Osteoarthritis (OA) is the most common form of arthritic

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1 THOMAS G. SUTLIVE, PT, PhD, OCS¹ DPT² DPT² DPT² DPT² MD³ PT, DSc, OCS, FAAOMPT 4 PT, PhD, MBA, OCS, FAAOMPT 5 Development of a Clinical Prediction Rule for Diagnosing Hip Osteoarthritis in Individuals With Unilateral Hip Pain Osteoarthritis (OA) is the most common form of arthritic disorders and one of the most common reasons for visiting a health care practitioner. 27 The estimated annual cost of managing OA in the United States is immense, accounting for billions of dollars in healthcare expenditures. 11,13,17 The hip is a common site for OA, affecting 10% to 25% of the population over the age of ,41 In addition to the economic impacts, decreased function associated with hip OA can have a substantial detrimental effect on Prospective cohort/predictive validity study. To determine the diagnostic accuracy of common clinical examination items and to construct a preliminary clinical prediction rule for diagnosing hip osteoarthritis (OA) in individuals with unilateral hip pain. The current gold standard for the diagnosis of hip OA is a standing anteroposterior (AP) radiograph of the pelvis. Other than for Altman s criteria, little research has been done to determine the accuracy of clinical examination findings for diagnosing hip OA. Seventy-two subjects completed the study. Each subject received a standardized history, physical examination, and standing AP radiograph of the pelvis. Subjects with a Kellgren and Lawrence score of 2 or higher based on the radiographs were considered to have definitive hip OA. Likelihood ratios (LRs) were computed to determine which clinical examination findings were most diagnostic of hip OA. Potential predictor variables were entered into a logistic regression model to determine the most accurate set of clinical examination items for diagnosing hip OA. Twenty-one (29%) of the 72 subjects had radiographic evidence of hip OA. A clinical prediction rule consisting of 5 examination variables was identified. If at least 4 of 5 variables were present, the positive LR was equal to 24.3 (95% confidence interval: ), increasing the probability of hip OA to 91%. The preliminary clinical prediction rule provides the ability to a priori identify patients with hip pain who are likely to have hip OA. A validation study should be done before the rule can be implemented in routine clinical practice. Diagnosis, level 2b. J Orthop Sports Phys Ther 2008;38(9): doi: /jospt arthritis, diagnosis, OA, predictive validity quality of life. Although there is no cure for hip OA, various forms of nonsurgical treatment have proven effective, including weight reduction, exercise, and manual therapy interventions ,43 Therefore, accurate diagnosis and timely intervention is essential to minimize the deleterious effects of OA and to maximize functional abilities. 9,25,40 Radiographs represent the current gold standard for diagnosing hip OA. 37 Osteoarthritis severity is determined based on the presence of hallmark radiographic findings, such as joint space narrowing, osteophytes, bony changes at the joint margins, and alterations of subchondral bone, according to the Kellgren and Lawrence scale. 26,37 Although radiographs are relatively inexpensive, understanding the diagnostic accuracy of key clinical examination findings would assist the clinician in expediting the evaluation process, initiating early management, and making appropriate referrals to specialty providers, and may obviate unnecessary radiation exposure. Altman and colleagues 1 identified several elements of the clinical examination that are diagnostic of hip OA in patients with hip pain. Although these criteria have proven to be valuable for decision mak- 1 Associate Professor, US Army-Baylor University Doctoral Program in Physical Therapy, San Antonio, TX. 2 Doctoral student, US Army-Baylor University Doctoral Program in Physical Therapy, San Antonio, TX. 3 Chief, Musculoskeletal Section, Department of Radiology and Radiology Residency Program Director, Brooke Army Medical Center, San Antonio, TX. 4 Assistant Professor, US Army-Baylor University Doctoral Program in Physical Therapy, San Antonio, TX. 5 Assistant Professor and Director of Research, US Army- Baylor University Doctoral Program in Physical Therapy, San Antonio, TX. The protocol for this study was approved by The Institutional Review Board of Brooke Army Medical Center. The opinions or assertions herein are the private views of the authors and are not to be construed as official or as reflecting the views of the United States Army or the Department of Defense. Address correspondence to Thomas G. Sutlive, US Army-Baylor University Doctoral Program in Physical Therapy, 3150 Stanley Road, Room 1303, ATTN: MCCS-HMT, Fort Sam Houston, TX thomas.sutlive@amedd.army.mil 542 september 2008 volume 38 number 9 journal of orthopaedic & sports physical therapy

