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1.  Patients with Severe Radiographic Osteoarthritis Have a Better Prognosis in Physical Functioning after Hip and Knee Replacement: A Cohort-Study 
PLoS ONE  2013;8(4):e59500.
Although Total Hip and Knee Replacements (THR/TKR) improve Health-Related Quality of Life (HRQoL) at the group level, up to 30% of patients are dissatisfied after surgery due to unfulfilled expectations. We aimed to assess whether the pre-operative radiographic severity of osteoarthritis (OA) is related to the improvement in HRQoL after THR or TKR, both at the population and individual level.
In this multi-center observational cohort study, HRQoL of OA patients requiring THR or TKR was measured 2 weeks before surgery and at 2–5 years follow-up, using the Short-Form 36 (SF36). Additionally, we measured patient satisfaction on a 11-point Numeric Rating Scale (NRSS). The radiographic severity of OA was classified according to Kellgren and Lawrence (KL) by an independent experienced musculoskeletal radiologist, blinded for the outcome. We compared the mean improvement and probability of a relevant improvement (defined as a patients change score≥Minimal Clinically Important Difference) between patients with mild OA (KL Grade 0–2) and severe OA (KL Grade 3+4), whilst adjusting for confounders.
Severe OA patients improved more and had a higher probability of a relevant improvement in physical functioning after both THR and TKR. For TKR patients with severe OA, larger improvements were found in General Health, Vitality and the Physical Component Summary Scale. The mean NRSS was also higher in severe OA TKR patients.
Patients with severe OA have a better prognosis after THR and TKR than patients with mild OA. These findings might help to prevent dissatisfaction after THR and TKR by means of patient selection or expectation management.
PMCID: PMC3616074  PMID: 23573200
2.  Socio-Economic Position Has No Effect on Improvement in Health-Related Quality of Life and Patient Satisfaction in Total Hip and Knee Replacement: A Cohort Study 
PLoS ONE  2013;8(3):e56785.
Considerable evidence suggests that patients with more advantaged Socio-Economic Positions undergo Total Hip and Knee Replacement (THR/TKR) more often, despite having a lower need. We questioned whether more disadvantaged Socio-Economic Position is associated with an lower improvement in Health-Related Quality of Life (HRQoL) and a lower patient satisfaction after THR/TKR.
Patients who underwent primary THR/TKR in one academic and three community hospitals between 2005 and 2009, were eligible for inclusion. The highest completed levels of schooling were aggregated to index social class. We compared the improvement in HRQoL and postoperative satisfaction with surgery (measured using the Short-Form 36 (SF36) and an 11-point numeric rating scale of satisfaction) between the aggregated groups of highest completed levels of schooling, using linear mixed model analysis, with center as a random effect and potential confounders (i.e. age, gender, Body Mass Index and Charnley's comorbidity classification) as fixed effects.
586 THR patients and 400 TKR patients (40% of all eligible patients) agreed to participate and completed all questionnaires sufficiently. We found no differences in HRQoL improvement in any dimension of the SF36 in THR patients. Patients with a higher completed level of schooling had a larger improvement in role-physical (9.38 points, 95%-CI:0.34–18.4), a larger improvement in general health (3.67 points, 95%-CI:0.56–6.79) and a smaller improvement in mental health (3.60 points, 95%-CI:0.82–6.38) after TKR. Postoperative patient satisfaction did not differ between different highest completed level of schooling groups.
Completed level of schooling has no effect on the improvement in HRQoL and patient satisfaction in a Dutch THR population and a small effect in a similar TKR population. Undertreatment of patients with more disadvantaged Socio-Economic Position cannot be justified, given the similar improvement in HRQoL and postoperative level of satisfaction with surgery between the social groups examined.
PMCID: PMC3592876  PMID: 23520456
3.  Hip and knee replacement patients prefer pen-and-paper questionnaires 
Bone & Joint Research  2013;2(11):238-244.
Electronic forms of data collection have gained interest in recent years. In orthopaedics, little is known about patient preference regarding pen-and-paper or electronic questionnaires. We aimed to determine whether patients undergoing total hip (THR) or total knee replacement (TKR) prefer pen-and-paper or electronic questionnaires and to identify variables that predict preference for electronic questionnaires.
We asked patients who participated in a multi-centre cohort study investigating improvement in health-related quality of life (HRQoL) after THR and TKR using pen-and-paper questionnaires, which mode of questionnaire they preferred. Patient age, gender, highest completed level of schooling, body mass index (BMI), comorbidities, indication for joint replacement and pre-operative HRQoL were compared between the groups preferring different modes of questionnaire. We then performed logistic regression analyses to investigate which variables independently predicted preference of electronic questionnaires.
A total of 565 THR patients and 387 TKR patients completed the preference question. Of the THR patients, 81.8% (95% confidence interval (CI) 78.4 to 84.7) preferred pen-and-paper questionnaires to electronic questionnaires, as did 86.8% (95% CI 83.1 to 89.8) of TKR patients. Younger age, male gender, higher completed level of schooling and higher BMI independently predicted preference of electronic questionnaires in THR patients. Younger age and higher completed level of schooling independently predicted preference of electronic questionnaires in TKR patients.
The majority of THR and TKR patients prefer pen-and-paper questionnaires. Patients who preferred electronic questionnaires differed from patients who preferred pen-and-paper questionnaires. Restricting the mode of patient-reported outcome measures to electronic questionnaires might introduce selection bias.
Cite this article: Bone Joint Res 2013;2:238–44.
