45-day mortality after 467,779 knee replacements for osteoarthritis from the National Joint Registry for England and Wales: an observational study

An analysis of 30-day mortality after weekend versus weekday elective joint arthroplasty in England and Wales

Aims

To investigate whether elective joint arthroplasty performed at the weekend is associated with a different 30-day mortality versus that performed between Monday and Friday.

Patients and Methods

We examined the 30-day cumulative mortality rate (Kaplan-Meier) for all elective hip and knee arthroplasties performed in England and Wales between 1st April 2003 and 31st December 2014, comprising 118 096 episodes undertaken at the weekend and 1 233 882 episodes performed on a weekday. We used Cox proportional-hazards regression models to assess for time-dependent variation and adjusted for identified risk factors for mortality.

Results

The cumulative 30-day mortality for hip arthroplasty was 0.15% (95% confidence interval (CI) 0.12 to 0.19) for patients operated on at the weekend versus 0.20% (95% CI 0.19 to 0.21) for patients undergoing surgery during the normal working week. For knee arthroplasty, the cumulative 30-day mortality was 0.14% (95% CI 0.11 to 0.17) for weekend-operated patients versus 0.18% (95% CI 0.17 to 0.19) for weekday-operated patients. These differences were independent of any differences in patient age, gender, American Society of Anaesthesiologists grade, surgeon seniority, surgical and anaesthetic practices, and thromboprophylaxis choice in weekend versus weekday-operated patients.

Conclusion

The 30-day mortality rate after elective joint arthroplasty is low. Surgery performed at the weekend is associated with lower post-operative mortality versus operations performed on a weekday. Cite this article: Bone Joint J 2017;99-B:1618–28.

Aspirin and the prevention of venous thromboembolism following total joint arthroplasty: commonly asked questions

The number of arthroplasties being performed increases each year. Patients undergoing an arthroplasty are at risk of venous thromboembolism (VTE) and appropriate prophylaxis has been recommended. However, the optimal protocol and the best agent to minimise VTE under these circumstances are not known. Although many agents may be used, there is a difference in their efficacy and the risk of bleeding. Thus, the selection of a particular agent relies on the balance between the desire to minimise VTE and the attempt to reduce the risk of bleeding, with its undesirable, and occasionally fatal, consequences.

Acetylsalicylic acid (aspirin) is an agent for VTE prophylaxis following arthroplasty. Many studies have shown its efficacy in minimising VTE under these circumstances. It is inexpensive and well-tolerated, and its use does not require routine blood tests. It is also a ‘milder’ agent and unlikely to result in haematoma formation, which may increase both the risk of infection and the need for further surgery. Aspirin is also unlikely to result in persistent wound drainage, which has been shown to be associated with the use of agents such as low-molecular-weight heparin (LMWH) and other more aggressive agents.

The main objective of this review was to summarise the current evidence relating to the efficacy of aspirin as a VTE prophylaxis following arthroplasty, and to address some of the common questions about its use.

There is convincing evidence that, taking all factors into account, aspirin is an effective, inexpensive, and safe form of VTE following arthroplasty in patients without a major risk factor for VTE, such as previous VTE.

Cite this article: Bone Joint J 2017;99-B:1420–30.

Hospital volume and the risk of revision in Oxford unicompartmental knee arthroplasty in the Nordic countries -an observational study of 14,496 cases

Background

High procedure volume and dedication to unicompartmental knee arthroplasty (UKA) has been suggested to improve revision rates. This study aimed to quantify the annual hospital volume effect on revision risk in Oxfordu nicompartmental knee arthroplasty in the Nordic countries.

Methods

14,496 cases of cemented medial Oxford III UKA were identified in 126 hospitals in the four countries included in the Nordic Arthroplasty Register Association (NARA) database from 2000 to 2012. Hospitals were divided by quartiles into 4 annual procedure volume groups (≤11, 12-23, 24-43 and ≥44). The outcome was revision risk after 2 and 10 years calculated using Kaplan Meier method. Multivariate Cox regression analysis was used to assess the Hazard Ratio (HR) of any revision due to specific reasons with 95% confidence intervals (CI).

Results

The implant survival was 80% at 10 years in the volume group ≤11 procedures per year compared to 83% in other volume groups. The HR adjusted for age category, sex, year of surgery and nation was 0.87 (95% CI: 0.76-0.99, p = 0.036) for the group 12-23 procedures per year, 0.78 (95% CI: 0.68-0.91, p = 0.002) for the group 24-43 procedures per year and 0.82 (95% CI: 0.70-0.94, p = 0.006) for the group ≥44 procedures per year compared to the low volume group. Log-rank test was p = 0.003. The risk of revision for unexplained pain was 40-50% higher in the low compared with other volume groups.

Conclusion

Low volume hospitals performing ≤11 Oxford III UKAs per year were associated with an increased risk of revision compared to higher volume hospitals, and unexplained pain as revision cause was more common in low volume hospitals.

A unified multi-level model approach to assessing patient responsiveness including; return to normal, minimally important differences and minimal clinically important improvement for patient reported outcome measures

OBJECTIVE

This article reviews and compares four commonly used approaches to assess patient responsiveness with a treatment or therapy (return to normal (RTN), minimal important difference (MID), minimal clinically important improvement (MCII), OMERACT-OARSI [Outcome Measures in Rheumatology-Osteoarthris Reseach Society International] (OO)) and demonstrates how each of the methods can be formulated in a multilevel modelling (MLM) framework.

DESIGN

Cohort study.

SETTING

A cohort of patients undergoing total hip and knee replacement were recruited from a single UK National Health Service hospital.

POPULATION

400 patients from the Arthroplasty Pain Experience cohort study undergoing total hip (n=210) and knee (n=190) replacement who completed the Intermittent and Constant Osteoarthritis Pain questionnaire prior to surgery and then at 3, 6 and 12 months after surgery.

PRIMARY OUTCOMES

The primary outcome was defined as a response to treatment following total hip or knee replacement. We compared baseline scores, change scores and proportion of individuals defined as 'responders' using traditional and MLM approaches with patient responsiveness.

