Relationship between physical activity and hip pain in persons with and without cam or pincer morphology: a population-based case-control study.

OBJECTIVES: The purpose of the study was to determine if physical activity (PA) is a risk factor for persistent or recurrent hip pain in young and middle-aged persons with and without radiographic findings of cam or pincer morphology (CPM). METHODS: A population sample of persons aged 20-49 with (cases) and without (controls) hip pain in Metro Vancouver, Canada, was selected through random digit dialing (RDD). Self-reported PA was expressed as average energy expenditure (MET-hours) per year, over lifetime. CPM was defined as alpha angle >55°, lateral centre edge angle (LCE) >40°, or positive cross-over sign. RESULTS: Data were obtained for 500 subjects, 269 cases and 231 controls. Prevalence of radiographic CPM was 49% in the cases and 44% in the controls. In a logistic regression model adjusted for age, gender and CPM, total lifetime PA, including occupational, domestic and recreational activities, was significantly associated with hip pain (Odds ratio (OR) 1.30 per 1000 MET-hours, 95% CI 1.15-1.38). The effect of total PA was observed in those with CPM (1.44, 1.17-1.78) and without CPM (1.23, 1.04-1.45). For domestic activities, the association was seen only in those with CPM (significant interaction). When PA was categorized into quartiles, higher levels of PA were associated with a greater risk of pain. CONCLUSIONS: PA, as measured by average energy expenditure over lifetime is a risk factor for hip pain in young and middle-aged persons. For some activities, the risk is likely increased in persons with radiographic evidence of CPM.

The validity of a non-radiologist reader in identifying cam and pincer femoroacetabular impingement (FAI) using plain radiography.

The purpose of this study was to evaluate the validity and reliability of a radiographic diagnosis of femoroacetabular impingement (FAI) by a non-radiologist. Symptomatic FAI is prevalent and thought to be a cause of hip osteoarthritis. However, the diagnosis is often delayed by 1-2 years, in large part because radiographic findings are often subtle and clinicians have been unaware of their significance. The purpose of this study was to evaluate the validity of a radiographic diagnosis of FAI by a non-radiologist. A population-based sample of 701 subjects was recruited in Vancouver, Canada. For the current study, 50 subjects were selected-40 randomly from the population sample and 10 from an orthopedic practice with confirmed FAI. An anterior-posterior pelvis and bilateral Dunn radiographs were acquired and read by a fellowship-trained musculoskeletal radiologist and a third-year medical student who received basic training in radiographic signs of FAI. Three radiographic signs were evaluated: the lateral center edge angle, alpha angle and crossover sign. Validity was assessed using sensitivity and specificity, Bland-Altman limits of agreement and kappa. The sample contained 65% women (n = 31), was 62% Caucasian and 38% Chinese and had a mean age of 38.3 years. For correctly diagnosing FAI, the non-radiologist reader had a sensitivity of 0.83 and specificity of 0.87. Intra-rater κ value was 0.72, and prevalence-adjusted bias-adjusted κ was 0.76. This study provides evidence that a non-radiologist can accurately and reliably identify FAI on plain films.

The relationship between subchondral sclerosis detected with MRI and cartilage loss in a cohort of subjects with knee pain: the knee osteoarthritis progression (KOAP) study.

PURPOSE: To assess the association between subchondral sclerosis detected at baseline with MRI and cartilage loss over time in the same region of the knee in a cohort of subjects with knee pain. METHODS: 163 subjects with knee pain participated in a longitudinal study to assess knee osteoarthritis progression (KOAP). Subjects received baseline knee radiographs as well as baseline and 3-year follow-up MRI examinations. Baseline subchondral sclerosis and bone marrow lesions (BMLs) were scored semiquantitatively on MRI in each region from 0 to 3. Cartilage morphology at baseline and follow-up was scored semiquantitatively from 0 to 4. The association between baseline subchondral sclerosis and cartilage loss in the same region of the knee was evaluated using logistic regression, adjusting the results for age, gender, body mass index, and the presence of concomitant BMLs. RESULTS: The prevalence of subchondral sclerosis detected by MRI in the regions of the knee varied between 1.6% (trochlea) and 17% (medial tibia). The occurrence of cartilage loss over time in regions varied between 6% (lateral tibia) and 13.1% (medial femur). The prevalence of radiographically-detected subchondral sclerosis in compartments varied from 2.9% (patellofemoral) to 14.2% (medial tibiofemoral). In logistic regression models, there were no significant associations between baseline subchondral sclerosis detected by MRI and cartilage loss in the same region of the knee. CONCLUSION: Baseline subchondral sclerosis as detected by MRI did not increase the risk of cartilage loss over time.

