Bergmann G, Graichen F, Rohlmann A
Oskar-Helene-Heim, Biomechanics Laboratory, Orthopaedic Hospital, Free University Berlin, Germany.
J Biomech. 1995 May;28(5):535-53. doi: 10.1016/0021-9290(94)00105-d.
Considerable forces and moments act at hip prostheses during most kinds of physical activities. High torque around the stem axis may contribute to implant loosening. With instrumented hip prostheses the joint force and its direction, the bending moment in the frontal plane and the torque were measured in two patients during upstairs, downstairs and level walking. The data give information on whether or not stairclimbing causes a more severe loading situation for the implants than walking. While going upstairs at normal speed the joint force is 10% higher than during walking at 3 km h-1. Downstairs it increases by 20%. The bending moments change by nearly the same amounts. Upstairs the torsional moment is about twice as high as during slow walking. But walking at 5 km h-1 or slow jogging causes forces and moments of similar magnitudes. Even higher loads were observed when the patients stumbled without falling. Although torque during staircase walking is high, extreme values exclusively during stairclimbing are not confirmed by our data. The torsional moments now observed in vivo are close to or even exceed the experimentally determined limits of the torsional strength of implant fixations, found in the literature. Obviously, torsional moments play an important role for the potential loosening of hip prostheses.
在大多数体育活动中，髋关节假体承受着相当大的力和力矩。假体柄轴周围的高扭矩可能会导致植入物松动。使用装有传感器的髋关节假体，在两名患者上下楼梯和平地行走过程中测量了关节力及其方向、额平面内的弯矩和扭矩。这些数据提供了关于爬楼梯是否比行走对植入物造成更严重负荷情况的信息。以正常速度上楼时，关节力比以3公里/小时的速度行走时高10%。下楼时则增加20%。弯矩的变化量几乎相同。上楼时的扭矩约为慢走时的两倍。但以5公里/小时的速度行走或慢跑时会产生大小相似的力和力矩。当患者绊倒但未摔倒时，观察到的负荷甚至更高。虽然楼梯行走时的扭矩很高，但我们的数据并未证实仅在爬楼梯时会出现极值。目前在体内观察到的扭矩接近甚至超过了文献中实验确定的植入物固定扭转强度极限。显然，扭矩对髋关节假体的潜在松动起着重要作用。