PMCID: PMC3834769  PMID: 24203164
Health-related quality of life; Total hip replacement; Total knee replacement; Patient-reported outcome measure; PROM; Questionnaire mode
4.  Decline in Health-Related Quality of Life reported by more than half of those waiting for joint replacement surgery: a prospective cohort study 
In many healthcare systems, people with severe joint disease wait months to years for joint replacement surgery. There are little empirical data on the health consequences of this delay and it is unclear whether people with substantial morbidity at entry to the waiting list continue to deteriorate further while awaiting surgery. This study investigated changes in Health-Related Quality of Life (HRQoL), health status and psychological distress among people waiting for total hip (THR) and knee replacement (TKR) surgery at a major metropolitan Australian public hospital.
134 patients completed questionnaires including the Assessment of Quality of Life (AQoL) instrument, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Kessler Psychological Distress Scale after entering an orthopaedic waiting list (baseline) and before surgery (preadmission). To quantify potential decline in wellbeing, we calculated the proportion of people experiencing clinically important deterioration using published guidelines and compared HRQoL and psychological distress outcomes with population norms.
Most participants (69%) waited ≥6 months for surgery (median 286 days, IQR 169-375 days). Despite poor physical and psychological wellbeing at baseline, there was an overall deterioration in HRQoL during the waiting period (mean AQoL change -0.04, 95%CI -0.08 to -0.01), with 53% of participants experiencing decline in HRQoL (≥0.04 AQoL units). HRQoL prior to surgery remained substantially lower than Australian population norms (mean sample AQoL 0.37, 95%CI 0.33 to 0.42 vs mean population AQoL 0.83, 95%CI 0.82 to 0.84). Twenty-five per cent of participants showed decline in health status (≥9.6 WOMAC units) over the waiting period and prevalence of high psychological distress remained high at preadmission (RR 3.5, 95%CI 2.8 to 4.5). Most participants considered their pain (84%), fatigue (76%), quality of life (73%) and confidence in managing their health (55%) had worsened while waiting for surgery.
Despite substantial initial morbidity, over half of the participants awaiting joint replacement experienced deterioration in HRQoL during the waiting period. These data provide much-needed evidence to guide health professionals and policymakers in the design of care pathways and resource allocation for people who require joint replacement surgery.
PMCID: PMC3121657  PMID: 21605398
5.  Health-related quality of life in patients waiting for major joint replacement. A comparison between patients and population controls 
Several quality-of-life studies in patients awaiting major joint replacement have focused on the outcomes of surgery. Interest in examining patients on the elective waiting list has increased since the beginning of 2000. We assessed health-related quality of life (HRQoL) in patients waiting for total hip (THR) or knee (TKR) replacement in three Finnish hospitals, and compared patients' HRQoL with that of population controls.
A total of 133 patients awaiting major joint replacement due to osteoarthritis (OA) of the hip or knee joint were prospectively followed from the time the patient was placed on the waiting list to hospital admission. A sample of controls matched by age, gender, housing and home municipality was drawn from the computerised population register. HRQoL was measured by the generic 15D instrument. Differences between patients and the population controls were tested by the independent samples t-test and between the measurement points by the paired samples t-test. A linear regression model was used to explain the variance in the 15D score at admission.
At baseline, 15D scores were significantly different between patients and the population controls. Compared with the population controls, patients were worse off on the dimensions of moving (P < 0.001), sleeping (P < 0.001), sexual activity (P < 0.001), vitality (P < 0.001), usual activities (P < 0.001) and discomfort and symptoms (P < 0.001). Further, psychological factors – depression (P < 0.001) and distress (P = 0.004) – were worse among patients than population controls. The patients showed statistically significantly improved average scores at admission on the dimensions of moving (P = 0.026), sleeping (P = 0.004) and discomfort and symptoms (P = 0.041), but not in the overall 15D score compared with the baseline. In patients, 15D score at baseline (P < 0.001) and body mass index (BMI) (P = 0.020) had an independent effect on patients' 15D score at hospital admission.
Although patients' HRQoL did not deteriorate while waiting, a consistently worse HRQoL was observed in patients waiting for major joint replacement compared with population controls.
PMCID: PMC1373609  PMID: 16423293
6.  Minimal clinically important differences in health-related quality of life after total hip or knee replacement 
Bone & Joint Research  2012;1(5):71-77.
We aimed first to summarise minimal clinically important differences (MCIDs) after total hip (THR) or knee replacement (TKR) in health-related quality of life (HRQoL), measured using the Short-Form 36 (SF-36). Secondly, we aimed to improve the precision of MCID estimates by means of meta-analysis.
We conducted a systematic review of English and non-English articles using MEDLINE, the Cochrane Controlled Trials Register (1960–2011), EMBASE (1991–2011), Web of Science, Academic Search Premier and Science Direct. Bibliographies of included studies were searched in order to find additional studies. Search terms included MCID or minimal clinically important change, THR or TKR and Short-Form 36. We included longitudinal studies that estimated MCID of SF-36 after THR or TKR.
Three studies met our inclusion criteria, describing a distinct study population: primary THR, primary TKR and revision THR. No synthesis of study results can be given.
Although we found MCIDs in HRQoL after THR or TKR have limited precision and are not validated using external criteria, these are still the best known estimates of MCIDs in HRQoL after THR and TKR to date. We therefore advise these MCIDs to be used as absolute thresholds, but with caution.
PMCID: PMC3626243  PMID: 23610674
Minimal clinically important differences; Health-related quality of life; SF-36; Total hip replacement; Total knee replacement; Systematic review
7.  Patient acceptable symptom states after total hip or knee replacement at mid-term follow-up 
Bone & Joint Research  2014;3(1):7-13.
