膝关节置换术后长期胫骨近端力学性能的预测

目的 分 析 膝 关 节 单 髁 置 换 术 ( unicompartmental knee arthroplasty, UKA) 和 全 膝 置 换 术 ( total knee arthroplasty, TKA)后长期胫骨近端力学性能的变化,探究 UKA 和 TKA 的失效原因。 方法 建立健康、UKA、TKA胫骨近端有限元模型,利用 Wolff 骨重建理论结合有限元法预测胫骨近端的密度分布和应力分布。 结果 UKA 外侧踝平均应力基本不变,但呈增大趋势,平均密度增加 2%,内侧踝平均密度减小 13%,平均应力均减少 11%。 TKA外侧踝平均密度减少 1. 5%,平均应力减少 14%,内侧踝平均密度减少 1. 4%,平均应力减少 19%,假体末端平均密度增加 10%,平均应力增加 15%。 结论 UKA、TKA 假体的植入会造成应力遮挡现象,可能是产生术后假体松动的主要原因。 TKA 假体末端应力增大,可能导致 TKA 的失效。 UKA 非置换侧平均应力随着骨重建的进行不断增大,可能就导致 UKA 中远期对侧骨关节炎恶化。 研究结果可以为降低 UKA、TKA 并发症发生概率提供数据支持。

Long-Term Mechanical Property Prediction of the Proximal Tibia after Knee Arthroplasty

Objective To study the short-term variation patterns of graft viscosity after anterior cruciate ligament reconstruction (ACLR) surgery. Methods Six male New Zealand rabbits were selected. The ACLR animal model of unilateral knee was made with Achilles tendon as the graft. The experimental rabbits were euthanized 15 days after ACLR surgery, with removal of the graft, healthy anterior cruciate ligament (ACL) and Achilles tendon. The cross-sectional area and viscosity coefficient of the graft were measured, and the creep experiments were carried out under equilibrium conditions of 0.1 MPa and 1 MPa, respectively. The viscosity coefficent was calculated. Variation patterns of graft viscosity were summarize. The grafts were compared with healthy ACL. Results The cross-sectional area of the graft increased slowly within 15 days after ACLR surgery. The viscosity of ACL and graft changed nonlinearly. The viscosity coefficient was quite different under different stresses. The viscosity coefficient of the graft decreased with the time after ACLR surgery, which was more obviously under the condition of low stress. Conclusions The results are helpful to guide the implementation of early postoperative rehabilitation plan after ACLR surgery .