The effect of pain after total knee arthroplasty on the contralateral, nonreplaced knee.

BACKGROUND: Osteoarthritis is associated with a strong biomechanical component. Persistent pain in the index knee after total knee arthroplasty could lead to pain in the contralateral knee. The purpose of the present study was to examine whether a change in the natural history of pain in the contralateral knee was related to postoperative pain in the index knee. METHODS: Seven hundred and seventy-two patients undergoing primary unilateral total knee arthroplasty with use of the Kinemax prosthesis for the treatment of osteoarthritis comprised the cohort (Kinemax Outcomes Study cohort). Patients were assessed preoperatively and were followed for twenty-four months after surgery with use of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). We collected separate WOMAC pain scores for the index knee and the contralateral knee. Our primary outcome measure was the WOMAC pain score (rescaled to 100, with 100 being the best score) for the contralateral knee at three, twelve, and twenty-four months. We examined whether within-subject changes in the WOMAC pain score for the contralateral knee were predicted by the WOMAC pain score for the index knee at three months with use of linear regression and multilevel models after adjustment for sex, age, country, body mass index, income, and mental well-being. RESULTS: Improvement in terms of pain was observed in both the index and contralateral knees between baseline and three months. Subsequently, there was a modest deterioration of 3.5 units per year (standard deviation, 9.8 units per year) in the contralateral knee (p < 0.001), which was not predicted by pain in the index knee shortly after surgery (p > 0.6). CONCLUSIONS: Pain in the index knee at three months after total knee arthroplasty did not appear to predict a symptomatic increase in pain in the contralateral knee over two years of follow-up in our cohort. The contralateral knee did not require any additional clinical surveillance over and above the patients' reports on their symptoms.

Comparison of patient-reported outcomes between hip resurfacing and total hip replacement.

This study compared the demographic, clinical and patient-reported outcomes after total hip replacement (THR) and Birmingham Hip Resurfacing (BHR) carried out by a single surgeon. Patients completed a questionnaire that included the WOMAC, SF-36 scores and comorbid medical conditions. Data were collected before operation and one year after. The outcome scores were adjusted for age, gender, comorbid conditions and, at one year, for the pre-operative scores. There were 214 patients with a THR and 132 with a BHR. Patients with a BHR were significantly younger (49 vs 67 years, p < 0.0001), more likely to be male (68% vs 42% of THR, p < 0.0001) and had fewer comorbid conditions (1.3 vs 2.0, p < 0.0001). Before operation there was no difference in WOMAC and SF-36 scores, except for function, in which patients awaiting THR were worse than those awaiting a BHR. At one year patients with a BHR reported significantly better WOMAC pain scores (p = 0.04) and in all SF-36 domains (p < 0.05). Patients undergoing BHR report a significantly greater improvement in general health compared with those with a THR.

Predicting range of movement after knee replacement: the importance of posterior condylar offset and tibial slope.

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 (i.e, 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.

Outcome following knee arthroplasty beyond 15 years.

There is a paucity of information detailing functional outcome following total knee arthroplasty for this length of follow-up. We collected data from 187 knees in 150 surviving patients, beyond 15 years from implantation. Survival of the implant was confirmed and a patient administered questionnaire including WOMAC, SF-36 and patient satisfaction was used, data was scrutinised for differences between primary and revision knee surgery. Seventy knees were revised at a mean of 10.8 years. The mean WOMAC Pain score was 72 indicating predominantly mild pain. The mean WOMAC Function scores were lower at 55 indicating moderate limitation of most activities. No significant differences were found between revised and un-revised patients. Long-term pain and satisfaction scores in this population were good illustrating the benefits of TKA in the long term even in patients who have undergone revision surgery.

Psychosocial and geriatric correlates of functional status after total hip replacement.