To define Patient Acceptable Symptom State (PASS) thresholds for the Oxford hip score (OHS) and Oxford knee score (OKS) at mid-term follow-up.
In a prospective multicentre cohort study, OHS and OKS were collected at a mean follow-up of three years (1.5 to 6.0), combined with a numeric rating scale (NRS) for satisfaction and an external validation question assessing the patient’s willingness to undergo surgery again. A total of 550 patients underwent total hip replacement (THR) and 367 underwent total knee replacement (TKR).
Receiver operating characteristic (ROC) curves identified a PASS threshold of 42 for the OHS after THR and 37 for the OKS after TKR. THR patients with an OHS ≥ 42 and TKR patients with an OKS ≥ 37 had a higher NRS for satisfaction and a greater likelihood of being willing to undergo surgery again.
PASS thresholds appear larger at mid-term follow-up than at six months after surgery. With- out external validation, we would advise against using these PASS thresholds as absolute thresholds in defining whether or not a patient has attained an acceptable symptom state after THR or TKR.
Cite this article: Bone Joint Res 2014;3:7–13.
PMCID: PMC3928564  PMID: 24421318
Health-related quality of life; Total hip replacement; Total knee replacement; Patient reported outcome measures; Patient Acceptable Symptom State; TKR; THR; PROMs
8.  Rationing of total knee replacement: a cost-effectiveness analysis on a large trial data set 
BMJ Open  2012;2(1):e000332.
Many UK primary care trusts have recently introduced eligibility criteria restricting total knee replacement (TKR) to patients with low pre-operative Oxford Knee Scores (OKS) to cut expenditure. We evaluate these criteria by assessing the cost-effectiveness of TKR compared with no knee replacement for patients with different baseline characteristics from an NHS perspective.
The cost-effectiveness of TKR in different patient subgroups was assessed using regression analyses of patient-level data from the Knee Arthroplasty Trial, a large, pragmatic randomised trial comparing knee prostheses.
34 UK hospitals.
2131 osteoarthritis patients undergoing TKR.
Interventions and outcome measures
Costs and quality-adjusted life years (QALYs) observed in the Knee Arthroplasty Trial within 5 years of TKR were compared with conservative assumptions about the costs and outcomes that would have been accrued had TKR not been performed.
On average, primary TKR and 5 years of subsequent care cost £7458 per patient (SD: £4058), and patients gained an average of 1.33 (SD: 1.43) QALYs. As a result, TKR cost £5623/QALY gained. Although costs and health outcomes varied with age and sex, TKR cost <£20 000/QALY gained for patients with American Society of Anaesthesiologists grades 1–2 who had baseline OKS <40 and for American Society of Anaesthesiologists grade 3 patients with OKS <35, even with highly conservative assumptions about costs and outcomes without TKR. Body mass index had no significant effect on costs or outcomes. Restricting TKR to patients with pre-operative OKS <27 would inappropriately deny a highly cost-effective treatment to >10 000 patients annually.
TKR is highly cost-effective for most current patients if the NHS is willing to pay £20 000–£30 000/QALY gained. At least 97% of TKR patients in England have more severe symptoms than the thresholds we have identified, suggesting that further rationing by OKS is probably unjustified.
Trial registration number
ISRCTN 45837371.
Article summary
Article focus
We assess the cost-effectiveness of total knee replacement (TKR) compared with no knee replacement for patients with different baseline characteristics from a NHS perspective.
In particular, we assess the appropriateness of eligibility criteria recently introduced by many UK primary care trusts, which restrict TKR to patients with low (ie, poor) pre-operative Oxford Knee Scores (OKS) to cut expenditure.
Key messages
We find TKR to be highly cost-effective, costing £5623 per quality-adjusted life year gained for the average patient.
TKR costs <£20 000 per quality-adjusted life year gained for healthy patients with OKS of <40 or <35 for patients who have other conditions restricting their daily activities.
We find no evidence to support the criteria for restricting access to TKR that have been proposed by some primary care trusts and calculate that restricting TKR to those patients with pre-operative OKS of 26 or less would deny a highly cost-effective treatment to >10 000 patients/year.
Strengths and limitations of this study
This is the first study assessing how the cost-effectiveness of TKR varies with OKS and the first assessing the clinical/economic implications of the newly introduced rationing criteria.
Analyses are based on patient-level data from a large pragmatic trial with detailed prospective collection of utilities, baseline characteristics and all major knee-related NHS resource use, including revisions and ambulatory care.
Our study makes several highly conservative assumptions: in particular, assuming that patients would have accrued no knee-related costs and remained at baseline utility without TKR. Furthermore, the Knee Arthroplasty Trial sample included only 37 patients with pre-operative OKS >35. As result, TKR may be also cost-effective for some patients with OKS above 39.
PMCID: PMC3269047  PMID: 22290396
9.  Analysis of disease patterns and cost of treatments for prevention of deep venous thrombosis after total knee or hip replacement: results from the Practice Analysis of THromboprophylaxis after Orthopaedic Surgery (PATHOS) study 
Venous thromboembolism (VTE) is a well-known complication of total hip replacement (THR) and total knee replacement (TKR). Various drugs have been introduced in an attempt to reduce the mortality as well as the short-term and long-term morbidity associated with the development of VTE. The aim of this study was to analyze drug utilization for thromboprophylaxis and the cost of illness in real clinical practice in patients with THR or TKR.
Materials and methods
A multicenter, retrospective, observational cohort study based on local health unit administrative databases was conducted. All patients (≥18 years old) discharged for THR/TKR procedures between January 1, 2007 and December 31, 2008 were included in the study. The date of first hospital discharge was the index date; patients were followed up for a period of 12 months.
