Outcome of hip resurfacing in obese patients

The effect of obesity on outcome for patients undergoing hip resurfacing has been evaluated. Pre and post-operative objective patient scored outcomes for a group of 181 cases of hip resurfacing performed over a three year period were collected. Cases have been stratified by body mass index (BMI) with evaluation of post-operative complications. Patient outcomes included: SF-36, WOMAC, and satisfaction scores, and were compared pre-operatively, and at one year. We found an increased rate of wound complications in the obese group (BMI > 30) with 4 cases of prolonged wound drainage and 2 superficial infections, compared to none in the non-obese group. A similar improvement in SF-36, WOMAC and patient satisfaction was found for both groups. No increase in the risk of femoral neck fracture or aseptic loosening was seen in the obese group. These results suggest excellent early outcomes for obese patients undergoing hip resurfacing with no added risk of early failure.     

Do pain referral patterns determine patient outcome after total hip arthroplasty?

Quality of life outcome and patient satisfaction after total hip arthroplasty are complex phenomena and many confounding determinants have been identified. Degenerative disease of the hip joint may present with variable patterns of pain referral in the lower limb. However the effect of varied preoperative pain referral patterns on patient outcome and satisfaction after total hip arthroplasty has not previously been examined. From 2000 to 2003, 236 eligible patients scheduled to undergo primary total hip arthroplasty were prospectively enrolled. The principal pain referral pattern (as hip, thigh or knee) was identified in all patients. Health related quality of life (HRQOL) was examined using the Harris Hip score (HHS), the Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and the 36-Item Short-Form Health Survey (SF-36) pre-operatively, 1 year and 2 years postoperatively and with the HHS at 3 months postoperatively. All patients were followed up for a minimum of 2 years. The frequency of the pain referral distributions were; hip pain 41%, knee pain 32% and thigh pain 27%. Patients in all groups were comparable preoperatively with respect to age, HHS, and both mean and domain specific WOMAC and SF-36 scores. The mean duration of symptoms was significantly greater in patients with knee pain when compared to the remaining two pain patterns. All patients demonstrated improvements in HHS, SF-36 and WOMAC scores after surgery. At all times postoperatively there were significant differences in mean HHS and mean and domain specific WOMAC and SF-36 scores between patients with hip or thigh pain and those with knee pain (p < 0.001). While notable, differences between hip and thigh pain were not as consistent however. Based on these findings, it appears that pre-operative pain referral patterns of hip arthritis are among the determinant factors for patient outcome and satisfaction after total hip arthroplasty, as measured using validated HRQOL scoring systems.     

Is Postoperative Function After Hip or Knee Arthroplasty Influenced by Preoperative Functional Levels?

Our objective was to evaluate functional outcomes after surgery in a subgroup of patients presenting for hip and knee surgery who had low functional scores before surgery. One hundred twenty-seven unilateral total hip and knee arthroplasty patients were assessed preoperatively and 3 consecutive years after arthroplasty using: Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Short Form 36 (SF-36), and the Quality of Well-Being index scales. Patients were placed into 2 groups based on preoperative WOMAC function scores; 51 points or more, worse functioning group, and less than 51 points, higher functioning group. Regardless of time, the worse functioning group in both procedures performed worse on the Quality of Well-Being index, SF-36 (function score), SF-36 (social score), and WOMAC total and pain scores (P ≤ .0001). The greatest change (range, 2%-638%) for all variables in both groups for both procedures occurred during the first year. Patients that had severe/extreme functional impairment had worse 3-year outcomes compared with patients getting surgery when their functional levels were better.     

A simple visual analog scale for pain is as responsive as the WOMAC,the SF-36, and the EQ-5D in measuring outcomes of revision hip arthroplasty: A prospective cohort study of 45 patients followed for 2 years

Background and purpose

Little is known about the comparative performance of patient-reported outcome measures in revision hip arthroplasty. We compared the performance of the WOMAC, the SF-36, the EQ-5D, and a pain-related visual analog scale (VAS) in revision hip arthroplasty.

Methods

45 patients with aseptic prosthetic loosening following primary hip arthroplasty completed the WOMAC, the SF-36, the EQ-5D, and a VAS for pain—at baseline and 2 years after revision. Responsiveness of the measures was compared with the effect size (with ≥ 0.8 being considered large). Agreement between scales measuring the same type of outcome (pain or physical function) was assessed with the Bland-Altman method.