RESULTS

Using existing approaches, baseline and change scores are underestimated, and the variance of baseline and change scores overestimated in comparison with MLM approaches. MLM increases the proportion of individuals defined as responding in RTN, MID and OO criteria compared with existing approaches. Using MLM with the MCII criteria reduces the number of individuals identified as responders.

CONCLUSION

MLM improves the estimation of the SD of baseline and change scores by explicitly incorporating measurement error into the model and avoiding regression to the mean when making individual predictions. Using refined definitions of responsiveness may lead to a reduction in misclassification when attempting to predict who does and does not respond to an intervention and clarifies the similarities between existing methods.

A pragmatic randomised controlled trial comparing the efficacy of a femoral nerve block and periarticular infiltration for early pain relief following total knee arthroplasty

AIMS

The aim of this study was to compare the effectiveness of a femoral nerve block and a periarticular infiltration in the management of early post-operative pain after total knee arthroplasty (TKA).

PATIENTS AND METHODS

A pragmatic, single centre, two arm parallel group, patient blinded, randomised controlled trial was undertaken. All patients due for TKA were eligible. Exclusion criteria included contraindications to the medications involved in the study and patients with a neurological abnormality of the lower limb. Patients received either a femoral nerve block with 75 mg of 0.25% levobupivacaine hydrochloride around the nerve, or periarticular infiltration with 150 mg of 0.25% levobupivacaine hydrochloride, 10 mg morphine sulphate, 30 mg ketorolac trometamol and 0.25 mg of adrenaline all diluted with 0.9% saline to make a volume of 150 ml.

RESULTS

A total of 264 patients were recruited and data from 230 (88%) were available for the primary analysis. Intention-to-treat analysis of the primary outcome measure of a visual analogue score for pain on the first post-operative day, prior to physiotherapy, was similar in both groups. The mean difference was -0.7 (95% confidence interval (CI) -5.9 to 4.5; p = 0.834). The periarticular group used less morphine in the first post-operative day compared with the femoral nerve block group (74%, 95% CI 55 to 99). The femoral nerve block group reported 39 adverse events, of which 27 were serious, in 31 patients and the periarticular group reported 51 adverse events, of which 38 were serious, in 42 patients up to six weeks post-operatively. None of the adverse events were directly attributed to either of the interventions under investigation.

CONCLUSION

Periarticular infiltration is a viable and safe alternative to femoral nerve block for the early post-operative relief of pain following TKA. Cite this article: Bone Joint J 2017;99-B:904-11.

Is decreasing mortality in total hip and knee arthroplasty patients dependent on patients' comorbidity?

Background and purpose - Mortality after primary total hip and knee arthroplasty (THA and TKA) has declined, and the proportion of THA and TKA patients with comorbid conditions has increased. We therefore wanted to examine changes in comorbidity burden over time and the impact of comorbid on mortality following primary total hip and knee arthroplasty in patients with osteoarthritis. Patients and methods - We used the Danish arthroplasty registers to identify THA and TKA patients from 1996 through 2013. From administrative databases, we collected data on pre-surgery hospital history for all patients, which were used to calculate the Charlson comorbidity index (CCI). Patients were divided into 4 groups: CCI-none, CCI-low, CCI-moderate, and CCI-high. We calculated the relative risk (RR) of mortality within 90 days after surgery with a 95% confidence interval (CI), with stratification according to CCI group and year of surgery. Results - 99,962 THAs and 63,718 TKAs were included. The proportion of THAs with comorbidity increased by 3-4% in CCI-low, CCI-moderate, and CCI-high patients, from 1996-1999 to 2010-2013. The overall 90-day mortality risk declined for both procedures. Compared to CCI-none, THA patients with low, moderate, and high comorbidity burdens had an RR of 90-day mortality of 1.9 (95% CI: 1.6-2.4), 1.9 (CI: 1.5-2.5), and 3.3 (CI: 2.6-4.2), respectively. Similar increases in proportions and RRs were observed in TKAs. Interpretation - Despite the fact that the proportion of THA and TKA patients with comorbidities has increased over the past 18 years, the overall mortality has declined. The mortality risk depended on the comorbidity burden and did not decline during the study period for THA and TKA patients with a moderate or high comorbidity burden at the time of surgery.

Five-year clinical and radiological outcomes in 257 consecutive cementless Oxford medial unicompartmental knee arthroplasties

Aims

Our aim was to examine the clinical and radiographic outcomes in 257 consecutive Oxford unicompartmental knee arthroplasties (OUKAs) (238 patients), five years post-operatively.

Patients and Methods

A retrospective evaluation was undertaken of patients treated between April 2008 and October 2010 in a regional centre by two non-designing surgeons with no previous experience of UKAs. The Oxford Knee Scores (OKSs) were recorded and fluoroscopically aligned radiographs were assessed post-operatively at one and five years.

Results

The median age of the 238 patients was 65.0 years (interquartile range (IQR) 59.0 to 73.0), the median body mas index was 30.0 (IQR 27.5 to 33.0) and 51.7% were male. There were no intra-operative complications. There was a significant improvement in the median OKS at six weeks (34, IQR 31.0 to 37.0), one year (38, IQR 29.0 to 43.0) and five years (37, IQR 27.0 to 42.0) when compared with the pre-operative scores (16, IQR 13.0 to 19.0) (all p = < 0.01). No patient had progressive radiolucent lines or loosening. A total of 16 patients had died by five years. The cumulative survival at five years was 98.8% and the mean survival time was 5.8 years (95% confidence interval 5.6 to 5.9). A total of seven OUKAs (2.7%) were revised; three within five years and four thereafter, between 5.1 and 5.7 years post-operatively. Five (1.9%) had re-operations within five years.

Conclusion

The proportion of patients requiring revision at five years is lower than that generally reported for UKA. These findings add support for the use of the cementless OUKA outside the design centre. Longer follow-up is required. Cite this article: Bone Joint J 2017;99-B:623–31.

