Laboratory of Biomechanics and Implant Research, Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany.
Clinic for Orthopedics and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany.
J Shoulder Elbow Surg. 2018 Sep;27(9):1679-1685. doi: 10.1016/j.jse.2018.02.063. Epub 2018 Apr 23.
Despite the positive results in total shoulder arthroplasties (TSAs), a higher revision rate is documented compared with total hip and knee replacements. Wear is the possible main cause of TSA failure in the long-term. This study investigated the effect of joint kinematics and the influence of the rotator cuff on the polyethylene wear performance in an anatomic TSA.
Lifting a load of 2 kg with an abduction/adduction of 0° to 90° was simulated for 2 × 10 cycles as a primary motion using a fully kinematic joint simulator. A combined rotation in anteversion-retroversion of ±5° and ±10° was also simulated. The force in the superior-inferior direction and the axial joint compression were applied under force control based on in vivo data of the shoulder. A soft tissue restraint model was used to simulate an intact and an insufficient rotator cuff.
The highest wear rate in the intact rotator cuff group was 58.90 ± 1.20 mg/10 cycles with a combined rotation of ±10°. When an insufficient rotator cuff was simulated, the highest polyethylene wear rate determined was 79.67 ± 4.18 mg/10 cycles.
This study confirms a high dependency of the polyethylene wear behavior and dimension on the joint kinematics in total shoulder replacement. This can be explained by an increasing cross-shear stress on the polyethylene component. The results obtained indicate that additional combined kinematics are an indispensable part of wear tests on anatomic shoulder replacements.
尽管全肩关节置换术（TSA）取得了积极的结果，但与全髋关节和膝关节置换术相比，其翻修率更高。磨损是 TSA 长期失效的可能主要原因。本研究调查了关节运动学的影响以及肩袖对解剖型 TSA 中聚乙烯磨损性能的影响。
使用全运动关节模拟器模拟以 0°至 90°的外展/内收进行 2×10 次循环的 2kg 负载提升作为主要运动。还模拟了±5°和±10°的前旋/后旋的组合旋转。根据肩部的体内数据，在力控制下施加上下方向的力和轴向关节压缩。使用软组织约束模型模拟完整和不完整的肩袖。
在完整肩袖组中，最高磨损率为 58.90±1.20mg/10 循环，组合旋转为±10°。当模拟不完整的肩袖时，确定的最高聚乙烯磨损率为 79.67±4.18mg/10 循环。
本研究证实了全肩关节置换中聚乙烯磨损行为和尺寸对关节运动学的高度依赖性。这可以通过聚乙烯组件上的交叉剪切应力增加来解释。所得结果表明，解剖型肩部置换的磨损试验中，附加的组合运动学是不可或缺的一部分。
