Development of a Clinical Prediction Rule for Classifying Patients With Patellofemoral Pain Syndrome Who Respond to Patellar Taping

Abstract

Study Design: Predictive validity/diagnostic test study. Objective: To determine the predictive validity and interrater reliability of selected clinical exam items and to develop a clinical prediction rule (CPR) to determine which patients respond successfully to patellar taping. Background: Patellar taping is often used to treat patients with PFPS. However, the characteristics of the patients who respond best to patellar taping intervention have not been identified. Methods and Measures: Fifty volunteers (27 males, 23 females) with PFPS underwent a standardized clinical examination. Diagnosis of PFPS was based on the complaint of retropatellar pain that was provoked by a partial squat or stair ascent/descent. Subjects performed 3 functional activities and rated their pain during each activity on a numerical rating scale (NPRS). All subjects received treatment with a medial glide patellar-taping technique and repeated the functional activities and pain ratings. An immediate 50% reduction in pain or moderate improvement on a global rating of change (GRC) questionnaire was considered a treatment success. Likelihood ratios (LRs) were calculated to determine which examination items were most predictive of treatment outcome. Logistic regression analysis identified items included in the CPR. Results: Twenty-six subjects (52%) had an immediate successful response to the intervention. Two examination items (positive patellar tilt test or tibial varum greater than 5°, +LR = 4.4) comprised the CPR. Application of the CPR improved the probability of a successful outcome from 52% to 83%. Fifty-eight percent of the lower extremity measures were associated with moderate to good reliability (reliability coefficient range, 0.52-0.84). The reliability coefficients for the items that comprised the CPR were 0.49 (patellar tilt) and 0.66 (tibial varum). Thomas G. Sutlive, 3151 Scott Road Suite 1230, Fort Sam Houston, TX 78234. E-mail: thomas.sutlive@cen.amedd.army.mil Conclusion: A CPR was developed to predict an immediate successful response to a medial glide patellar taping technique. Validation of the CPR in an independent sample is necessary before widespread clinical use can be recommended.

The Measurement of Patellar Alignment in Patellofemoral Pain Syndrome: Are We Confusing Assumptions With Evidence?

“…Importantly, in terms of reliability, the measurements of medial/lateral position were performed on a single patella. This reduces the strength of the study's findings when compared to those of Fitzgerald and McClure, 22 Tomisch et al, 94 and Watson et al, 102 who assessed the intertester reliability of measurements of mediolateral patellar position on 66, 27, and 101 knees, respectively, and Lesher et al, 52 who examined patellar orientation on 50 knees. Also, the intertester reliability of the MRI measure in Herrington's 32 study was untested, as was the intratester reliability of the clinical measures.…”

“…They concluded that both visual estimation and instrumented measurements of patellar orientation produced results that were clinically unacceptable and unreliable. In a recent study, Lesher et al 52 examined the intertester reliability of a battery of orthopaedic tests, including patellar orientation, performed on 50 patients with PFPS by 2 testers. Patellar orientation was visually estimated and categorized as medial, neutral, or lateral.…”

Concurrent Criterion-Related Validity and Reliability of a Clinical Test to Measure Femoral Anteversion

“…3 With respect to reliability, several investigations have assessed the interrater reliability of the clinical test for femoral anteversion. 10,14,15,19,23,24 The results of these studies vary considerably, as illustrated by the wide range of reported reliability coefficients (0.17-0.97) and measurement error (1.1°-8.4°). Of these studies, only 1 investigated intrarater reliability of the clinical test for femoral anteversion.…”

Potential Pitfalls of Clinical Prediction Rules

“…Th e rules are algorithmic in nature and involve condensed information that identifi es the smallest number of indicators that are statistically diagnostic to the targeted condition 6 . Th e number of derived or validated CPRs is increasing 6 , specifi cally in rehabilitation medicine where prescriptive studies have been developed for musculoskeletal interventions for low back pain 7,8 , cervical pain 9,10 , and knee dysfunction 11,12 . Clinical prediction rules may best be classifi ed into three distinct groups: 1) diagnostic, 2) prognostic, and 3) prescriptive 1,13 .…”