OBJECTIVE: To determine whether psychosocial factors, chronic diseases, and common geriatric problems are associated with poor physical function 3 years after primary total hip replacement (THR). METHODS: We studied a sample of Medicare recipients in Ohio, Pennsylvania, and Colorado (n = 922) who underwent primary THR in 1995 (mean +/- SD age 73.1 +/- 5.6 years, 32% men). Participants completed a questionnaire regarding lifestyle factors, medical history, and quality of life approximately 3 years after the surgery. Physical function was measured using the function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index. We assessed the relationship between functional outcome 3 years postsurgery and 4 predictor domains: pain or complications in the operated hip, other musculoskeletal comorbidity, medical factors (obesity, chronic medical comorbidity, rheumatoid arthritis, and such common geriatric problems as falls, poor balance, or incontinence), and psychosocial factors (mental health, regular alcohol consumption, smoking, provider role, living alone, and education). RESULTS: Ten percent of subjects had poor functional status. In a logistic regression model controlling for sex and age, the following factors were associated with an increased risk for poor functional status (in order of importance): pain in the back or lower extremity, severe pain in the operated hip, poor mental health, more than 1 common geriatric problem, obesity, and less than college education. CONCLUSION: Pain in the operated hip was strongly associated with poor functional status 3 years after THR. However, other factors associated with poor functional status were not related to the hip. Our results suggest that a comprehensive assessment of functional status in elderly THR patients should include assessment of common geriatric problems, mental health status, and weight.

Development and testing of a reduced WOMAC function scale.

We used prospective data from 862 total knee and 716 total hip replacements three years after surgery in order to derive and validate a reduced Western Ontario and McMasters University Osteoarthritis Index (WOMAC) function scale. The reduced scale was derived using the advice of clinical experts as well as analysis of data. The scale was tested for validity, reliability and responsiveness. Items which were retained included: ascending stairs, rising from sitting, walking on the flat, getting in or out of a car, putting on socks, rising from bed, and sitting. The reduced and full scales had comparable, moderate correlations with other measures of function, confirming convergent validity. Cronbach's alpha was high (alpha > 0.85) with the reduced scale confirming reliability. Responsiveness was greater for the reduced scale (full = 1.4, reduced = 1.6). This reduced version of the WOMAC function scale provides a practical, valid, reliable and responsive alternative to the full function scale for use after total joint replacement. Further work is needed to demonstrate its wider applicability.

Validity and responsiveness of the Knee Society Clinical Rating System in comparison with the SF-36 and WOMAC.

BACKGROUND: The aim of this study was to validate the Knee Society Clinical Rating System (knee and function scores) and to compare its responsiveness with that of the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Medical Outcomes Study Short Form-36 (SF-36). METHODS: Patients were recruited as part of a prospective observational study of the outcomes of primary total knee arthroplasty for the treatment of osteoarthritis in four centers in the United States, six centers in the United Kingdom, and two centers in Australia. Independent research assistants at each site collected the Knee Society clinical data. The WOMAC, SF-36, patient satisfaction, and demographic data were obtained with self-administered questionnaires. RESULTS: A total of 862 eligible patients were recruited, and complete preoperative and twelve-month data were available for 697 (80.9%) of them. The mean age was seventy years (range, thirty-eight to ninety years), and the majority of the patients (58.9%) were women. Low correlations were found among the items of both the knee and the function score at both assessment times. The Knee Society pain and function scores had moderate-to-strong correlations with the corresponding pain and function domains of the WOMAC and SF-36 (r = 0.31 to 0.72). Measurement of the standardized response mean showed the Knee Society knee score to be more responsive (standardized response mean, 2.2) than the WOMAC (standardized response means, 2.0 for pain and 1.4 for function) and the SF-36 (standardized response means, 1.0 for bodily pain and 1.1 for physical functioning). The Knee Society function score was the least responsive measure (standardized response mean, 0.8). Correlation of changes in scores at twelve months with patient reports of satisfaction and improvement in health status showed the WOMAC and SF-36 to be more responsive than the Knee Society scores. CONCLUSIONS: There is a poor correlation among the items of the Knee Society Clinical Rating System, but the rating system has adequate convergent construct validity. The WOMAC and SF-36 are more responsive measures of outcome of total knee arthroplasty. As they are less labor-intensive for researchers to use and as use of these instruments removes observer bias from the study design, they are preferable for knee arthroplasty outcome studies.