Characteristics of Orthopedic Publications in High-Impact General Medical Journals

Orthopedic studies are occasionally published in high-impact general medical journals; these studies are often given high visibility and have significant potential to impact health care policy and inform clinical decision-making. The purpose of this review was to investigate the characteristics of operative orthopedic studies published in high-impact medical journals. The number of orthopedic studies published in high-impact medical journals is relatively low; however, these studies demonstrate methodological characteristics that may bias toward nonoperative treatment. Careful analysis and interpretation of orthopedic studies published in these journals is warranted. [Orthopedics. 2017; 40(3):e405-e412.].

The effect of patient age at intervention on risk of implant revision after total replacement of the hip or knee: a population-based cohort study

BACKGROUND

Total joint replacements for end-stage osteoarthritis of the hip and knee are cost-effective and demonstrate significant clinical improvement. However, robust population based lifetime-risk data for implant revision are not available to aid patient decision making, which is a particular problem in young patient groups deciding on best-timing for surgery.

METHODS

We did implant survival analysis on all patients within the Clinical Practice Research Datalink who had undergone total hip replacement or total knee replacement. These data were adjusted for all-cause mortality with data from the Office for National Statistics and used to generate lifetime risks of revision surgery based on increasing age at the time of primary surgery.

FINDINGS

We identified 63 158 patients who had undergone total hip replacement and 54 276 who had total knee replacement between Jan 1, 1991, and Aug 10, 2011, and followed up these patients to a maximum of 20 years. For total hip replacement, 10-year implant survival rate was 95·6% (95% CI 95·3-95·9) and 20-year rate was 85·0% (83·2-86·6). For total knee replacement, 10-year implant survival rate was 96·1% (95·8-96·4), and 20-year implant survival rate was 89·7% (87·5-91·5). The lifetime risk of requiring revision surgery in patients who had total hip replacement or total knee replacement over the age of 70 years was about 5% with no difference between sexes. For those who had surgery younger than 70 years, however, the lifetime risk of revision increased for younger patients, up to 35% (95% CI 30·9-39·1) for men in their early 50s, with large differences seen between male and female patients (15% lower for women in same age group). The median time to revision for patients who had surgery younger than age 60 was 4·4 years.

INTERPRETATION

Our study used novel methodology to investigate and offer new insight into the importance of young age and risk of revision after total hip or knee replacement. Our evidence challenges the increasing trend for more total hip replacements and total knee replacements to be done in the younger patient group, and these data should be offered to patients as part of the shared decision making process.

FUNDING

Oxford Musculoskeletal Biomedical Research Unit, National Institute for Health Research.

The Main Cause of Death Following Primary Total Hip and Knee Replacement for Osteoarthritis: A Cohort Study of 26,766 Deaths Following 332,734 Hip Replacements and 29,802 Deaths Following 384,291 Knee Replacements

BACKGROUND

Patients undergoing primary total joint replacement are selected for surgery and thus (other than having a transiently increased mortality rate postoperatively) have a lower mortality rate than age and sex-matched individuals do. Understanding the causes of death following joint replacement would allow targeted strategies to reduce the risk of death and optimize outcome. We aimed to determine the rates and causes of mortality for patients undergoing primary total hip or knee replacement compared with individuals in the general population who were matched for age and sex.

METHODS

We compared causes and rates of mortality between age and sex-matched individuals in the general population (National Joint Registry for England, Wales and Northern Ireland; Hospital Episode Statistics; and Office for National Statistics) and a linked cohort of 332,734 patients managed with total hip replacement (26,766 of whom died before the censoring date) and 384,291 patients managed with primary total knee replacement (29,802 of whom died before the censoring date) from 2003 through 2012.

RESULTS

The main causes of death were malignant neoplasms (33.8% [9,037] of 26,766 deaths in patients with total hip replacement and 33.3% [9,917] of 29,802 deaths in patients with total knee replacement), circulatory system disorders (32.8% [8,784] of the deaths in patients with total hip replacement and 33.3% [9,932] of the deaths in patients with total knee replacement), respiratory system disorders (10.9% [2,928] of the deaths in patients with total hip replacement and 9.8% [2,932] of the deaths in patients with total knee replacement), and digestive system diseases (5.5% [1,465] of the deaths in patients with total hip replacement and 5.3% [1,572] of the deaths in patients with total knee replacement). There was a relative reduction in mortality (39%) compared with the individuals in the general population that equalized to the rate in the general population by 7 years for hips (overall standardized mortality ratio [SMR], 0.61; 95% confidence interval [CI], 0.60 to 0.62); for knees, the relative reduction (43%) partially attenuated by 7 years but still had not equalized to the rate in the general population (overall SMR, 0.57; 95% CI, 0.56 to 0.57). Ischemic heart disease was the most common cause of death within 90 days (29% [431] of the deaths in patients with primary hip replacement and 31% [436] of the deaths in patients with primary knee replacement). There was an elevated risk of death from circulatory, respiratory, and (most markedly) digestive system-related causes within 90 days postoperatively compared with 91 days to 1 year postoperatively.

CONCLUSIONS

Ischemic heart disease is the leading cause of death in the 90 days following total joint replacement, and there is an increase in postoperative deaths associated with digestive system-related disease following joint replacement. Interventions targeted at reducing these diseases may have the largest effect on mortality in total joint replacement patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Cause-Specific Mortality Trends Following Total Hip and Knee Arthroplasty

BACKGROUND

While studies have demonstrated that mortality after total hip (THA) and total knee (TKA) arthroplasty is better than the general population, the causes of death are not well established. We evaluated cause-specific mortality after THA and TKA.

METHODS

The study included population-based cohorts of patients who underwent THA (N = 2019) and TKA (N = 2259) between 1969 and 2008. Causes of death were classified using the International Classification of Diseases 9th and 10th editions. Cause-specific standardized mortality ratios (SMR) and 95% confidence intervals (CI) were calculated by comparing observed and expected mortality. Expected mortality was derived from mortality rates in the United States white population of similar calendar year, age, and sex characteristics.

