Birmingham Metal-on-metal total hip resurfacing (BHR) is a bone-conserving option for patients with advanced articular damage. While the outcomes of Total Hip Replacement (THR) are well documented, there is a paucity of literature comparing the patient reported outcomes of BHR versus THR. This study aims to compare the patient reported outcomes for an impact on quality of life between patients who had a BHR vs. THR after correcting for selection bias.

Patients who underwent a BHR or THR between July 2003 and December 2006 were included. Patient questionnaires included demographic details, co-morbidities, WOMAC, SF-36 Scores. In addition, a 4 point Likert scale was used to measure satisfaction post-operatively. The above data was collected pre-operatively and at 1, 2, 3 and 5 years post-operatively. Data was analysed with SPSS (version 19) software package. All analysis was adjusted for Age, gender, Co-morbidity and pre-operative score by using Multivariate regression analysis using a General Liner Model to rule out the effect of these predictors on outcomes between groups.

337 patients were included (205 for THR and 132 for BHR). BHR patients were younger than THR patients (49 vs. 67 years, p<0.01), were more likely to be male (68% vs. 42% of THR, p<0.01), reported fewer co-morbidities (1.06 vs. 1.59, p<0.01). BHR patients reported better WOMAC pain and function scores at 5 years (p<0.05). For SF-36 scores, BHR patients reported higher scores for all 8 domains at 1 year and 5 year follow up (p<0.05). BHR patients reported higher satisfaction than THR group for return to Activities of Daily Living and Recreational activities at 1 and 5 years (p<0.05)

After correction for patient variability, BHR patients reported better improvement in pain and function and enjoyed a better quality of life in relation to return to ADL and recreational activities over to 5 years post-surgery.

Introduction

Cemented stems have shown 90–100% survivorship when coupled with polyethylene acetabular component. This study aims to compare cemented stem behaviour in combination with large metal on metal (MOM) vs. metal on poly (MOP) bearings.

Introduction

This project reports differences in outcome measures after total ankle arthroplasty (TAA) for patients with Osteoarthritis (OA), Rheumatoid Arthritis (RA) and Post-traumatic Osteoarthritis (PTOA).

Introduction

Peri prosthetic fracture is a recognised complication following Total ankle arthroplasty (TAA). There is limited literature on post operative management following TAA and controversies exist based on surgeon preferences. This project reports the incidence of peri- prosthetic fractures in patients managed with 2 different post-operative protocols.

We aimed to identify whether patients in lower socioeconomic groups had worse function prior to total knee arthroplasty and to establish whether these patients had worse post-operative outcome following total knee arthroplasty.

Data were obtained from the Kinemax outcome study, a prospective observational study of 974 patients undergoing primary total knee arthroplasty for osteoarthritis. The study was undertaken in thirteen centres, four in the United States, six in the United Kingdom, two in Australia and one in Canada. Pre-operative data were collected within six weeks of surgery and patients were followed for two years post-operatively. Pre-operative details of the patient's demographics, socioeconomic status (education and income), height, weight and co-morbid conditions were obtained. The WOMAC and SF-36 scores were also obtained. Multivariate regression was utilised to analyse the association between socioeconomic status and the patient's pre-operative scores and post-operative outcome. During the analysis, we were able to control for variables that have previously been shown to effect pre-operative scores and post-operative outcome.

Patients with a lower income had a significantly worse pre-operative WOMAC pain (p=0.021) and function score (p=0.039) than those with higher incomes. However, income did not have a significant impact on outcome except for WOMAC Pain at 12-months (p=0.014). At all the other post-operative assessment times, there was no correlation between income and WOMAC Pain and WOMAC Function. Level of education did not correlate with pre-operative scores or with outcome at any time during follow-up. This study demonstrates that across all four countries, patients with lower incomes appear to have a greater need for total knee arthroplasty. However, level of income and educational status did not appear to affect the final outcome following total knee arthroplasty. Patients with lower incomes appear able to compensate for their worse pre-operative score and obtain similar outcomes post-operatively.

The aim of this study was to investigate the possible benefit of large-head metal-on-metal bearing on a stem for primary hip replacement compared with a 28 mm diameter conventional metal-on-polyethylene bearing in a prospective randomised controlled trial. We investigated cemented stem behaviour between these two different bearings using Einzel-Bild-Röntgen-Analyse, clinical and patient reported measures (Harris hip score, Western Ontario and McMaster Universities osteoarthritis index, Short Form-36 and satisfaction) and whole blood metal ion levels at two years. A power study indicated that 50 hips were needed in each group to detect subsidence of > 5 mm at two years with a p-value of < 0.05.

