring systems, which may not accurately reflect level of improvement in some patients. CONCLUSIONS: Cement fixation, using a polyethylene cup and a standard sized head offers good outcomes, with the lowest risks and at the lowest costs. The most commonly used cementless and resurfacing implants were associated with higher risk of revision and were more costly, while perceptions of improved function and longevity were unsupported.

No functional benefit of larger femoral heads and alternative bearings at 6 months following primary hip replacement.

BACKGROUND AND PURPOSE: There has been a recent trend towards the use of greater femoral head sizes in an attempt to improve function and enhance stability after primary hip replacement. This has been associated with the use of alternative bearings, theoretically to reduce wear and improve implant longevity. METHODS: We examined the influence of these variables on patient-reported outcome measures (PROMs) for a consecutive series of primary hip replacements using National Joint Registry (NJR) and PROMs-linked data. To minimize the confounding influence of implant design factors, the single most commonly used brand in England and Wales (DePuy Corail Pinnacle) was examined. Improvement in patient hip-specific outcomes (Oxford hip score, OHS), general health outcomes (Euroqol, EQ-5D), and rates of self-reported complications (bleeding, wound problems, re-admission, and reoperation) were compared for different head sizes (28-mm, 32-mm, and 36-mm) and bearings (metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), and ceramic-on-ceramic (CoC)), adjusting for differences in case mix. RESULTS: At a mean follow-up of 7 months, improvements in OHS and EQ5D index were similar for 28-mm and 36-mm heads. A 32-mm head was associated with poorer function (OHS: 20, 99% CI: 19-21, p = 0.002; EQ5D index: 0.39, 99% CI: 0.36-0.42, p = 0.004), although these small differences may not be of clinical importance. There were no statistically significant benefits of either CoP or CoC bearings compared to a MoP bearing. Complication rates were similar within comparisons of head sizes or bearings. INTERPRETATION: In this short-term study, we did not find any functional benefits of larger head sizes or alternative bearings, after adjusting for other influences. We question their use in routine primary hip replacement given the lack of evidence of improved long-term survival in the literature.

Have cementless and resurfacing components improved the medium-term results of hip replacement for patients under 60 years of age?

BACKGROUND AND PURPOSE: The optimal hip replacement for young patients remains unknown. We compared patient-reported outcome measures (PROMs), revision risk, and implant costs over a range of hip replacements. METHODS: We included hip replacements for osteoarthritis in patients under 60 years of age performed between 2003 and 2010 using the commonest brand of cemented, cementless, hybrid, or resurfacing prosthesis (11,622 women and 13,087 men). The reference implant comprised a cemented stem with a conventional polyethylene cemented cup and a standard-sized head (28- or 32-mm). Differences in implant survival were assessed using competing-risks models, adjusted for known prognostic influences. Analysis of covariance was used to assess improvement in PROMs (Oxford hip score (OHS) and EQ5D index) in 2014 linked procedures. RESULTS: In males, PROMs and implant survival were similar across all types of implants. In females, revision was statistically significantly higher in hard-bearing and/or small-stem cementless implants (hazard ratio (HR) = 4) and resurfacings (small head sizes (< 48 mm): HR = 6; large head sizes (≥ 48 mm): HR = 5) when compared to the reference cemented implant. In component combinations with equivalent survival, women reported significantly greater improvements in OHS with hybrid implants (22, p = 0.006) and cementless implants (21, p = 0.03) (reference, 18), but similar EQ5D index. For men and women, National Health Service (NHS) costs were lowest with the reference implant and highest with a hard-bearing cementless replacement. INTERPRETATION: In young women, hybrids offer a balance of good early functional improvement and low revision risk. Fully cementless and resurfacing components are more costly and do not provide any additional benefit for younger patients.

A comparison of surgical approaches for primary hip arthroplasty: a cohort study of patient reported outcome measures (PROMs) and early revision using linked national databases.

The posterior and lateral approaches to primary hip arthroplasty were compared using national data from England and Wales. Specific component combinations of the most commonly used cemented and cementless implant brands were analysed separately. There was no significant difference between the approaches for all-cause revision risk (cemented: P = 0.726, cementless: P = 0.295) and revision for dislocation (P = 0.176, P = 0.695) at 12 months following 37,593 procedures, after adjusting for patient and surgical variables. Analysis of 3881 linked episodes found the posterior approach was associated with significantly higher improvement in function (Oxford Hip Score: 20.8 versus 18.9, P < 0.001 (cemented procedures); 21.7 versus 20.2, P = 0.008 (cementless), EQ5D index: 0.416 versus 0.383, P = 0.003; 0.431 versus 0.384, P = 0.003). The posterior approach may offer a functional benefit (albeit small clinically), without increased revision risk.