RESULTS

All-cause mortality was lower than expected following both THA and TKA. However, there was excess mortality due to mental diseases such as dementia following both THA (SMR 1.40, 95% CI 1.08, 1.80) and TKA (SMR 1.49, 95% CI 1.19, 1.85). There was also excess mortality from inflammatory musculoskeletal diseases in THA (SMR 3.50, 95% CI 2.11, 5.46) and TKA (SMR 4.85, 95% CI 3.29, 6.88). When the cohorts were restricted to patients with osteoarthritis as the surgical indication, the excess risk of death from mental diseases still persisted in THA (SMR 1.36, 95% CI 1.02, 1.78) and TKA (SMR 1.52, 95% CI 1.20, 1.91).

CONCLUSION

THA and TKA patients experience a higher risk of death from mental and inflammatory musculoskeletal diseases. These findings warrant further research to identify drivers of mortality and prevention strategies in arthroplasty patients.

Time course and reasons for 90-day mortality in fast-track hip and knee arthroplasty

BACKGROUND

Post-operative mortality is an important adverse outcome, including in total hip (THA) and knee arthroplasty (TKA). However, whether mortality is due to anaesthetic/surgical complications, surgically induced organ dysfunction or unrelated to surgery is rarely considered.

METHODS

Prospective observational study in 13,775 consecutive THA/TKAs with similar fast-track protocols and a median length of stay of 2 days. Complete 90-days follow-up through national registries, followed by review of medical records and death certificates. Relation between mortality and surgically induced organ dysfunction were classified as certain, probable, possible or unlikely.

RESULTS

Of a total of 44 deaths (0.3%), 28 (0.2%) were found to have certain or probably relation with surgery and were considered as surgery-related. Surgery-related deaths were more common after THA than TKA (0.3% vs. 0.1% P = 0.044), occurred after median 14 days and 19 of 28 were between day 0-30. Of the remaining 16 deaths (0.1%), nine were found to be possible and seven to be unlikely related to surgery, and occurred a median of 42 and 61 days after surgery. The most common initial organ dysfunction for surgery-related deaths was pulmonary (6/28) and gastrointestinal (6/28), while the most common reported cause of death were pulmonary (9/28) and cardiac events (6/28). In five of the seven unlikely related deaths mortality was attributed to underlying cancer.

CONCLUSION

Ninety-days mortality was 0.3% in THA and TKA, but only 28 of 44 deaths (64%) were found to be surgery-related. Reporting total mortality rate or cause of death without considerations on surgery induced organ dysfunction, may be insufficient for future aims to reduce post-operative mortality.

Improved Survival of Computer-Assisted Unicompartmental Knee Arthroplasty: 252 Cases With a Minimum Follow-Up of 5 Years

BACKGROUND

Unicompartmental knee arthroplasty (UKA) is an underutilized implant for medial tibiofemoral arthritis despite proven benefits in performance and reduced complications. This is likely related to registry recorded higher revision rates compared with total knee arthroplasty. It is our feeling that better component alignment resulting from the usage of computer-assisted surgery should improve longer-term functional results and survival of UKAs.

METHODS

Between August 2003 and June 2007, 265 medial UKAs were performed in 264 consecutive patients using navigation.

RESULTS

Eighty-eight women and 176 men with an average age of 51.7 (±4.63) years were assessed for function and survival over a follow-up period of 92.6 (63-120) months (7.7 years). The final survival rate over 5 years for this cohort was 97.6% at 5 years.

CONCLUSION

We conclude that computer-assisted UKA, to treat medial tibiofemoral joint arthritis, produces 5-year survival rates that are comparable with total knee arthroplasty.

Minimally invasive Oxford medial unicompartmental knee arthroplasty in young patients

PURPOSE

Advanced knee arthritis in young patients is a challenging problem that may necessitate surgical treatment. There are few published studies of mobile-bearing unicompartmental knee arthroplasty (UKA) in young patients, while indications have expanded to its use in this demanding patient group.

METHODS

The clinical and radiographic results of the first 118 consecutive Oxford medial UKAs (OUKA) using a minimally invasive technique (phase 3) in 101 patients 60 years of age or younger at the time of surgery were evaluated. Median age at surgery was 57 (25-60) years. Kaplan-Meier survivorship analysis was used to estimate implant survival.

RESULTS

Mean time of follow-up evaluation was five (SD 1.6) years. At final follow-up, three patients (three knees) had died, and two patients (three knees) were lost to follow-up. Five knees were revised: three for unexplained pain, one for early infection and one for bearing fracture. There was one impending revision for progression of osteoarthritis in the lateral compartment. The radiographic review demonstrated that 5 % of the knees had progressive arthritis in the lateral knee compartment, of those 2 % with full joint space loss and pain. The Kaplan-Meier survival analysis, using revision for any reason as the endpoint, estimated the five-year survival rate at 97 % (95 % CI 91-99). Ninety-six per cent of the non-revised patients were satisfied with the outcome, and 4 % were dissatisfied. The mean Oxford knee score was 41 (SD 7), with 6 % of the knees having a poor result. The mean AKSS was 89 (SD 14), mean flexion was 129° (SD 13) and the mean UCLA score was 6.8 (SD 1.5).

CONCLUSION

Minimally invasive Oxford medial UKA was reliable and effective in this young and active patient cohort providing high patient satisfaction at mid-term follow-up. Progressive arthritis in the lateral knee compartment was a relevant failure mode in this age group. Most revisions were performed for unexplained pain, while we did not find loosening or wear in any patient.

LEVEL OF EVIDENCE

IV.