Results

The mean preoperative scores for the pain and physical function scales of WOMAC and SF-36, EQ-5D index, and VAS for pain improved statistically significantly 2 years after revision. The effect size for the WOMAC pain was 1.7, that for SF-36 pain was 1.4, that for WOMAC physical function was 1.6, that for SF-36 physical function was 0.8, and that for EQ-5D index was 1.2. The VAS for pain had an effect size of 2.1, which was larger than that for SF-36 pain and for the EQ-5D index (p ≤ 0.03) but not for WOMAC pain (p = 0.2). The limits of agreement between WOMAC pain, SF-36 pain, and the VAS scale measuring pain—and between the WOMAC and SF-36 scales measuring physical function—were wide. Internal-consistency reliability was high for the WOMAC and SF-36 scales but low for the EQ-5D.

Interpretation

In patients with first-time revision hip arthroplasty done for aseptic loosening, the WOMAC, SF-36, and EQ-5D showed high responsiveness in measuring patient-reported outcomes and the simple VAS for pain performed equally well.In clinical research involving primary hip arthroplasty, health and quality-of-life outcomes have commonly been measured with the WOMAC and the SF-36 questionnaires. The EQ-5D is also being increasingly used, for example in some national joint registries such as the Swedish Hip Arthroplasty Register (Rolfson et al. 2011). Several studies have shown good validity, reliability, and responsiveness of patient-reported outcome measures in primary hip arthroplasty (Nilsdotter et al. 2001). Although patient-relevant outcomes with regard to primary hip arthroplasty have been studied extensively, less is known about these outcomes following revision arthroplasty. In previous studies of revision arthroplasty, pain and physical function have been evaluated with clinician-based scores such as the Harris hip score and the Merle d’Aubigné score (Lubbeke et al. 2007). A few studies have used patient-based outcome measures such as the WOMAC and SF-36 (Davis et al. 2006, Lubbeke et al. 2007). Measures that have demonstrated good responsiveness in primary hip arthroplasty do not necessarily perform similarly in revision arthroplasty. Apart from responsiveness, the length of an outcome measure is an important factor with regard to the cost of administration and the response rate, 2 essential elements when using the measure in an arthroplasty registry. Head-to-head comparisons of patient-reported outcome measures in hip arthroplasty can provide important information, but there have been very few studies of that kind.We compared the performance of the WOMAC, the SF-36, the EQ-5D, and a visual analog scale (VAS) for pain in patients undergoing revision hip arthroplasty. We hypothesized that these measures of patient-reported outcomes would vary in their responsiveness in measuring outcomes.     

Comparison of the responsiveness of the SF-36 and WOMAC in patients undergoing total hip arthroplasty

This study examines the responsiveness of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Short Form-36 (SF-36) in patients undergoing total hip arthroplasty. Eighty-nine patients completed the WOMAC and SF-36 preoperatively and postoperatively. Standardized response means (SRMs) and effect sizes (ES) were used to measure responsiveness. Mean follow-up was 17 months. The SRMs for the WOMAC ranged from -0.93 to -1.49, and the ES ranged from -1.02 to -1.53. The SRMs for the SF-36 ranged from 0.22 to 1.64, and the ES ranged from 0.20 to 1.97. The highest values occurred with the physical functioning, bodily pain, and Physical Component Summary Scales. This study demonstrates a similar level of responsiveness of the WOMAC and several components of the SF-36. This suggests that the isolated use of the SF-36 may be adequate to monitor outcomes after total hip arthroplasty. There may still be a role for the WOMAC when comparing outcomes of specific designs or techniques of total hip arthroplasty.     

Functional outcomes after nonrecurrent dislocation of primary total hip arthroplasty

The influence of dislocation on functional outcomes of primary total hip arthroplasty is unclear. The purpose of this study was to assess the effect of nonrecurrent dislocations treated with closed reduction after primary total hip arthroplasty on postoperative outcome in the short to medium term. Ninety-six patients were enrolled in this retrospective case-control study. There were 32 patients who had a postoperative dislocation. The control group consisted of 64 matched patients who did not dislocate. All patients had a minimum of 1-year follow-up. The 2 groups were compared using the SF-12, reduced WOMAC, and satisfaction questionnaire. There was no statistical difference between the 2 groups in subjective functional outcomes using the WOMAC or SF-12. However, there was a trend toward better quality of life scores in the control group, and they were more satisfied with their surgery compared with the dislocation group.     