Mid-term survival following primary hinged total knee replacement is good irrespective of the indication for surgery.

PURPOSE: The use of 'hinged' knee prostheses for primary knee arthroplasty procedures is increasing. This analysis reports the rates of implant survival, modes of failure, revision details and functional outcomes with particular reference to the primary indication for surgery for a cohort of patients treated with primary hinged knee replacement. METHODS: Systematic review with supplementary analysis using data from the National Joint Registry and Department of Health. Analysis included 964 patients undergoing primary hinged knee replacement between April 2003 and December 2010. Survival at a maximum of 7 years was calculated for the group as a whole and dependent upon the indication for surgery (osteoarthritis vs. rheumatoid/inflammatory arthritis vs. post-traumatic arthritis). Functional outcomes (pre- and post-operative Oxford Knee and Euroqol-5D scores and post-operative satisfaction) were available for 46 patients. RESULTS: In total, 20 cases required revision. The 5-year survival rate (96.8% [95% CI 95.1-98.4%]) was not dependent upon the primary surgical indication (p = n.s.). The commonest reasons for revision were infection (8 cases), peri-prosthetic fracture (4 cases) and aseptic loosening (3 cases). Patients reported substantial improvements in their Oxford Knee Score (mean improvement = 17.6, [95% CI 14.4-20.8]) and EQ5D index (mean improvement = 0.357, [95% CI 0.248-0.467]). Levels of post-operative satisfaction were high. CONCLUSIONS: Hinged knee replacement can be considered as a viable alternative to more traditional unconstrained designs in the complex primary setting. These findings are clinically relevant as they support the increasing use of hinged knee replacements for the arthritic knee in which there is concomitant severe bone loss, deformity or instability. Surgeons using these implants can have confidence that their mid-term performance is comparable to more conventional knee designs. LEVEL OF EVIDENCE: Prospective cohort study, Level II.

Center and surgeon volume influence the revision rate following unicondylar knee replacement: an analysis of 23,400 medial cemented unicondylar knee replacements.

BACKGROUND: Revision rates following unicondylar knee replacement vary among reporting institutions. Revision rates from institutions involved in the design of these implants and independent single-center series are comparable with those following total knee replacement, suggesting that higher operative volumes and surgical enthusiasm improve revision outcomes. METHODS: This registry-based cohort study involved the analysis of 23,400 medial cemented Oxford unicondylar knee replacements for the treatment of osteoarthritis. Total center and surgeon operative volumes were calculated over an eight-year time span since the inception of the registry (April 2003 to December 2010). The revision rate was calculated according to center volume and surgeon volume, each of which was grouped into five categories. The groups were compared with use of life tables, Kaplan-Meier plots, and Cox regression models that adjusted for variations in age, sex, and American Society of Anesthesiologists (ASA) grade among the groups. RESULTS: A total of 919 surgeons and a total of 366 centers performed at least one replacement, with the majority performing a small number of procedures. The revision rate for the centers with the lowest volume (fifty or fewer procedures over the eight-year study period) was 1.62 (95% confidence interval [CI], 1.42 to 1.82) revisions per 100 component years; this was significantly higher than the rate for the centers with the highest volume (more than 400 procedures), which was 1.16 (95% CI, 0.97 to 1.36) revisions per 100 component years. The five-year implant survival rate of 92.3% (95% CI, 91.2% to 93.3%) for the lowest-volume centers was significantly lower than the rate of 94.1% (95% CI, 93.0% to 95.2%) for the highest-volume centers. Similarly, the revision rate for the surgeons with the lowest volume (twenty-five or fewer procedures), 2.16 (95% CI, 1.91 to 2.41) revisions per 100 component years, was significantly higher than that for the surgeons with the highest volume (more than 200 procedures), 0.80 (95% CI, 0.62 to 0.98) revisions per 100 component years. The five-year survival rate of 90.1% (95% CI, 88.8% to 91.3%) for the lowest-volume surgeons was also significantly lower than the rate of 96.0% (95% CI, 95.0% to 97.0%) for the highest-volume surgeons. When center and surgeon volume were considered simultaneously, the hazard of revision was greater for lower-volume surgeons at lower-volume centers compared with higher-volume surgeons at higher-volume centers (hazard ratio = 1.87 [95% CI, 1.58 to 2.22], p < 0.001). CONCLUSIONS: High-volume centers and surgeons specializing in such procedures had superior results following unicondylar knee replacement compared with their low-volume counterparts. These results suggest that centers and surgeons should undertake a minimum of thirteen such procedures per year to achieve results comparable with the high-volume operators.