2 the diagnostic accuracy of commonly used clinical examination procedures thought to be suggestive of hip OA, but that may have not previously been considered by Altman s criteria, and to develop a preliminary clinical prediction rule that maximizes the accuracy of diagnosing hip OA, based on clinical examination findings. Measurement of the Patrick s test using an inclinometer. ing, 2,21,22,35,40 their utilization may require laboratory testing, such as erythrocyte sedimentation rate (ESR). Additionally, the development of these criteria did not include several clinical examination findings commonly thought to be associated with hip OA, such as the presence of a capsular pattern of motion restriction, identification of certain abnormal end feels at the end range of passive rangeof-motion testing, and reproduction of a patient s pain with provocative testing. Cyriax 10 stated that a capsular pattern is a unique pattern of range-of-motion restrictions that is suggestive of OA. For the hip, Cyriax stated that the capsular pattern consisted of a gross limitation in internal rotation, flexion, and abduction. It was also suggested that an early capsular end feel, a spasm end feel (in the absence of acute trauma), and a boneto-bone end feel may indicate possible degenerative changes at the hip. 10 Clinical examination procedures, such as the Patrick s test, hip flexion test, scour test, and squat test, are also commonly used by clinicians in the assessment of patients with hip pain 31 and designed to reproduce a patient s symptoms ( provocative tests ). These tests are frequently used to determine the location and irritability of a patient s symptoms and to select appropriate treatment interventions. Although preliminary evidence suggests that positive findings from these procedures may be useful in diagnosing hip OA, their diagnostic accuracy has not been thoroughly studied. Therefore, the purposes of this study were to determine METHODS Subjects e utilized a single-group, cross-sectional study design to determine the diagnostic accuracy of selected special tests and measures for the diagnosis of hip OA. Seventyeight subjects were recruited from the military healthcare beneficiary system at Fort Sam Houston in San Antonio, TX. Volunteers were required to be over 40 years of age and have a chief complaint of unilateral pain in the buttock, groin, or anterior thigh. We excluded patients with a current diagnosis of cancer, history of hip surgery, and females who were pregnant at the time of the study. Urine pregnancy tests were performed on all premenopausal females. The study was approved by the Brooke Army Medical Center (San Antonio, Texas) Institutional Review Board, and all patients provided consent prior to their participation. Each subject received a standardized history and physical examination by physical therapists in the US Army-Baylor University Doctoral Program in Physical Therapy. Examiner teams were comprised of 2 physical therapist doctoral students, with one serving as the examiner and the other as a recorder. Examiners underwent a standardized training regimen prior to the beginning of data collection to develop consistent measurements based on the operational definitions for the clinical examination procedures. Examiners completed several training sessions to standardize the measurements in accordance with the operational definitions, followed by a final testing session to establish pilot Measurement of passive hip internal rotation using an inclinometer. reliability data in a sample of 10 healthy subjects. The first 30 subjects enrolled in the study were also assessed by teams of 2 examiner blinded to each other s findings to establish definitive reliability of the testing procedures. The physical examination included range-of-motion measurements, end feel testing according to Cyriax, and 3 provocative maneuvers: Patrick s test ( ), the scour test, and the squat test. Operational definitions of the physical examination items are provided in the to facilitate replication of our study. The positional order of testing (ie, standing, supine, prone) was counterbalanced to mitigate the potential for an order effect to occur. Range of motion for hip flexion, extension, abduction, and adduction were obtained using a standard 18-cm plastic goniometer. An inclinometer was used to assess range of motion for hip internal and external rotation ( ). Immediately following each measurement, subjects were asked whether the movement changed their symptoms. To assess end feels, examiners utilized standardized passive range-of-motion assessment techniques with overpressure. End feels were recorded into 1 of 7 categories as defined by Cyriax 10 : bone to bone, spasm, early capsular, capsular, tissue approximation, empty, and springy. For the purposes of data analysis, end feels were dichotomized into capsular and noncapsular. According to Cyriax, 10 the end feels of early capsular, spasm, and bone-tobone are considered capsular end feels and indicative of degenerative changes of journal of orthopaedic & sports physical therapy volume 38 number 9 september

