Abstract
Introduction: Patients with femoroacetabular impingement (FAI) often experience limited hip mobility which is often associated with difficulties with balance and stability. The star excursion balance test (SEBT) has been an instrumental tool in evaluating dynamic postural control as well as its association with hip mobility. The aim of this study was to examine differences in balance and stability during the performance of the SEBT in patients with cam FAI compared with healthy controls. Methods: Eight patients with symptomatic FAI (confirmed by symptoms and imaging) were matched with eight sex- and age-matched healthy control participants. Each participant underwent MRI to assess anatomical hip parameters and confirm pathoanatomy (Synopsys Simpleware IP, UK). Each participant underwent biomechanical assessments, capturing their hip functional kinematics using retroreflective markers and motion capture cameras (Motion Analysis, USA); and kinetics using instrumented force plates (AMTI, USA). Each participant completed the SEBT by performing single-limb squats using their affected/symptomatic side while using the unaffected/asymptomatic limb to reach as far as possible to touch a point along one of eight specified lines on the ground. The reach distance during SEBT was normalized by leg length and statistical analyses were conducted using non-parametric Mann-Whitney U tests. Results: The FAI patients demonstrated similar reach distances in many of the anterior, medial, and lateral directions compared to the control participants. However, the FAI group was unable to reach as far in the posterior (0.86) and posteromedial directions (0.89) compared to controls (0.98, p = 0.038; 1.01, p = 0.026). The FAI patients exhibited substantial difficulty in reaching anteriorly and anteromedially, with several patients (6/8) needing to lift their heel off the ground to complete the tasks. Discussion: The FAI group demonstrated worse dynamic postural control when using their symptomatic hip for balancing in order to reach posteriorly and posteromedially with the contralateral hip. This may relate to restrictions in hip range of motion or periarticular muscle function in FAI patients compared with control subjects while performing similar tasks. As the dynamics SEBT can help assess physical performance, joint instability, and postural control, it can help identify individuals who may be at potentially greater risks for FAI-related injuries.