Clinical validation of an Internet-based questionnaire for ascertaining hip and knee osteoarthritis.

OBJECTIVE: To evaluate the measurement properties of an Internet-based self-administered questionnaire in ascertaining cases of hip and knee osteoarthritis (OA). METHODS: Questionnaire data from 4269 Canadian subjects aged 45-85 were collected on hip and knee joint health including self-reported items on medically-diagnosed hip and knee OA and joint replacement. A sub-cohort of 100 subjects was recruited for clinical examination. The self-reported outcomes were evaluated using the American College of Rheumatology clinical classification criteria for hip and knee OA as the gold standard for clinical verification. Analysis was at the joint level (200 knees, 200 hips). Validity was examined using sensitivity, specificity, and predictive values; to account for correlated joints of the same subject, bootstrapping was performed to yield valid 95% confidence interval (CI's). RESULTS: Self-reported measures for a medical diagnosis of knee OA had a positive predictive value of 86%, negative predictive value 91%, sensitivity 73% and specificity 96% for correctly identifying clinical knee OA. For hip OA, the values were 61%, 98%, 81% and 94% respectively. CONCLUSION: Internet self-report of medically-diagnosed hip and knee OA in metro Vancouver residents correctly identified most cases and non-cases of clinical OA when compared with the ACR clinical classification criteria gold standard. In particular, specificity was very high, important in risk factor studies due to the profound effect of even small losses in specificity on the measure of association. The findings provide evidence that these questionnaire case definitions have utility for identifying hip and knee OA in community and population-based studies when the purpose is to link potential risk factors with knee and hip health.

Natural history of cartilage damage and osteoarthritis progression on magnetic resonance imaging in a population-based cohort with knee pain.

OBJECTIVES: To determine the natural history of cartilage damage and of osteoarthritis (OA) progression using magnetic resonance imaging (MRI); to evaluate whether OA progression varies by stage of disease. METHODS: A population-based cohort with knee pain was assessed clinically, with X-ray (Kellgren-Lawrence [KL] grading) and MRI. Cartilage was graded 0-3 on six joint surfaces. Frequency of cartilage damage change was determined for each joint site. Progression of OA was defined as a worsening of MRI cartilage damage by ≥1 grade in at least two joint sites or ≥2 grades in at least one joint site. The association of KL grade with OA progression was evaluated using parametric lifetime regression analysis. RESULTS: 163 subjects were assessed at baseline and follow-up (mean 3.2 years). KL grade ≥2 was present in 39.4% at baseline. An increase in cartilage damage by ≥1 grade was seen in 8.0-14.1% of subjects at different joint sites. OA progression on MRI was present in 15.5%. Baseline KL grade was a significant predictor of OA progression with hazard ratio (HR) of 6.5 (95% confidence interval [CI] 1.4-30.7), 6.1 (95% CI 1.3-28.9), and 9.2 (95% CI 1.9-44.9) for KL grades 1, 2 and ≥3, respectively. CONCLUSION: A low OA progression rate was seen over 3 years in this population-based symptomatic cohort. Radiographic severity, including KL grade 1, was a significant predictor of OA progression. Future interventions aimed at reducing progression will need to target not only radiographic OA, but also those with early abnormalities suggestive of pre-radiographic OA.

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.

Influence of lifetime hip joint force on the risk of self-reported hip osteoarthritis: a community-based cohort study.