Significant improvement (p < 0.001) was found in the mean clinical and patient reported outcomes at two years for both groups. Comparison of outcomes between the groups at two years showed no statistically significant difference for mean stem migration, clinical and patient reported outcomes; except overall patient satisfaction which was higher for metal-on-metal group (p = 0.05). Metal ion levels were raised above the Medicines and Healthcare products Regulatory Agency advised safety level (7 µg per litre) in 20% of the metal-on-metal group and in one patient in metal-on-polyethylene group (who had a metal-on-metal implant on the contralateral side). Two patients in the metal-on-metal group were revised, one for pseudotumour and one for peri-prosthetic fracture.

Use of large modular heads is associated with a risk of raised whole blood metal ion levels despite using a proven bearing from resurfacing. The head-neck junction or excess stem micromotion are possibly the weak links warranting further research.

Introduction and Aims: Morbid obesity (BMI> 40) has been shown to cause increased perioperative morbidity and poorer long-term implant survivorship following total knee arthroplasty (TKA). The aim of this study was to determine the impact of morbid obesity on patient-reported outcomes following TKA.

Methods: Patients undergoing primary TKA were invited to complete questionnaires preoperatively and one year after surgery. Questionnaires include the WOMAC and SF-36 health status measures, demographics, self-reported comorbid medical conditions, height and weight. At follow-up, satisfaction with results of TKA is included. Patients were categorised by their preoperative BMI categories as ideal weight (20–25), overweight (> 25–30), obese (> 30–40) or morbidly obese (> 40). We used multivariate analysis to adjust for known significant correlates of WOMAC and SF-36, namely age, gender and comorbid medical conditions. Adjusted mean scores for each assessment were compared by BMI category.

Results: A total of 769 patients were included in the study which included 27 morbidly obese, 280 obese, 314 overweight and 148 ideal weight patients. Morbidly obese patients when compared with non-obese patients had significantly worse preoperative WOMAC pain and function and a trend for worse SF36 scores (Vitality significantly worse, p=0.04). There was no significant difference between the BMI categories at one year for WOMAC or SF-36 scores (trend for the Physical Functioning score to be lower, p=0.052). Morbidly obese patients were all satisfied with pain relief after surgery but were less satisfied with functional results when compared to the non-obese groups.

Discussion: This study shows that morbidly obese patients report significantly worse health status prior to TKA but their post-operative improvement is greater than the non-obese population. Although morbid obesity should not be an absolute contraindication to TKA, patients should be carefully selected balancing the risk of perioperative complications and earlier failure against the demonstrated marked improvement in quality of life.

Total Ankle Arthroplasty (TAA) using the uncemented three component mobile design has shown encouraging results. There is limited literature on the optimal postoperative management. In our centre, TAA patients are mobilised 48 hours after surgery without a short leg plaster. The aim of this prospective audit was to measure the outcomes of these patients to ascertain if this is a safe and effective protocol.

Patients who underwent primary TAA between March 2006 and March 2008 were invited to participate in the audit. Assessment included patient questionnaires which collected demographics, height and weight, Foot and Ankle Outcome Score (FAOS) and Short-Form-36 (SF-36). Clinical examination collected American Orthopaedic Foot and Ankle Score (AOFAS). Data was collected pre-operatively and at 3 and 6 months after surgery.

A total of 48 ankle replacements in 46 patients were included. Primary diagnosis was osteoarthritis (25), post-traumatic osteoarthritis (9), and rheumatoid arthritis (12). Mean age was 63 years (range 33 to 83) and the majority were males (29, 60%). The average body mass index was 28 (SD 5.3). There were significant improvements to 3-months after surgery for AOFAS (mean 29 to 76, p< 0.0001), FAOS (mean scores changes: Pain 36 to 72, Function 41 to 68, Stiffness 38 to 65, p< 0.001) and physical domains of the SF-36 (means score changes: Physical Functioning 25 to 39, Role Physical 27 to 40, Bodily Pain 29 to 48 and Vitality 42 to 50, p< 0.05). All outcome scores were maintained with a non-significant trend for better scores from 3 to 6 months.