Bias and unicompartmental knee arthroplasty

We recently published a paper comparing the incidence of adverse outcomes after unicompartmental and total knee arthroplasty (UKA and TKA). The conclusion of this study, which was in favour of UKA, was dismissed as “biased” in a review in Bone & Joint 360. Although this study is one of the least biased comparisons of UKA and TKA, this episode highlights the biases that exist both for and against UKA. In this review, we explore the different types of bias, particularly selection, reporting and measurement. We conclude that comparisons between UKA and TKA are open to bias. These biases can be so marked, particularly in comparisons based just on national registry data, that the conclusions can be misleading. For a fair comparison, data from randomised studies or well-matched, prospective observational cohort studies, which include registry data, are required, and multiple outcome measures should be used. The data of this type that already exist suggest that if UKA is used appropriately, compared with TKA, its advantages outweigh its disadvantages.

Cite this article: Bone Joint J 2017;99-B:12–15.

Cost utility modeling of early vs late total knee replacement in osteoarthritis patients

Given the dramatic increase in the number of total knee replacement (TKR) surgeries in developed countries, the issue of the best time for surgery needs to be addressed from an economic perspective.

OBJECTIVE

To assess, from the perspective of the healthcare payer, the cost-utility of two surgical strategies in which knee replacement is performed at the early or late stage of the disease in patients with knee osteoarthritis (OA).

DESIGN

Patient data and evidence from published literature on economic costs and outcomes in OA, including utilities, non-pharmacological, pharmacological and surgical options, combined with population life tables were entered in a Markov model of OA. The model represented the lifetime experience of a cohort of patients following their therapeutic management, discounting costs (euros) and utilities (quality-adjusted life-years) at 4% annually.

RESULTS

In the base-case scenario, early TKR cost €6,624 more than late TKR (€76,223 vs €69,599) with a 0.15 gain in QALYs (18.675 vs 18.524). This yielded an incremental cost-utility ratio (ICUR) of 43,631 €/QALY. Sensitivity analyses of the most influential uncertain parameters were performed and did not modify the direction of the conclusions: early TKR cost between €3,655 and €7,194 more than late TKR with a gain in QALYs between 0.15 and 0.39. The ICUR ranged from 17,131 €/QALY to 48,241 €/QALY.

CONCLUSION

Our data do not support the early TKR strategy over the late TKR strategy in knee OA patients from a medico-economic perspective.

Survivorship and clinical outcome of the minimally invasive Uniglide medial fixed bearing, all-polyethylene tibia, unicompartmental knee arthroplasty at a mean follow-up of 7.3years

BACKGROUND

Medial UKA performed in England and Wales represents seven to 11% of all knee arthroplasty procedures, and is most commonly performed using mobile-bearing designs. Fixed bearing eliminates the risk of bearing dislocation, however some studies have shown higher revision rates for all-polyethylene tibial components compared to those that utilize metal-backed implants. The aim of the study is to analyse survivorship and maximum eight-year clinical outcome of medial fixed bearing, Uniglide unicompartmental knee arthroplasty performed using an all-polyethylene tibial component with a minimal invasive approach.

METHODS

Between 2002 and 2009, 270 medial fixed UKAs were performed in our unit. Patients were reviewed pre-operatively, five and eight years post-operatively. Clinical and radiographic reviews were carried out. Patients' outcome scores (Oxford, WOMAC and American Knee Score) were documented in our database and analysed.

RESULTS

Survival and clinical outcome data of 236 knees with a mean of 7.3years follow-up are reported. Every patient with less than 4.93years of follow-up underwent a revision. The patients' average age at the time of surgery was 69.5years. The American Knee Society Pain and Function scores, the Oxford Knee Score and the WOMAC score all improved significantly. The five-year survival rate was 94.1% with implant revision surgery as an end point. The estimated 10years of survival rate is 91.3%. Fourteen patients were revised before the five-year follow-up.

CONCLUSION

Fixed bearing Uniglide UKA with an all-polyethylene tibial component is a valuable tool in the management of a medial compartment osteoarthritis, affording good short-term survivorship. Level of evidence IV.

Incidence, Risk Factors, and Sources of Sepsis Following Total Joint Arthroplasty

BACKGROUND

Sepsis is a rare but serious complication following total joint arthroplasty (TJA). Common sources include urinary tract infection (UTI), surgical site infection (SSI), and pneumonia. The purpose of this study is to characterize the incidence, risk factors, and sources of sepsis following TJA.

METHODS

Patients undergoing primary total hip arthroplasty or total knee arthroplasty during 2005-2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Independent associations were tested for using multivariate regression adjusting for baseline characteristics.

RESULTS

A total of 117,935 patients were identified (45,612 undergoing total hip arthroplasty and 72,323 undergoing total knee arthroplasty). Of these, 402 (0.34%) developed sepsis following surgery. Patients who developed sepsis had an elevated mortality rate (3.7% vs 0.1%, P < .001). Among the 402 patients who developed sepsis, 124 (31%) had concomitant UTI, 110 (27%) SSI, and 60 (15%) pneumonia. Twenty-one patients (5%) had multiple infectious sources and 129 patients (32%) had no identifiable source. Independent risk factors for sepsis included greater age, male sex, functional dependence, insulin-dependent diabetes, hypertension, chronic obstructive pulmonary disease, current smoker, and greater operative time.

CONCLUSION

These findings suggest that the rate of sepsis following TJA is about 1 in 300, and that sepsis is associated with a high risk of mortality. The most common sources of sepsis are UTI, SSI, and pneumonia, potentially accounting for at least two-thirds of cases. The information provided here can be used to guide the diagnostic workup of sepsis in patients following TJA.

No Increased Risk for Primary Osteoarthritis in Liver Cirrhosis - A Danish Nationwide Cohort Study

Objective

Chronic synovial inflammation causes primary osteoarthritis, but it is unknown whether chronic systemic inflammation does, too. Patients with cirrhosis have chronic systemic inflammation and therefore we examined the association between cirrhosis and primary osteoarthritis of the hip and knee.

Methods

In Danish healthcare databases we identified all residents over 60 years diagnosed with cirrhosis in 1994–2011, and for each of them we sampled five age- and gender-matched reference persons from the general population. We excluded everyone with risk factors for secondary osteoarthritis and computed incidence rates of primary osteoarthritis of the hip or knee. We used stratified Cox regression to estimate the hazard ratios of primary osteoarthritis for cirrhosis patients vs. reference persons in strata defined by gender, age, cirrhosis etiology, and ascites vs. no ascites. We also computed separate HRs for primary osteoarthritis of the hips or knees.