Cemented, cementless, and hybrid prostheses for total hip replacement: cost effectiveness analysis.

OBJECTIVE: To compare the cost effectiveness of the three most commonly chosen types of prosthesis for total hip replacement. DESIGN: Lifetime cost effectiveness model with parameters estimated from individual patient data obtained from three large national databases. SETTING: English National Health Service. PARTICIPANTS: Adults aged 55 to 84 undergoing primary total hip replacement for osteoarthritis. INTERVENTIONS: Total hip replacement using either cemented, cementless, or hybrid prostheses. MAIN OUTCOME MEASURES: Cost (£), quality of life (EQ-5D-3L, where 0 represents death and 1 perfect health), quality adjusted life years (QALYs), incremental cost effectiveness ratios, and the probability that each prosthesis type is the most cost effective at alternative thresholds of willingness to pay for a QALY gain. RESULTS: Lifetime costs were generally lowest with cemented prostheses, and postoperative quality of life and lifetime QALYs were highest with hybrid prostheses. For example, in women aged 70 mean costs were £6900 ($11 000; €8200) for cemented prostheses, £7800 for cementless prostheses, and £7500 for hybrid prostheses; mean postoperative EQ-5D scores were 0.78, 0.80, and 0.81, and the corresponding lifetime QALYs were 9.0, 9.2, and 9.3 years. The incremental cost per QALY for hybrid compared with cemented prostheses was £2500. If the threshold willingness to pay for a QALY gain exceeded £10 000, the probability that hybrid prostheses were most cost effective was about 70%. Hybrid prostheses have the highest probability of being the most cost effective in all subgroups, except in women aged 80, where cemented prostheses were most cost effective. CONCLUSIONS: Cemented prostheses were the least costly type for total hip replacement, but for most patient groups hybrid prostheses were the most cost effective. Cementless prostheses did not provide sufficient improvement in health outcomes to justify their additional costs.

Patient reported outcome measures after revision of the infected TKR: comparison of single versus two-stage revision.

PURPOSE: Two-stage revision is the 'gold standard' treatment for infected total knee replacement. Single-stage revision has been successful in the hip and, in carefully chosen knee revisions, may offer the advantage of a single surgical insult with improved functional outcome. METHODS: Patient Reported Outcome Measures (PROMs) for 33 single- and 89 two-stage revisions performed for infection were analysed in combination with data from the National Joint Registry for England and Wales. Outcomes including the Oxford Knee Score (OKS), Euroqol-5D (EQ5D) and patient satisfaction were examined with the aim of investigating the following questions: does single- or two-stage revision for infection result in (1) better knee function; (2) better overall perception of health status; (3) better patient perceived success and satisfaction? RESULTS: No statistical difference was found between the groups for any reported outcome measure. Mean OKS following surgery was 24.9 (95 %CI, 20.5-29.4) for single- and 22.8 (95 %CI, 20.2-25.4) for two-stage (n.s.). Mean EQ5D index following surgery was 0.495 (95 %CI, 0.357-0.632) for single and 0.473 (95 %CI, 0.397-0.548) for two-stage (n.s.). Patients reporting Excellent/Very good/Good satisfaction were similar between the groups (single = 61 % vs. two stage = 57 %, (n.s.)). In total, 66 % single- and 60 % two-stage operations were rated 'successful' (n.s.). CONCLUSIONS: This study found no demonstrable benefit of single-stage compared to two-stage revision for the infected total knee replacement using a variety of PROMs. Thus, we recommend that decision making must be based on other factors such as re-infection rate.

The association between body mass index and the outcomes of total knee arthroplasty.

