Reliability of a Low-Cost Assessment of Tibial Torsion and Transverse-Plane Posture of the Lower Limb and Pelvis Using a Smartphone Compass

The purpose of this study was to investigate intra- and interrater reliability and minimal detectable change (MDC) of clinical measures proposed to assess tibial torsion and the posture of the lower limbs and pelvis in the transverse plane. Twenty-five able-bodied and asymptomatic participants (mean age 27 ± 4.03, 12 women) were assessed during relaxed standing with a compass application on a smartphone coupled to a caliper. Two trained examiners measured tibial torsion and angular postures of the pelvis, hip, femur, and tibia. Intraclass correlation coefficients (ICC) were used to investigate reliabilities, and MDCs were calculated. The results showed predominantly good-to-excellent reliability for the measures of the femur, hip, and tibia postures and tibial torsion (0.77 < ICC < 0.94), including some moderate-to-good reliability (0.65 < ICC < 0.75). The pelvic posture measure was predominantly moderate to good (0.55 < ICC < 0.86). MDCs have been reported (2.14°-7.86°) to assist clinicians in identifying postural changes that are within or outside the random measure variation. The use of a smartphone digital compass coupled to a caliper showed to be a reliable method to assess tibial torsion and transverse-plane postures of the lower limb and pelvis.