These early results demonstrate encouraging outcomes for TAA patients who are mobilised early after surgery without a short leg plaster. Further studies of post-operative management are needed to compare outcomes after TAA between patients undergoing this protocol and patients who are immobilised in plaster.

We have attempted to quantify the influence of clinical, radiological and prosthetic design factors upon flexion following knee replacement. Our study examined the outcome following 101 knee replacements performed in two prospective randomized trials using similar cruciate retaining implants. Multivariate analyses, after adjusting for age, sex, diagnosis and the type of prosthesis revealed that the only significant correlates for range of movement at 12-months were the difference in posterior condylar offset ratio (p< 0.001), tibial slope (p< 0.001) and preoperative range of movement (p=0.025). We found a moderate correlation between 12-month range of movement and posterior tibial slope (R=0.58) and the difference of post femoral condylar offset (that is, post-operative minus preoperative posterior condylar offset, R=0.65). Posterior condylar offset had the greatest impact upon final range of movement highlighting this as an important consideration for the operating surgeon at pre-operative templating when choosing both the design and size of the femoral component.

Background: The determinants of range of movement following knee replacement may be surgically modifiable (tibial slope, posterior condylar offset or the level of the joint line) or non modifiable (pre-operative range of movement, sex or BMI). We aimed to quantify the influence of these factors upon restoration of flexion in the arthritic knee following knee replacement

Methods: Patients were included from two prospective trials for three different designs of knee replacement. Range of movement was recorded using a standard measuring technique preoperatively and 12 months after surgery. Radiological measurement was done by an independent observer and included the preoperative posterior condylar offset and the postoperative tibial slope, posterior condylar offset, posterior condylar offset ratio, varus-valgus alignment and Insall ratio. Multivariate analysis using stepwise selection was performed to determine the significant predictors of the range of movement at 12 months.

Results: The study includes 133 knee replacements performed on 125 patients. Complete clinical and radiographic data for preoperative and 12-month assessment was available for 101 knees and only these were included for the analyses. There was no significant difference between the three groups in terms of postoperative range of movement or the radiological parameters measured. Multivariate analysis after adjusting for age, sex, diagnosis and the type of prosthesis revealed that the only significant correlates of range of movement at 12-months were the difference in posterior condylar offset ratio, tibial slope and preoperative range of movement. Moderate correlation was noted between range of movement at 12 months and posterior tibial slope (R=0.58) and the difference of post femoral condylar offset (that is, post-operative minus preoperative posterior condylar offset, R=0.65). Preoperative range of movement had only a weak correlation with post-operative range of movement (R=0.20).

Conclusions: We found that the posterior femoral condylar offset had the greatest impact upon final range of movement. We would encourage the operating surgeon at pre-operative templating to take this into account when choosing size and design of femoral component.

Introduction: There is relatively little known about patient-reported health status in patients with ankle arthritis awaiting arthroplasty. This study aims to compare the preoperative health status of patients awaiting ankle, hip and knee arthroplasty.

Materials and Methods: Patients admitted for primary ankle, hip or knee arthroplasty to an NHS teaching hospital were invited to participate. Preoperative questionnaire included the WOMAC, SF-36 and self-reported height and weight providing body mass index (BMI). Comparisons of WOMAC and SF-36 data were adjusted for age, gender and BMI.

Results: A total of 2,196 patients were recruited between July 2003 and May 2007; including 35 ankle arthroplasty (TAA), 899 hip arthroplasty (THA) and 1,262 total arthroplasty (TKA) cases. There was no significant difference in age across the 3 groups but a significantly higher proportion of TAA patients were male (69 percent vs. 38 percent for THA and 43 percent for TKA, p=0.0002). BMI of the TKA patients was significantly higher than the THA patients (29.4 vs. 27.3, p< 0.0001). Multivariate analysis which adjusted for age, gender and BMI demonstrated that THA patients were significantly worse (p< 0.05) than the TKA patients on all domains except for WOMAC stiffness and the SF-36 general health and mental health domains. TAA patients were not significantly different from either group on any measure.

Conclusions: Patients awaiting TAA reported similar WOMAC and SF-36 scores as the TKA patients. Patients awaiting THA report worse pain and function related to their hip and worse SF-36 scores except for general health and mental health domains.

