title: Eccentric hip muscle function in females with and without patellofemoral pain syndrome.
abstract: BACKGROUND
  Patellofemoral pain syndrome (PFPS) is a common knee condition in athletes. Recently, researchers have indicated that factors proximal to the knee, including hip muscle weakness and motor control impairment, contribute to the development of PFPS. However, no investigators have evaluated eccentric hip muscle function in people with PFPS.
  
  
  OBJECTIVE
  To compare the eccentric hip muscle function between females with PFPS and a female control group.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Musculoskeletal laboratory.
  
  
  METHODS
  two groups of females were studied: a group with PFPS (n = 10) and a group with no history of lower extremity injury or surgery (n = 10).
  
  
  METHODS
  Eccentric torque of the hip musculature was evaluated on an isokinetic dynamometer.
  
  
  METHODS
  Eccentric hip abduction, adduction, and external and internal rotation peak torque were measured and expressed as a percentage of body mass (Nm/kg x 100). We also evaluated eccentric hip adduction to abduction and internal to external rotation torque ratios. The peak torque value of 5 maximal eccentric contractions was used for calculation. Two-tailed, independent-samples t tests were used to compare torque results between groups.
  
  
  RESULTS
  Participants with PFPS exhibited much lower eccentric hip abduction (t(18) = -2.917, P = .008) and adduction (t(18) = -2.764, P = .009) peak torque values than did their healthy counterparts. No differences in eccentric hip external (t(18) = 0.45, P = .96) or internal (t(18) = -0.742, P = .47) rotation peak torque values were detected between the groups. The eccentric hip adduction to abduction torque ratio was much higher in the PFPS group than in the control group (t(18) = 2.113, P = .04), but we found no difference in the eccentric hip internal to external rotation torque ratios between the 2 groups (t(18) = -0.932, P = .36).
  
  
  CONCLUSIONS
  Participants with PFPS demonstrated lower eccentric hip abduction and adduction peak torque and higher eccentric adduction to abduction torque ratios when compared with control participants. Thus, clinicians should consider eccentric hip abduction strengthening exercises when developing rehabilitation programs for females with PFPS.
authors.affiliation: São Carlos Federal University, São Paulo, Brazil.
authors.forename: Rodrigo de Marche
authors.initials: Rde M
authors.lastname: Baldon
authors.forename: Theresa Helissa
authors.initials: TH
authors.lastname: Nakagawa
authors.forename: Thiago Batista
authors.initials: TB
authors.lastname: Muniz
authors.forename: César Ferreira
authors.initials: CF
authors.lastname: Amorim
authors.forename: Carlos Dias
authors.initials: CD
authors.lastname: Maciel
authors.forename: Fábio Viadanna
authors.initials: FV
authors.lastname: Serrão
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D006615:Hip / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D010147:Pain Measurement; D046788:Patellofemoral Pain Syndrome / Q000503:physiopathology*; D012399:Rotation; D019415:Torque