Are Hip Resurfacing Arthroplasties Meeting the Needs of Our Patients? : A 2-Year Follow-Up Study

Hip resurfacing arthroplasty (HRA) is a treatment of end-stage hip arthritis in young patients with excellent bone stock. One hundred four consecutive HRAs (Depuy ASR, Warsaw, Ind) were performed with 36-Item Short Form Health Survey (SF-36), Western Ontario and McMaster University Osteoarthritis Index, Harris Hip Scores, and University of California, Los Angeles activity ratings obtained preoperatively, at 6 months, and at 1 and 2 years postoperatively. Four patients required conversion to total hip arthroplasty. All patients showed significant improvements in their activity, pain, stiffness, and function postoperatively. Patients with lower SF-36 mental component scores (MCSs) improved their MCS compared with those of the general population, as well as improving their pain and physical functioning scores. These findings demonstrate reliable improvements in standard quality of life measures in patients undergoing HRA, including those with low preoperative SF-36 MCS.     

The accuracy of assessing total hip arthroplasty outcomes: a prospective correlation study of walking ability and 2 validated measurement devices

The Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and the SF-36 are used to assess subjective outcome after total hip arthroplasty (THA). Although these indices have been validated, neither the WOMAC nor the SF-36 has been tested for accuracy against objective data in this clinical setting. Thirty osteoarthritic patients undergoing elective primary THA were subjectively evaluated preoperatively and 1 year postoperatively with the WOMAC and the SF-36 and objectively evaluated at the same interval with basic stride analysis and the 6-minute walk test. Correlation analysis of the subjective and objective data (both perioperative improvement and postoperative absolute scores) yielded Pearson coefficients of r = 0.50-0.81. This work demonstrates a sound statistical relationship between walking ability and the functional aspects of the WOMAC and the SF-36, supporting the use of these instruments in assessing the functional outcome after THA.     

The expectations of patients undergoing revision hip arthroplasty

Sixty patients were prospectively assessed using the Western Ontario and McMaster Osteoarthritis Index (WOMAC) scale for osteoarthritis of the hip and the Short Form 36 (SF-36) general health status scale as well as the expectation WOMAC, which asked patients to estimate how they expected to feel 6 months after revision hip arthroplasty. There was a wide range of expectations, but we were unable to find any significant correlation between the patients' preoperative pain and stiffness levels and their expectations for pain and stiffness after revision hip arthroplasty. There was no significant correlation between the SF-36 scores and the patients' expectations. Our findings suggest that the expectations of patients awaiting revision hip arthroplasties are high and are not related closely to the level of preoperative disability.     

Revision of hip resurfacing arthroplasty

Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation or aseptic loosening after conversion of any resurfacing arthroplasty. Valgus neck-shaft angle (P < .03) was associated with aseptic failure of MOM hip resurfacing. Conversion of aseptic failure of hip resurfacing to conventional THA leads to clinical outcomes similar to those of patients who undergo uncomplicated hip resurfacing. The orientation of the femur and the components placed play a large role in implant survival in hip resurfacing. More work needs to be done to further elucidate these radiographic parameters.     

Predictors of functional outcome two years following revision hip arthroplasty

BACKGROUND: Little is known about factors that might predict functional outcome following revision hip arthroplasty. The purpose of this study was to identify predictors of pain and physical function at two years following revision total hip arthroplasty and to evaluate whether the time that the patient waited for the surgery and whether the patient had complications were significant predictors of outcome. METHODS: One hundred and twenty-six patients (126 hips) were entered prospectively into the study when their name was placed on the waiting list for surgery. Baseline measures included demographic factors, comorbidities, and the responses to the Short Form-36 (SF-36) and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) questionnaires. Follow-up was carried out at six-month intervals while the patient was waiting for the surgery; within one week prior to the surgery; and at six, twelve, and twenty-four months after the surgery. Patient age and gender, the preoperative WOMAC pain and function scores, the physical and mental component scores of the SF-36, comorbidities, the number of revisions, bilateral joint replacement, and the severity of the revision were evaluated as possible predictors of ultimate pain and function as measured with the WOMAC instrument. RESULTS: The mean age of the patients was 68.6 years. Improvement in WOMAC pain and function scores plateaued at six months. The mean pain score (and standard deviation) improved from 9.4 +/- 4.1 points preoperatively to 3.9 +/- 3.9 points at six months postoperatively, and the mean function score improved from 35.4 +/- 14.1 to 19.1 +/- 13.2 points. Preoperative pain (p = 0.002) and comorbidity (p = 0.02) were significant predictors of pain at two years. There was a trend toward preoperative function predicting function at twenty-four months (p = 0.07). There was no significant deterioration in the WOMAC pain or function score while the patients waited for surgery. Twenty-eight patients had complications. When the time that the patient waited for the surgery and complications were added to the models, only complications were found to be predictive of outcome (p = 0.04 for pain and p = 0.05 for function). Four patients required repeat revision during the follow-up period. CONCLUSIONS: Patients with better preoperative pain scores and fewer comorbidities have better outcomes following revision total hip arthroplasty. Although the time that the patient waited for the revision was not predictive of the ultimate WOMAC pain and function scores, we believe that performing revision arthroplasty before the patient has substantial functional compromise potentially improves the outcome.     

