Short-term pain reduction after low-dose radiotherapy in patients with severe osteoarthritis of the hip or knee joint: a cohort study and literature review.

BACKGROUND: Low-dose radiotherapy (LDRT) for pain reduction in osteoarthritis (OA) is a frequently used treatment in Germany and Eastern European countries. The evidence on the effects of LDRT on pain in patients with OA remains unclear. This study evaluated the effect of LDRT on pain in patients with severe OA of the hip or knee joint. METHODS: This prospective study included a total of 16 joints in 12 patients (4 hips and 12 knees). The inclusion criteria were: patients older than 50 years, severe OA (Kellgren-Lawrence grade III-IV) of the hip or knee joint, patients not responding to conservative treatment and patients who are inoperable or not willing to undergo surgery. The joint was irradiated with a total dose of 6.0 Gray. The Numeric Rating Scale for pain (NRS-pain) and patient-reported outcome measures were obtained at pre-, 6, 13, 26, 39 and 52 weeks post-radiation. A decrease of two points on the NRS-pain was defined as clinical relevant. RESULTS: The median age of the included patients was 74 years (range 58-89). In 50% of the joints (n = 8, 3 hip and 5 knee joints), a clinical relevant difference in pain at 6 weeks post-radiation was observed. This clinical relevant difference decreased to 25% at 52 weeks post-radiation. CONCLUSION: LDRT showed a clinical relevant pain relief at 6 weeks after radiotherapy. The long-term effect of LDRT, however, was limited. A randomized placebo-controlled trial is necessary to assess the effect of LDRT on pain in patients with OA of the hip or knee joint.

Long-term results of valgus osteotomy for terminal-stage osteoarthritis of the hip.

INTRODUCTION: Pauwels' femoral osteotomy is a classical and joint-preserving method for osteoarthritis of the hip caused by acetabular dysplasia and/or subluxation. However, its application for terminal-stage osteoarthritis of the hip, and the long-term results, have not yet been reported. We herein aim to investigate the long-term results of valgus osteotomy for terminal-stage osteoarthritis of the hip. METHODS: Eighty-two hips of 75 patients (74 women and 1 man, mean age: 48.1 years) classified as having terminal-stage osteoarthritis by Kellgren and Laurence were indicated for valgus osteotomy from 1984 to 1993. Sixty-three hips of 57 patients were followed for more than 20 years (mean: 298 months). Follow-up rate was 77%. RESULTS: Preoperative mean hip score (Harris Hip Score) was 46.4 points. Thirty-two hips were later converted to total hip arthroplasty (THA) (mean: 185 months after surgery). Of the hips without conversion to THA, 31 hips scored 72.8 points on average, and 21 hips scored 70 or more points at the final follow-up. Kaplan-Meier survivorship analysis revealed that 40% of the hips, classified as non-atrophic type (according to Bombelli's classification) at the time of operation, maintained their joint space width for 20 years (endpoint: less than 1 mm at the weight-bearing segment, i.e., recurrence of osteoarthritis) and also revealed that 60% of the hips were not converted for 20 years after the initial operation (endpoint: conversion to THA). Cox's proportional hazard model revealed that those with the atrophic type had a hazard risk 24 times greater than those with the non-atrophic type of osteoarthritis. CONCLUSION: This is the first report of the long-term results of osteotomy for terminal-stage osteoarthritis of the hip showing satisfactory results with a lengthy follow-up period. Pauwels' valgus femoral osteotomy for terminal-stage osteoarthritis, excluding atrophic type, could be an acceptable alternative to THA.

Reliability of Tönnis classification in early hip arthritis: a useless reference for hip-preserving surgery.