3 Kellgren and Lawrence Grading Scale for Hip Osteoarthritis 26 Standing antero-posterior radiograph of the pelvis, with evidence of Kellgren and Lawrence grade 4 osteoarthritis in both hips. the joint. End feels classified as noncapsular included soft tissue approximation, capsular (ie, normal resistance of the capsule at the end range of some joints), springy block, and empty end feels. We also recorded the effect of the movement on the patient s symptoms, such as pain location (verified by the subject pointing to the site of pain) and replication of previous pain for each measurement. Cyriax 10 stated that the capsular pattern of restriction for the hip was gross limitation of internal rotation, flexion, and abduction, and that this pattern was suggestive of hip OA. He also stated that in very early hip arthrosis, internal rotation is the first movement to become restricted, followed by flexion. 10 Based on Cyriax s definitions, we determined whether a capsular pattern of restriction existed in our subjects based on fulfillment of 1 of the 2 following conditions: (1) loss of hip internal rotation greater than loss of hip flexion greater than loss of hip abduction, or (2) loss of hip internal rotation greater than loss of hip abduction greater than loss of hip flexion. Loss of each range of motion was expressed as a percentage of restricted motion based on published normal values. 15 For example, based on a published normal value of 45, a subject with 35 of hip internal rotation was considered to have a 10 restriction or a 22% (10/45) loss of motion No evidence of joint space narrowing, osteophyte formation, or sclerosis (normal radiograph) 1 Possible narrowing of the joint space medially and possible osteophytes around the femoral head 2 Definite narrowing of the joint space, definite osteophytes, and slight sclerosis 3 Marked narrowing of the joint space, slight osteophytes, some sclerosis, and cyst formation, and deformity of the femoral head and acetabulum 4 Gross loss of joint space with sclerosis and cysts, marked deformity of femoral head and acetabulum, large osteophytes Following the physical examination, each subject received a standing antero-posterior (AP) radiograph of the pelvis ( 3). The average SD number of days between the physical examination and radiographic testing was days (range, 0-46 days), and the median was 1.5 days. All radiographs were examined and scored by the same staff radiologist who had more than 15 years of experience in musculoskeletal imaging. Scoring was based on the Kellgren and Lawrence scale ( Demographics and Baseline Characteristics of Subjects P Value* Age, mean y (SD) 58.6 (11.2) 61.1 (12.7) 58.3 (10.6).36 Gender, n (%) females 40 (56%) 7 (10%) 33 (46%).02 Current pain, mean (SD) 2.8 (2.3) 3.4 (2.8) 2.5 (2.1).03 Duration of symptoms, n.22 6 wk wk-6 mo mo-1 y y y Mode of onset, n.05 Gradual Sudden (minutes with no perturbation) Sudden (traumatic) Location of symptoms, n Lumbar spine Buttock Groin Anterior thigh Posterior thigh Lower leg/foot Abbreviation: OA, osteoarthritis. * Difference between groups. Numeric pain rating scale: 0 to 10, with 0 as no pain and 10 as the worst possible pain. 1). 26 The Kellgren and Lawrence grading scheme has proven to be reliable 16 and has been accepted by the World Health Organization as the reference standard for cross-sectional and longitudinal studies of hip OA. 37 Subjects with a Kellgren and Lawrence score of 2 or higher were considered to have hip OA. 24,34,37 The radiologist and examiners were blinded to each other s findings to eliminate the potential for 544 september 2008 volume 38 number 9 journal of orthopaedic & sports physical therapy

4 rater bias. Only clinical examination data from the patient s self-reported symptomatic side were considered for subjects who were judged to have bilateral radiographic evidence of hip OA. Data Analysis All statistical analyses were performed using SPSS software, Version 12.0 (SPSS Inc, Chicago, IL). Descriptive statistics and measures of central tendency and variability were calculated to summarize the demographic characteristics of the sample. Descriptive statistics and interrater reliability coefficients were determined for each of the physical examination items. Interrater reliability coefficients were calculated using Cohen s kappa coefficient and percent agreement for categorical variables and intraclass correlation coefficients (ICC 2,1 ) for continuous variables. Standard errors of the measurement (SEM) were determined Interrater Reliability (ICC 2,1 ), SEM, and MDC for Hip Range of Motion Measurements, the Squat, and Patrick s Test 2,1 Flexion 0.85 (0.64 to 0.93) Abduction 0.85 (0.68 to 0.93) Adduction 0.54 ( 0.19 to 0.81) External rotation 0.77 (0.53 to 0.89) Internal rotation 0.88 (0.74 to 0.94) Extension 0.68 (0.32 to 0.85) Squat 0.80 (0.59 to 0.91) Patrick s test 0.90 (0.78 to 0.96) Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; MDC, minimum detectable change; SEM, standard error of the measurement. Percent Agreement for Hip End Feel Dichotomized Into Capsular and Noncapsular End Feels Flexion (involved side) 0.21 ( 0.22 to 0.64) 70.0 Internal rotation (involved side) 0.51 (0.19 to 0.83) 76.7 Scour test (involved side) 0.52 (0.08 to 0.96) 86.7 Patrick s test (involved side) 0.47 (0.12 to 0.81) 76.7 Hip flexion test (involved side) 0.52 (0.09 to 0.96) 86.7 Abbreviation: CI, confidence interval. for each of the continuous variables according to the following equation: SD (1 ICC). The minimum detectable change (MDC) was calculated as SEM 1.96 (z score for 95% confidence) 2. Individual variables from the history and physical examination were tested for their association with the radiograph reference criterion using independent-samples t tests for continuous variables and 2 tests for categorical variables. Variables with a significance level of P.10 were retained as potential predictors. A more liberal P value was utilized to avoid eliminating potentially meaningful variables during the initial screening process. For continuous variables with a significant