Outcome assessment in the elderly after total hip arthroplasty

An analysis of the Short-Form 36 (SF-36) and Oxford Hip questionnaires, were used to assess 2 randomized groups, by either mail or interview, at a minimum 10-year follow up after total hip arthroplasty. Ninety-nine patients (median age 77 years) were reviewed at a median 11 years after total hip arthroplasty. There was a 91% response rate to participation in the study. There was no significant difference between the groups for missing values. The mode of administration did not affect the mean Oxford scores (P > .1), but significant differences were noted in SF-36 health scales Role Emotional and Role Physical (P = .01). Analysis of other demographic variables revealed unexpectedly that comorbidity affected the Pain score in the Oxford questionnaire (P = .002) and that age had no effect on scores obtained in either questionnaire (P > .05). The uses of both general health and disease-specific questionnaires complement each other in the assessment of such groups. The SF-36 and Oxford questionnaires give a more accurate reflection of health status when self-completed while accepting higher missing values in an elderly population.     

Validity and reliability of Swedish WOMAC osteoarthritis index: A self-administered disease-specific questionnaire (WOMAC) versus generic instruments (SF-36 and NHP)

We assessed whether a disease-specific, self-administered questionnaire could replace a generic instrument as an outcome tool after total hip replacement, and tested the validity and reliability of the Swedish WOMAC osteoarthritis index. 58 patients operated on with total hip arthroplasty 2-10 years ago were randomized to the study. All patients were asked to answer one disease-specific questionnaire (WOMAC osteoarthritis index) and two generic instruments (NHP and SF-36) in the same week. The procedure was repeated after 4 weeks. We tested content validity, construct validity, criterion validity, test-retest reliability and internal consistency reliability according to total score, domains and items. We found that both the generic instruments (NHP and SF-36) and the disease-specific test (WOMAC) had a high validity, i.e., measuring what they were supposed to measure (high validity). The questionnaires were also reproducible over time (high reliability). We suggest the Swedish WOMAC to be used after total hip arthroplasty in future studies.     

Validity and reliability of Swedish WOMAC osteoarthritis index: A self-administered disease-specific questionnaire (WOMAC) versus generic instruments (SF-36 and NHP)

We assessed whether a disease-specific, self-administered questionnaire could replace a generic instrument as an outcome tool after total hip replacement, and tested the validity and reliability of the Swedish WOMAC osteoarthritis index. 58 patients operated on with total hip arthroplasty 2-10 years ago were randomized to the study. All patients were asked to answer one disease-specific questionnaire (WOMAC osteoarthritis index) and two generic instruments (NHP and SF-36) in the same week. The procedure was repeated after 4 weeks. We tested content validity, construct validity, criterion validity, test-retest reliability and internal consistency reliability according to total score, domains and items. We found that both the generic instruments (NHP and SF-36) and the disease-specific test (WOMAC) had a high validity, i.e., measuring what they were supposed to measure (high validity). The questionnaires were also reproducible over time (high reliability). We suggest the Swedish WOMAC to be used after total hip arthroplasty in future studies.     

Validity and reliability of Swedish WOMAC osteoarthritis index: a self-administered disease-specific questionnaire (WOMAC) versus generic instruments (SF-36 and NHP)

We assessed whether a disease-specific, self-administered questionnaire could replace a generic instrument as an outcome tool after total hip replacement, and tested the validity and reliability of the Swedish WOMAC osteoarthritis index. 58 patients operated on with total hip arthroplasty 2-10 years ago were randomized to the study. All patients were asked to answer one disease-specific questionnaire (WOMAC osteoarthritis index) and two generic instruments (NUP and SF-36) in the same week. The procedure was repeated after 4 weeks. We tested content validity, construct validity, criterion validity, test-retest reliability and internal consistency reliability according to total score, domains and items. We found that both the generic instruments (NHP and SF-36) and the disease-specific test (WOMAC) had a high validity, i.e., measuring what they were supposed to measure (high validity). The questionnaires were also reproducible over time (high reliability). We suggest the Swedish WOMAC to be used after total hip arthroplasty in future studies.     

