The accuracy of the palpation meter (PALM) for measuring pelvic crest height difference and leg length discrepancy

Study Design: Test-retest reliability and validity. Objective: To determine the validity and reliability of the Palpation Meter (PALM). Background: Leg length discrepancy (LLD) has been associated with a variety of musculoskeletal disorders. Therefore, the clinical measurement of LLD has become a routine and important part of the physical examination. The PALM is an instrument that was recently developed to indirectly measure LLD, but little is known about its measurement properties. Methods and Measures: Fifteen healthy and 15 symptomatic subjects with suspected LLD participated in this study. Measurements of pelvic crest height difference (PD) were obtained by 2 examiners using the PALM. A standing antero-posterior (AP) radiograph of each subject's pelvis was taken, and PD and LLD (femoral head height difference) were determined from the radiograph for comparison with the PALM values. Intraclass correlation coefficients (ICCs) were calculated to determine the validity and reliability estimates of the PALM. Results: For all subjects, the validity estimates (ICC2,3) of the PALM for PD were excellent (0.90 for rater 1 and 0.92 for rater 2) when compared with the standing AP radiograph of the pelvis. The PALM was less accurate (ICC2,3 of 0.76 and 0.78 for rater 1 and 2, respectively) as an indirect estimate of LLD. Intrarater reliability for each rater was excellent (ICC2,3 = 0.97 and 0.98) and interrater reliability was very good (ICC2,3 = 0.88). Conclusion: The PALM is a reliable and valid instrument for measuring PD. Clinicians should consider this convenient, cost-effective clinical tool as an alternative to radiographic measurement of pelvic crest height difference.