OBJECTIVE: To investigate the influence of cumulative lifetime hip joint force on the risk of self-reported medically-diagnosed hip osteoarthritis (OA). DESIGN: Prospective cohort. SETTING: General population. PARTICIPANTS: Members of Canadian Association of Retired Persons, community-dwelling. MAIN OUTCOME: Health-professional diagnosed hip OA, self-reported. METHODS: Exposure data on lifetime physical activity type (occupational, household, sport) and dose (frequency, intensity, duration) was collected in 2005. Subjects were ranked in terms of a 'cumulative peak force index' (CFPI), a measure of lifetime mechanical hip joint force. Multivariable survival analyses were performed to obtain adjusted effects for mean lifetime exposure and during 5-year age periods. RESULTS: Of 2918 subjects aged 45-85, 176 (6.03%) developed hip OA during the 2-year follow up (43 men, 133 women). The highest quintile of mean lifetime hip CPFI (HR 2.32; 95% CI 1.31-4.12), and high hip force in three age periods (35-39, 40-44, 45-49) were independently associated with hip OA. Previous hip injury was an approximate five-fold risk for development of hip OA across all models. In analysis by activity domain (occupation, sport, household), there was a trend (non-significant) for the highest quintile of occupational force, but not sport or household, to be associated with hip OA. CONCLUSIONS: A newly proposed measure of lifetime mechanical hip force was used to estimate the risk of self-reported, medically-diagnosed hip OA. While there are important limitations, this prospective study suggests that lifelong physical activity is generally safe. Very high levels of lifetime force from all domains combined, and in particular from occupational forces, may be important in the etiology of hip OA.

The association of magnetic resonance imaging (MRI)-detected structural pathology of the knee with crepitus in a population-based cohort with knee pain: the MoDEKO study.

Osteoarthritis (OA) is the most common arthropathy of the knee joint(1). Symptoms reported by patients and signs noted during physical examination guide clinicians in identifying subjects with knee OA(2-4). Pain is one of the most important symptoms reported by subjects with knee OA(2,3). Although very common, pain is a non-specific symptom, related to pathology in several structures within the knee joint, and includes synovitis(5), subchondral bone marrow lesions(6), and joint effusion(7). Further, pain is a subjective symptom that cannot be directly measured or assessed during physical examination. Crepitus or crepitation in association with arthritis is defined as a crackling or grinding sound on joint movement with a sensation in the joint. Crepitus may occur with or without pain and is a common finding during physical examination in subjects with knee OA(2-4,8,9). It is not known whether crepitus is related to pathology in various structures within the knee. The aim of our study was to determine the cross-sectional associations of structural pathologies within the knee with crepitus in a population-based cohort with knee pain, using magnetic resonance imaging (MRI). Subjects with knee pain were recruited as a random population sample, with crepitus assessed in each compartment of the knee using a validated and standardized approach during physical examination(10). MRI of the knee was performed to assess cartilage morphology, meniscal morphology, osteophytes, cruciate ligaments, and collateral ligaments. For both compartment-specific and whole-knee analyses, a multiple logistic regression analysis was performed to assess the associations of MRI-detected structural pathology with crepitus, adjusting for potential confounders. Variables were selected by backwards elimination within each compartment and in the overall knee models, and only statistically significant variables remained in the "selected" models; remaining variables in these models are adjusted for each other. An increased risk for compartment-specific crepitus was associated with osteophytes at the patellofemoral (PF) and lateral tibiofemoral (LTF) joints. Crepitus was associated with osteophytes and medial collateral ligament (MCL) pathology at the medial tibiofemoral (MTF) compartment, but cartilage damage was negatively associated with crepitus at this compartment. In the selected whole-knee model, only meniscal tears were associated with an increased risk for general crepitus. Thus, it seems that crepitus may be associated with pathology in several internal structures.

Development of a population-based microsimulation model of osteoarthritis in Canada.

OBJECTIVES: The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN: We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS: Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS: We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature.

Agreement among Ayurvedic practitioners in the identification and treatment of three cases of inflammatory arthritis.