Results

We identified 10,049 cirrhosis patients. Their median age was 67 years, and 65% were men. Among the cirrhosis patients the crude incidence rate of primary osteoarthritis was 8.40 (95% CI: 7.30–9.63) per 1000 person-years. The rate was similar in the reference persons: 8.76 (95% CI: 8.43–9.12) per 1000 person-years. Accordingly, the hazard ratio for primary osteoarthritis for cirrhosis patients vs. reference persons was 0.99 (95% CI: 0.85–1.16), and we found the same null association in all patient strata and in both joints.

Conclusion

Cirrhosis, and thus chronic systemic inflammation, is not a risk factor for primary osteoarthritis.

Defining an International Standard Set of Outcome Measures for Patients With Hip or Knee Osteoarthritis: Consensus of the International Consortium for Health Outcomes Measurement Hip and Knee Osteoarthritis Working Group

OBJECTIVE

To define a minimum Standard Set of outcome measures and case-mix factors for monitoring, comparing, and improving health care for patients with clinically diagnosed hip or knee osteoarthritis (OA), with a focus on defining the outcomes that matter most to patients.

METHODS

An international working group of patients, arthroplasty register experts, orthopedic surgeons, primary care physicians, rheumatologists, and physiotherapists representing 10 countries was assembled to review existing literature and practices for assessing outcomes of pharmacologic and nonpharmacologic OA therapies, including surgery. A series of 8 teleconferences, incorporating a modified Delphi process, were held to reach consensus.

RESULTS

The working group reached consensus on a concise set of outcome measures to evaluate patients' joint pain, physical functioning, health-related quality of life, work status, mortality, reoperations, readmissions, and overall satisfaction with treatment result. To support analysis of these outcome measures, pertinent baseline characteristics and risk factor metrics were defined. Annual outcome measurement is recommended for all patients.

CONCLUSION

We have defined a Standard Set of outcome measures for monitoring the care of people with clinically diagnosed hip or knee OA that is appropriate for use across all treatment and care settings. We believe this Standard Set provides meaningful, comparable, and easy to interpret measures ready to implement in clinics and/or registries globally. We view this set as an initial step that, when combined with cost data, will facilitate value-based health care improvements in the treatment of hip and knee OA.

Evaluation of three co-morbidity measures to predict mortality in patients undergoing total joint arthroplasty

OBJECTIVE

To evaluate the 90 days and 1 year mortality predictive ability of the RxRisk-V, Charlson, and Elixhauser co-morbidity measures in total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients.

METHOD

A retrospective study of 11,848 THAs and 18,972 TKAs (2001-2002) was conducted. Death within 90 days and 1 year of the surgery were the main endpoints. Co-morbidity measures were calculated using either medication or hospitalisation history. Logistic regression models were employed and discrimination and calibration were assessed. Specifically, models with unweighted and weighted measure scores, models with the specific conditions, and a model combining conditions identified by all measures were assessed.

RESULTS

In THAs, the best performing prediction models included co-morbidities from all three measures (90 days: c = 0.84, P = 0.284, 1 year: c = 0.79, P = 0.158). Individually, the model with Charlson conditions performed best at 90 days mortality (c = 0.80, P = 0.777) and the Charlson and Elixhauser performed similarly at 1 year (both c = 0.77, P > 0.05). In TKAs, the best performing prediction model included co-morbidities from all measures (90 days: c = 0.82, P = 0.349, 1 year: c = 0.78, P = 0.873). Individually, the model with Elixhauser conditions performed best with 90 days mortality (c = 0.79, P = 0.435) and all performed similarly at 1 year (c = 0.74-0.75, all P > 0.05).

CONCLUSIONS

A combined model with co-morbidities identified by the Elixhauser, Charlson, and RxRisk-V was the best mortality prediction model. The RxRisk-V did not perform as well as the others. Because of the Elixhauser and Charlson's similar performance we suggest basing the choice of measurement use on factors such as the need of specific conditions and modelling limitations.

Inpatient mortality after elective primary total hip and knee joint arthroplasty in Botswana

PURPOSE

Total hip and knee joint arthroplasty (TJA) rank among the most successful orthopaedic operations. Several developing countries in Africa have started to perform these procedures that are routine in developed countries. The aims of this study were to measure the incidence and assess the determinants of in-hospital mortality after elective primary TJA in our unit and compare it with published data.

METHODS

This was a retrospective study of the first consecutive cohort of patients who underwent elective primary TJA in Princess Marina Hospital, Botswana between March 2009 and October 2015 (6.5 years).

RESULTS

346 elective joint replacements were performed comprising 153 total hip arthroplasties (THA) and 193 total knee arthroplasties (TKA); 36 % of the THA were in female patients and 82 % of TKA were in females. The mean age was 64.5 years (range 26-86). Three patients died giving an inpatient mortality rate of 0.86 %. These three mortalities represent 1.55 % (three out of 193) of all the TKA. There were no deaths after THA. The cause of mortality in two patients was an adverse cardiac event while the third mortality was due to pulmonary embolism.

CONCLUSION

The inpatient mortality rate of 0.86 % following TJA is higher than the reported rates in the developed countries but comparable with data from other developing countries. The inpatient mortality rate following TKA was higher than that following THA and cardiovascular events proved to be the main cause of death. We recommend formal cardiology assessment and close peri-operative monitoring of all patients with a history of cardiovascular disease undergoing TJA.

Venous thromboembolism after lower limb arthroplasty: is chemical prophylaxis still needed?

BACKGROUND

Venous thromboembolism (VTE) is a significant complication of lower limb arthroplasty. The National Institute for Health and Care Excellence recommends routine use of chemical and mechanical prophylaxis to prevent VTE. Our high-volume, elective, arthroplasty unit adopted this guidance in 2008.