We aimed to identify whether patients in lower socioeconomic groups had worse function prior to total knee arthroplasty and to establish whether these patients had worse post-operative outcome following total knee arthroplasty. Data was obtained from the Kinemax outcome study, this was a prospective observational study of 974 patients undergoing primary total knee arthroplasty for osteoarthritis. The study was undertaken in thirteen centers, four in the United States, six in the United Kingdom, two in Australia and one in Canada. Pre-operative data was collected within six weeks of surgery and patients were followed for two years post-operatively. Pre-operative details of the patient’s demographics, socioeconomic status (education and income), height, weight and co-morbid conditions were obtained. The WOMAC and SF-36 scores were also obtained. Multivariate regression was utilised to analyse the association between socioeconomic status and the patient’s pre-operative scores and post-operative outcome. During the analysis, we were able to control for variables that have previously been shown to effect pre-operative scores and post-operative outcome. Patients with a lower income had a significantly worse pre-operative WOMAC pain (p=0.021) and function score (p=0.039) than those with higher incomes. However, income did not have a significant impact on outcome except for WOMAC Pain at 12-months (p=0.014). At all the other post-operative assessment times, there was no correlation between income and WOMAC Pain and WOMAC Function. Level of education did not correlate with pre-operative scores or with outcome at any time during follow-up. This study demonstrates that across all four countries, patients with lower incomes appear to have a greater need for total knee arthroplasty. However, level of income and educational status did not appear to effect the final outcome following total knee arthroplasty. Patients with lower incomes appear able to compensate for their worse pre-operative score and obtain similar outcomes post-operatively.

We compared patient-reported outcomes of the Kinemax fixed- and mobile-bearing total knee replacement in a multi-centre randomised controlled trial. Patients were randomised to the fixed- or the mobile-bearing prosthesis via a sealed envelope method after the bone cuts had been made in the operating theatre. Randomisation was stratified by centre and diagnosis. Patients were assessed pre-operatively and at eight to 12 weeks, one year and two years post-operatively. Validated questionnaires were used which included the Western Ontario MacMasters University, Short-Form 12, Mental Health Index-5, Knee Injury and Osteoarthritis Outcome Score for Knee-Related Quality of Life and Function in Sport and Recreation scales and a validated scale of satisfaction post-operatively. In total, 242 patients (250 knees) with a mean age of 68 years (40 to 80) were recruited from four NHS orthopaedic centres. Of these, 132 patients (54.5%) were women.

No statistically significant differences could be identified in any of the patient-reported outcome scores between patients who received the fixed-bearing or the mobile-bearing knee up to two-years post-operatively.

Background: Falls are a major concern in the elderly population both from a clinical perspective and that of health resource provision. This study evaluates the incidence of falls in patients awaiting hip or knee replacement and the impact of joint replacement surgery 2 years later.

Method: Patients aged 65-80 years listed for primary hip or knee arthroplasty for osteoarthritis (OA) were invited to participate. Patients completed a questionnaire including Western Ontario and McMaster University OA Index (WOMAC) scores 0-100, 100 best, history of falls and fractures. Function was measured using Timed Up and Go (TUG) walk test. All tests were repeated at two years.

Results: One hundred and ninety-nine patients (84 hips, 115 knees) were recruited with a mean age of 72 years (standard deviation 4.0) and predominantly female (57 %). At two years 144 patients were reviewed of whom 128 had undergone arthroplasty. After surgery, 29/128 (23%) reported falling compared to 55 of these 128 (43%) falling at baseline; only 13/128 (11%) had fallen more than once. Fifteen patients sustained minor injuries and one patient reported a fractured wrist. Of the patients who had undergone joint replacement and fell at baseline 36/55 (66%) patients reported no falls at follow-up, whilst there were 11 new fallers. Patients reporting falls had significantly lower WOMAC pain and function scores, and slower TUG scores at both baseline and two-year review.

Conclusion: Patients with severe hip and knee OA awaiting arthroplasty reported a higher incidence of falls compared to the normal population but reported fewer falls after surgery. However, almost one in four patients were still reporting falling at the two-year review. Injury including periprosthetic fractures can have serious clinical and economic consequences. This study highlights the need to evaluate a falls prevention programme in arthroplasty management.

This study aimed to determine the prevalence of osteoporosis in patients awaiting hip and knee replacement for osteoarthritis and to review them two years later to determine the changes in bone density following joint replacement.

Patients aged between 65 and 80 years awaiting total hip or knee replacement were invited to participate. Lumbar spine, bilateral femoral and forearm bone mineral density (BMD) measurements were obtained using dual energy x-ray absorptiometry. BMD values were standardised using previously published T-scores and Z-scores. To assess clinical status, patients completed a questionnaire including the Western Ontario and McMaster University OA Index (WOMAC). All measurements were repeated at two-years.

