Differences in Hip Joint Biomechanics and Muscle Activation in Individuals With Femoroacetabular Impingement Compared With Healthy, Asymptomatic Individuals: Is Level-Ground Gait Analysis Enough?

backgroundFemoroacetabular impingement (FAI) is a recognized cause of hip and groin pain and a significant factor in hip joint function during sport. Objective tests for understanding hip function are lacking in this population. PURPOSE: To determine whether biomechanical and electromyographic features of hip function during level-ground walking differ between a group diagnosed with FAI and those with no symptoms of FAI. STUDY

designControlled laboratory study.

methodsA total of 20 asymptomatic individuals and 20 individuals with FAI walked on a dual-belt instrumented treadmill at self-selected walking velocities. Sagittal and frontal plane joint motions, moments, and muscle activation for the gluteus medius, gluteus maximus, rectus femoris, and medial and lateral hamstrings were analyzed. Discrete measures were extracted from each biomechanical waveform, and principal component analysis was used to determine hip joint muscle activation and hip adduction moment patterns. Statistical significance was determined by use of Student

resultsIndividuals with FAI walked more slowly (

conclusionIndividuals with FAI were generally deconditioned and reported significantly more functional limitations. No biomechanical differences existed between groups during level walking, yet hamstring and gluteus maximus activation differed when the symptomatic group was compared with the asymptomatic group. CLINICAL RELEVANCE: The field lacks objective testing of hip joint function to understand implications of FAI for dynamic movements, particularly with applications to biomechanics and electromyography. Level walking was of limited value for understanding FAI hip function, and the development of a more challenging gait assessment is warranted.