INTRODUCTION: The Tönnis classification is widely accepted for grading hip arthritis, but its usefulness as a reference in hip-preserving surgery is yet to be demonstrated. We aimed to evaluate reproducibility of the Tönnis classification in early stages of hip osteoarthritis, and thus determine whether it is a reliable reference for hip-preserving surgery. MATERIALS AND METHODS: Three orthopaedic surgeons with different levels of experience examined 117 hip X-rays that were randomly mixed of two groups: a group of 31 candidates for hip-preserving surgery and a control group of 30 patients that were asymptomatic with respect to the hip joint. The surgeons were asked to rate an eventual osteoarthritis according to the Tönnis classification. After 2 months, the surgeons were asked to re-evaluate the X-rays in a random order. Intra- and interobserver reliabilities were calculated by comparing the observers' two estimations using Kappa statistics. RESULTS: Kappa values for interobserver reliability were slight or fair (range 0.173-0.397). Kappa values for intraobserver reproducibility were fair (range 0.364-0.397). Variance in grading no and slight osteoarthritis was the most frequent cause for intra- and interobserver disagreements (76.3 and 73.01% of the non-concordant observations, respectively). The confidence interval analysis showed that the observers' experience did not affect reproducibility. CONCLUSIONS: The Tönnis classification is a poor method to assess early stages of hip osteoarthritis. These findings suggest that its routine use in therapeutic decision-making for conservative hip surgery should be reconsidered.

Correlation between mechanical stress by finite element analysis and 18F-fluoride PET uptake in hip osteoarthritis patients.

18F-fluoride positron emission tomography (18F-fluoride PET) is a functional imaging modality used primarily to detect increased bone metabolism. Increased 18F-fluoride PET uptake suggests an association between increased bone metabolism and load stress at the subchondral level. This study therefore examined the relationship between equivalent stress distribution calculated by finite element analysis and 18F-fluoride PET uptake in patients with hip osteoarthritis. The study examined 34 hips of 17 patients who presented to our clinic with hip pain, and were diagnosed with osteoarthritis or pre-osteoarthritis. The hips with trauma, infection, or bone metastasis of cancer were excluded. Three-dimensional models of each hip were created from computed tomography data to calculate the maximum equivalent stress by finite element analysis, which was compared with the maximum standardized uptake value (SUVmax) examined by 18F-fluoride PET. The SUVmax and equivalent stress were correlated (Spearman's rank correlation coefficient ρ=0.752), and higher equivalent stress values were noted in higher SUVmax patients. The correlation between SUVmax and maximum equivalent stress in osteoarthritic hips suggests the possibility that 18F-fluoride PET detect increased bone metabolism at sites of stress concentration. This study demonstrates the correlation between mechanical stress and bone remodeling acceleration in hip osteoarthritis.

Interobserver and intraobserver reliability of the radiographic analysis of femoroacetabular impingement and dysplasia using computer-assisted measurements.

BACKGROUND: A comprehensive evaluation of hip radiographs in the young adult with hip pain has become increasingly complex and time consuming. The interobserver reliability of manually performed measurements of femoroacetabular impingement, including the alpha angle, has been questioned. Methods to improve the reliability of a radiographic evaluation may increase the clinical utility of these parameters. PURPOSE: To determine the interobserver and intraobserver reliability of a computer-assisted radiographic analysis of the young adult hip in a clinically relevant setting. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: A reliability study of a comprehensive computer-assisted radiographic evaluation was performed, which included 25 radiographic parameters of proximal femoral morphology, acetabular morphology, hip osteoarthritis, and pelvic tilt/rotation. Anteroposterior pelvis and 45° Dunn lateral radiographs of 70 consecutive patients undergoing hip preservation surgery were included. Each radiograph was analyzed by 4 experienced hip surgeons. The reliability of continuous measurements was analyzed using intraclass correlation coefficients (ICCs), while categorical parameters were analyzed using κ values and percentages of agreement. RESULTS: The interobserver reliability of the parameters of proximal femoral morphology, acetabular morphology, and osteoarthritis was generally substantial to excellent. Parameters with lesser interobserver reliability included the alpha angle (ICC, 0.43), Tönnis osteoarthritis classification (κ = 0.22), and classification of pelvic tilt (using the coccyx or sacrococcygeal joint) (κ = 0.43 and 0.61, respectively). CONCLUSION: A computer-assisted analysis of young adult hip radiographs generally demonstrates substantial to excellent levels of interobserver reliability for most parameters. However, alpha angle measurements demonstrated only moderate interobserver reliability, despite excellent intraobserver reliability. Measurements of the joint space width appear to be significantly more reliable than the use of the Tönnis osteoarthritis classification in this population. The classification of pelvic tilt utilizing the coccyx or sacrococcygeal joint is only moderately reliable.

