title: The influence of knee position on ankle dorsiflexion - a biometric study.
abstract: BACKGROUND
  Musculus gastrocnemius tightness (MGT) can be diagnosed by comparing ankle dorsiflexion (ADF) with the knee extended and flexed. Although various measurement techniques exist, the degree of knee flexion needed to eliminate the effect of the gastrocnemius on ADF is still unknown. The aim of this study was to identify the minimal degree of knee flexion required to eliminate the restricting effect of the musculus gastrocnemius on ADF.
  
  
  METHODS
  Bilateral ADF of 20 asymptomatic volunteers aged 18-40 years (50% female) was assessed prospectively at six different degrees of knee flexion (0°, 20°, 30°, 45°, 60°, 75°, Lunge). Tests were performed following a standardized protocol, non weightbearing and weightbearing, by two observers. Statistics comprised of descriptive statistics, t-tests, repeated measurement ANOVA and ICC.
  
  
  RESULTS
  20 individuals with a mean age of 27 ± 4 years were tested. No significant side to side differences were observed. The average ADF [95% confidence interval] for non weightbearing was 4° [1°-8°] with the knee extended and 20° [16°-24°] for the knee 75° flexed. Mean weightbearing ADF was 25° [22°-28°] for the knee extended and 39° [36°-42°] for the knee 75° flexed. The mean differences between 20° knee flexion and full extension were 15° [12°-18°] non weightbearing and 13° [11°-16°] weightbearing. Significant differences of ADF were only found between full extension and 20° of knee flexion. Further knee flexion did not increase ADF.
  
  
  CONCLUSIONS
  Knee flexion of 20° fully eliminates the ADF restraining effect of the gastrocnemius. This knowledge is essential to design a standardized clinical examination assessing MGT.
authors: Department of Trauma Surgery - Campus Innenstadt, Munich University Hospital, Nussbaumstr, 20, 80336 Munich, Germany. sebastian.baumbach@med.uni-muenchen.de.
authors: Sebastian F
authors: SF
authors: Baumbach
authors: Mareen
authors: M
authors: Brumann
authors: Jakob
authors: J
authors: Binder
authors: Wolf
authors: W
authors: Mutschler
authors: Markus
authors: M
authors: Regauer
authors: Hans
authors: H
authors: Polzer
mesh_terms: D000293:Adolescent; D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D001699:Biometry; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D011446:Prospective Studies; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D016474:Weight-Bearing; D055815:Young Adult