Gitter A, Czerniecki J, Weaver K
Department of Physical Medicine & Rehabilitation, Seattle Veterans Affairs Medical Center, WA 98108, USA.
Am J Phys Med Rehabil. 1995 Sep-Oct;74(5):332-8.
Above-knee (AK) amputation substantially increases the metabolic cost of ambulation. Although the biomechanical mechanisms contributing to the increase have not been well studied, it has been assumed that altered center-of-mass (COM) kinematics and increased mechanical work account for the adverse effect on oxygen consumption. To understand better the relationship between mechanical work and the metabolic cost, 8 normal subjects and 8 traumatic AK amputees were studied during overground ambulation. Using segmental energy and inverse dynamics analyses, trunk COM excursion, the mechanical work associated with movement of the COM, and the work done by the major lower limb sagittal plane muscle groups were determined. Oxygen consumption was measured using the Douglas bag technique. The metabolic cost was 27% higher in amputees compared with normal subjects (P > 0.01), but no significant differences were noted in the excursion of or the work done on the trunk COM. The muscle work needed to complete a stride was significantly greater in normal subjects compared with amputees. These results indicate that the role of abnormal kinematics and their effect on the mechanical work of walking are complex and incompletely understood, but may be overemphasized as a cause of the increased metabolic cost. Alternative mechanisms for the metabolic inefficiency must be considered.
膝上截肢显著增加了行走的代谢成本。尽管导致这种增加的生物力学机制尚未得到充分研究，但据推测，质心（COM）运动学的改变和机械功的增加是导致氧耗增加的不利因素。为了更好地理解机械功与代谢成本之间的关系，对8名正常受试者和8名创伤性膝上截肢者进行了地面行走研究。采用节段能量和逆动力学分析，确定了躯干质心偏移、与质心运动相关的机械功以及主要下肢矢状面肌肉群所做的功。使用道格拉斯袋技术测量氧耗。与正常受试者相比，截肢者的代谢成本高出27%（P>0.01），但在躯干质心的偏移或所做的功方面未发现显著差异。与截肢者相比，正常受试者完成一步所需的肌肉功明显更大。这些结果表明，异常运动学的作用及其对行走机械功的影响是复杂的，尚未完全理解，但作为代谢成本增加的一个原因可能被过度强调了。必须考虑代谢效率低下的其他机制。