Function and osteoarthritis progression after arthroscopic treatment of femoro-acetabular impingement: a prospective study after a mean follow-up of 4.6 (4.2-5.5) years.

BACKGROUND: Outcomes after arthroscopic femoro-acetabular impingement (FAI) surgery are promising in the short-term but have rarely been evaluated in the mid-term (e.g., about 5 years). Here, our objectives were to obtain mid-term data on functional and radiographic outcomes, to identify prognostic factors, and to determine the mid-term rate of arthroplasty revision with the associated risk factors. HYPOTHESIS: We hypothesized that the results of arthroscopic FAI surgery were sustained over time. MATERIALS AND METHODS: We conducted a prospective multi-surgeon study of 53 Tönnis grade 0 or 1 hips treated arthroscopically for symptomatic FAI (23 cam, 10 pincer, and 20 mixed deformities). We obtained short-term (10 months) and mid-term (4.6 years) data on the functional outcome (WOMAC and satisfaction scores), proportion of patients without revision arthroplasty, and development of osteoarthritis (graded using the Tönnis classification). RESULTS: In the patients without revision arthroplasty, the WOMAC score improved significantly (P<0.01) from baseline (61.4 ± 15.6) to 10 months (84.2 ± 15.6) and last follow-up (85.2 ± 15.5) but remained unchanged between the two postoperative time points, confirming the stability of the results. The proportion of satisfied patients was 79% after 10 months and 68% (36/53) at last follow-up (NS). Osteoarthritis developed in 13/35 (37%) hips for which radiographs were obtained at last follow-up. At last follow-up, 46/53 hips (87%; 95%CI, 78-96) did not required revision surgery; arthroplasty was required in the 7 remaining hips. The main prognostic factor was the preoperative osteoarthritis Tönnis grade: at last follow-up, compared to Tönnis grade 0 hips, Tönnis grade 1 hips had lower WOMAC scores (77 vs. 88), lower satisfaction rates (50% versus 77%), a higher rate of osteoarthritis progression (57% versus 24%), and a higher rate of arthroplasty (33.3% versus 2.9%). DISCUSSION: Our results are consistent with published data. The outcomes of arthroscopic FAI surgery are sustained over time and the preoperative osteoarthritis status is the main predictor of mid-term outcomes. LEVEL OF EVIDENCE: IV, prospective cohort study.

Patient-related outcome questionnaires in the assessment of the results of total hip replacement.

A variety of patient-related outcome questionnaires have been used for the assessment of results of total hip replacement. Generic core scales (SF-12, SF-36) and disease-specific scales like: Harris Hip Score, Western Ontario and McMaster University Osteoarthritis Index, Hip dysfunction and Osteoarthritis Outcome Score, Oxford Hip Score, American Academy of Orthopedic Surgeons hip and knee Questionnaire, Lower Extremity Functional Scale are used most frequently. Even though all of them were assessed in terms of construct and content validity, reproducibility and sensitivity, there are still some problems related to bias when total hip replacement evaluation is performed in the presence of comorbidities, contralateral hip disease and ceiling effect influencing the final score. As a result, there is a need for development of a new PRO questionnaire in order to improve total hip replacement assessment, enable early detection of postoperative complications or to evaluate the results of surgery in both hips separately. It is crucial that such measuring device has to be deprived of the influence of irrelevant factors on the final score.

