title: Hip strength and hip and knee kinematics during stair descent in females with and without patellofemoral pain syndrome.
abstract: METHODS
  Cross-sectional.
  
  
  OBJECTIVE
  To determine if females presenting with patellofemoral pain syndrome (PFPS) from no discernable cause other than overuse demonstrate hip weakness and increased hip internal rotation, hip adduction, and knee valgus during stair descent.
  
  
  BACKGROUND
  Historically, PFPS has been viewed exclusively as a knee problem. Recent findings have indicated an association between hip weakness and PFPS. Researchers have hypothesized that patients who demonstrate hip weakness would exhibit increased hip internal rotation, hip adduction, and knee valgus during functional activities. To date, researchers have not simultaneously examined hip and knee strength and kinematics in subjects with PFPS to make this determination.
  
  
  METHODS
  Eighteen females diagnosed with PFPS and 18 matched controls participated. Strength measures were taken for the hip external rotators and hip abductors. Hip and knee kinematics were collected as subjects completed a standardized stair-stepping task. Independent t tests were used to determine between-group differences in strength and kinematics during stair descent.
  
  
  RESULTS
  Subjects with PFPS generated 24% less hip external rotator (P = .002) and 26% less hip abductor (P =. 006) torque. No between-group differences (P > .05) were found for average hip and knee transverse and frontal plane angles during stair descent.
  
  
  CONCLUSIONS
  Subjects with PFPS had significant hip weakness but did not demonstrate altered hip and knee kinematics as previously theorized. Additional investigations are needed to better understand the association between hip weakness and PFPS etiology.
authors: Medical College of Georgia, School of Allied Health Sciences, Department of Physical Therapy, Augusta, GA, USA. lbolgla@mail.mcg.edu
authors: Lori A
authors: LA
authors: Bolgla
authors: Terry R
authors: TR
authors: Malone
authors: Brian R
authors: BR
authors: Umberger
authors: Timothy L
authors: TL
authors: Uhl
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006615:Hip / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D007717:Knee / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D010147:Pain Measurement; D046788:Patellofemoral Pain Syndrome / Q000209:etiology / Q000503:physiopathology*; D012307:Risk Factors; D016138:Walking / Q000502:physiology*