Unicompartmental knee arthroplasty (UKA) has advantages over total knee arthroplasty but national joint registries report a significantly higher revision rate for UKA. As a result, most surgeons are highly selective, offering UKA only to a small proportion (up to 5%) of patients requiring arthroplasty of the knee, and consequently performing few each year. However, surgeons with large UKA practices have the lowest rates of revision. The overall size of the practice is often beyond the surgeon’s control, therefore case volume may only be increased by broadening the indications for surgery, and offering UKA to a greater proportion of patients requiring arthroplasty of the knee.

The aim of this study was to determine the optimal UKA usage (defined as the percentage of knee arthroplasty practice comprised by UKA) to minimise the rate of revision in a sample of 41 986 records from the for National Joint Registry for England and Wales (NJR).

UKA usage has a complex, non-linear relationship with the rate of revision. Acceptable results are achieved with the use of 20% or more. Optimal results are achieved with usage between 40% and 60%. Surgeons with the lowest usage (up to 5%) have the highest rates of revision. With optimal usage, using the most commonly used implant, five-year survival is 96% (95% confidence interval (CI) 94.9 to 96.0), compared with 90% (95% CI 88.4 to 91.6) with low usage (5%) previously considered ideal.

The rate of revision of UKA is highest with low usage, implying the use of narrow, and perhaps inappropriate, indications. The widespread use of broad indications, using appropriate implants, would give patients the advantages of UKA, without the high rate of revision.

Cite this article: Bone Joint J 2015;97-B:1506–11.

Whether to use total or unicompartmental knee replacement (TKA/UKA) for end-stage knee osteoarthritis remains controversial. Although UKA results in a faster recovery, lower rates of morbidity and mortality and fewer complications, the long-term revision rate is substantially higher than that for TKA. The effect of each intervention on patient-reported outcome remains unclear. The aim of this study was to determine whether six-month patient-reported outcome measures (PROMs) are better in patients after TKA or UKA, using data from a large national joint registry (NJR).

We carried out a propensity score-matched cohort study which compared six-month PROMs after TKA and UKA in patients enrolled in the NJR for England and Wales, and the English national PROM collection programme. A total of 3519 UKA patients were matched to 10 557 TKAs.

The mean six-month PROMs favoured UKA: the Oxford Knee Score was 37.7 (95% confidence interval (CI) 37.4 to 38.0) for UKA and 36.1 (95% CI 35.9 to 36.3) for TKA; the mean EuroQol EQ-5D index was 0.772 (95% CI 0.764 to 0.780) for UKA and 0.751 (95% CI 0.747 to 0.756) for TKA. UKA patients were more likely to achieve excellent results (odds ratio (OR) 1.59, 95% CI 1.47 to 1.72, p < 0.001) and to be highly satisfied (OR 1.27, 95% CI 1.17 to 1.39, p <  0.001), and were less likely to report complications than those who had undergone TKA.

UKA gives better early patient-reported outcomes than TKA; these differences are most marked for the very best outcomes. Complications and readmission are more likely after TKA. Although the data presented reflect the short-term outcome, they suggest that the high revision rate for UKA may not be because of poorer clinical outcomes. These factors should inform decision-making in patients eligible for either procedure.

Cite this article: Bone Joint J 2015;97-B:793–801.

Patient-reported outcome measures (PROMs) are increasingly being used to assess functional outcome and patient satisfaction. They provide a framework for comparisons between surgical units, and individual surgeons for benchmarking and financial remuneration. Better performance may bring the reward of more customers as patients and commissioners seek out high performers for their elective procedures. Using National Joint Registry (NJR) data linked to PROMs we identified 22 691 primary total knee replacements (TKRs) undertaken for osteoarthritis in England and Wales between August 2008 and February 2011, and identified the surgical factors that influenced the improvements in the Oxford knee score (OKS) and EuroQol-5D (EQ-5D) assessment using multiple regression analysis. After correction for patient factors the only surgical factors that influenced PROMs were implant brand and hospital type (both p < 0.001). However, the effects of surgical factors upon the PROMs were modest compared with patient factors. For both the OKS and the EQ-5D the most important factors influencing the improvement in PROMs were the corresponding pre-operative score and the patient’s general health status. Despite having only a small effect on PROMs, this study has shown that both implant brand and hospital type do influence reported subjective functional scores following TKR. In the current climate of financial austerity, proposed performance-based remuneration and wider patient choice, it would seem unwise to ignore these effects and the influence of a range of additional patient factors.