The classification of degenerative hip disease.

It is probable that both genetic and environmental factors play some part in the aetiology of most cases of degenerative hip disease. Geneticists have identified some single gene disorders of the hip, but have had difficulty in identifying the genetics of many of the common causes of degenerative hip disease. The heterogeneity of the phenotypes studied is part of the problem. A detailed classification of phenotypes is proposed. This study is based on careful documentation of 2003 consecutive total hip replacements performed by a single surgeon between 1972 and 2000. The concept that developmental problems may initiate degenerative hip disease is supported. The influences of gender, age and body mass index are outlined. Biomechanical explanations for some of the radiological appearances encountered are suggested. The body weight lever, which is larger than the abductor lever, causes the abductor power to be more important than body weight. The possibility that a deficiency in joint lubrication is a cause of degenerative hip disease is discussed. Identifying the phenotypes may help geneticists to identify genes responsible for degenerative hip disease, and eventually lead to a definitive classification.

Radiographic evaluation of osteoarthritis of the hip: an inter-observer study of 61 hips treated for late-detected developmental hip dislocation.

BACKGROUND AND PURPOSE: Different methods have been used to classify osteoarthritis (OA) of the hip. We evaluated the reliability of different classifications in order to find which grading system is most appropriate for use in clinical practice. PATIENTS AND METHODS: 49 patients (61 affected hips) with late-detected developmental dislocation of the hip (DDH) were studied. The mean age at follow-up was 45 (32-49) years. 3 classifications of OA were compared. The gradings by Kellgren and Lawrence (1957) (K&L) and Croft et al. (1990) are global visual assessments based on osteophytes, cysts, subchondral sclerosis, and narrowing of the joint space. The third classification is based on narrowing in the upper, weight-bearing part of the joint and defines as OA a minimum joint space width (JSW) of less than 2.0 mm at the narrowest part. 2 experienced observers, one radiologist and one orthopedic surgeon, assessed and measured the radiographs. RESULTS: Minimum JSW (< 2.0 mm in 9 hips) gave the best inter-observer agreement (kappa value = 0.87). Using the K&L grading, inter-observer agreement was moderate (kappa = 0.55), but kappa increased when the number of categories was reduced from 5 to 3 (no OA, mild OA, and severe OA). The Croft classification gave similar agreement as the K&L grading. The intra-observer agreement was better than inter-observer agreement, irrespective of the grading system. There was a good accordance between the minimum JSW and the 2 other methods. INTERPRETATION: Joint space narrowing using a minimum JSW of < 2.0 mm as criterion for OA was the simplest and most reproducible classification in long-term follow-up of patients with DDH. A classification based on global visual assessment can be used in addition if only hips with severe OA are included.

Intermediate to long-term results of periacetabular osteotomy in patients younger and older than forty years of age.

BACKGROUND: The treatment of middle-aged patients with periacetabular osteotomy remains controversial. The goal of the present retrospective study was to analyze the intermediate to long-term functional and radiographic results of periacetabular osteotomy in patients below and above the age of forty years. METHODS: Between February 1990 and December 2004, 166 periacetabular osteotomies were performed in 146 patients. We evaluated 158 hips in 139 patients who had a mean age of thirty-two years at the time of surgery. The mean duration of follow-up was eleven years (range, five to twenty years). We compared thirty-six patients (forty-one hips) who were forty years of age or older with 103 patients (117 hips) who were younger than forty years of age at the time of surgery. RESULTS: The average Harris hip score increased from 70 points preoperatively to 90 points postoperatively. The mean Harris hip scores at the time of the five-year follow-up were similar in the older and younger groups (p = 0.57), although the latest follow-up scores were significantly higher in the younger group than in the older group (91 compared with 88 points; p = 0.02). The average modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function score (with 0 representing the worst score and 100 representing the best score) was higher for the younger group than for the older group (92 compared with 90 points; p = 0.03). Kaplan-Meier analysis with progression of the Tönnis grade of osteoarthritis as the end point showed a ten-year survival rate of 90.8% (95% confidence interval, 88.3% to 93.3%) and a fifteen-year survival rate of 83.0% (95% confidence interval, 78.5% to 87.5%); the ten-year survival rates in the younger and older groups were 94.4% and 81.3%, respectively, and the fifteen-year survival rates were 86.9% and 71.2%, respectively (p = 0.025). CONCLUSIONS: Periacetabular osteotomy yielded similar results for the two groups at the time of the five-year follow-up, although the results for the older group deteriorated thereafter. Decrease in physical function due to aging and increased susceptibility to the progression of osteoarthritis may be responsible for the poorer results over time in the older group.