A total of 10,389 patients were included: 3516 males (33.8%, 69.4 ± 10.4 years) and 6873 females (66.2%, 71.7 ± 9.0 years), of which 5483 (52.8%) were discharged for THR and 4906 (47.2%) for TKR. First antithrombotic treatments after discharge were enoxaparin (3937, 37.9%), heparin (3752, 36.1%), antiplatelet agents (658, 6.3%), vitamin K antagonists (276, 2.7%), fondaparinux (136, 1.3%), combinations (185, 1.8%), and no therapy (1445, 13.9%). Overall, we observed 2347 (22.6%) treatment changes; median duration of antithrombotic treatment was 23 days (range 11–47) for THR and 22 days (range 11–46) for TKR. During the follow-up period, we observed 129 cases of VTE (120 per 10,000 patients), five post-thrombotic syndrome (4.8 per 10,000 patients), and three heparin-induced thrombocytopenia (2.9 per 10,000 patients). Median cost for both THR and TKR was €9052.00 (range €8063.00–€9084.96), with a median length of stay of 9.0 days (range 6.0–12.0).
PMCID: PMC3536354  PMID: 23300348
venous thromboembolism; VTE; total hip replacement; THR; total knee replacement; TKR; real practice; cost of illness; antithrombotic therapy
10.  The effect of local anaesthetic wound infiltration on chronic pain after lower limb joint replacement: A protocol for a double-blind randomised controlled trial 
For the majority of patients with osteoarthritis (OA), joint replacement is a successful intervention for relieving chronic joint pain. However, between 10-30% of patients continue to experience chronic pain after joint replacement. Evidence suggests that a risk factor for chronic pain after joint replacement is the severity of acute post-operative pain. The aim of this randomised controlled trial (RCT) is to determine if intra-operative local anaesthethic wound infiltration additional to a standard anaethesia regimen can reduce the severity of joint pain at 12-months after total knee replacement (TKR) and total hip replacement (THR) for OA.
300 TKR patients and 300 THR patients are being recruited into this single-centre double-blind RCT. Participants are recruited before surgery and randomised to either the standard care group or the intervention group. Participants and outcome assessors are blind to treatment allocation throughout the study. The intervention consists of an intra-operative local anaesthetic wound infiltration, consisting of 60 mls of 0.25% bupivacaine with 1 in 200,000 adrenaline. Participants are assessed on the first 5 days post-operative, and then at 3-months, 6-months and 12-months. The primary outcome is the WOMAC Pain Scale, a validated measure of joint pain at 12-months. Secondary outcomes include pain severity during the in-patient stay, post-operative nausea and vomiting, satisfaction with pain relief, length of hospital stay, joint pain and disability, pain sensitivity, complications and cost-effectiveness. A nested qualitative study within the RCT will examine the acceptability and feasibility of the intervention for both patients and healthcare professionals.
Large-scale RCTs assessing the effectiveness of a surgical intervention are uncommon, particulary in orthopaedics. The results from this trial will inform evidence-based recommendations for both short-term and long-term pain management after lower limb joint replacement. If a local anaesthetic wound infiltration is found to be an effective and cost-effective intervention, implementation into clinical practice could improve long-term pain outcomes for patients undergoing lower limb joint replacement.
Trial registration
Current Controlled Trials ISRCTN96095682
PMCID: PMC3056874  PMID: 21352559
11.  Health-related quality of life after total hip replacement: a Taiwan study 
International Orthopaedics  2008;33(5):1217-1222.
This study applied the generalised estimating equations (GEE) in a large-scale prospective cohort study of predictors of health-related quality of life (HRQoL) in a Taiwan population. The study population included all patients who had undergone primary total hip replacement (THR) performed between March 1998 and December 2002 by either of two orthopaedic surgeons in two hospitals. The SF-36 was used in pre- and postoperative assessments of 335 patients. Young age, male gender, minimal comorbidity, use of epidural anaesthesia, lack of readmission within the previous 30 days, and higher preoperative functional status were positively associated with HRQoL (P < 0.05). Patients should be advised that their postoperative HRQoL may depend not only on their postoperative health care but also on their preoperative functional status. These analytical results should be applicable to other Taiwan hospitals and to other countries with similar social and cultural practices.
PMCID: PMC2899131  PMID: 18974987
12.  Evaluation and prediction of health-related quality of life for total hip replacement among Chinese in Taiwan 
International Orthopaedics  2006;32(1):27-32.
The objective of this study was to examine and predict the time trend of health-related quality of life (HRQoL) after total hip replacement (THR). A total of 383 patients receiving primary THR at two medical centers in Taiwan during 1997 to 2000 were enrolled for the study. Face-to-face interviews were conducted by using physician-rated Harris hip score and patient-reported short-form 36-item health survey (SF-36) immediately before the surgery and at 3, 6, 12, 24, and 60 months after surgery. Data analysed by piecewise linear regression revealed remarkable improvements in HRQoL dimensions at the third month after surgery and kept improving until the threshold level of from 39 months to 81 months, at which it reached a plateau. Role limitations due to physical and emotional problems and social functioning after surgery saw the most remarkable improvements, which appear to be related to improvements in functioning in many other dimensions of health. Such interdependence of the dimensions should be examined carefully to see if improvements in social roles can help improve the overall HRQoL in a more effective manner. The results should be applicable to other hospitals in Taiwan and in other countries with similar social and cultural practices.
