单髁置换术应用于骨关节炎合并前交叉韧带缺失的三维有限元研究

目的采用有限元方法比较前交叉韧带(anterior cruciate ligament,ACL)完整与缺失的骨关节炎患者单髁关节置换(unicompartmental knee arthroplasty,UKA)术后膝关节生物力学特性,分析ACL缺失对膝关节单髁置换术后的运动和应力的影响。方法根据膝关节CT、MRI图像,建立有限元模型。采用逆向工程技术重建活动衬垫单髁假体,加载入该正常膝关节三维有限元模型。在不同屈膝角度(0°、30°、60°、90°、120°)加载载荷,观察在ACL完整(ACL-intact,ACLI)和缺失(ACL-deficiency,ACLD)情况下,膝关节的最大接触压和位移程度。结果 UKA-ACLI与UKA-ACLD模型在膝关节屈膝各角度,各部位(外侧股骨软骨、胫骨软骨、半月板、股骨假体、胫骨假体、衬垫)最大应力无明显差异,ACLD模型在膝关节屈膝0°和30°位前后位移明显大于ACLI模型,在膝关节屈膝0°位股骨相对内旋减小,在膝关节屈膝30°位股骨相对外旋增加。结论标准位置假体植入情况下,ACL缺失并不会导致UKA术后应力异常增大,会导致在膝关节伸直位时位移增加。

Finite element analysis of unicompartmental knee arthroplasty in anterior cruciate ligament deficiency osteoarthritis patients

Objective To study the biomechanics of the unicompartmental knee arthroplasty in osteoarthritis patients with or without an intact anterior cruciate ligament using finite element analysis. To explore the role of ACL in motion and stress changes of knee after unicompartmental knee arthroplasty. Methods The knee of a healthy adult male volunteer was scanned with computed tomography(CT) and magnetic resonance imaging(MRI). Bone resections and protheses assembling were simulated according to the standard surgical techniques of Oxford Phase-III prostheses, then the three-dimensional solid model of mobile-bearing unicompartmental knee arthroplasty was developed. Five flexion angles (0°,30°,60°,90°,120°) were analyzed. The load distribution, stresses and displacement were calculated and compared. Results The UKA-ACLD model (lateral femoral cartilage, tibial cartilage, lateral meniscus, femoral component, tibial component and bearing) had the similar Von Mises stress with the UKA-ACLI model at five flexion. The UKA-ACLD model had greater anterior- posterior translation compared to the UKA-ACLI model at 0°and 30° of flexion. Conclusion ACLD after UKA has the same contact stresses with that of ACLI. Kinematic differences were found between the deficient and intact knees after mobile UKA, the anteroposterior motion of the ACLD was increased in knee extension position.