PURPOSE

We examined our incidence of VTE before and after introduction of chemical thromboprophylaxis to determine whether the incidence of VTE reduced.

METHODS

We retrospectively gathered data on 2 cohorts of patients-from January 2004 to August 2007 (Group 1) and January 2010 to December 2012 (Group 2). Patients in Group 1 received mechanical prophylaxis only (unless particularly high risk for VTE), and patients in Group 2 received mechanical and chemical prophylaxis. We recorded VTE occurring within 6 months of surgery. Patients in Group 1 receiving chemical prophylaxis were excluded.

RESULTS

Group 1 had 2320 cases of primary and revision lower limb arthroplasty, and Group 2 had 1430 cases. VTE occurred in 37 cases in Group 1 (1.6 %), and in 17 cases in Group 2 (1.2 %). This difference was not statistically significant (p = 0.26). In Group 1, 1 patient died within 6 months due to pulmonary embolism (0.04 %); there were no VTE-related deaths in Group 2 (0 %). This was also not statistically significant (p = 0.06).

CONCLUSIONS

Although our VTE rate reduced by 0.4 % and our VTE-related mortality reduced by 0.04 % after introduction of chemical thromboprophylaxis, these differences were not statistically significant. Chemical thromboprophylaxis may not be required in all patients undergoing arthroplasty providing appropriate mechanical prophylaxis is used.

Aspirin for thromboprophylaxis after primary lower limb arthroplasty: early thromboembolic events and 90 day mortality in 11,459 patients

AIMS

The aim of this study was to present data on 11 459 patients who underwent total hip (THA), total knee (TKA) or unicompartmental knee arthroplasty (UKA) between November 2002 and April 2014 with aspirin as the primary agent for pharmacological thromboprophylaxis.

PATIENTS AND METHODS

We analysed the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) then compared the 90-day all-cause mortality with the corresponding data in the National Joint Registry for England and Wales (NJR).

RESULTS

The incidence of PE was 0.6% after THA, 1.47% after TKA and 1.2% after UKA. The 90-day mortality was 0.39% after THA and 0.44% after TKA. No deaths occurred after UKA. The main causes of death were ischaemic heart disease and respiratory failure. PE was responsible for only 18% of deaths. There was a decline in 90-day mortality, from 0.64% between 2002 and 2007, to 0.21% between 2008 and 2013 after THA, and from 0.47% to 0.39% after TKA for the corresponding period. The standardised mortality ratio (SMR) declined from 86.5 (confidence interval (CI) 63.0 to 137.7) to 39.7 (CI 31.2 to 54.3) p = 0.024. The incidence of proximal DVT was 0.3%.

TAKE HOME MESSAGE

With individualised risk assessment and as part of a multimodal approach, Aspirin is safe to use as the main thromboprophylactic agent in primary arthroplasty. It is not associated with an increased incidence of symptomatic DVT, PE or death.

PPAR-α Agonist WY-14643 Inhibits LPS-Induced Inflammation in Synovial Fibroblasts via NF-kB Pathway

Osteoarthritis (OA), the most prevalent form of arthritis that results from breakdown of joint cartilage and underlying bone, has been viewed as a chronic condition manifested by persistence of inflammatory responses and infiltration of lymphocytes. Regulation of the inflammatory responses in synovial fibroblasts might be useful to prevent the development and deterioration of osteoarthritis. WY-14643, a potent peroxisome proliferator activator receptor-α (PPAR-α) agonist, has been described to beneficially regulate inflammation in many mammalian cells. Here, we investigate the potential anti-inflammatory role of WY-14643 in lipopolysaccharide (LPS)-induced synovial fibroblasts. WY-14643 greatly inhibited the production of NO and PGE2 induced by LPS. In addition, the mRNA expression of intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), endothelin-1 (ET-1), and tissue factor (TF) was significantly suppressed by WY-14643, as well as the secretion of pro-inflammatory cytokines including interleukin-6 (IL-6), IL-1β, tumor necrosis factor-α (TNF-α), and monocyte chemotactic protein-1 (MCP-1). Furthermore, the transcription activity and nuclear translocation of NF-kB were found to be markedly decreased by WY-14643, while the phosphorylation of IkB was enhanced, indicating that the anti-inflammatory role of WY-14643 was meditated by NF-kB-dependent pathway. The application of WY-14643 failed to carry out its anti-inflammatory function in PPAR-α silenced cells, suggesting the role of PPAR-α. These findings may facilitate further studies investigating the translation of pharmacological PPAR-α activation into clinical therapy of OA.

Long-Term Mortality Trends After Total Hip and Knee Arthroplasties: A Population-Based Study

BACKGROUND

Mortality after total hip and knee arthroplasty is lower than that in the general population, but it is unknown whether there are differences by surgery type, demographics, and calendar year. Our objective was to evaluate trends and determinants of long-term mortality among patients with total hip and knee arthroplasties.

METHODS

Using a historical cohort study design, we passively followed up population-based cohorts of total hip and total knee arthroplasty patients with degenerative arthritis who underwent surgery between January 1, 1969 and December 31, 2008. Patients were followed up until death or August 31, 2014. Observed and expected survival was compared using standardized mortality ratios (SMRs). Poisson regression models were used to examine relative mortality patterns by surgery type, age, sex, calendar year, and time since surgery.

RESULTS

The overall age- and sex-adjusted mortality was significantly lower than that in the general population after both total hip (SMR: 0.82, 95% CI: 0.76-0.88) and total knee (SMR = 0.80, 95% CI: 0.75-0.86) arthroplasties. Despite the low relative mortality within the first 8 years of surgery, we observed a worsening of relative mortality beyond 15 years after total knee arthroplasty surgery. Both short- and long-term mortality improved over calendar time, and the improvement occurred about a decade earlier in total knee arthroplasty than in total hip arthroplasty.

CONCLUSION

Survival after total hip and total knee arthroplasties is better than that in the general population for about 8 years after surgery. Secular trends are encouraging and suggest that survival after both procedures has been improving even further in recent years.

