title: Hip flexor muscle size, strength and recruitment pattern in patients with acetabular labral tears compared to healthy controls.
abstract: Acetabular labral tears are a source of hip pain and are considered to be a precursor to hip osteoarthritis. Hip flexor muscles contribute to hip joint stability and function but it is unknown if their size and function is altered in the presence of labral pathology. This study aimed to investigate hip flexor muscle size, strength and recruitment pattern in patients with hip labral pathology compared to control subjects. 12 subjects diagnosed with an unilateral acetabular labral tear were compared to 12 control subjects matched for age and gender. All subjects underwent magnetic resonance imaging (MRI) of their lumbo-pelvic region. Average muscle cross-sectional area (CSA) of the iliacus, psoas, iliopsoas, sartorius, tensor fascia latae and rectus femoris muscles were measured. Hip flexion strength was measured by an externally fixed dynamometer. Individual muscle recruitment pattern during a resisted hip flexion exercise task was measured by muscle functional MRI. Hip flexor muscle strength was found to be decreased in patients with labral pathology compared to control subjects (p < 0.01). No difference between groups or sides was found for hip flexor muscle size (all p > 0.17) and recruitment pattern (all p > 0.53). Decreased hip flexor muscle strength may affect physical function in patients with hip labral pathology by contributing to altered gait patterns and functional tasks. Clinical rehabilitation of these patients may need to include strengthening exercises for the hip flexor muscles.
authors.affiliation: School of Physiotherapy, Faculty of Health Sciences, Australian Catholic University, PO Box 456, Brisbane, Virginia, QLD 4014, Australia. Electronic address: dilani.mendis@acu.edu.au.
authors.forename: M Dilani
authors.initials: MD
authors.lastname: Mendis
authors.affiliation: The University of Queensland, School of Information Technology and Electrical Engineering, Brisbane, Australia.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wilson
authors.affiliation: Brisbane Orthopaedic & Sports Medicine Centre, Brisbane, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Hayes
authors.affiliation: Brisbane Orthopaedic & Sports Medicine Centre, Brisbane, Australia.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Watts
authors.affiliation: School of Physiotherapy, Faculty of Health Sciences, Australian Catholic University, PO Box 456, Brisbane, Virginia, QLD 4014, Australia.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Hides
mesh_terms: D000077:Acetabulum; D000328:Adult; D002358:Cartilage, Articular / Q000293:injuries*; D016022:Case-Control Studies; D005260:Female; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007593:Joint Instability / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000503:physiopathology*
keywords: Hip injuries; Magnetic resonance imaging; Muscle strength; Osteoarthritis