Pitfalls of using patient recall to derive preoperative status in outcome studies of total knee arthroplasty.

BACKGROUND: It is essential to adjust for the level of preoperative pain and functional status when measuring the outcome of total knee arthroplasty. Some study designs rely on postoperative patient recall to derive preoperative status. In this study, we compared prospectively collected preoperative data with data derived from patient recall of preoperative status three months after total knee arthroplasty. METHODS: Patients were recruited as part of a prospective observational study of the outcome of primary total knee arthroplasty for osteoarthritis at four centers in the United States, six centers in the United Kingdom, and two centers in Australia. Independent research assistants recruited patients and collected data with use of a uniform documentation system preoperatively and three months postoperatively. Preoperative data included the findings of a clinical history and physical examination, demographic information, socioeconomic status, and scores from two health-status instruments: the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the Medical Outcomes Study Short Form-36 Health Survey (SF-36). Postoperative data included the WOMAC and SF-36 scores and patient recall of preoperative status on selected items from these health-status measures. RESULTS: A total of 862 patients were recruited, and recall data were available for 770 patients (89%). The mean age was seventy years (range, thirty-eight to ninety years), and 59% of the patients were women. Comparisons of prospective and recall data on individual pain and function items showed poor-to-fair agreement (weighted kappa, 0.20 to 0.41). Patients recalled significantly more pain than they had reported preoperatively (p < 0.001), but there were random recollection errors for the function items. There was only moderate correlation between the prospective and recalled summary scores for pain (Spearman r = 0.53) and function (Spearman r = 0.48). In addition, 61% of the recalled pain scores and 50% of the recalled function scores differed from the prospective scores by more than 10 points (10% of the total range). CONCLUSIONS: Patients' recall of preoperative pain and functional status three months after total knee arthroplasty demonstrated only moderate agreement with what the patients had reported prospectively. Researchers who use recall data to derive preoperative status must recognize these limitations when drawing conclusions about the effectiveness of total knee arthroplasty.

Management and care of patients undergoing total knee arthroplasty: variations across different health care settings.

OBJECTIVES: To examine variation in the process of care for total knee arthroplasty (TKA) and to highlight the need for rigorous research into the ideal management of TKA. We hypothesize that variation in the process of care for TKA across and within health care systems is associated with identifiable financial and historical factors. METHODS: We compared access to TKA and typical postoperative rehabilitation management in 12 orthopedic centers in the United States (4 centers), United Kingdom (6 centers), and Australia (2 centers). We collected data from two sources: 1) Empirical data on length of stay and discharge management were collected as part of a prospective study of the outcomes of primary TKA for patients with a diagnosis of osteoarthritis; 2) Structured qualitative interviews were conducted at each of the participating centers to collect data on academic status and reimbursement structure, as well as waiting times for orthopedic consultation and TKA surgery once it had been scheduled. RESULTS: We demonstrated differences in length of acute hospital stay, use of extended care facilities, home physical therapy, and outpatient physical therapy within our cohort of hospitals. The publicly funded hospitals had a significantly longer acute hospital length of stay (mean 11.8 days, SD 7.1) than the private hospitals (mean 6.6 days, SD 4.1; P < 0.0001). Variation in waiting times was associated with the method of surgeon reimbursement and whether the hospital is publicly funded or private. Patients attending private hospitals waited 1-8 weeks for the first consultation and 2-12 weeks for a surgical date after scheduling. In contrast, patients attending publicly funded hospitals waited 4-12 months for a first consultation and 12-18 months for a surgical date after scheduling. CONCLUSIONS: Our observations are consistent with the hypothesis that financial reimbursement schemes influence the management of TKA. Further research needs to be done to quantify effects of varying processes of care on the outcome of TKA surgery across different health care settings. This data would elucidate the optimal management of TKA using objective evidence rather than relying on financial incentives or the preservation of historical practices.