Purpose. To review the Five year survivorship of Kinnemax TKA performed at the NHS Treatment Cantre, Weston-Super-Mare (WSM), and compare it to a similar cohort from our institution. Introduction. As part of the government's initiative to reduce waiting times for major joint surgery in Wales, the Cardiff and Vale NHS Trust (CAVOC) sent 224 patients (258 knees) to the NHS Treatment Centre in Weston-Super-Mare (WSM) for total knee arthroplasty. Controversy remains as to the unexpectedly high revision rates previously seen. Method. Between April 2004 and January 2006, 224 patients (258 TKAs) were performed at WSM. 90% have been followed up to five years. The WSM Cohort was compared to a similar cohort of 260 consecutive TKAs from CAVOC over a similar time period (2004/5) performed by a number of surgeons. Oxford Knee Score, EQ5D, VAS for pain, re-operation and overall satisfaction were obtained. Statistical testing was performed with chi-squared tests using SPSS v16.0 (a=0.05). Results. Mean age in years at date of operation was 68 (36-85) from WSM and 70 (41 to 87) fromCAVOC. The 5 year cumulative survival rate using ‘revision any cause’ as the endpoint, was 79.9% (95% CI 72.46 to 85.9) in the WSM cohort and 96.4% (95%CI 94.1 to 99.1) in the CAVOC cohort. The relative risk for revision at the ISTC as opposed to the referring centre was 3.76 (p<0.001). The mean Oxford Knee Score was 27.5 (range 2-48) for the WSM cohort. The average, non-revised, oxford knee score for the WSM cohort lower than expected at 29. This is lower than other published series of primary TKA. Conclusion. This is the first published five year survivorship for total knee arthroplasty performed at a first generation ISTC in the UK. Revision rates, functional outcomes, and overall health status results are below expected when compared to a similar cohort from a standard NHS Orthopaedic Unit

Following arthroplasty of the knee, the patient’s perception of improvement in symptoms is fundamental to the assessment of outcome. Better clinical outcome may offset the inferior survival observed for some types of implant. By examining linked National Joint Registry (NJR) and patient-reported outcome measures (PROMs) data, we aimed to compare PROMs collected at a minimum of six months post-operatively for total (TKR: n = 23 393) and unicondylar knee replacements (UKR: n = 505). Improvements in knee-specific (Oxford knee score, OKS) and generic (EuroQol, EQ-5D) scores were compared and adjusted for case-mix differences using multiple regression. Whereas the improvements in the OKS and EQ-5D were significantly greater for TKR than for UKR, once adjustments were made for case-mix differences and pre-operative score, the improvements in the two scores were not significantly different. The adjusted mean differences in the improvement of OKS and EQ-5D were 0.0 (95% confidence interval (CI) -0.9 to 0.9; p = 0.96) and 0.009 (95% CI -0.034 to 0.015; p = 0.37), respectively.

We found no difference in the improvement of either knee-specific or general health outcomes between TKR and UKR in a large cohort of registry patients. With concerns about significantly higher revision rates for UKR observed in worldwide registries, we question the widespread use of an arthroplasty that does not confer a significant benefit in clinical outcome.

As part of the national initiative to reduce waiting times for joint replacement surgery in Wales, the Cardiff and Vale NHS Trust referred 224 patients to the NHS Treatment Centre in Weston-Super-Mare for total knee replacement (TKR). A total of 258 Kinemax TKRs were performed between November 2004 and August 2006. Of these, a total of 199 patients (232 TKRs, 90%) have been followed up for five years. This cohort was compared with 258 consecutive TKRs in 250 patients, performed at Cardiff and Vale Orthopaedic Centre (CAVOC) over a similar time period. The five year cumulative survival rate was 80.6% (95% confidence interval (CI) 74.0 to 86.0) in the Weston-Super-Mare cohort and 95.0% (95% CI 90.2 to 98.2) in the CAVOC cohort with revision for any reason as the endpoint. The relative risk for revision at Weston-Super-Mare compared with CAVOC was 3.88 (p < 0.001). For implants surviving five years, the mean Oxford knee scores (OKS) and mean EuroQol (EQ-5D) scores were similar (OKS: Weston-Super-Mare 29 (2 to 47) vs CAVOC 29.8 (3 to 48), p = 0.61; EQ-5D: Weston-Super-Mare 0.53 (-0.38 to 1.00) vs CAVOC 0.55 (-0.32 to 1.00), p = 0.79). Patients with revised TKRs had significantly lower Oxford knee and EQ-5D scores (p < 0.001).

The results show a higher revision rate for patients operated at Weston-Super-Mare Treatment Centre, with a reduction in functional outcome and quality of life after revision. This further confirms that patients moved from one area to another for joint replacement surgery fare poorly.

