title: Structure and function of the abductors in patients with hip osteoarthritis: Systematic review and meta-analysis.
abstract: BACKGROUND
  Hip osteoarthritis (OA) is a major cause of morbidity. Rehabilitation for this population focuses on strengthening the hip muscles, particularly the abductors, however the deficit in function of these muscles is unclear.
  
  
  OBJECTIVE
  To review the evidence for the differences in structure and function of hip abductors (gluteus medius and minimus and tensor fascia lata) in hip OA.
  
  
  METHODS
  A systematic review was conducted using MEDLINE, AMED, CINAHL and SportDISCUS, from the earliest date to September 2013. Studies that compared hip OA patients with controls, or the unaffected contralateral hip were included. Studies needed to report data on an outcome related to gross gluteal muscle function.
  
  
  RESULTS
  An initial yield of 141 studies was reduced to 22 after application of inclusion/exclusion criteria. Meta-analysis confirmed greater hip abductor strength in the control group (standardized mean difference = SMD -0.93, 95%CI -1.70 to -0.16) and the unaffected limb (SMD -0.26, 95%CI -0.48 to -0.04). Meta-analyses showed no differences in muscle size either between groups or limbs. Few electromyography studies have been reported and meta-analysis was not possible.
  
  
  CONCLUSIONS
  Hip abductor strength is reduced in OA patients when compared to healthy controls and to the unaffected limb. Data on muscle size and activity is limited.
authors.affiliation: La Trobe University, Rural Health School, Bendigo, VIC, Australia.
authors.forename: Amelia Rose
authors.initials: AR
authors.lastname: Marshall
authors.affiliation: La Trobe University, Rural Health School, Bendigo, VIC, Australia.
authors.forename: Marcos de
authors.initials: M
authors.lastname: Noronha
authors.affiliation: La Trobe University, Rural Health School, Bendigo, VIC, Australia.
authors.forename: Anita
authors.initials: A
authors.lastname: Zacharias
authors.affiliation: Bendigo Health Care Group, Bendigo, VIC, Australia.
authors.forename: Theo
authors.initials: T
authors.lastname: Kapakoulakis
authors.affiliation: La Trobe University, Rural Health School, Bendigo, VIC, Australia.
authors.forename: Rodney
authors.initials: R
authors.lastname: Green
mesh_terms: D005260:Female; D006615:Hip / Q000473:pathology / Q000503:physiopathology*; D006621:Hip Joint / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology*; D015207:Osteoarthritis, Hip / Q000473:pathology / Q000503:physiopathology*
keywords: Electromyography; lower extremity; muscle strength; osteoarthritis