Hip Osteoarthritis MRI Scoring System (HOAMS): reliability and associations with radiographic and clinical findings.

OBJECTIVE: To develop a semiquantitative MRI-based scoring system (HOAMS) of hip osteoarthritis (OA) and test its reliability and validity. DESIGN: Fifty-two patients with chronic hip pain were included. 1.5T magnetic resonance imaging (MRI) was performed on all patients. Pelvic radiographs were scored according to the Kellgren-Lawrence (KL) system. Clinical outcomes were assessed by the hip osteoarthritis outcome score (HOOS). MRIs were analyzed using a novel whole-joint MRI score that incorporated 13 articular features. Reliability was determined on a random subset of 15 cases. Weighted-kappa statistics and overall agreement were used as a measure of intra- and inter-observer reliability. Associations between MRI features and radiographic OA severity were calculated using Cochran-Armitage test for trend. Ordinal logistic regression was used to assess associations between MRI features and severity of pain and functional limitation. RESULTS: Distribution of radiographic grading was: KL 0=12 (27%), KL 1=11 (25%), KL 2=14 (32%), KL 3=5 (11%) and KL 4=2 (5%). Intra-reader reliability for the different features ranged from 0.18 (cysts) to 0.85 (cartilage). Inter-reader reliability ranged between 0.15 (cysts) and 0.85 (BMLs). Low kappas were due to low frequencies of some features as overall percent agreement was good to excellent (83.8% and 83.1%). There was a strong association between MRI-detected lesions and radiographic severity (P=0.002). Non-significant trends were observed between MRI features and clinical outcomes. CONCLUSION: MRI-based semiquantitative assessment of the hip shows adequate reliability. Presence of more severe MRI-detected intraarticular pathology shows a strong association with radiographic OA. The results suggest possible associations between MRI-detected pathology and clinical symptoms.

Degenerative osteoarthritis after Perthes' disease: a 36-year follow-up.

BACKGROUND: Although the prognosis of Perthes' disease at skeletal maturity is considered favorable, little is known about the long-term results after middle age. METHODS: We retrospectively analyzed the radiographic and functional outcomes of 67 patients (70 hips) who had been treated for Perthes' disease. Of these patients, 28 patients (29 hips) were evaluated using JOA (Japanese Orthopaedic Association) score and radiographs at follow-up (Group 1), 39 patients (41 hips) were evaluated by a postal questionnaire (Group 2). The mean follow-up period was 36.1 years. The mean age at follow-up was 43.1 years. RESULTS: Group 1, good radiographic results (Stulberg class I or II) were achieved in 59% of hips. No osteoarthritis (Tönnis Grade 0) was observed in only 48% of hips. The clinical results were good (JOA score ≥ 70) in 79% of hips. Disturbance of walking ability and activities of daily living was little. The Tönnis grade and JOA score declined after 40 years of age. All patients older than 50 years showed severe osteoarthritis. The severity of osteoarthritis correlated significantly with age at follow-up. Group 2, the clinical results were good (JOA score ≥ 56) in 76% of hips. In both groups, no patient had undergone total hip arthroplasty. Younger age at diagnosis (<8 years) correlated significantly with a better result. The JOA score correlated significantly with age at follow-up. CONCLUSION: Patients who were treated for Perthes' disease have a risk of osteoarthritis and a clinically poor outcome after the age of 40-50 years.