PMCID: PMC2219949  PMID: 17061126
13.  Predictors of outcomes of recovery following total hip replacement surgery 
Bone & Joint Research  2013;2(11):248-254.
To investigate psychosocial and biomedical outcomes following total hip replacement (THR) and to identify predictors of recovery from THR.
Patients with osteoarthritis (OA) on the waiting list for primary THR in North West England were assessed pre-operatively and at six and 12 months post-operatively to investigate psychosocial and biomedical outcomes. Psychosocial outcomes were anxiety and depression, social support and health-related quality of life (HRQoL). Biomedical outcomes were pain, physical function and stiffness. The primary outcome was the Short-Form 36 (SF-36) Health Survey Total Physical Function. Potential predictors of outcome were age, sex, body mass index, previous joint replacement, involvement in the decision for THR, any comorbidities, any complications, type of medication, and pre-operative ENRICHD Social Support Instrument score, Hospital Anxiety and Depression scores and Western Ontario and McMaster Universities osteoarthritis index score.
The study included 206 patients undergoing THR. There were 88 men and 118 women with a mean age of 66.3 years (sd 10.4;36 to 89). Pain, stiffness and physical function, severity of OA, HRQoL, anxiety and depression all improved significantly from pre-operative to 12-month assessment (all p < 0.001), with the greatest improvement occurring in the first six months (all p < 0.001). The predictors that were found to influence recovery six months after THR were: pain (p < 0.001), anxiety (p = 0.034), depression (p = 0.001), previous joint replacement (p = 0.006) and anti-inflammatory drugs (p = 0.012).
The study identified the key psychosocial and biomedical predictors of recovery following THR. By identifying these predictors, we are able to identify and provide more support for patients at risk of poor recovery following THR.
Cite this article: Bone Joint Res 2013;2:248–54.
PMCID: PMC3842616  PMID: 24285780
Osteoarthritis; Hip replacement; Recovery; Patient-reported outcomes; Predictors; THR
14.  A population-based survival analysis describing the association of body mass index on time to revision for total hip and knee replacements: results from the UK general practice research database 
BMJ Open  2013;3(11):e003614.
Against a backdrop of rising levels of obesity, we describe and estimate associations of body mass index (BMI), age and gender with time to revision for participants undergoing primary total hip (THR) or knee (TKR) replacement in the UK.
Population-based cohort study.
Routinely collected primary care data from a representative sample of general practices, including linked data on all secondary care events.
Population-based cohort study of 63 162 patients with THR and 54 276 with TKR in the UK General Practice Research Database between 1988 and 2011.
Primary and secondary outcomes
Risk of THR and TKR revision associated with BMI, age and gender, after adjusting for the competing risk of death.
The 5-year cumulative incidence rate for THR was 2.2% for men and 1.8% for women (TKR 2.3% for men, 1.6% for women). The adjusted overall subhazard ratio (SHR) for patients with THR undergoing subsequent hip revision surgery, with a competing risk of death, were estimated at 1.020 (95% CI 1.009 to 1.032) per additional unit (kg/m2) of BMI, 1.23 (95% CI 1.10 to 1.38) for men compared with women and 0.970 (95% CI 0.967 to 0.973) per additional year of age. For patients with TKR, the equivalent estimates were 1.015 (95% CI 1.002 to 1.028) for BMI; 1.51 (95% CI 1.32 to 1.73) for gender and 0.957 (95% CI 0.951 to 0.962) for age. Morbidly obese patients with THR had a 65.5% increase (95% CI 15.4% to 137.3%, p=0.006) in the subhazard of revision versus the normal BMI group (18.5–25). The effect for TKR was smaller (a 43.9% increase) and weaker (95% CI 2.6% to 103.9%, p=0.040).
BMI is estimated to have a small but statistically significant association with the risk of hip and knee revision, but absolute numbers are small. Further studies are needed in order to distinguish between effects for specific revision surgery indications.
PMCID: PMC3845068  PMID: 24285628
15.  A multi-perspective cost-effectiveness analysis comparing rivaroxaban with enoxaparin sodium for thromboprophylaxis after total hip and knee replacement in the German healthcare setting 
Patients undergoing major orthopaedic surgery (MOS), such as total hip (THR) or total knee replacement (TKR), are at high risk of developing venous thromboembolism (VTE). For thromboembolism prophylaxis, the oral anticoagulant rivaroxaban has recently been included in the German diagnosis related group (DRG) system. However, the cost-effectiveness of rivaroxaban is still unclear from both the German statutory health insurance (SHI) and the German hospital perspective.
To assess the cost-effectiveness of rivaroxaban from the German statutory health insurance (SHI) perspective and to analyse financial incentives from the German hospital perspective.
Based on data from the RECORD trials and German cost data, a decision tree was built. The model was run for two settings (THR and TKR) and two perspectives (SHI and hospital) per setting.
Prophylaxis with rivaroxaban reduces VTE events (0.02 events per person treated after TKR; 0.007 after THR) compared with enoxaparin. From the SHI perspective, prophylaxis with rivaroxaban after TKR is cost saving (€27.3 saving per patient treated). However, the cost-effectiveness after THR (€17.8 cost per person) remains unclear because of stochastic uncertainty. From the hospital perspective, for given DRGs, the hospital profit will decrease through the use of rivaroxaban by €20.6 (TKR) and €31.8 (THR) per case respectively.
Based on our findings, including rivaroxaban for reimbursement in the German DRG system seems reasonable. Yet, adequate incentives for German hospitals to use rivaroxaban are still lacking.
