Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: The instantaneous helical axis of the subtalar and talocrural joints: a non-invasive in vivo dynamic study. | Sheehan Journal of Foot and Ankle Research 2010 3 13 http content 3 1 13 JOURNAL OF FOOT AND ANKLE RESEARCH RESEARCH Open Access The instantaneous helical axis of the subtalar and talocrural joints a non-invasive in vivo dynamic study FrancesT Sheehan Abstract Background An understanding of rear-foot talocrural and subtalar joints kinematics is critical for diagnosing foot pathologies designing total ankle implants treating rear-foot injuries and quantifying gait abnormalities. The majority of kinematic data available have been acquired through static cadaver work or passive in vivo studies. The applicability of these data to dynamic in vivo situations remains unknown. Thus the purpose of this study was to fully quantify subtalar talocrural and calcaneal-tibial in vivo kinematics in terms of the instantaneous helical axis IHA in twenty-five healthy ankles during a volitional activity that simulated single-leg toe-raises with partial-weight support requiring active muscle control. Methods Subjects were each placed supine in a T MRI and asked to repeat this simulated toe-raise while a full sagittal-cine-phase contrast dynamic MRI dataset was acquired. From the cine-phase contrast velocity a full kinematic description for each joint was derived. Results Nearly all motion quantified at the calcaneal-tibial joint was attributable to the talocrural joint. The subtalar IHA orientation and position were highly variable whereas the talocrural IHA orientation and position were extremely consistent. Conclusion The talocrural was well described by the IHA and could be modeled as a fixed-hinge joint whereas the subtalar could not be. Background An understanding of rear-foot kinematics is critical for diagnosing treating foot pathologies and injuries 1-3 designing total ankle implants 4 5 and quantifying gait abnormalities. The complicated foot-ankle complex is composed of 26 bones that transfer ground reaction forces to the lower limb. Due to its role
