Buttermann G R, Kahmann R D, Lewis J L, Bradford D S
Department of Orthopaedic Surgery, University of Minnesota, Minneapolis 55455.
J Biomech Eng. 1991 Nov;113(4):375-86. doi: 10.1115/1.2895415.
A technique is described for measuring load magnitude and resultant load contact location in the facet joint in response to applied loads and moments, and the technique applied to the canine lumbar spine motion segment. Due to the cantilever beam geometry of the cranial articular process, facet joint loads result in surface strains on the lateral aspect of the cranial articular process. Strains were quantified by four strain gages cemented to the bony surface of the process. Strain measured at any one gage depended on the loading site on the articular surface of the caudal facet and on the magnitude of the facet load. Determination of facet loads during in vitro motion segment testing required calibration of the strains to known loads of various magnitudes applied to multiple sites on the caudal facet. The technique is described in detail, including placement of the strain gages. There is good repeatability of strains to applied facet loads and the strains appear independent of load distribution area. Error in the technique depends on the location of the applied facet loads, but is only significant in nonphysiologic locations. The technique was validated by two independent methods in axial torsion. Application of the technique to five in vitro canine L2-3 motion segments testing resulted in facet loads (in newtons, N) of 74+ / -23 N (mean + / -STD) in 2 newton-meter, Nm, extension, to unloaded in flexion. Lateral bending resulted in loads in the right facet of 40+ / -32 N for 1 Nm right lateral bending and 54+ / -29 N for 1 Nm left lateral bending. 4 Nm Torsion with and without 100 N axial compression resulted in facet loads of 92+ / -27 N and 69+ / -19 N, respectively. The technique is applicable to dynamic and in vivo studies.
本文描述了一种用于测量小关节在施加负荷和力矩时的负荷大小及合成负荷接触位置的技术，并将该技术应用于犬腰椎运动节段。由于颅侧关节突的悬臂梁几何结构，小关节负荷会导致颅侧关节突外侧表面产生应变。通过粘贴在关节突骨表面的四个应变片对应变进行量化。在任何一个应变片处测得的应变取决于尾侧小关节关节面的加载部位以及小关节负荷的大小。在体外运动节段测试过程中确定小关节负荷需要将应变校准到施加于尾侧小关节多个部位的不同大小的已知负荷。详细描述了该技术，包括应变片的放置。对应变片施加小关节负荷时应变具有良好的可重复性，并且应变似乎与负荷分布区域无关。该技术的误差取决于所施加小关节负荷的位置，但仅在非生理位置时才显著。该技术在轴向扭转中通过两种独立方法得到验证。将该技术应用于五个体外犬L2-3运动节段测试，在2牛顿·米（Nm）伸展至屈曲无负荷状态下，小关节负荷（以牛顿，N为单位）为74±23 N（平均值±标准差）。在1 Nm右侧侧弯时，右侧小关节负荷为40±32 N，在1 Nm左侧侧弯时为54±29 N。在有和没有100 N轴向压缩的情况下进行4 Nm扭转时，小关节负荷分别为92±27 N和69±19 N。该技术适用于动态和体内研究。