PMCID: PMC3551680  PMID: 22776616
‘Clinical course of venous thromboembolism’; ‘Major orthopaedic surgery’; ‘Thromboembolic prophylaxis’; ‘Cost-effectiveness analysis’
16.  Patient-reported history of leg ulceration 12–16 years after total primary knee or hip replacement 
Acta Orthopaedica  2011;82(4):471-474.
Background and purpose
Deep vein thrombosis is common after total joint replacement. It is frequently asymptomatic, and it is unclear whether this leads to longer-term problems such as post-thrombotic syndrome and leg ulceration. We investigated whether the postoperative prevalence of ulceration in patients who had undergone primary total hip replacement (THR) or total knee replacement (TKR) was higher than that found in a control group who had not undergone total joint replacement.
The study group consisted of patients who had undergone THR or TKR at one orthopedic center 12–16 years previously without routine chemothromboprophylaxis, and who had not undergone revision surgery. The control group was recruited via primary care. All participants were recruited by post and asked to complete a questionnaire. Age- and sex-adjusted prevalence of self-reported leg ulceration was calculated, and logistic regression was used to determine whether there were any associations between THR or TKR and leg ulceration.
Completed questionnaires were received from 441 THR patients (54% response rate), 196 TKR patients (48%) and 967 control participants (36%). No statistically significant differences in age- and sex-adjusted prevalence of ulceration were found between the groups, for either lifetime prevalence or prevalence over the previous 15 years.
Patients who undergo THR and TKR without chemothromboprophylaxis are unlikely to be at a higher risk of long-term venous ulceration than the normal population.
PMCID: PMC3237039  PMID: 21751860
17.  Predictors for moderate to severe acute postoperative pain after total hip and knee replacement 
International Orthopaedics  2012;36(11):2261-2267.
The ability to identify and focus care to patients at higher risk of moderate to severe postoperative pain should improve analgesia and patient satisfaction, and may affect reimbursement. We undertook this multi-centre cross-sectional study to identify preoperative risk factors for moderate to severe pain after total hip (THR) and knee (TKR) replacement.
A total of 897 patients were identified from electronic medical records. Preoperative information and anaesthetic technique was gained by retrospective chart review. The primary outcomes were moderate to severe pain (pain score ≥ 4/10) at rest and with activity on postoperative day one. Logistic regression was performed to identify predictors for moderate to severe pain.
Moderate to severe pain was reported by 20 % at rest and 33 % with activity. Predictors for pain at rest were female gender (OR 1.10 with 95 % CI 1.01–1.20), younger age (0.96, 0.94–0.99), increased BMI (1.02, 1.01–1.03), TKR vs. THR (3.21, 2.73–3.78), increased severity of preoperative pain at the surgical site (1.15, 1.03–1.30), preoperative use of opioids (1.63, 1.32–2.01), and general anaesthesia (8.51, 2.13–33.98). Predictors for pain with activity were TKR vs. THR (1.42, 1.28–1.57), increased severity of preoperative pain at the surgical site (1.11, 1.04–1.19), general anaesthesia (9.02, 3.68–22.07), preoperative use of anti-convulsants (1.78, 1.32–2.40) and anti-depressants (1.50, 1.08–2.80), and prior surgery at the surgical site (1.28, 1.05–1.57).
Our findings provide clinical guidance for preoperative stratification of patients for more intensive management potentially including education, nursing staffing, and referral to specialised pain management.
PMCID: PMC3479283  PMID: 22842653
18.  Association between occupation and knee and hip replacement due to osteoarthritis: a case-control study 
Arthritis Research & Therapy  2010;12(3):R102.
The objective of this study was to examine the association between occupation and osteoarthritis (OA) leading to total knee (TKR) or hip (THR) joint replacement.
The following is the case-control study design. All patients still living in Iceland who had had a TKR or THR due to OA as of the end of 2002 were invited to participate. First degree relatives of participating patients served as controls. N = 1,408 cases (832 women) and n = 1,082 controls (592 women), 60 years or older and who had adequately answered a questionnaire were analyzed. Occupations were classified according to international standards. Inheritance of occupations was calculated by using the Icelandic Genealogy Database.
The age adjusted odds ratio (OR) for male farmers getting a TKR due to OA was 5.1 (95% confidence interval (CI) 2.1 to 12.4) and for a male farmer getting a THR due to OA the OR was 3.6 (95% CI 2.1 to 6.2). The OR for a fisherman getting a TKR was 3.3 (95% CI 1.3 to 8.4). No other occupations showed increased risk for men. For women there was no increased risk for any occupation. Farming and fishing were also the occupations that showed the greatest degree of inheritance.
These results support an association in males between occupations with heavy physical load and both TKR and THR for OA.
PMCID: PMC2911890  PMID: 20497530
19.  Trends in hip and knee joint replacement: socioeconomic inequalities and projections of need 
Annals of the Rheumatic Diseases  2004;63(7):825-830.
Objectives: To examine trends in primary and revision joint (hip and knee) replacement in England between 1991 and 2000.
Methods: Analysis of hospital episodes statistics between 1 April 1991 and 30 March 2001 for total hip replacement (THR) and total knee replacement (TKR). Descriptive statistics and regression modelling were used to summarise patients' demographic and clinical characteristics and to explore variations in joint surgery rates by age, sex, and deprivation.
Results: Between 1991 and 2000, the incidence of primary THR increased by 18%, while the incidence of revision THR more than doubled. The incidence of primary TKR doubled, with revision TKR increasing by 300%. Over the 10 year period, the proportion of THR episodes that involved revision operations rose from 8% to 20%. Substantial variations in operation rates by socioeconomic status were seen, with the most deprived fifth of the population experiencing significantly lower rates. Projections estimate that primary THR numbers could rise by up to 22% by the year 2010, with primary TKR numbers rising by up to 63%.
