Greenwald R M, Janes P C, Swanson S C, McDonald T R
Orthopedic Biomechanics Institute, Salt Lake City, Utah, USA.
Am J Sports Med. 1998 Nov-Dec;26(6):825-30. doi: 10.1177/03635465980260061501.
The purpose of this study was to compare the dynamic impact response of braced and unbraced cadaveric wrists using a commercially available wrist guard. Twelve arms were harvested from six cadavers. Each pair of forearms, one with and one without a brace, were impacted using a modified guillotine-type drop fixture placed over a force platform. Using a piece-wise linear regression analysis, we identified four phases of dynamic loading in the vertical force profile before fracture. These phases included an initial linear loading phase starting at impact, followed by a nonlinear phase, a second rapid linear loading phase, and a final nonlinear loading phase to failure. Three transition points were identified that defined the boundaries of the linear loading phases. Vertical force and impulse were significantly higher (P < 0.01) at each transition point and at failure in all braced specimens compared with unbraced specimens. However, the most noticeable differences were found during the initial two loading phases. Time to each transition point and to failure was not significantly different (P > 0.27) between the braced and unbraced wrists. The results of this study differ from those obtained under more quasistatic loading conditions. Dynamic impact testing suggests that wrist guards may have a prophylactic effect during low-energy dynamic impact situations.
本研究的目的是使用市售护腕比较有支撑和无支撑的尸体手腕的动态冲击响应。从六具尸体上取下了十二条手臂。每对前臂，一条有支撑，一条无支撑，通过放置在测力平台上的改良断头台式落锤装置进行冲击。使用分段线性回归分析，我们确定了骨折前垂直力曲线中的四个动态加载阶段。这些阶段包括从冲击开始的初始线性加载阶段，接着是非线性阶段、第二个快速线性加载阶段以及到失效的最终非线性加载阶段。确定了三个转变点，它们定义了线性加载阶段的边界。与无支撑的标本相比，所有有支撑的标本在每个转变点和失效时的垂直力和冲量均显著更高（P < 0.01）。然而，最显著的差异出现在最初的两个加载阶段。有支撑和无支撑的手腕到达每个转变点和失效的时间没有显著差异（P > 0.27）。本研究的结果与在更多准静态加载条件下获得的结果不同。动态冲击测试表明，护腕在低能量动态冲击情况下可能具有预防作用。