Introduction. We conducted a study of 312 patients undergoing primary hip and knee arthroplasty in 2005. The aim was to identify the correlation between length of stay, ASA (American society of Anaesthesiologist) grade and BMI (Body Mass Index). Method and materials. 312 patients underwent hip and knee arthroplasty in 2005. ASA grade for surgery was documented by the anaesthetist and BMI by the nurses. 67 patients had inadequate documentation. SPSS software was used for analysis. Results. Of the 245 patients; 35 had ASA grade 1, 144 had ASA grade 2, 64 had ASA grade 3 and 2 had ASA grade 4. Mean length of stay for ASA grade 1 was 6.8 days, ASA grade 2 was 9.75 days, ASA grade 3 was 12.5 days and ASA grade 4 was 13.5 days. There was significant positive correlation (p < 0.01) between the ASA grade and post-operative length of stay. BMI was graded as I (<18.5), II (18.5-24.9), III (25-29.9) and IV (>30). There was no correlation (Pearson's correlation coefficient = 0.184) between BMI and post-operative length of stay. Conclusion. As the ASA grade increases the length of stay in hospital increases. ‘Cherry picking’ of ASA grade I and II patients by the ISTC will increase the average length of stay in NHS hospitals resulting in increased cost. Length of stay on its own is not a good indicator of hospital performance

Purpose. A comparison of patient satisfaction of service provided by independent sector treatment centres versus an index NHS hospital in total knee replacement surgery. Methods. Patients were all initially listed for total knee replacement (TKR) by a single consultant from the index NHS hospital, Derbyshire Royal Infirmary (DRI). Patients were sent a postal questionnaire and asked to rate the TKR service provided by a given hospital, based on recent inpatient experience. Questions covered quality of care delivered by hospital staff and quality of ward environment. Overall satisfaction was rated. Patients electing surgery under Patient Choice at an independent sector treatment centre (ISTC) were asked about factors that influenced their hospital choice. 100 consecutive patients undergoing TKR at DRI and 100 patients choosing ISTC hospitals were identified. All surgery occurred between April 2003 and September 2006. Results. Questionnaire response rates were 79% for DRI patients and 54% for ISTC. Overall patient satisfaction for TKR service was 95% for DRI and 87% for ISTC. An equal 61% rated the surgeons as excellent in both DRI and ISTC hospitals. Nurses and physiotherapists (& occupational therapists) both scored more highly in ISTC groups (Nurses 69% v 45%; physio/OT 57% v 35%). Ward environment rated excellent in 73% for ISTC and 24% for DRI. The most common reason for choosing ISTC was shorter waiting list (42%). Conclusion. ISTC hospitals scored more highly in terms of nurses, physiotherapy & occupational therapy, and ward environment. In part, this may arise from better staffing levels and newer facilities in the ISTC sector. Despite this, overall patient satisfaction for TKR service remained greater at the index NHS hospital. This suggests overall satisfaction depends on more complex factors than staff and ward environment. Further work is needed to compare objective clinical outcomes of TKR between hospital groups within the NHS

Independent sector treatment centres (ISTCs) were introduced in October 2003 in the United Kingdom in order to reduce waiting times for elective operations and to improve patient choice and experience. Many concerns have been voiced from several authorities over a number of issues related to these centres. One of these concerns was regarding the practice of ‘cherry-picking’. Trusts are paid according to ‘payment by results’ at national tariffs. The national tariff is an average of costs occurring in an average mix of patients. The assumption is that the higher the co-morbidities of the patients the more likely they are to consume a higher amount of resource and to require a longer length of stay. Cherry-picking may also affect the quality of training available to trainees. This audit was aimed at identifying if, and how much this practice occurs. It also identifies what affect this has on the case-load of patients left for the NHS hospitals. We looked at the number of co-morbidities amongst 198 consecutive patients undergoing hip and knee primary total arthroplasty at an ISTC, a district general hospital whose PCTs provide patient to the ISTC (Doncaster Royal Infirmary - DRI), and a district general hospital in the same area whose PCT did not provide choice at that time and who therefore did not send patients to the ISTC (Bassetlaw District General Hospital - BDGH). We found a statistically significant difference in the number of co-morbidities per patient at the ISTC compared with the DRI (1.23 vs. 2.05) and the ISTC compared with the BDGH (1.23 vs. 1.76). We were unable to show a statistically significant difference between the DRI and the BDGH. We conclude that cherry-picking does take place, and further work should be done to assess the impact on training and finance