univariate relationship, sensitivity and specificity values were calculated for all possible cutoff points and then plotted as a receiver operator characteristic (ROC) curve. The point on the curve nearest the upper left-hand corner represented the value with the best diagnostic accuracy, and this point was selected as the cut-off defining a positive test. Sensitivity, specificity, and positive and negative likelihood ratios (LR) were calculated for potential predictor variables. Potential predictor variables were entered into a stepwise logistic regression model to determine the most accurate set of variables for prediction of diagnostic success. A significance level of greater than.10 was required for removal from the equation to minimize the likelihood of excluding potentially helpful variables. Variables retained in the regression model were used to formulate the clinical prediction rule. Seventy-eight volunteers were recruited for this study. Six subjects failed to complete their radiograph examination. Seventy-two subjects (40 female, 32 male; mean SD age, years) completed the study. Demographic and baseline characteristics are shown in. Twenty-one of the 72 subjects were classified as having hip OA, resulting in a pretest probability of 29% (21/72). The number of subjects who had Kellgren and Lawrence scores of 0, 1, 2, 3, and 4 were 19 (26%), 32 (44%), 13 (18%), 3 (4%), and 5 (7%), respectively. Interrater reliability (ICC 2,1 ) and 95% confidence intervals (CIs) for range-of-motion measurements, squat test, and Patrick s tests are shown in. Values ranged from 0.54 to The kappa coefficients with 95% CIs for end feel testing ranged from 0.21 to 0.52 (). Because of the low prevalence of some end feel categories and limited variability between examiners, kappa coefficients might have been artificially deflated. 39 Therefore, we also calculated percent agreement, which ranged from 70.0% to 86.7% (). 39 The sensitivity, specificity, and positive likelihood ratios for individual variables journal of orthopaedic & sports physical therapy volume 38 number 9 september

5 Sensitivity, Specificity, and Likelihood Ratios (95% CI) for Individual Variables With a Significant Relationship With Positive Radiographic Findings Gender 0.67 (0.43 to 0.85) 0.65 (0.50 to 0.77) 1.9 (1.1 to 3.0) 0.52 (0.28 to 0.96) Constant LBP/buttock pain 0.52 (0.30 to 0.74) 0.92 (0.80 to 0.97) 6.4 (2.4 to 17.4) 0.52 (0.33 to 0.81) Groin pain same side 0.29 (0.12 to 0.52) 0.92 (0.80 to 0.97) 3.6 (1.2 to 11.0) 0.78 (0.59 to 1.00) Self-reported squatting as aggravating factor 0.76 (0.52 to 0.91) 0.57 (0.42 to 0.70) 1.8 (1.2 to 2.6) 0.42 (0.19 to 0.93) Squat causing posterior pain 0.24 (0.09 to 0.48) 0.96 (0.85 to 0.99) 6.1 (1.5 to 25.6) 0.79 (0.62 to 1.00) Active hip flexion causing lateral pain 0.43 (0.23 to 0.66) 0.88 (0.75 to 0.95) 3.6 (1.5 to 8.7) 0.65 (0.44 to 0.94) Scour with adduction causing lateral or groin pain 0.62 (0.39 to 0.81) 0.75 (0.60 to 0.85) 2.4 (1.4 to 4.3) 0.51 (0.29 to 0.89) Passive IR (0.52 to 0.91) 0.61 (0.46 to 0.74) 1.9 (1.3 to 3.0) 0.39 (0.18 to 0.86) Patrick s (0.34 to 0.77) 0.71 (0.56 to 0.82) 1.9 (1.1 to 3.4) 0.61 (0.36 to 1.00) Active hip extension causing hip pain 0.52 (0.30 to 0.74) 0.80 (0.66 to 0.90) 2.7 (1.3 to 5.3) 0.59 (0.37 to 0.94) Abduction or adduction causing groin pain 0.33 (0.15 to 0.57) 0.94 (0.83 to 0.98) 5.7 (1.7 to 18.6) 0.71 (0.52 to 0.96) Abbreviations: CI, confidence interval; IR, internal rotation; LBP, low back pain. demonstrating a significant relationship with positive radiographic findings are shown in. The 5 variables that emerged from the subsequent logistic regression analysis were used to form the preliminary clinical prediction rule: (1) self-reported squatting as an aggravating factor; (2) active hip flexion causing lateral hip pain; (3) scour test with adduction causing lateral hip or groin pain; (4) active hip extension causing pain; and (5) passive internal rotation of less than or equal to 25 ( and ). Having at least 3 out of the 5 predictor variables resulted in a positive likelihood ratio equal to 5.2 (95% CI: ), increasing the likelihood of having hip OA from a pretest probability of 29% to a 68% posttest probability. If at least 4 out of 5 variables were present, the positive likelihood ratio was equal to 24.3 (95% CI: ), increasing the posttest probability of having hip OA to 91%. DISCUSSION The ability to identify patients with hip OA based on key clinical examination findings is useful to guide diagnostic decision making and to assist clinicians in determining which patients require further testing and evaluation, and when to initiate early management, which may minimize the deleterious effects of hip OA and maximize function. Improving the clinical diagnosis of hip OA may also minimize the costs associated with unnecessary radiographic procedures and avoid the risks of radiation exposure. Each variable retained in the final clinical prediction rule demonstrated moderate to good reliability, 29,36 falling within the ranges of those previously reported. 9,12,18,23 We chose to report the positive likelihood ratio because the purpose of this study was to maximize the potential of making an accurate diagnosis of hip OA, while minimizing the potential of false positive findings. 