Correlation of MAPT scores with clinical and radiographic assessment of patients awaiting THR/TKR.

BACKGROUND: The Multi-attribute Arthritis Prioritisation Tool (MAPT) score is used as a tool to prioritize referrals to specialist clinics and care given to patients with hip and knee problems. Our pilot study aimed to determine the extent of any relationship between the MAPT scores and the clinician's assessment of severity of disease in terms of surgical waiting list (SWL) categories and radiological assessment. METHODS: This is a retrospective study of patients with symptomatic hip or knee osteoarthritis (OA) that were referred via the orthopaedic waiting list project between January and July 2009 to the Bendigo Health's orthopaedic outpatients clinic and were waitlisted for a total hip replacement (THR)/total knee replacement (TKR). The MAPT score was calculated and the Surgical waitlist Category was obtained from the surgical booking office. The radiographs of all these patients were reviewed and graded independently according to the Kellgren and Lawrence radiographic grading for severity of arthritis. The relationships between MAPT score, SWL category and the Kellgren and Lawrence radiographic grades were examined using graphical methods and Kendall's tau correlation coefficients. RESULTS: There were 62 patients in the study. The Kendall-tau sample correlation coefficient between MAPT score and the radiographic grade is τ(b) = -0.091 (P = 0.330) and between MAPT score and SWL category is τ(b) = 0.007 (P = 0.951). CONCLUSIONS: The sample data suggests that there is no significant relationship between the MAPT score and radiographic severity of OA, or between MAPT score and surgical waitlist category of patients with OA waitlisted for a THR/TKR.

[Schulthess Hip Score (5 items) for assessing disability in patients undergoing total hip arthroplasty. Development and validation]. / Patientenorientierter Schulthess-Hüftscore (5 Items) zur Evaluation von Koxarthrose- und Hüftarthroplastikpatienten. Entwicklung und Validierung.

BACKGROUND: We developed and validated a five-item self-report questionnaire for assessing disability as defined by the International Classification of Functioning, Disability, and Health conceptual model in patients with hip osteoarthritis (OA). MATERIAL AND METHODS: The psychometric properties of the new score (Schulthess hip score, SHS) were examined in 105 consecutive patients (mean age 63 years; 48 women) undergoing total hip arthroplasty (THA). RESULTS: The completion rate (97%) and reproducibility (intraclass correlation coefficient 0.90) of the SHS were excellent. Exploratory factor analysis indicated that all items that loaded on one factor only that accounted for 69.4% of the total variance. Cronbach's alpha was 0.88. Evidence of validity was provided by moderate to high correlations (r=-0.37-0.78) with the scores of traditionally used self-reported outcome measures. The SHS was very responsive, with an effect size of 2.15 and a standardized response mean of 1.74 for changes recorded 6 months after THA. CONCLUSION: These results provide evidence to support use of the SHS for assessing disability in patients with hip OA.

Analysis of interobserver reliability for radiographic staging of coxarthrosis and indexes of acetabular dysplasia: a preliminary study.

