title: Coordination of deep hip muscle activity is altered in symptomatic femoroacetabular impingement.
abstract: Diagnosis of femoroacetabular impingement (FAI) is increasing, yet the associated physical impairments remain poorly defined. This morphological hip condition can cause joint pain, stiffness, impaired function, and eventually hip osteoarthritis. This exploratory study compared coordination of deep hip muscles between people with and without symptomatic FAI using analysis of muscle synergies (i.e., patterns of activity of groups of muscles activated in synchrony) during gait. Fifteen individuals (11 males) with symptomatic FAI (clinical examination and imaging) and 14 age- and sex-comparable controls without morphological FAI underwent testing. Intramuscular fine-wire and surface electrodes recorded electromyographic activity of selected deep and superficial hip muscles. A non-negative matrix factorization algorithm extracted three synergies which were compared between groups. Information regarding which muscles were activated together in the FAI group (FAI group synergy vector) was used to reconstruct individual electromyography patterns and compare groups. Variance accounted for (VAF) by three synergies was less for the control (94.8 [1.4]%) than FAI (96.0 [1.0]%) group (p = 0.03). VAF of obturator internus was significantly higher in the FAI group (p = 0.02). VAF of the reconstructed individual electromyography patterns with the FAI or control group vector were significantly higher for the FAI group (p < 0.01). Following reconstruction, VAF of quadratus femoris was significantly more reduced in controls (p = 0.04), indicating greater between-subject variability. Coordination of deep hip muscles in the synergy related to hip joint control during early swing differed between groups. This phase involves movement towards the impingement position, which has relevance for the interpretation of synergy differences and potential clinical importance. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1494-1504, 2017.
authors: Department of Physiotherapy, Center for Health, Exercise and Sports Medicine, The University of Melbourne, School of Health Sciences, 161 Barry Street, Parkville, Victoria, 3010, Australia.
authors: Laura E
authors: LE
authors: Diamond
authors: Center of Clinical Research Excellence in Spinal Pain, Injury and Health, The University of Queensland, School of Health and Rehabilitation Sciences, Brisbane, Queensland, 4072, Australia.
authors: Wolbert
authors: W
authors: Van den Hoorn
authors: Department of Physiotherapy, Center for Health, Exercise and Sports Medicine, The University of Melbourne, School of Health Sciences, 161 Barry Street, Parkville, Victoria, 3010, Australia.
authors: Kim L
authors: KL
authors: Bennell
authors: Department of Physiotherapy, Center for Health, Exercise and Sports Medicine, The University of Melbourne, School of Health Sciences, 161 Barry Street, Parkville, Victoria, 3010, Australia.
authors: Tim V
authors: TV
authors: Wrigley
authors: Department of Physiotherapy, Center for Health, Exercise and Sports Medicine, The University of Melbourne, School of Health Sciences, 161 Barry Street, Parkville, Victoria, 3010, Australia.
authors: Rana S
authors: RS
authors: Hinman
authors: St Vincent's Hospital, East Melbourne, Australia.
authors: John
authors: J
authors: O'Donnell
authors: Center of Clinical Research Excellence in Spinal Pain, Injury and Health, The University of Queensland, School of Health and Rehabilitation Sciences, Brisbane, Queensland, 4072, Australia.
authors: Paul W
authors: PW
authors: Hodges
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D057925:Femoracetabular Impingement / Q000503:physiopathology*; D006615:Hip / Q000503:physiopathology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D055815:Young Adult
keywords: electromyography; femoroacetabular impingement; gait; hip joint; muscle coordination