OBJECTIVE: To conduct a preliminary investigation into the consistency of approach between three Ayurvedic medicine experts on treatments for inflammatory polyarthritis. METHODS: A convenience sample of three experienced Ayurvedic practitioners was recruited. These practitioners independently assessed three subjects with inflammatory polyarthritis for health status, treatment history, and lifestyle, conducted a physical examination, and then independently determined the treatment plan. The treatment plan was recorded on standardized collection forms. The subject examination order was randomized for each practitioner. Following completion of the assessments, a facilitated discussion among the practitioners permitted each to discuss all aspects of the recommended therapies. Proceedings were audio-taped and the content analyzed. RESULTS: All three practitioners agreed upon a unified concept of Ayurvedic disease origin, disease diagnosis, and treatment approach for each patient. Seven specific treatment groupings (i.e. modalities) emerged: diet, exercise, relaxation, analgesic, anti-inflammatory, immune-enhancing, and detoxification/cleansing. Based on the single visit, the practitioners agreed upon 17 of 21 treatment groups for the three patients. CONCLUSION: Despite Ayurvedic medicine's individualized approach, considerable agreement existed among the practitioners studied. The identified Ayurvedic treatment approaches require investigation in a controlled clinical setting.

A single measure of patellar kinematics is an inadequate surrogate marker for patterns of three-dimensional kinematics in healthy knees.

Patellofemoral disorders, such as osteoarthritis and patellofemoral pain, are thought to be associated with abnormal patellar kinematics. However, assessments of three-dimensional patellar kinematics are time consuming and expensive. The aim of this study was to determine whether a single static measure of three-dimensional patellar kinematics provides a surrogate marker for three-dimensional patellar kinematics over a range of flexion angles. We assessed three-dimensional patellar kinematics (flexion, tilt and spin; lateral, anterior and proximal translation) at sequential static angles through approximately 45 degrees of loaded knee flexion in 40 normal subjects using a validated, MRI-based method. The surrogate marker was defined as the static measure at 30 degrees of knee flexion and the pattern of kinematics was defined as the slope of the linear best fit line of each subject's kinematic data. A regression model was used to examine the relationship between the surrogate marker and pattern of kinematics. The surrogate marker predicted 26% of the variance in pattern of patellar flexion (p<0.001), 27% of the variance in pattern of patellar spin (p=0.003), 11% of the variance in pattern of proximal translation (p=0.037) and 39% of the variance in pattern of anterior translation (p<0.001). No relationships were seen between the surrogate marker and tilt or lateral translation. The results suggest that a single measure of patellar parameters at 30 degrees knee flexion is an inadequate surrogate marker of three-dimensional patellar kinematics; therefore, a complete assessment of patellar kinematics, over a range of knee flexion angles, is preferable to adequately assess patterns of patellar kinematics.

Understanding the pain experience in hip and knee osteoarthritis--an OARSI/OMERACT initiative.

OBJECTIVE: To examine the pain experience of people with hip or knee osteoarthritis (OA), particularly changes over time and most distressing features. METHOD: Focus groups in individuals aged 40+ years with painful hip or knee OA obtained detailed descriptions of OA pain from early to late disease. A modified Patient Generated Index (PGI) was used to assess the features of OA pain that participants found most distressing. Content analysis was performed to examine response patterns; descriptive statistics were used to summarize PGI responses. RESULTS: Mean age of the 143 participants (52 hip OA; 91 knee OA) was 69.5 years (47-92 years); 60.8% were female and 93.7% Caucasian. Participants described two distinct types of pain - a dull, aching pain, which became more constant over time, punctuated increasingly with short episodes of a more intense, often unpredictable, emotionally draining pain. The latter, but not the former, resulted in significant avoidance of social and recreational activities. From PGI responses, distressing pain features were: the pain itself (particularly intense and unpredictable pain) and the pain's impact on mobility, mood and sleep. CONCLUSIONS: Two distinct pain types were identified. Intermittent intense pain, particularly when unpredictable, had the greatest impact on quality of life.

Development and preliminary psychometric testing of a new OA pain measure--an OARSI/OMERACT initiative.

