title: Clinical and instrumented measurements of hip laxity and their associations with knee laxity and general joint laxity.
abstract: BACKGROUND
  Hip-joint laxity may be a relevant anterior cruciate ligament injury risk factor. With no devices currently available to measure hip laxity, it is important to determine if clinical measurements sufficiently capture passive displacement of the hip.
  
  
  OBJECTIVE
  To examine agreement between hip internal-external-rotation range of motion measured clinically (HIER(ROM)) versus internal-external-rotation laxity measured at a fixed load (HIER(LAX)) and to determine their relationships with knee laxity (anterior-posterior [KAP(LAX)], varus-valgus [KVV(LAX)], and internal-external rotation [KIER(LAX)]) and general joint laxity (GJL). Design : Cross-sectional study.
  
  
  METHODS
  Controlled research laboratory.
  
  
  METHODS
  Thirty-two healthy adults (16 women, 16 men; age = 25.56 ± 4.08 years, height = 170.94 ± 10.62 cm, weight = 68.86 ± 14.89 kg).
  
  
  METHODS
  Participants were measured for HIER(ROM), HIER(LAX) at 0° and 30° hip flexion (-10 Nm, 7 Nm), KAP(LAX) (-90 N to 133 N), KVV(LAX) (±10 Nm), KIER(LAX) (±5 Nm), and GJL. We calculated Pearson correlations and 95% limits of agreement between HIER(ROM) and HIER(LAX)_0° and HIER(LAX)_30°. Correlation analyses examined the strength of associations between hip laxity, knee laxity, and GJL.
  
  
  RESULTS
  The HIER(ROM) and HIER(LAX) had similar measurement precision and were strongly correlated (r > 0.78). However, HIER(ROM) was systematically smaller in magnitude than HIER(LAX) at 0° (95% limits of agreement = 29.0° ± 22.3°) and 30° (21.4° ± 19.3°). The HIER(ROM) (r = 0.51-0.66), HIER(LAX)_0° (r = 0.52-0.69) and HIER(LAX)_30° (r = 0.53-0.76) were similarly correlated with knee laxity measures and GJL. The combinations of KVV(LAX) and either HIER(ROM), HIER(LAX)_0°, or HIER(LAX)_30° (R2 range, 0.42-0.44) were the strongest predictors of GJL.
  
  
  CONCLUSIONS
  Although HIER(ROM) and HIER(LAX) differed in magnitude, they were measured with similar consistency and precision and were similarly correlated with knee laxity and GJL measures. Individuals with greater GJL also had greater hip laxity. These findings are relevant to clinicians and investigators conducting prospective risk factor studies, given the need for accessible, efficient, and low-cost alternatives for characterizing an individual's laxity profile.
authors.affiliation: Shandong Normal University, Jinan, China.
authors.forename: Lixia
authors.initials: L
authors.lastname: Fan
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Copple
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Tritsch
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000503:physiopathology; D007718:Knee Injuries / Q000175:diagnosis / Q000503:physiopathology*; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D010808:Physical Examination / Q000379:methods*; D011446:Prospective Studies; D016059:Range of Motion, Articular / Q000502:physiology*; D015599:Trauma Severity Indices; D055815:Young Adult
keywords: anterior cruciate ligament injuries; lower extremity; risk factors
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