BACKGROUND: In the United Kingdom, organizations involved in health-care commissioning have recently introduced legislation limiting access to total knee arthroplasty through the introduction of arbitrary thresholds unsupported by the literature and based on body mass index. This study aimed to establish the relationship between body mass index and patient-reported specific and general outcomes on total knee arthroplasty. METHODS: Using national patient-reported outcome measures (PROMs) linked to the National Joint Registry, we identified 13,673 primary total knee arthroplasties performed for the treatment of osteoarthritis. The PROMs project involves the collection of condition-specific and general health outcomes before and at six months following total knee arthroplasty. The relationships between body mass index and the Oxford Knee Score, EuroQol 5D index, and EuroQol 5D Visual Analogue Scale were assessed with use of scatterplots and linear regression. The improvement in these measures was compared for three distinct groups based on body mass index (Group I [15 to 24.9 kg/m(2)], Group II [25 to 39.9 kg/m(2)], and Group III [40 to 60 kg/m(2)]) with use of multiple regression analysis to adjust for differences in age, sex, American Society of Anesthesiologists grade, general health rating, and number of comorbidities. RESULTS: The preoperative and postoperative patient-reported outcome measures declined to a similar extent with increasing body mass index. The gradient of the linear regression equation relating to the change in scores was positive in all cases, indicating that there was a tendency for scores to improve to a greater extent as body mass index increased. After adjustment, the changes in patient-reported outcome measures in Group I and Group III were equivalent for the Oxford Knee Score (mean difference, 0.5 point [95% confidence interval, -0.5 to 1.5 points]; p = 0.78), the EuroQol 5D index (mean difference, 0.014 point [95% confidence interval, -0.021 to 0.048 point]; p = 1.00), and the EuroQol 5D Visual Analogue Scale (mean difference, 1.9 points [95% confidence interval, -0.4 to 4.1 points]; p = 0.13). Wound complications were significantly higher (p < 0.001) at a rate of 17% (168 of 1018 patients) in Group III compared with 9% (121 of 1292 patients) in Group I. CONCLUSIONS: The improvements in patient-reported outcome measures experienced by patients were similar, irrespective of body mass index. Health policy should be based on the overall improvements in function and general health gained through surgery. Obese patients should not be excluded from the benefit of total knee arthroplasty, given that their overall improvements were equivalent to those of patients with a lower body mass index.

Revision for unexplained pain following unicompartmental and total knee replacement.

BACKGROUND: Unicompartmental knee arthroplasty has been associated with consistently worse implant survival rates than total knee arthroplasty in worldwide arthroplasty registers. The rate of revision and the proportion of revisions performed for unexplained knee pain after either a unicompartmental or total knee arthroplasty were studied to assess if there is evidence to support the hypothesis that the numbers of revisions performed for unexplained knee pain differ between these two implant types. METHODS: Using data from the National Joint Registry (NJR) of England and Wales, we identified 402,714 primary knee arthroplasties (366,965 total knee arthroplasties and 35,749 unicompartmental knee arthroplasties) that were consecutively entered from April 2003 to December 2010. The status of all implants was assessed as of December 2010, at which time 6075 implants (4503 total knee implants and 1572 unicompartmental knee implants) had been revised at a maximum of eight years. Survival analysis and Cox regression analysis with adjustment of differences in age, sex, American Society of Anesthesiologists (ASA) grade, and indication for arthroplasty were performed with use of the end points of revision for any reason, revision for unexplained pain, and revision for other reasons. RESULTS: Revision for unexplained pain was more common after unicompartmental knee arthroplasty than after total knee arthroplasty (representing 23% of revisions as compared with 9% of revisions; p < 0.001). The five-year rate of revision for unexplained pain was 1.6% for the unicompartmental knee arthroplasty group and 0.2% for the total knee arthroplasty group. With use of Cox regression, the hazard ratio (HR) for unicompartmental knee arthroplasty relative to total knee arthroplasty with the end points of revision for any reason, revision for unexplained pain, and revision for all other reasons were 2.82 (95% confidence interval [CI], 2.66 to 2.99; p < 0.001), 6.76 (95% CI, 5.84 to 7.83; p < 0.001), and 2.39 (95% CI, 2.24 to 2.56; p < 0.001), respectively. The mean time from primary implantation to revision was similar for both implant types. CONCLUSIONS: While more unicompartmental knee implants than total knee implants were revised for unexplained pain, when these revisions for unexplained pain were discounted, unicompartmental knee arthroplasty still had a significantly greater risk of revision from other reasons than did total knee arthroplasty. The revision rate in isolation may not be a reliable way to compare different implant designs and should instead be considered in the context of the reason for failure.

Reason for revision influences early patient outcomes after aseptic knee revision.