Participants included 199 patients (84 hips and 115 knees) with a mean age of 72 years (SD 4.0) and were predominantly female (hips 67%, knees 50%). At baseline 46/199 (23%) patients (39 females) had evidence of osteoporosis (WHO definition) at one or more sites with the highest prevalence at the forearm (14%). At two-years 144 patients attended for review with 128 having undergone hip (56) or knee (72) replacement. At this review 39/144 (27%) patients (33 females) had evidence of osteoporosis at one or more sites with the highest prevalence at the forearm (22%). The greatest bone loss occurred at the forearm with median BMD change of minus 4% for females (25th percentile minus 7.3%, 75th percentile minus 1.9%) and minus 2.9% for males (25th percentile minus 4.6%, 75th percentile minus 1.1%). There was a significant difference in WOMAC Pain scores at follow-up between the osteo-porotic and non-osteoporotic knee patients (67 versus 81, p=0.002) indicating that osteoporotic patients had greater knee pain.

We have identified the forearm as not only the site with the highest prevalence of osteoporosis but also the greatest bone loss at follow-up. Further evaluation of forearm bone density measurements in the preopera-tive assessment and follow-up of patients awaiting joint replacement for hip and knee OA is required. Larger studies are needed to confirm our finding that the presence of osteoporosis is predictive of worse patient-reported outcomes of knee replacement.

Purpose: The purpose of this study was to determine the rate of clinically detected deep venous thrombosis and pulmonary embolism in patients with trunk or extremity bone or soft tissue sarcomas.

Patients and methods: The clinical records of patients with a confirmed diagnosis of primary bone or soft tissue sarcoma presenting between 1998 and 2003 were reviewed. Data relating to clinical features, risk factors for thromboembolism and clinical thromboembolic events were retrieved.

Results: 252 patients were identified. 94 had a diagnosis of primary bone sarcoma and 158 a diagnosis of primary soft tissue sarcoma. The mean age was 53 (range 15 to 94); 137 (54%) were male.

37 patients were suspected clinically of having a deep venous thrombosis, 10 of which were confirmed radiologically, giving a rate of 4%. Nine patients had a suspected pulmonary embolism, 2 of which were confirmed radiologically and one of whom died of pulmonary embolism, giving an overall rate of fatal pulmonary embolism of 0.4%. All patients with thromboembolic events had lower extremity tumours and all were surgical patients. However, the majority of thromboembolic events (6 of 10 deep venous thromboses and 2 of 3 pulmonary embolisms) occurred prior to surgery.

Discussion: The risk of a clinically apparent thromboembolic event in patients with bone or soft tissue sarcomas is comparable to that in other orthopaedic patients. Risk factors for venous thromboembolism include lower extremity sarcomas and mechanical obstruction of the venous system. Consideration should be given to excluding deep venous thrombosis before surgery.

Introduction Presently, many instruments exist for assessing both patient and surgeon-based satisfaction after joint replacement, including both generic and disease specific measures. Our aim was to derive and assess the validity of a reduced function scale of the WOMAC for patients with osteoarthritis of the hip and knee.

Methods All unilateral data from 12 centres world-wide (UK, US, Canada and Australia) involved in an international, multi-centre outcome study for patients undergoing TKR were included for analysis. The reduced scale was derived from pre-operative and three month postoperative data using a combination of data-driven analysis and purely clinical methods. The reduced WOMAC was then extensively validated in three key areas; validity, reliability and responsiveness using 12 month post-operative data from the study and data from the Medicare Hip Replacement Study. Data from 898 patients pre-operatively and 806 patients at three months was used for the data driven section of analysis. For the clinical section, 30 members of the orthopaedic community were surveyed as to their opinions of which items should be retained in the reduced version of the scale. These results were then combined to produce a reduced function scale of seven items to be used in conjunction with the five item pain scale. This reduced scale was then scrutinised to ensure it’s validity (both construct and content), reliability (both internal consistency and reproducibility) and responsiveness (using Standardised Response Means).

Results The items retained were: ascending stairs, rising from sitting, getting in/out of car, going shopping, rising from bed, taking off socks and sitting. The scales’s construct validity was confirmed by significant positive correlation with the SF-36 physical component score, the knee society function score, the Oxford knee score, and for the hip data, the Harris Hip Score and SF-12 physical component score. Cronbach’s alpha was consistently high (a> 0.85) with the reduced scale, showing it to be reliable.