6,14 Furthermore, requiring that subjects had at least Kellgren and Lawrence grade 2 radiographic changes increased the likelihood that The Number of Subjects in Each Group at Each Level* (1.4%) 3 (4.2%) 4 1 (1.4%) 10 (13.9%) 3 7 (9.7%) 15 (20.1%) 2 20 (27.8%) 17 (23.6%) 1 42 (58.3%) 20 (27.8%) 0 9 (12.5%) 1 (1.4%) Abbreviation: K & L, Kellgren and Lawrence. * The 5 variables forming the clinical prediction rule are (1) self-reported squatting as an aggravating factor, (2) scour test with adduction causing groin or lateral pain, (3) active hip flexion causing lateral pain, (4) active hip extension causing hip pain, and (5) passive hip internal rotation less than or equal to 25. Scores are n (%). they would experience clinically relevant symptoms and might benefit from nonsurgical management. Twenty-one of the 72 subjects in our study had a Kellgren and Lawrence score of equal or greater to 2, based on their radiographs. Thus the pretest probability of having hip OA in our sample was 29%. If a subject exhibited only 1 or 2 of the predictor variables, the posttest probability of having hip OA only increased to 33% and 46%, respectively (). However, if a subject had at least 3 predictors present, the likelihood of having hip OA increased from 29% to 68%. If a subject exhibited at least 4 of the 5 predictors, the posttest probability increased further to 91%. However, this latter com- 546 september 2008 volume 38 number 9 journal of orthopaedic & sports physical therapy

6 Combination of Predictor Variables and Associated Accuracy Statistics With 95% Confidence Intervals 5.14 (.04 to.37).98 (.88 to 1.0) 7.3 (1.1 to 49.1).87 (.73 to 1.1) 75 (25 to 96) 4.48 (.26 to.70).98 (.88 to 1.0) 24.3 (4.4 to 142.1).53 (.35 to.80) 91 (58 to 99) 3.71 (.48 to.88).86 (.73 to.94) 5.2 (2.6 to 10.9).33 (.17 to.66) 68 (51 to 82) 2.81 (.57 to.94).61 (.46 to.74) 2.1 (1.4 to 3.1).31 (.13 to.78) 46 (36 to 56) 1.95 (.74 to 1.0).18 (.09 to.31) 1.2 (.99 to 1.4).27 (.04 to 2.0) 33 (29 to 36) Abbreviations: CI, confidence interval; OA, osteoarthritis. * The posttest probability of diagnosis of hip OA is calculated using the positive likelihood ratio and assumes 29% of patients have hip OA (our study prevalence) regardless of number of predictors present. bination of predictors was associated with a wide 95% CI, creating uncertainty as to the stability of this point estimate. If the intent is to conservatively estimate when to order imaging studies, refer patients to specialty providers, or to initiate appropriate nonsurgical management, a reasonably sufficient degree of diagnostic accuracy exists based on the presence of at least 3 predictors. Altman and colleagues 1 described clinical examination variables that are commonly used for establishing a diagnosis of patients with hip OA. According to their study, a patient was classified as having hip OA if they presented with hip pain and either (1) hip internal rotation greater than or equal to 15, pain present on internal rotation of the hip, morning stiffness of the hip for less than or equal to 60 minutes, and an age of greater than 50 years, or (2) hip internal rotation of less than 15 and an ESR less than or equal to 45 mm/h. If no ESR was obtained, hip flexion less than or equal to 115 was substituted. Either of these sets of criteria had a sensitivity of 86%, a specificity of 75%, and a positive likelihood ratio of 3.4 for the diagnosis of hip OA, with radiographs serving as the reference standard. However, Altman et al s criteria were based on a limited examination and did not consider a number of routinely used tests and measures that are thought to be diagnostic of hip OA. Therefore, we believed that it was necessary to examine the diagnostic accuracy of these additional clinical examination procedures. Hip pain and limited hip internal rotation were common predictors of hip OA in both our study () and the clinical criteria reported by Altman and colleagues. 1 Although a limitation of hip flexion range of motion was one of Altman et al s criteria, it was not retained as a variable in our final rule. However, active hip flexion that reproduced symptoms was predictive of hip OA. Cyriax 10 proposed that each joint might have a characteristic proportional pattern of motion restriction that, when detected, indicates the presence of a capsular pattern, which is suggestive of a lesion to the synovial membrane of the joint. Cyriax described the capsular pattern of the hip to be a marked limitation of internal rotation followed by losses of flexion and abduction. He further postulated that in the early onset of hip OA, internal rotation is the first movement to be measurably restricted, followed by a slight flexion limitation. 