Takumi Kobayashi1, Eiichi Suzuki1, Naohito Yamazaki1, Makoto Suzukawa1, Atsushi Akaike1, Kuniaki Shimizu1, Kazuyoshi Gamada2. 1. Department of Physical Therapy, Hokkaido Chitose Institute of Rehabilitation Technology, Hokkaido, Japan (TK)Department of Orthopaedics, Kanagawa Prefectural Shiomidai Hospital, Kanagawa, Japan (ES)Department of Medical Radiation, Kanagawa Prefectural Shiomidai Hospital, Kanagawa, Japan (NY)Department of Rehabilitation, Yokohama Sports Medical Center, Kanagawa, Japan (MS)Department of Orthopaedics, Yokohama Sports Medical Center, Kanagawa, Japan (AA, KS)Department of Rehabilitation, Hiroshima International University, Hiroshima, Japan (KG). 2. Department of Physical Therapy, Hokkaido Chitose Institute of Rehabilitation Technology, Hokkaido, Japan (TK)Department of Orthopaedics, Kanagawa Prefectural Shiomidai Hospital, Kanagawa, Japan (ES)Department of Medical Radiation, Kanagawa Prefectural Shiomidai Hospital, Kanagawa, Japan (NY)Department of Rehabilitation, Yokohama Sports Medical Center, Kanagawa, Japan (MS)Department of Orthopaedics, Yokohama Sports Medical Center, Kanagawa, Japan (AA, KS)Department of Rehabilitation, Hiroshima International University, Hiroshima, Japan (KG) kazgamada@ortho-pt.com.
Abstract
BACKGROUND: Functional ankle instability (FAI) may involve abnormal kinematics and contact mechanics during ankle internal rotation. Understanding of these abnormalities is important to prevent secondary problems in patients with FAI. However, there are no in vivo studies that have investigated talocrural joint contact mechanics during weightbearing ankle internal rotation. The objective of this study to determine talocrural contact mechanics during weightbearing ankle internal rotation in patients with FAI. METHODS: Twelve male subjects with unilateral FAI (age range, 18-26 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities were obtained during weightbearing passive ankle joint complex rotation. Three-dimensional bone models created from the computed tomographic images were matched to the fluoroscopic images to compute 6 degrees of freedom for talocrural joint kinematics. The closest contact area in the talocrural joint in ankle neutral rotation and maximum internal rotation during either dorsiflexion or plantar flexion was determined using geometric bone models and talocrural joint kinematics data. RESULTS: The closest contact area in the talus shifted anteromedially during ankle dorsiflexion-internal rotation, whereas it shifted posteromedially during ankle plantar flexion-internal rotation. The closest contact area in FAI joints was significantly more medial than that in healthy joints during maximum ankle internal rotation and was associated with excessive talocrural internal rotation or inversion. DISCUSSION: This study demonstrated abnormal talocrural kinematics and contact mechanics in FAI subjects. Such abnormal kinematics may contribute to abnormal contact mechanics and may increase cartilage stress in FAI joints. LEVEL OF EVIDENCE: Therapeutic, Level IV: cross-sectional case-control study.
BACKGROUND: Functional ankle instability (FAI) may involve abnormal kinematics and contact mechanics during ankle internal rotation. Understanding of these abnormalities is important to prevent secondary problems in patients with FAI. However, there are no in vivo studies that have investigated talocrural joint contact mechanics during weightbearing ankle internal rotation. The objective of this study to determine talocrural contact mechanics during weightbearing ankle internal rotation in patients with FAI. METHODS: Twelve male subjects with unilateral FAI (age range, 18-26 years) were enrolled. Computed tomography and fluoroscopic imaging of both lower extremities were obtained during weightbearing passive ankle joint complex rotation. Three-dimensional bone models created from the computed tomographic images were matched to the fluoroscopic images to compute 6 degrees of freedom for talocrural joint kinematics. The closest contact area in the talocrural joint in ankle neutral rotation and maximum internal rotation during either dorsiflexion or plantar flexion was determined using geometric bone models and talocrural joint kinematics data. RESULTS: The closest contact area in the talus shifted anteromedially during ankle dorsiflexion-internal rotation, whereas it shifted posteromedially during ankle plantar flexion-internal rotation. The closest contact area in FAI joints was significantly more medial than that in healthy joints during maximum ankle internal rotation and was associated with excessive talocrural internal rotation or inversion. DISCUSSION: This study demonstrated abnormal talocrural kinematics and contact mechanics in FAI subjects. Such abnormal kinematics may contribute to abnormal contact mechanics and may increase cartilage stress in FAI joints. LEVEL OF EVIDENCE: Therapeutic, Level IV: cross-sectional case-control study.