Conclusions: Provision of joint replacement surgery in English NHS hospitals has increased substantially over the past decade. Revision operations in particular have increased markedly. The growth in primary operations has mostly occurred among those aged 60 years and over; rates among young people have changed very little. There is a significant deprivation based gradient in rates. If current trends continue there would be almost 47 000 primary hip and 54 000 primary knee operations annually by 2010.
PMCID: PMC1755069  PMID: 15194578
20.  Smoking and primary total hip or knee replacement due to osteoarthritis in 54,288 elderly men and women 
The reported association of smoking with risk of undergoing a total joint replacement (TJR) due to osteoarthritis (OA) is not consistent. We evaluated the independent association between smoking and primary TJR in a large cohort.
The electronic records of 54,288 men and women, who were initially recruited for the Second Australian National Blood Pressure study, were linked to the Australian Orthopaedic Association National Joint Replacement Registry to detect total hip replacement (THR) or total knee replacement (TKR) due to osteoarthritis. Competing risk regressions that accounted for the competing risk of death estimated the subhazard ratios for TJR. One-way and probabilistic sensitivity analyses were undertaken to represent uncertainty in the classification of smoking exposure and socioeconomic disadvantage scores.
An independent inverse association was found between smoking and risk of THR and TKR observed in both men and women. Compared to non-smokers, male and female smokers were respectively 40% and 30% less likely to undergo a TJR. This significant association persisted after controlling for age, co-morbidities, body mass index (BMI), physical exercise, and socioeconomic disadvantage. The overweight and obese were significantly more likely to undergo TJR compared to those with normal weight. A dose–response relationship between BMI and TJR was observed (P < 0.001). Socioeconomic status was not independently associated with risk of either THR or TKR.
The strengths of the inverse association between smoking and TJR, the temporal relationship of the association, together with the consistency in the findings warrant further investigation about the role of smoking in the pathogenesis of osteoarthritis causing TJR.
PMCID: PMC3844303  PMID: 24006845
Total joint replacement; Smoking; Socioeconomic status; Exposure misclassification; Sensitivity analysis
21.  Evaluation of health outcomes in osteoarthritis patients after total knee replacement: a two-year follow-up 
To quantify the improvement in health outcomes in patients after total knee replacement (TKR).
This was a two-year non-randomized prospective observational study in knee osteoarthritis (OA) patients undergone TKR. Patients were interviewed one week before, six months after, and two years after surgery using a standardized questionnaire including the SF-36, the Oxford Knee Score (OKS), and the Knee Society Clinical Rating Scale (KSS). A generalized estimating equation (GEE) model was used to estimate the magnitudes of the changes with and without the adjustment of age, ethnicity, BMI, and years with OA.
A total of 298 (at baseline), 176 (at six-months), and 111 (at two-years) eligible patients were included in the analyses. All the scores changed significantly over time, with the exception of SF-36 social functioning, vitality, and mental health. With the adjustment of covariates, the magnitude of changes in these scores was similar to those without the adjustment.
Both general and knee-specific physical functioning had been significantly improved after TKR, while other health domains have not been substantially improved after the surgery.
PMCID: PMC2933708  PMID: 20723239
22.  Determinants of satisfaction 1 year after total hip arthroplasty: the role of expectations fulfilment 
Between 7% and 15% of patients are dissatisfied after total hip arthroplasty (THA). To assess predictors and postoperative determinants of satisfaction and expectation fulfilment one year after (THA).
Before THA surgery, 132 patients from three tertiary care centres and their surgeons were interviewed to assess their expectations using the Hospital for Special Surgery Total Hip Replacement Expectations Survey (THR survey). One year after surgery, patients (n = 123) were contacted by phone to complete a questionnaire on expectation fulfilment (THR survey), satisfaction, functional outcome (Womac), and health-related quality of life (SF 12). Univariate and multivariate analyses were performed.
Preoperative predictors of satisfaction were a good mental wellbeing (adjusted OR 1.09 [1.02; 1.16], p = 0.01) and optimistic surgeons expectations (1.07 [1.01; 1.14], p = 0.02). The main postoperative determinant of satisfaction was the fulfilment of patient’s expectations (1.08 [1.04; 1.12], p < 0.001). Expectation fulfilment could be predicted before surgery by young age (regression coefficient −0.55 [−0.88; -0.21], p = 0.002), good physical function (−0.96 [−1.82; -0.10], p = 0.03) and good mental wellbeing (0.56 [0.14; 0.99], p = 0.01). Postoperative determinants of expectation fulfilment were functional outcome (−2.10 [−2.79; -1.42], p <0.001) and pain relief (−14.83 [−22.38; -7.29], p < 0.001).
To improve patient satisfaction after THA, patients’ expectations and their fulfilment need to be carefully addressed. Patients with low mental wellbeing or physical function should be identified and specifically informed on expected surgical outcome. Surgeons’ expectations are predictive of satisfaction and information should aim to lower discrepancy between surgeons’ and patients’ expectations.
PMCID: PMC3936828  PMID: 24564856
Total hip arthroplasty; Expectations; Expectations’ fulfilment; Satisfaction; Outcome
23.  Total hip and knee replacement surgery results in changes in leukocyte and endothelial markers 
It is estimated that over 8 million people in the United Kingdom suffer from osteoarthritis. These patients may require orthopaedic surgical intervention to help alleviate their clinical condition. Investigations presented here was to test the hypothesis that total hip replacement (THR) and total knee replacement (TKR) orthopaedic surgery result in changes to leukocyte and endothelial markers thus increasing inflammatory reactions postoperatively.