10 The emphasis on internal rotation followed by flexion appears to correlate with the results of recent studies on clinical indicators of hip joint OA. 1,42 While limited hip internal rotation emerged as a predictor of hip OA in our study, the presence of a capsular pattern of restriction did not emerge in the final rule. This finding is consistent with previous reports questioning the concept of a capsular pattern of restriction of the hip. 4,28 Klassbo and colleagues 28 examined 168 patients with a variety of hip disorders and found no evidence to support the existence of a capsular pattern in their subjects who had hip OA. Similarly, Bijl et al 4 examined the validity of the concept of a capsular pattern in patients with a clinical diagnosis of hip or knee OA, and concluded that the capsular pattern cannot be regarded as a valid test for the diagnosis of OA in either of these patient populations. To our knowledge, no previous investigation has determined reliability for the end feel assessment of hip motions. Prior studies have shown that intrarater reliability for the determination of knee and shoulder end feels is moderate and that interrater reliability is low. 5,19 Chesworth et al 5 reported moderate intrarater kappa coefficients and substantial interrater kappa values for the assessment of shoulder lateral rotation in patients with shoulder disorders. Hayes and Petersen 5,19 reported kappa values ranging from 0.01 to 0.70 in their study of subjects with unilateral knee or shoulder pain. However, their values for percent agreement were generally high, which was consistent with our findings for end feel assessment of hip internal rotation and flexion (). Although end feel assessment of hip internal rotation or flexion did not emerge as a predictor of hip OA, the interrater reliability established in this study may help to improve the clinician s confidence in utilizing these techniques during the examination of patients with hip pain. Our study includes several limitations. It is important to note that the diagnostic accuracy of the rule actually diminished when all 5 predictors were present. However, only 4 subjects had all 5 criteria journal of orthopaedic & sports physical therapy volume 38 number 9 september

7 present. Because 1 of these subjects did not have hip OA, the low total number of subjects magnified this error. Larger studies with more individuals having all 5 criteria present would likely demonstrate higher levels of diagnostic accuracy were all 5 criteria present. Additionally, while 11 variables were entered into the logistic regression analysis, only 21 subjects exhibited a positive response to those variables. It is possible that the small sample of positive findings and the number of variables entered into the logistic regression may have resulted in overfitting of the model, which could have led to spurious findings. However, in the development stage of a clinical prediction rule it is important and necessary to include all the potential predictor variables, and any variable that may have been identified as a predictor should be re-examined in future validation studies. 8 We also considered a limited number of examination procedures performed primarily by physical therapists and other practitioners who examine patients in a musculoskeletal or orthopedic clinical setting. The clinical examination procedures included in this study were chosen because they are routinely performed during the examination of patients with hip pain, allowing comparison of our results with previous work. 1 It is also possible that some of the predictor variables emerged by chance. Therefore, future studies done in a variety of clinical practice settings and populations are necessary to replicate and validate our findings before being recommended for widespread use in clinical practice. 32 If the rule is validated, an impact analysis should be conducted to determine the impact of the rule on decreasing radiographic utilization, clinical practice patterns, outcomes, and costs of care. The eventual value of the rule may be to help clinicians determine when to initiate nonsurgical management strategies, such as physical therapy, that have proven to be effective for patients with hip OA. 21,22,30 Alternatively, clinicians may be interested in ruling out hip OA as a significant contributor to hip pain. Therefore, future investigations may also explore the best combination of clinical factors for ruling out the diagnosis of hip OA. CONCLUSION e have completed the first step in the development of a preliminary rule that identifies patients with hip OA. We believe that the results of this study may assist clinicians in expediting the evaluation process, initiating early management, and making appropriate referrals to specialty providers in this patient population. Future studies to replicate and validate our findings are necessary before the rule can be recommended for widespread use in clinical practice. A preliminary clinical prediction rule was developed for identifying patients with hip osteoarthritis (OA) based on key clinical examination criteria. The clinical prediction rule developed in this study may assist clinicians in expediting the evaluation process, initiating early management, and making appropriate referrals of patients with hip OA. This study involved a small sample size (n = 72) and must be validated in replication studies in a variety of clinical settings and populations before it can be advocated for widespread clinical use. 1. Altman R, Alarcon G, Appelrouth D, et al. 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Reliability of assessing end-feel and pain and resistance sequence in subjects with painful shoulders and knees. J Orthop Sports Phys Ther. 2001;31: Hochberg MC, Altman RD, Brandt KD, et al. 548 september 2008 volume 38 number 9 journal of orthopaedic & sports physical therapy