Conclusions The SRM’s indicated that the reduced scale may even be better at detecting change than the full scale.

This paper aims to determine if preoperative characteristics have a significant impact on functional outcome as measured by the WOMAC at 2-years following total knee replacement (TKR) surgery. Patients were recruited as part of a prospective study of outcomes of primary TKR for osteoarthritis in centres in the US (4 centres), UK (6 centres) and Australia (2 centres). Research assistants recruited eligible patients and collected clinical history and physical examination data preoperatively, 3, 12 and 24-months post surgery. The WOMAC, SF-36, patients satisfaction and demographic data were obtained by self-administered questionnaires. All scores were transformed to 0–100 scale (100 best).

We recruited 860 eligible patients and have complete 12-month WOMAC data on 736 patients (86%) and 2-year data on 701 patients (78%). Mean age was 70 years (SD 10), 59% were female, 50% were from the UK, 30% from the US and 20% from Australia. Mean preoperative clinical measures were: knee flexion 107° (SD18), SF36 Mental Health 72 (SD19), body mass index 29 (SD 6) and WOMAC Function 45 (SD 19). 46% of patients reported more than 2 comorbid conditions.

There was no significant difference between mean WOMAC Function scores at 12-months (73, SD 21) and 2-years (74, SD21). In a linear regression model (model R- square= 25), the preoperative predictors of worse WOMAC Function at 2-years, in order of decreasing importance, were: low WOMAC Function (p< 0.0001), higher number of comorbid conditions (p=0.0002), UK patients (p=0.0002), low SF36 Mental Health (p=0.01) and restricted preoperative knee flexion (p=0.02). Patients who come to surgery with poor function, restricted knee flexion, low mental health and other comorbid conditions are more likely to have worse functional outcomes 2-years following surgery. After adjusting for these predictors, the UK patients had significant lower WOMAC Function scores than the US and Australia.

Presently, many instruments exist for assessing both patient - and surgeon-based satisfaction after joint replacement, including both generic (measures of general health status) and disease specific measures. As such, the US PORT study (1995) recommends use of both the WOMAC and SF-36. However, this means that studies need to incorporate at least these two lengthy questionnaires into protocols, which increases the pressure on patients for both time and difficulty, but also introduces some duplication of data.

The SF-36 has been successfully reduced and validated to a 12 item questionnaire (SF-12) which can be used as a summarised generic health score. It would be of great benefit if a reduced version of the WOMAC could be derived to give a similar summarised disease-specific measurement tool.

To derive and assess the validity of a reduced function scale of the WOMAC for patients with osteoarthritis of the hip and knee.

All unilateral data from 12 centres world-wide (UK US Canada and Australia) involved in an international, multi-centre outcome study for patients undergoing TKR were included for analysis. The reduced scale was derived from pre-op and 3 month post op data using a combination of data-driven analysis and purely clinical methods. The reduced WOMAC was then extensively validated in three key areas; validity, reliability and responsiveness using 12 month post-op data from the study and data from the Medicare Hip Replacement Study.

Data from 898 patients pre-operatively and 806 patients at 3-months were used for the data driven section of analysis. For the clinical section, 30 members of the orthopaedic community were surveyed as to their opinions of which items should be retained in the reduced version of the scale. These results were then combined to produce a reduced function scale of 7 items to be used in conjunction with the 5-item pain scale. The questions remaining in the scale (and their original number in the scale) were: 2) ascending stairs, 3) rising from sitting, 6) walking on flat, 7) getting in/out of car, 9) putting on socks/stockings, 10) rising from bed and 14) sitting. This reduced scale was then scrutinised to ensure it’s validity (both construct and content), reliability (both internal consistency and reproducibility) and responsiveness (using Standardised Response Means). When examining 12 month data the reduced scale compared favourably with the full scale both overall, and when sub-divided by age, sex and country. It’s construct validity was confirmed by significant positive correlation with the SF-36 physical component score, the knee society function score, the Oxford knee score, and for the hip data, the Harris hip score and SF-12 physical component score. Cronbach’s alpha was consistently high (α> 0.85) with the reduced scale, showing it to be reliable, and the SRM’s indicated that the reduced scale may even be better at detecting change than the full scale.

This reduced WOMAC has been successfully derived and validated for use as a summarised and more practical version of the full WOMAC scale.