OBJECTIVE: To evaluate the measurement properties of a new osteoarthritis (OA) pain measure. METHODS: The new tool, comprised of 12 questions on constant vs intermittent pain was administered by phone to 100 subjects aged 40+ years with hip or knee OA, followed by three global hip/knee questions, the Western Ontario and McMaster Universities (WOMAC) pain subscale, the symptom subscales of the Hip Disability and OA Outcome Score (HOOS) or Knee Injury and OA Outcome Score (KOOS), and the limitation dimension of the Late Life Function and Disability Instrument (LLFDI). Test-retest reliability was assessed by re-administration after 48-96h. Item response distributions, inter-item correlations, item-total correlations and Cronbach's alpha were assessed. Principle component analysis was performed and test-retest reliability was assessed by intra-class correlation coefficient (ICC). RESULTS: There was good distribution of response options across all items. The mean intensity was higher for intermittent vs constant pain, indicating subjects could distinguish the two concepts. Inter-item correlations ranged from 0.37 to 0.76 indicating no item redundancy. One item, predictability of pain, was removed from subsequent analyses as correlations with other items and item-total correlations were low. The 11-item scale had a corrected inter-item correlation range of 0.54-0.81 with Cronbach's alpha of 0.93 for the combined sample. Principle components analysis demonstrated factorial complexity. As such, scoring was based on the summing of individual items. Test-retest reliability was excellent (ICC 0.85). The measure was significantly correlated with each of the other measures [Spearman correlations -0.60 (KOOS symptoms) to 0.81 (WOMAC pain scale)], except the LLFDI, where correlations were low. CONCLUSIONS: Preliminary psychometric testing suggests this OA pain measure is reliable and valid.

Rheumatoid arthritis and the risk of malignancy.

OBJECTIVE: To determine the relative risks of malignancy and of site-specific malignancies in patients with rheumatoid arthritis (RA). METHODS: In a prospective cohort study, 862 patients with RA (96% white) were enrolled from 1966 to 1974 and were followed up for up to 35 years (mean 17.4 years) at the University of Saskatchewan Rheumatic Disease Unit. All diagnoses of cancer were cross-referenced with the Provincial Cancer Registry. Expected cancer incidence rates were determined based on province of Saskatchewan population statistics matched to each study patient for age, sex, and calendar year. Standardized incidence ratios (SIRs) of the observed-to-expected cancer incidence and 95% confidence intervals (95% CI) were then calculated. RESULTS: A total of 136 cases of cancer were observed compared with 168 expected (SIR 0.80, P = 0.011 [95% CI 0.67-0.95]). The relative risk of colorectal malignancy was significantly reduced in the RA study population (SIR 0.52, P = 0.037 [95% CI 0.25-0.96]). A significant excess of leukemia was found (SIR 2.47, P = 0.026 [95% CI 1.12-4.69]), whereas the incidence rates for Hodgkin's disease and non-Hodgkin's lymphoma and all other site-specific malignancies were not found to be significantly different from general population rates. CONCLUSION: In our cohort of RA patients, colorectal cancer was detected in only half the expected number of patients. This risk reduction may be related to long-term nonsteroidal antiinflammatory drug (NSAID) use in RA, as has been suggested in several other studies of long-term NSAID use. An increased risk of leukemia was confirmed. This may be due to the persistent immune stimulation associated with RA itself, since other potential explanatory factors for increased leukemia were not apparent. Despite the excess of hemopoietic malignancy and despite treatment of RA with potentially oncogenic agents, the overall risk of malignancy was reduced in this RA cohort.

Systemic lupus erythematosus and the risk of malignancy.

The objective of this study was to determine the relative risks of malignancy and of site-specific malignancies in patients with systemic lupus erythematosus (SLE). A cohort of 297 patients (91% Caucasian) with SLE were seen between 1975 and 1994 and followed for a mean of 12 years at the University of Saskatchewan Rheumatic Disease Unit. Expected cancer incidence rates were determined based on Province of Saskatchewan population statistics matched to each study patient for age, sex and calendar year of follow-up. Standardized incidence ratios (SIRs) of observed to expected cancers and 95% confidence intervals (95% CI) were calculated. A total of 27 cases of cancer were observed, whereas only 16.9 were expected (SIR 1.59 (95% CI 1.05-2.32)). For site-specific malignancies, an excess of cancer of the cervix (SIR 8.15 (95% CI 1.63-23.81)) as well as hemopoietic malignancy (SIR 4.9 (95% CI 1.57-11.43)) was found. The hemopoietic cancers were predominantly non-Hodgkin's lymphoma (SIR 7.01 (95% CI 1.88-17.96)). We did not find an association of malignancy with known risk factors, including use of cytotoxic agents. Increased risk of malignancy, notably non-Hodgkin's lymphoma and perhaps cervical cancer, should be regarded as a complication of SLE.