Introduction: The emergence of Independent Sector Treatment Centres (ISTCs) in the UK for the provision of elective orthopaedic services began in 2002–3. Within our trust the bulk of elective orthopaedic surgery is performed in an ISTC however there is a small but significant cohort of patients who are deemed not suitable for treatment at the ISTC. Patients with a BMI (body mass index) ≥40 or an ASA (American society of anaesthesiologists) grade of 3 or more are automatically rejected. With increasing levels of obesity and an aging population the size of the reject cohort is going to rise. These patients are then returned to the NHS to be placed on a new (complex elective) waiting list for their surgery. The aim of this study was to assess the early outcomes and complications following primary knee arthroplasty on our high risk patients. Methods: A retrospective review of a consecutive series of 214 primary knee arthroplasties in patients rejected from the ISTC was performed. Data (demographics, ASA grade, BMI, length of stay, complications, range of knee movement and requirement for HDU/ICU) were collected from preoperative assessments, inpatient notes, anaesthetic charts, discharge summaries and follow up clinic letters. All patients were followed up for a minimum of 6 months. Results: 155 (72%) patients were female. 140 (65%) had ASA of 3 or more. 88 (41%) had a BMI of 40 or more. Median length of stay was 8 days (6 to 11 IQR) and did not vary with increasing BMI but increased to 10 days in the ASA 3 and 12 days in the ASA 4 group. There were a total 90 complications in 71 patients. The most common complications were 22 superficial wound infections (10.3%), 11 Pneumonias (5.1%), and 9 symptomatic DVTs (4.2%). There were 16 severe complications (2 Deep infections, 4 PEs, 2 CVAs, 4 acute renal failures and 4 dislocations) in 15 patients. Patients with a BMI < 40 had a total complication rate of 38% (7.9% severe) compared with 26% (5.7% severe) in BMI ≥40 group. Patients with an ASA < 3 had a complication rate of 31% (4.1% severe) vs. 34% (8.6% severe) in patients with an ASA ≥ 3. HDU/ICU beds were required postoperatively for 20 patients (9 planned and 11 unplanned). At six months 72% achieved a knee range of movement ≥ 0 to 90 degrees. Surgeons who performed high volumes of surgery in this difficult group had lower complications then lower volume surgeons. Conclusion: This is one of the largest consecutive groups of high risk patients undergoing primary total knee arthroplasty. Our results show that elevated BMI does not appear to adversely affect complication rates in knee arthroplasty in our series although ASA grades of 3 and 4 are associated with increased length of stay and complication rates. It is also clear that small groups of surgeons operating on these difficult patients may reduce complications

Recent publication of reports showing high revision rates for hip and knee replacements carried out in Independent Sector Treatment Centres (ISTCs) has raised doubts regarding their ability to provide high quality healthcare. The high revision rates also create a financial burden to the NHS. The poor quality of data collected at ISTCs makes their performance difficult to evaluate. Funds may be better spent improving existing NHS facilities rather than establishing parallel ISTCs.

Introduction: Elective Orthopaedics has been targeted by the department of health in the U.K. as a maximum six-month waiting time for operations could not be met. National Orthopaedic project was initiated as a consequence and Independent Sector Treatment Centres (ISTC) and well established private hospitals were utilised to treat NHS long wait patients. Materials and Methods: We audited the primary total hip replacements performed in our hospital in 1998 and 2003 to compare the differences in the patient characteristics in particular age, length of stay and ASA grade. Results: The number of hip replacements increased to 308 in year 2003 from 194 in year 1998. Whilst, the number of ASA I patients were the same, the ASA II. III, IV increased by 40%, 260%, 266% respectively. The average length of stay decreased from 14.3 to 11.9 days which was statistically significant, in spite of increased numbers of ASA II – IV patients. Discussion: The NHS hospitals are treating increasing number of patients who have a higher anaesthetic risk and are likely to stay longer in the hospital in the post-operative period. The case mix for primary total hip replacements in large tertiary referral hospitals have changed due to altered patient flow due to cherry picking of NHS waiting lists by the ISTC. NHS hospitals should be appropriately remunerated for dealing with complex cases and for managing complications referred by ISTC hospitals. In fact, the National joint registry’s 2. nd. annual report confirms that 40% of primary total hip replacements operated in ISTC’s were ASA I while only 25% of primary total hip replacements operated in NHS hospitals were ASA I. None of the ISTC’s performed complex primary THRs

Background: Independent Sector Treatment Centres (ISTC) are now providing significant volumes of elective orthopaedic care in the UK. They have been the subject of considerable publicity. The ISTC in Plymouth was the first newly built orthopaedic centre to open. This paper describes the methods of working and analyses the early results of nearly a thousand joint replacements implanted between May 2005 and April 2006. It is the first set of such results to be become available. Methods: Data on each case was collected prospectively and entered into a database. This included demographic information, surgical and implant data, blood loss and transfusion requirements, length of stay, patient satisfaction, readmission rate, complications and mortality. One hundred consecutive postoperative hip replacement x-rays were scored by an independent orthopaedic surgeon. The alignment of one hundred consecutive postoperative knee x-rays was evaluated by long leg views. Comparison is made to published UK and international data. Results: Ongoing. Conclusion: Ongoing