Intrinsic foot muscle size and quality in a single leg weight bearing position across foot posture types in individuals with Patellofemoral Pain compared to healthy

Abstract

ObjectiveTo identify if any differences exist in IFM size and quality in single leg weight bearing position between healthy and PFP participants based on foot posture. DesignCross-sectional, matched case-comparison study SettingUniversity Laboratory Setting Participants35 PFP (age:20.46 ± 3.79yrs, mass:73.28 ± 26.58 kg, height:170.80 ± 11.91 cm) and 35 healthy (age:20.40 ± 3.16yrs, mass:64.76 ± 11.52 kg, height:169.55 ± 9.10 cm) participants MethodsAfter measuring Foot Posture Index (FPI), ultrasound images (USI) of Abductor Hallucis (AH), Flexor Digitorum Brevis (FDB) and Quadratus Plantae (QP) were taken in a single limb weight bearing position. Cross-sectional area (CSA) and echogenicity were measured on the USI. ResultsFPI was not different between groups (PFP:2.34 ± 3.76, Healthy:2.34 ± 3.10, 9 pronated and 26 non-pronated in both groups). AH CSA was smaller in PFP than healthy group (PFP:0.030 ± 0.01 cm2/kg, Healthy:0.042 ± 0.01 cm2/kg, P < 0.001) with a large effect (d = −1.20(-1.71, −0.69). There were no other significant group main effects or group-by-FP interactions in AH/FDB/QP CSA or echogenicity. ConclusionAH CSA was smaller in PFP than healthy controls, but no difference in CSA or echogenicity of FDB/QP exist, as well as no difference in foot posture between groups. While single limb weight bearing, the PFP group presented with a smaller IFM which provides eccentric control of medial longitudinal arch, which may have implications up the chain during weight bearing functional tasks.