Schneider E, Michel M C, Genge M, Zuber K, Ganz R, Perren S M
M.E. Mueller-Institute for Biomechanics, University of Bern, Murtenstrasse 30, CH-3010, Bern, Switzerland.
J Biomech. 2001 Jul;34(7):849-57. doi: 10.1016/s0021-9290(01)00037-9.
The form and function of the musculo-skeletal system is closely related to the forces acting in its components. Significant forces are present in the long bones, but their magnitudes have so far only been estimated from mathematical models. Fracture fixation by means of metal implants provides an opportunity to measure the implant-born forces and to estimate the long bone forces before healing occurs. The load changes during fracture healing may provide additional information. Therefore, a telemetrized, interlocking femoral nail for wireless transmission of forces and moments acting across the fracture site was developed. The design was based on the geometry and material of a 16 mm AO nail with a circular, closed cross-section allowing full protection of the electronic circuits from the body fluids. After careful testing, it was implanted in a 33-year-old patient who had sustained a multifragmentary fracture of the left femur. Measurements at a rate of approx. 0.4 Hz were performed in different patient postures between the 2nd and 26th postoperative week. Significant axial forces and bending moments were measured during several activities such as sitting, unsupported leg elevation and partial weight bearing in a standing position. Forces orthogonal to the nail axis remained small. The reductions of the implant loads due to fracture consolidation were in the order of 50%. Dynamization of the nail did not change the forces. Even though the telemetry system did not allow for dynamic measurements and the results presented here provide data from one subject only, the new information will be useful with respect to implant design, biomechanics of fracture fixation and evaluation of healing progression.
肌肉骨骼系统的形态和功能与其各组成部分所受的力密切相关。长骨中存在显著的力，但其大小迄今仅通过数学模型进行估算。借助金属植入物进行骨折固定为测量植入物所承受的力以及在骨折愈合前估算长骨所受的力提供了机会。骨折愈合过程中的负荷变化可能会提供更多信息。因此，研发了一种用于无线传输作用于骨折部位的力和力矩的遥测式交锁股骨髓内钉。该设计基于一根16毫米AO髓内钉的几何形状和材料，其横截面为圆形且封闭，能使电子电路完全免受体液影响。经过仔细测试后，将其植入一名33岁的左股骨多段骨折患者体内。在术后第2周和第26周之间，以约0.4赫兹 的速率对不同患者姿势进行了测量。在诸如坐、无支撑抬腿和站立位部分负重等几种活动过程中测量到了显著的轴向力和弯矩。与髓内钉轴线正交的力仍然较小。由于骨折愈合，植入物负荷的降低幅度约为50%。髓内钉动力化并未改变力的大小。尽管遥测系统不允许进行动态测量，且此处呈现的结果仅来自一名受试者，但这些新信息对于植入物设计、骨折固定生物力学以及愈合进程评估将是有用的。