8 Guidelines for the medical management of osteoarthritis. Part I. Osteoarthritis of the hip. American College of Rheumatology. Arthritis Rheum. 1995;38: Hoeksma HL, Dekker J, Ronday HK, Breedveld FC, Van den Ende CH. Manual therapy in osteoarthritis of the hip: outcome in subgroups of patients. Rheumatology (Oxford). 2005;44: keh Hoeksma HL, Dekker J, Ronday HK, et al. Comparison of manual therapy and exercise therapy in osteoarthritis of the hip: a randomized clinical trial. Arthritis Rheum. 2004;51: dx.doi.org/ /art Holm I, Bolstad B, Lutken T, Ervik A, Rokkum M, Steen H. Reliability of goniometric measurements and visual estimates of hip ROM in patients with osteoarthrosis. Physiother Res Int. 2000;5: Ingvarsson T, Hagglund G, Lindberg H, Lohmander LS. Assessment of primary hip osteoarthritis: comparison of radiographic methods using colon radiographs. Ann Rheum Dis. 2000;59: Jorring K. Osteoarthritis of the hip. Epidemiology and clinical role. Acta Orthop Scand. 1980;51: Kellgren JH, Lawrence JS. Radiological assessment of osteo-arthrosis. Ann Rheum Dis. 1957;16: Kelsey JL, Hochberg MC. Epidemiology of chronic musculoskeletal disorders. Annu Rev Public Health. 1988;9: org/ /annurev.pu Klassbo M, Harms-Ringdahl K, Larsson G. Examination of passive ROM and capsular patterns in the hip. Physiother Res Int. 2003;8:1-12. Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33: MacDonald CW, Whitman JM, Cleland JA, Smith M, Hoeksma HL. Clinical outcomes following manual physical therapy and exercise for hip osteoarthritis: a case series. J Orthop Sports Phys Ther. 2006;36: org/ /jospt Magee DJ. Orthopedic Physical Assessment. 4th ed. Philadelphia, PA: W.B. Saunders Company; McGinn TG, Guyatt GH, Wyer PC, Naylor CD, Stiell IG, Richardson WS. Users guides to the medical literature: XXII: how to use articles about clinical decision rules. Evidence-Based Medicine Working Group. JAMA. 2000;284: Norkin CC, White DJ. Measurement of Joint Motion. A Guide to Goniometry. 2nd ed. Philadelphia, PA: F.A. Davis Company; Odding E, Valkenburg HA, Algra D, Vandenouweland FA, Grobbee DE, Hofman A. Associations of radiological osteoarthritis of the hip and knee with locomotor disability in the Rotterdam Study. Ann Rheum Dis. 1998;57: Pincus T, Koch G, Lei H, et al. Patient Preference for Placebo, Acetaminophen (paracetamol) or Celecoxib Efficacy Studies (PACES): two randomised, double blind, placebo controlled, crossover clinical trials in patients with knee or hip osteoarthritis. Ann Rheum Dis. 2004;63: Portney L, Watkins M. Foundations of Clinical Research: Applications to Practice. 2nd ed. Upper Saddle River, NJ: Prentice Hall Health; Reijman M, Hazes JM, Koes BW, Verhagen AP, Bierma-Zeinstra SM. Validity, reliability, and ap- The physical examination included range-of-motion measurements, end feel testing according to Cyriax, 10 and provocative tests such as the scour test, Patrick s test, and squat test. Range of motion for hip flexion, extension, abduction, and adduction was obtained using a standard 18-cm plastic goniometer. 3 An inclinometer was used to assess range of motion for hip internal and external rotation. 12 Before each of the range-of-motion measurements was taken, an assessment of mobility of the involved hip relative to the uninvolved hip (normal, hypomobile, hypermobile) and end feel assessment was made. The effect of the movement on the patient s symptoms was also recorded (pain, no pain, location of pain). Squat Test The patient was standing with the feet aligned on a 20-cm strip of tape placed on the floor. The big toe of each foot was positioned at each end of the tape. With the patient in upright stance, the therapist zeroed out the inclinometer along the tibial shaft approximately 1 to 2 cm below the tibial tuberosity on the involved side. While looking straight ahead, patients plicability of seven definitions of hip osteoarthritis used in epidemiological studies: a systematic appraisal. Ann Rheum Dis. 2004;63: Ross MD, Nordeen MH, Barido M. Test-retest reliability of Patrick s hip range of motion test in healthy college-aged men. J Strength Cond Res. 2003;17: Sim J, Wright CC. The kappa statistic in reliability studies: use, interpretation, and sample size requirements. Phys Ther. 2005;85: Steultjens MP, Dekker J, van Baar ME, Oostendorp RA, Bijlsma JW. Range of joint motion and disability in patients with osteoarthritis of the knee or hip. Rheumatology (Oxford). 2000;39: Tepper S, Hochberg MC. Factors associated with hip osteoarthritis: data from the First National Health and Nutrition Examination Survey (NHANES-I). Am J Epidemiol. 1993;137: Theiler R, Stucki G, Schutz R, et al. Parametric and non-parametric measures in the assessment of knee and hip osteoarthritis: interobserver reliability and correlation with radiology. Osteoarthritis Cartilage. 1996;4: van Baar ME, Assendelft WJ, Dekker J, Oostendorp RA, Bijlsma JW. Effectiveness of exercise therapy in patients with osteoarthritis of the hip or knee: a systematic review of randomized clinical trials. Arthritis Rheum. 1999;42: were instructed to keep the trunk upright, with hands on hips, and squat as if they were trying to lower their buttocks between their feet as far as possible, keeping the knees in line with the second toe and the heels on the floor. Maximum squat was achieved either when the patient reported being unable to go further due to pain limitations, was noticed to begin leaning forward, or if the heels began to lift off the ground. Once maximum squat was achieved, the range-of-motion measurement was recorded to the nearest degree, and any change in symptoms was recorded. 7 The subject was supine. The hip was passively flexed to 90º and comfortable knee flexion was allowed to follow. The knee was then moved toward the opposite shoulder and an axial load was applied in a direction parallel to the long axis of the femur. The examiner judged the test to be positive or negative based on the provocation of the patient s symptoms in the groin. Internal rotation and axial compression and then adduction and axial compression were added, with overpressure applied to the lateral surface of journal of orthopaedic & sports physical therapy volume 38 number 9 september

