title: Acute influence of restricted ankle dorsiflexion angle on knee joint mechanics during gait.
abstract: BACKGROUND
  Restrictions in range of ankle dorsiflexion (DF) motion can persist following ankle injuries. Ankle DF is necessary during terminal stance of gait, and its restricted range may affect knee joint kinematics and kinetics. The purpose of this study was to investigate the acute influence of varied levels of restricted ankle DF on knee joint sagittal and frontal plane kinematics and kinetics during gait.
  
  
  METHODS
  Thirty healthy volunteers walked with a custom-designed ankle brace that restricted ankle DF. Kinematics and kinetics were collected using a 7-camera motion analysis system and two force plates. Ankle dorsiflexion was restricted in 10-degree increments, allowing for four conditions: Free, light (LR), moderate (MR) and severe restriction (SR). Knee angles and moments were measured during terminal stance.
  
  
  RESULTS
  Real peak ankle DF for Free, LR, MR, and SR were 13.7±4.8°, 11.6±5.0°, 7.5±5.3°, and 4.2±7.2°, respectively. Peak knee extension angles under the same conditions were -6.7±6.7°, -5.4±6.4°, -2.5±7.5°, and 0.6±7.8°, respectively, and the peak knee varus moment was 0.48±0.17 Nm/kg, 0.47±0.17 Nm/kg, 0.53±0.20 Nm/kg, and 0.57±0.20 Nm/kg. The knee varus moment was significantly increased from MR condition with an 8-degree restriction in ankle DF.
  
  
  CONCLUSIONS
  Knee joint kinematics and kinetics in the sagittal and frontal planes were affected by reduced ankle DF during terminal stance of gait. Differences were observed with restriction in ankle DF range of approximately 8°.
  
  
  METHODS
  level III.
authors: Department of Rehabilitation and Care, Seijoh University, Tokai 476-8588, Japan. Electronic address: ota-s@seijoh-u.ac.jp.
authors: S
authors: S
authors: Ota
authors: Division of Rehabilitation, Syutaikai Hospital, Yokkaichi 510-0823, Japan.
authors: M
authors: M
authors: Ueda
authors: Department of Advanced Medicine, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan.
authors: K
authors: K
authors: Aimoto
authors: Department of Advanced Medicine, National Center for Geriatrics and Gerontology, Obu 474-8511, Japan.
authors: Y
authors: Y
authors: Suzuki
authors: Division of Biokinesiology & Physical Therapy, University of Southern California, Los Angeles 90089-9006, CA, United States.
authors: S M
authors: SM
authors: Sigward
mesh_terms: D000843:Ankle Joint / Q000503:physiopathology*; D001696:Biomechanical Phenomena / Q000502:physiology; D001915:Braces; D005260:Female; D005684:Gait / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D007719:Knee Joint / Q000503:physiopathology*; D008297:Male; D016059:Range of Motion, Articular / Q000502:physiology; D055815:Young Adult
keywords: Ankle dorsiflexion angle; Gait; Knee extension angle; Knee varus moment; Terminal stance