BACKGROUND: We are planning a multicenter survey on coxarthrosis and acetabular dysplasia in Japan. To collect reliable data, we performed a preliminary study to elucidate the observer agreement on assessment items. METHODS: We collected radiographs of hip joints in eight patients with various findings of coxarthrosis. Twelve registered orthopedic specialists evaluated them regarding the roentgenographic stage of coxarthrosis and five indexes of acetabular dysplasia (acetabular angle, center-edge angle, acetabular roof obliquity, acetabular head quotient, approximate acetabular quotient). To assess observer agreement, we calculated the value of the kappa statistic for stages and the coefficient of variation for the indexes. The same 12 specialists then assessed the coxarthritis stage on the same radiographs 1 month after the first evaluation based on our own descriptions of the roentgenographic stages. RESULTS: For the first evaluation of the roentgenographic stage, the value of the kappa statistic was 0.448; and for the second evaluation it was 0.600. The results of the coefficient of variation for the indexes of acetabular dysplasia, ranked in ascending order, were as follows: acetabular angle, acetabular head quotient, acetabular roof obliquity, center-edge angle, approximate acetabular quotient. CONCLUSIONS: For the upcoming multicenter survey, clear descriptions of the stages of coxarthrosis and selection of appropriate indexes can be helpful for collecting dependable results.

[Update on total hip arthroplasty]. / Le point sur la prothèse totale de hanche.

Total hip arthroplasty (THA) is one of the most common surgical procedures performed by orthopedic surgeons. Frequent indications for THA include osteoarthrosis of the hip joint that can be primary origin or secondary to dysplasia or traumatic origin, as well as fractures of the femoral neck in active patients. Other common indications include rheumatoid arthritis and osteonecrosis of the femoral head. It is a surgical intervention giving very good results giving patients pain relief and mobility with a success rate in more than 90% of cases. The point of this article is to inform the medical community on the actual situation of hip prosthetics in fields including epidemiology, clinical results, indications, contraindications, different types of prosthetic materials as well as surgical approaches.

Classification of acetabular changes in osteoarthritis: a histological and radiological analysis of 122 consecutive drill biopsies routinely taken during THA.

BACKGROUND: Aseptic acetabular loosening cannot be explained with a single theory and lots of studies deal with the influence of implant design and surgical technique on implant survival. Implant registers show the effect of demographic and patient-related parameters on acetabular loosening. There is little information about the influence of the acetabular bone quality on cup loosening. METHODS: In a prospective study, we investigated the first 122 consecutive routinely taken biopsies out of acetabular bone stock taken during primary total hip arthroplasty (THA) before reaming of the cup. Undecalcified bone samples should be classified in respect to architecture and vitality in different histological types. Four types were defined and the primary diagnosis and the severity of the preoperative radiological changes were correlated to this classification. RESULTS: A total number of 110 (90%) out of 122 biopsies could be classified to one specific type of biopsy, nine were not classifiable and three showed special entities [rheumatoid arthritis (RA) and coxitis]. Double examination showed a high intraobserver agreement (kappa 0.972). There was a correlation between the four defined types of bone biopsies and the radiological severity of osteoarthritis (P<0.0001) but not with the diagnosis (P=0.104). CONCLUSION: Histological changes during the development of osteoarthritis of the hip occur regularly, can be classified in four groups and are predictable from radiological changes on preoperative radiographs.

Validation for the reduced Western Ontario and McMaster Universities Osteoarthritis Index function scale.

PURPOSE: To assess the criterion validity, repeatability, and the missing value protocol of the reduced Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) function scale ('reduced scale'). METHODS: Three separate studies were performed: a cross-over study to compare the full- and reduced-scale scores in 66 UK patients for validity, a test-retest study for repeatability in 103 Australian patients, and a study for the missing value protocol of the reduced-scale questionnaire. RESULTS: There was no significant difference between scores for the full- and reduced-scale questionnaires in both cross-over and test-retest studies. For the missing value protocol of the reduced-scale questionnaire, when 3 or more of the 7 items were missing, the patient's response was regarded as invalid and the sub-scale score was eliminated from further analysis; when 2 or fewer items were missing, the mean value of the sub-scale was substituted for the missing values. CONCLUSIONS: The reduced-scale questionnaire retains excellent validity and repeatability. Its use is recommended along with the original pain dimension in studies of total joint replacement.