Jansson V
Orthopädische Klinik, Klinikum Grosshadern, Ludwig-Maximilians-Universität, München.
Z Orthop Ihre Grenzgeb. 1990 Nov-Dec;128(6):606-11. doi: 10.1055/s-2008-1040012.
Recent reports of fractures of the tibial component of total knee prostheses have raised the question of their long term endurance. The mechanical load for the tibial plateau consists of the two forces deriving from the condyles of the femur. As the collateral and crucial ligaments always allow a little play for the femoral and tibial components, the location of the load of the condyles on the tibial plateau is either on the medial or lateral side depending on minor disturbances during gait. For a tibial plateau with only little medullary anchorage this load pattern means an alternating induction of compression and tensile stresses for the underlying bone. This alternating stress pattern is discussed as a possible mechanism of aseptic loosening of such tibial components. For two cases of such aseptic loosening and consecutive fracture of the tibial plateau of a metal backed unconstrained sledge knee prosthesis the radiologic findings are demonstrated and correlated to the biomechanical mechanisms described. It is demonstrated that the structural endurance of the tibial plateau does not withstand the mechanical stresses of such a situation of aseptic loosening. In these cases further loosening or fracture of the tibial plateau results.
近期关于全膝关节假体胫骨部件骨折的报道引发了其长期耐用性的问题。胫骨平台的机械负荷由来自股骨髁的两种力组成。由于侧副韧带和关键韧带总是允许股骨和胫骨部件有一点活动空间，髁在胫骨平台上的负荷位置取决于步态中的微小干扰，位于内侧或外侧。对于髓内固定较少的胫骨平台，这种负荷模式意味着其下方骨骼会交替受到压缩应力和拉伸应力。这种交替应力模式被认为是此类胫骨部件无菌性松动的一种可能机制。对于两例金属背衬无约束雪橇式膝关节假体胫骨平台无菌性松动并连续骨折的病例，展示了其放射学表现，并与所描述的生物力学机制相关联。结果表明，胫骨平台的结构耐久性无法承受这种无菌性松动情况下的机械应力。在这些病例中，胫骨平台会进一步松动或骨折。