Responsiveness and clinically important differences for the WOMAC and SF-36 after hip joint replacement

OBJECTIVES: To study responsiveness and establish the minimal clinically important differences (MCID) and minimal detectable change (MDC) in patients undergoing total hip replacement (THR) using the Short Form 36 (SF-36) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). METHODS: We conducted a prospective observational study in three public hospitals of all consecutive patients with a diagnosis of hip osteoarthritis (OA) on waiting lists to undergo THR. Patients completed the SF-36 and the WOMAC (subscales transformed to 0 to 100), which measured the health-related quality of life (HRQoL), before intervention and 6 months and 2 years later, and additional transitional questions, which measured the changes in the joint 6 months postoperatively. RESULTS: Improvements at 6 months after a THR were between 37 (stiffness) and 39 points (pain), depending on the WOMAC domain. The SF-36 domains also showed improvements: physical function (31.91), physical role (33.71), and bodily pain (29.77). From 6 months to 2 years, improvements ranged from 2 to 5 points, except for role physical (13.25). A ceiling effect was detected on some WOMAC domains as well as a floor effect on the SF-36. The MCID ranged from 25.91 (stiffness) to 29.26 (pain) on the WOMAC and from 10.78 (physical role) to 20.40 (physical function) on the SF-36. The MDC ranged from 21.38 (pain) to 27.98 (stiffness) on the WOMAC and from 18.99 (physical function) to 42.05 (social function) on the SF-36. CONCLUSIONS: These values indicate expected gains after THR. However, the MCID and MDC values must be viewed cautiously due to the uncertainty of these estimators and should not be considered as absolute thresholds.     

全髋关节置换术后病人健康相关生存质量评估

[目的]评价Harris评分在全髋关节置换术疗效评估中的局限性。[方法]对2005年9月~2006年1月47例(50髋)接受全髋关节置换术的病人进行6个月的前瞻性研究。在术前和术后6个月均对病人进行Harris评分和评估健康相关生存质量的SF-36简明健康状况调查量表(MOS36-item Short Form Health Survey,SF-36)评分,并分析Harris评分和SF-36各项评分之间的相关性。[结果]病人术后6个月的Harris评分和SF-36各项评分均较术前有统计学意义上的差异(P<0.001),但SF-36各项评分的改善程度并不一致。Harris评分和SF-36生理功能(PF)和躯体疼痛(BP)项评分有相关性(r>0.4,P<0.001),但与SF-36其它方面评分无明显相关性(r<0.4),或无相关性(P>0.05)。[结论]虽然Harris评分能较好地评估全髋关节置换术对改善病人生理功能和缓解疼痛的疗效,但对于评价病人健康相关生存质量和其它方面的改善还存在局限性。因此,有必要将SF-36评分引入到全髋关节置换术的疗效评估中。     

Total hip arthroplasty in congenital dysplasia of the hip: follow-up of a small-dimensioned, cemented straight stem

AIM: The aim of this study is to report the survival and mid-term results including patient-relevant outcome measures with a small-sized cemented stem (CDH-stem) for the treatment of coxarthrosis secondary to developmental dysplasia of the hip. METHOD: 33 total hip replacements were performed with the CDH stem, 29 of which (88 %) were included in the follow-up after an average of 7.6 years. According to the classification system of Hartofilakidis et al., 10 hips were classified as type 1, 15 as type 2, and 3 as type 3. Survival was predicted using Kaplan-Meier survivorship analysis with revision as the end point. Results were assessed using the Harris hip score, as well as the WOMAC and SF-36 as patient-relevant outcome measures. RESULTS: Survival at thirteen years was predicted to be 92.4 % for the stem and 87.6 % for the varying acetabular implants used. At the time of the final follow-up, the average Harris hip score was 82.45 points. The global WOMAC index averaged 2.1, the average SF-36 score was 66.2 points. CONCLUSIONS: The data support the use of a small-sized cemented stem in small femora for total replacement of the dysplastic hip. To the best of our knowledge, this is the first study utilising the well validated WOMAC and SF-36 as patient-relevant outcome measures in this subgroup of patients.