During this 'pilot study', ten test subjects were all scheduled for THR or TKR elective surgery due to osteoarthritis. Leukocyte concentrations were measured using an automated full blood count analyser. Leukocyte CD11b (Mac-1) and CD62L cell surface expression, intracellular production of H2O2 and elastase were measured as markers of leukocyte function. Von Willebrand factor (vWF) and soluble intercellular adhesion molecule-1 (sICAM-1) were measured as markers of endothelial activation.
The results obtained during this study demonstrate that THR and TKR orthopaedic surgery result in similar changes of leukocyte and endothelial markers, suggestive of increased inflammatory reactions postoperatively. Specifically, THR and TKR surgery resulted in a leukocytosis, this being demonstrated by an increase in the total leukocyte concentration following surgery. Evidence of leukocyte activation was demonstrated by a decrease in CD62L expression and an increase in CD11b expression by neutrophils and monocytes respectively. An increase in the intracellular H2O2 production by neutrophils and monocytes and in the leukocyte elastase concentrations was also evident of leukocyte activation following orthopaedic surgery. With respect to endothelial activation, increases in vWF and sICAM-1 concentrations were demonstrated following surgery.
In general it appeared that most of the leukocyte and endothelial markers measured during these studies peaked between days 1-3 postoperatively. It is proposed that by allowing orthopaedic surgeons access to alternative laboratory markers such as CD11b, H2O2 and elastase, CD62L, vWF and sICAM-1, an accurate assessment of the extent of inflammation due to surgery per se could be made. Ultimately, the leukocyte and endothelial markers assessed during this investigation may have a role in monitoring potential infectious complications that can occur during the postoperative period.
PMCID: PMC2820000  PMID: 20148137
24.  Incidence and risk factors for development of venous thromboembolism in Indian patients undergoing major orthopaedic surgery: results of a prospective study 
Postgraduate Medical Journal  2006;82(964):136-139.
The incidence of venous thromboembolism (VTE) in Western populations undergoing major orthopaedic surgery without any thromboprophylaxis has been reported to range from 32% to 88%. There is however limited information on incidence of VTE in Indian patients and most of the Indian patients undergoing these surgeries do not receive any form of prophylaxis regardless of their risk profile.
A prospective study was performed on 147 patients undergoing major orthopaedic surgery for total knee replacement (TKR), total hip replacement (THR), and proximal femur fracture fixation (PFF) without any prophylaxis. These patients were profiled for presence of the known risk factors responsible for development of VTE. A duplex ultrasound on both lower limbs was done 6 to 10 days after surgery. Twenty three patients underwent THR, 22 patients underwent TKR, and 102 underwent surgery for PFF. The patients were assessed clinically for any signs of deep venous thrombosis (DVT) and pulmonary embolism (PE). A helical CT scan was done in case of suspicion of PE and a duplex ultrasound was done in case of clinical suspicion of DVT irrespective of the stage of study.
The overall incidence of VTE was 6.12% and that of PE was 0.6%. The risk factors that were found to be significantly responsible for development of VTE (p < 0.05) were: immobility greater than 72 hours, malignancy, obesity, surgery lasting more than two hours.
The study reconfirms the belief that DVT has a lower incidence in Indian patients as compared with other ethnic groups.
PMCID: PMC2596707  PMID: 16461477
deep venous thrombosis; pulmonary embolism; thromboprophylaxis
25.  Variability of indication criteria in knee and hip replacement: an observational study 
Total knee (TKR) and hip (THR) replacement (arthroplasty) are effective surgical procedures that relieve pain, improve patients' quality of life and increase functional capacity. Studies on variations in medical practice usually place the indications for performing these procedures to be highly variable, because surgeons appear to follow different criteria when recommending surgery in patients with different severity levels. We therefore proposed a study to evaluate inter-hospital variability in arthroplasty indication.
The pre-surgical condition of 1603 patients included was compared by their personal characteristics, clinical situation and self-perceived health status. Patients were asked to complete two health-related quality of life questionnaires: the generic SF-12 (Short Form) and the specific WOMAC (Western Ontario and Mcmaster Universities) scale. The type of patient undergoing primary arthroplasty was similar in the 15 different hospitals evaluated.
The variability in baseline WOMAC score between hospitals in THR and TKR indication was described by range, mean and standard deviation (SD), mean and standard deviation weighted by the number of procedures at each hospital, high/low ratio or extremal quotient (EQ5-95), variation coefficient (CV5-95) and weighted variation coefficient (WCV5-95) for 5-95 percentile range. The variability in subjective and objective signs was evaluated using median, range and WCV5-95. The appropriateness of the procedures performed was calculated using a specific threshold proposed by Quintana et al for assessing pain and functional capacity.
The variability expressed as WCV5-95 was very low, between 0.05 and 0.11 for all three dimensions on WOMAC scale for both types of procedure in all participating hospitals. The variability in the physical and mental SF-12 components was very low for both types of procedure (0.08 and 0.07 for hip and 0.03 and 0.07 for knee surgery patients). However, a moderate-high variability was detected in subjective-objective signs. Among all the surgeries performed, approximately a quarter of them could be considered to be inappropriate.
A greater inter-hospital variability was observed for objective than for subjective signs for both procedures, suggesting that the differences in clinical criteria followed by surgeons when indicating arthroplasty are the main responsible factors for the variation in surgery rates.
PMCID: PMC2987974  PMID: 20977745

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