9 the knee. The examiner also judged this part of the test to be positive or negative based on the provocation of the subject s symptoms in the hip or groin. 31 The patient was supine. The hip was maintained in neutral abduction/adduction and rotation. The patient was instructed to flex the knee and hip of the opposite extremity to be measured to maintain a neutral lumbar spine position during the measurement. The lower extremity was held in that position, and the subject was then instructed to actively flex the tested hip as far as possible. The examiner observed the motion, making sure that the patient did not rotate the hips posteriorly or externally rotate at the hip. The range of motion was measured for each hip using a universal goniometer. The fulcrum was centered over the greater trochanter, the proximal arm along the midline of the pelvis, and the distal arm along the midline of the femur, in line with the lateral femoral epicondyle. 3,33 The patient was supine. The hip was maintained in neutral flexion/extension and rotation. The patient was instructed to actively move his/her hip to a position of maximum abduction. Next, the range of motion was measured using a universal goniometer. The fulcrum was centered over the anterior superior iliac spine (ASIS) of the side being measured, the proximal arm along a line joining the ASIS, and the distal arm along the midline of the thigh. 3,33 The patient was supine. The hip was maintained in neutral flexion/extension and rotation. The patient was instructed to actively move the hip to a position of maximum adduction. Next, the range of motion was measured using a universal goniometer. The fulcrum was centered over the ASIS, the proximal arm along a line joining the ASIS, and the distal arm along the midline of the femur. A second examiner held the untested extremity in hip flexion to allow for full motion of the measured hip. 3,33 The patient was supine. The hip was moved to a position of flexion, abduction, and external rotation by placing the lateral malleolus on the contralateral knee. Slight overpressure was applied to stabilize the opposite ASIS. The effect of the movement on the patient s symptoms was also recorded (pain, no pain, location of pain). 31,38 The examiner next assessed the Patrick s test in a similar manner on the involved hip. In addition to the traditional performance of the Patrick s test, an assessment of mobility of the involved hip relative to the uninvolved hip (normal, hypomobile, hypermobile) was made. After zeroing a bubble inclinometer against a wall, the range of motion was measured for each hip with the inclinometer placed approximately 2.5 cm proximal to the patient s flexed knee. The patient was prone. The hip was maintained in neutral flexion/extension and adduction/abduction. The knee was flexed to 90º, and the hip was passively moved to a position of maximum internal rotation. The examiner noted maximal internal rotation when the patient s opposite hip/buttock began to rise from the table. The range of motion was measured for each hip using a bubble inclinometer placed just proximal to the lateral malleolus. 12 The patient was prone. The hip was maintained in neutral flexion/extension and adduction/abduction. The opposite hip was passively placed in slight abduction to avoid impeding motion of the tested hip. The knee was flexed to approximately 90, and the hip was passively moved to a position of maximum external rotation. The examiner noted maximal external rotation when the patient s hip began to rise from the table. The range of motion was measured using a bubble inclinometer placed just proximal to the lateral malleolus. 12 The patient was prone. The hip was maintained in neutral abduction/adduction and rotation. The knee was extended and the patient was instructed to actively move his/her hip into a position of maximum extension, while maintaining ASIS contact with the table. The examiner observed the motion making sure the patient did not contract his/her back musculature when attempting maximum hip extension. The range of motion was measured using a universal goniometer. The fulcrum was centered over the greater trochanter, the proximal arm along the midline of the pelvis, and the distal arm along the midline of the femur, in line with the lateral femoral epicondyle. 3,33 FIND Author Instructions & Tools on the Journal s Website JOSPT s instructions to authors are available at by clicking AUTHOR TOOLS & INSTRUCTIONS in the upper right-hand column of the home page, or by visiting INFORMATION FOR AUTHORS, located in the site s navigation bar in the left-hand column. The Journal s editors have assembled a list of useful tools and links for authors as well as reviewers. 550 september 2008 volume 38 number 9 journal of orthopaedic & sports physical therapy