BACKGROUND: Revision TKA less consistently produces improvements in clinical function and quality of life when compared with primary TKA. The reasons for this difference are unclear. QUESTIONS/PURPOSES: We determined differences in patient-reported outcomes and rates of satisfaction between primary and revision TKAs, and determine whether the reason for revision influences patient-reported outcomes after revision TKA. METHODS: We retrospectively analyzed prospectively collected patient-reported outcome measures (PROMs) for 24,190 patients (23,393 TKAs; 797 aseptic revision TKAs). We compared patient-reported outcomes using the Oxford Knee Score (OKS), EuroQol (EQ-5D), and patient satisfaction between primary TKA and revision TKA, and for subsets of the revision TKA cohort. The followup data were collected between 6 and 12 months (7 months average) postoperatively. RESULTS: Improvements in the OKS (10) and EQ-5D (0.231) were smaller after revision when compared with primary TKA (OKS, 15; EQ-5D, 0.303). Patients who had revision TKA were less satisfied (66% versus 83%). Revisions for aseptic loosening or lysis were associated with the best patient outcomes (OKS improvement = 11; EQ-5D improvement = 0.232; satisfaction = 72%). Revisions for stiffness had the worst results (OKS improvement = 6; EQ-5D improvement = 0.176; satisfaction = 47%). CONCLUSIONS: The early improvements in knee function and general health after revision TKA are only 69% to 76% of those observed for primary TKA. Levels of patient-reported knee function, general health, and satisfaction after revision are varied and related to the reason for revision. Even the best revision group does not approach the levels of function and satisfaction observed after primary TKA at a mean of 7 months postoperatively. Longer-term followup would be required to determine whether conclusions from these early data will need to be modified. LEVEL OF EVIDENCE: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Revision following patello-femoral arthoplasty.

PURPOSE: To describe the population of patients undergoing patello-femoral arthroplasty (PFA) revision and the reasons for which these implants are being revised. To compare this information with the observed failure patterns described in other national registries and with those seen for total knee replacement (TKR). METHODS: Using data accessed from the National Joint Registry for England and Wales, we identified 4634 primary PFA implanted between 1 April 2003 and 30 June 2010. As of 1 July 2010, 195 PFAs had been revised. The epidemiology of PFA revision is described with specific emphasis upon the reasons for revision. RESULTS: The median age at revision was 61 years (145 F:50 M). Revision occurred at a median of 2.0 years following primary surgery. Sixty of the 98 centres (61%) performing PFA revisions undertook only one such procedure. The 195 revisions were undertaken by 140 different consultants. Unexplained pain was the reason for revision in 46% of cases where a reason was stated. Progression of tibio-femoral arthritis was seen in only 14% of cases. Undiagnosed pain remained the most common reason for revision irrespective of patient age and time to revision, and was twice as common for PFA revision when compared to a matched group of failed TKR (43% vs. 19%, P < 0.001). CONCLUSIONS: Unexplained pain is the principal indication for early revision of the failing PFA. The high proportion of revisions performed for unexplained pain raises questions about the adequacy of surgical selection for patients undergoing PFA. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Monitoring the introduction and performance of a joint replacement: the United Kingdom metal-on-metal alert.

Recent events have made us question our ability to monitor the introduction and performance of a new prosthetic joint replacement. These concerns are mirrored in many other countries, even those with joint registries and other systems for detecting poorly performing implants. In the United Kingdom, as is the case in most European Union countries, we have assessment processes in place, particularly the CE (Conformité Européenne) mark, the National Joint Registry, and the Orthopaedic Data Evaluation Panel. It is important to realize that these organizations can only react to poor performance; it is not within their power as monitoring agencies to prevent a poor implant from entering the market. When an implant has been shown to perform badly, it is referred to the Medicines and Healthcare products Regulatory Agency (MHRA), which then discusses the report with the manufacturer. When it is deemed that there is unequivocal evidence of a serious problem with the implant, the MHRA issues alerts to all hospitals and practitioners. We have continuing concerns about how to assess and monitor modifications to already existing devices. Suggestions are made for improvements to this system, and the authors will welcome feedback.

Functional outcome of PFC Sigma fixed and rotating-platform total knee arthroplasty. A prospective randomised controlled trial.

The aim of this study was to determine whether there is a difference in functional outcome between the PFC Sigma fixed-bearing and rotating-platform total knee replacement systems. One hundred twenty patients were randomised to receive either a fixed-bearing or rotating-platform PFC Sigma total knee replacement. Range of movement (ROM), Oxford knee score (OKS) and Knee Society score (KSS) were assessed independently before and one year after surgery. Weight-bearing X-rays were taken immediately and one year post surgery to determine the incidence of osteolysis and loosening. At a mean follow-up of 13.4 months there was no statistically significant difference in mean ROM, OKS and KSS between the two groups. There was no evidence of osteolysis or loosening in either of the groups and no revision for infection or implant failure. This study shows that there is no statistically significant difference in functional outcome between the two types of implants at short-term follow-up.

