Reliability and Validity of Plantar Pressures and the Modified ICPBL Test vs. Telemetry for Diagnosing Anatomical Discrepancies: A Pilot Study

Background/Objectives: Several methods have been proposed to assess lower limb-length discrepancies; however, none have demonstrated sufficient reliability and validity for diagnosing anatomical discrepancies (DA). Objectives: This study primarily aims to evaluate the accuracy of two traditional tests—the Modified Iliac Crests Palpation and Pelvimeter with Blocks test (ICPBL) and plantar pressure analysis—by comparing them with the gold standard telemetry (TE) method for diagnosing DA. The secondary objective is to assess the intra-rater reliability of these two tests and determine their potential applicability in clinical settings. Methods: Thirty subjects between the ages of 20 and 80 were enrolled in the present prospective, cross-sectional diagnostic accuracy pilot study; thirteen with a positive TE for DA of more than 3 mm were classified into the group with the condition DA, and 17 were classified into the group without the condition DA. Pelvic tilting and plantar pressures were evaluated. Results: The TE revealed a difference of 8.09 ± 3.24 mm between the short and long limbs, while subjects without DA had only a 0.41 mm difference (p < 0.001). Similarly, the Modified ICPBL test showed a 4.38 ± 2.10 mm difference in subjects with DA, compared to 0.51 ± 0.53 mm in those without DA (p < 0.001). Additionally, plantar pressure measurements supported these findings, with a difference of 5.17 ± 3.28 kg/cm2 between the short and long limbs in subjects with DA, versus 2.28 ± 1.77 kg/cm2 in subjects without DA (p < 0.05). The area under the receiver operating characteristic (ROC) curve was 0.783 (95% CI: 0.456–0.877) for plantar pressures and 1.000 (95% CI: 0.742–0.942) for the Modified ICPBL test. Conclusions: The Modified ICPBL and plantar pressure tests demonstrated high diagnostic accuracy within the sample studied, suggesting they are useful tools for supporting the diagnosis of DA. In this pilot study, the Modified ICPBL showed very high discriminative ability, while plantar pressure testing demonstrated moderate sensitivity. Both methods may serve as preliminary practical alternatives to telemetry TE, potentially reducing X-ray exposure; however, these results should be interpreted with caution due to the limited sample size and the specific clinical setting of this study.