The constraints on day-case total knee arthroplasty: the fastest fast track

Total knee arthroplasty (TKA) is a major orthopaedic intervention. The length of a patient's stay has been progressively reduced with the introduction of enhanced recovery protocols: day-case surgery has become the ultimate challenge. This narrative review shows the potential limitations of day-case TKA. These constraints may be social, linked to patient's comorbidities, or due to surgery-related adverse events (e.g. pain, post-operative nausea and vomiting, etc.). Using patient stratification, tailored surgical techniques and multimodal opioid-sparing analgesia, day-case TKA might be achievable in a limited group of patients. The younger, male patient without comorbidities and with an excellent social network around him might be a candidate. Demographic changes, effective recovery programmes and less invasive surgical techniques such as unicondylar knee arthroplasty, may increase the size of the group of potential day-case patients. The cost reduction achieved by day-case TKA needs to be balanced against any increase in morbidity and mortality and the cost of advanced follow-up at a distance with new technology. These factors need to be evaluated before adopting this ultimate 'fast-track' approach.

Optimal usage of unicompartmental knee arthroplasty

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.

Patient-reported outcomes after total and unicompartmental knee arthroplasty: a study of 14,076 matched patients from the National Joint Registry for England and Wales

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.

Effect of Age on Outcomes in Total Ankle Arthroplasty

BACKGROUND

Little is known about the efficacy and durability of total ankle arthroplasty (TAA) in younger patients. The purpose of this study was to determine the effect of age on the clinical, radiographic, and patient-reported outcomes of patients with end-stage ankle arthritis treated with TAA using modern prostheses.

METHODS

Patients who underwent primary TAA from June 2007 to July 2011 were prospectively enrolled in the study. Three hundred and ninety-five consecutive patients were reviewed with a mean follow-up of 3.5 years (range, 2-5.4 years). Patients were divided into 3 groups based on age at the time of surgery (<55, 55-70, and >70 years). Patient-reported outcome scores, physical performance scores, and weight-bearing radiographs were used to assess patients preoperatively and at yearly postoperative office visits. Revision was defined as failure of either the tibial or talar components requiring removal of the metallic implants. A repeated-measures analysis of variance with post hoc testing and the Pearson chi-square test were used to assess differences between the 3 groups. Statistical significance was set at an alpha level of .05.

RESULTS

Patients under the age of 55 had a greater improvement in Short-Form 36 (SF-36) Vitality (P = .026) and American Orthopaedic Foot & Ankle Society (AOFAS) Function scores (P < .001) compared with patients over the age of 70 at most recent follow-up. There were no differences in the Visual Analog Scale (VAS) pain score or the physical performance outcomes between the age groups. The incidence of wound complications, need for reoperation, and revision were not different between groups.

CONCLUSIONS

Outcomes of TAA in younger patients were similar to outcomes in older patients at early follow-up. This study establishes a cohort of patients that will be followed to determine the effect of age on the long-term outcomes of TAA with an emphasis on the need for reoperation and revision.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

No difference between unicompartmental versus total knee arthroplasty for the management of medial osteoarthtritis of the knee in the same patient: a systematic review and pooling data analysis

INTRODUCTION

One-third of patients with knee osteoarthritis (OA) has involvement of only one compartment, especially the medial one.

SOURCES OF DATA

We performed a comprehensive search of studies comparing unicompartmental knee arthoplasty (UKA) and total knee arthroplasty (TKA) in the same patient on PubMed, OVID/Medline, Cochrane, CINAHL, Google scholar and Embase databases.

AREAS OF AGREEMENT

UKA is indicated in knee with medial OA, no flexion deformity, no joint instability and no varus deformity.

AREAS OF CONTROVERSY

Although high tibial osteotomy, UKA and TKA have been proposed to address medial OA of the knee, the best management is still controversial.

GROWING POINTS

Studies investigating surgical management of medial OA of the knee are increasingly frequent.

AREAS TIMELY FOR DEVELOPING RESEARCH

Large, multicentre, powered, randomized trials comparing UKA and TKA are needed to identify the best management for medial OA of the knee. Moreover, new score systems for satisfaction of the patient should be formulated.

Adverse outcomes after total and unicompartmental knee replacement in 101,330 matched patients: a study of data from the National Joint Registry for England and Wales

BACKGROUND

Total knee replacement (TKR) or unicompartmental knee replacement (UKR) are options for end-stage osteoarthritis. However, comparisons between the two procedures are confounded by differences in baseline characteristics of patients undergoing either procedure and by insufficient reporting of endpoints other than revision. We aimed to compare adverse outcomes for each procedure in matched patients.

METHODS

With propensity score techniques, we compared matched patients undergoing TKR and UKR in the National Joint Registry for England and Wales. The National Joint Registry started collecting data in April 1, 2003, and is continuing. The last operation date in the extract of data used in our study was Aug 28, 2012. We linked data for multiple potential confounders from the National Health Service Hospital Episode Statistics database. We used regression models to compare outcomes including rates of revision, revision/reoperation, complications, readmission, mortality, and length of stay.

FINDINGS

25,334 UKRs were matched to 75,996 TKRs on the basis of propensity score. UKRs had worse implant survival both for revision (subhazard ratio [SHR] 2·12, 95% CI 1·99–2·26) and for revision/reoperation (1·38, 1·31–1·44) than TKRs at 8 years. Mortality was significantly higher for TKR at all timepoints than for UKR (30 day: hazard ratio 0·23, 95% CI 0·11–0·50; 8 year: 0·85, 0·79–0·92). Length of stay, complications (including thromboembolism, myocardial infarction, and stroke), and rate of readmission were all higher for TKR than for UKR.

INTERPRETATION

In decisions about which procedure to offer, the higher revision/reoperation rate of UKR than of TKR should be balanced against a lower occurrence of complications, readmission, and mortality, together with known benefits for UKR in terms of postoperative function. If 100 patients receiving TKR received UKR instead, the result would be around one fewer death and three more reoperations in the first 4 years after surgery.

FUNDING

Royal College of Surgeons of England and Arthritis Research UK.