Revision rates after primary hip and knee replacement in England between 2003 and 2006.

BACKGROUND: Hip and knee replacement are some of the most frequently performed surgical procedures in the world. Resurfacing of the hip and unicondylar knee replacement are increasingly being used. There is relatively little evidence on their performance. To study performance of joint replacement in England, we investigated revision rates in the first 3 y after hip or knee replacement according to prosthesis type. METHODS AND FINDINGS: We linked records of the National Joint Registry for England and Wales and the Hospital Episode Statistics for patients with a primary hip or knee replacement in the National Health Service in England between April 2003 and September 2006. Hospital Episode Statistics records of succeeding admissions were used to identify revisions for any reason. 76,576 patients with a primary hip replacement and 80,697 with a primary knee replacement were included (51% of all primary hip and knee replacements done in the English National Health Service). In hip patients, 3-y revision rates were 0.9% (95% confidence interval [CI] 0.8%-1.1%) with cemented, 2.0% (1.7%-2.3%) with cementless, 1.5% (1.1%-2.0% CI) with "hybrid" prostheses, and 2.6% (2.1%-3.1%) with hip resurfacing (p < 0.0001). Revision rates after hip resurfacing were increased especially in women. In knee patients, 3-y revision rates were 1.4% (1.2%-1.5% CI) with cemented, 1.5% (1.1%-2.1% CI) with cementless, and 2.8% (1.8%-4.5% CI) with unicondylar prostheses (p < 0.0001). Revision rates after knee replacement strongly decreased with age. INTERPRETATION: Overall, about one in 75 patients needed a revision of their prosthesis within 3 y. On the basis of our data, consideration should be given to using hip resurfacing only in male patients and unicondylar knee replacement only in elderly patients.

Assessing bone loss on radiographs of the knee in osteoarthritis: a cross-sectional study.

OBJECTIVE: The only established system to grade subchondral bone attrition in knee osteoarthritis (OA) has low interobserver reliability. In this study, our aim was to convert this system into a reliable tool for the assessment of subchondral bone loss in knee OA. METHODS: Templates that were designed to outline the normal contours of the knee were overlaid onto conventional radiographs of a random sample of 100 knees of OA patients who were awaiting total knee replacement (TKR). Seventy-five films from individuals with chronic knee pain who were not awaiting TKR and 75 films from asymptomatic control subjects were also assessed. Bone loss was graded from 0 (no attrition) to 3 (severe attrition of >10 mm); other established radiologic features were also graded. Spearman's rho was used to determine the correlation of attrition scores with other features, and logistic regression was used to explore whether definite bone attrition was associated with night pain. RESULTS: The inter- and intraobserver reliability values were high for attrition scores and for the presence of definite attrition (score > or =2). Bone attrition was evident in 62% of films from patients awaiting TKR, in 9% of films from individuals with chronic knee pain who were not awaiting TKR, and in 1% of films from controls. In all groups, the correlation between attrition and other features was weak to moderate. There was a nonsignificant association between definite bone attrition and night pain. CONCLUSION: Bone attrition is an additional dimension of knee OA that can be measured reliably. Definite attrition may be associated with night pain.

Equity and need when waiting for total hip replacement surgery.

OBJECTIVES: To explore sociodemographic and health status factors associated with waiting times both for first outpatient appointment and for total hip replacement surgery (THR). METHODS: A survey of THR in five former English regions was conducted between September 1996 and October 1997. Every patient listed for THR was asked to fill out a questionnaire preoperatively. This questionnaire included the 12-item Oxford Hip Score (OHS) questionnaire and two questions on the length of time patients waited for an outpatient appointment and subsequently for their operation. RESULTS: From multiple logistic regression analyses, region, private vs. public sector, housing tenure and preoperative OHS were all independently associated with a waiting time for an outpatient appointment for > 3 months. Region, housing tenure and gender were also independently associated with a wait of >or= 6 months on the surgical waiting list. CONCLUSIONS: A large proportion of patients had long waiting times both for an outpatient appointment and while on a surgical waiting list. There were significant differences in waiting time according to social, geographical and health care system factors. Patients with a worse pain and disability at surgery waited longer for an outpatient appointment. The longer patient waited, the worse was their pain and disability, suggesting that patients were not prioritized by these criteria. Benefits of prioritizing should be tested.