单髁置换术后胫骨平台近端愈合前后的生物力学研究

Biomechanical Study of Tibial Plateau Proximal Before and After Healing After Unicompartmental Knee Arthroplasty

研究单间室膝关节置换术后胫骨平台近端愈合前后的生物力学规律,探讨临床上胫骨平台近端术后骨折及疼痛机理等并发症的力学机制。根据单髁手术技术,规划3种不同胫骨切割面模型:锐角切割模型,过切割模型,圆角优化的切割模型,分别研究单髁置换术后,在即刻稳定期(愈合前)与长期稳定期(愈合后),胫骨近端在轴向加载条件下的应力-应变分布。相对于手术正常切割的锐角模型,胫骨切割面过切时,最大主应力增加了2.5倍。切割面拐角处倒圆后,相对于过切模型,最大主应力降低了73.8%,相对于锐角模型,最大主应力降低了35%.在即刻稳定期,过切模型的切割面拐角处最小主微应变较锐角模型增加了65%,圆角模型的最小主微应变较锐角模型降低了23.6%.长期稳定后,圆角模型的微应变值均低于其余两个模型的微应变值。术中过切失误会大大增加胫骨近端的应力与微应变,削弱胫骨平台的支撑能力,将增加骨折的风险。术中圆角切割模型可明显降低胫骨平台近端的应力-应变分布,且能避免术中过切。同时,也为临床中单髁术后胫骨平台近端骨折及术后疼痛并发症的机理探讨提供一定的理论依据。研究结果对单髁置换术及临床应用具有实际意义。

The changes of stress and strain in the proximal end of the tibial plateau proximal before and after healing after unicompartmental knee arthroplasty(UKA)were studied,and the mechanical mechanism of postoperative fracture and pain mechanism in the proximal tibial plateau was explored.According to UKA surgery technique,three different tibia cutting surface models were planned:acute angle cutting model,over-cutting model,and rounded-optimized cutting model.After UKA,in the immediate stable and long-term stable period,the stress-strain distribution of the proximal end under axial loading conditions was investigared.The maximum principal stress increased by a factor of 2.5 when the humeral cut surface was overcut relative to the acute angle model of normal surgical cutting.After rounding at the corner of the cutting surface,the maximum principal stress was reduced by 73.8%compared to the overcutting model,and reduced by 35%compared to the acute angle model.In the stable period,the minimum principal strain at the corner of the cut surface of the overcut model was increased by 65%compared with the acute angle model,and the minimum principal strain of the fillet model was reduced by 23.6%compared with the acute angle model.After long-term stability,the strain value of the fillet model was lower than the strain values of the other two models.Conclusion:Owing to intraoperative over-cutting,unicompartmental knee arthroplasty greatly increased the stress and strain at the proximal end of the tibia,weakened the support capacity of the tibial plateau,and increased the risk of fracture.Intraoperative fillet cutting model significantly reduced the stress and strain distribution at the proximal end of the tibial plateau,and avoided overcutting during the operation.This research provides a certain theoretical basis for the clinical investigation of the mechanism of proximal tibial plateau fracture and postoperative pain complications after unicompartmental knee arthroplasty.The results of this study have practical significance for unicompartmental knee arthroplasty and its clinical application.