Laboratory for Mechanical Systems Engineering, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland.
Biomed Eng Online. 2022 Mar 19;21(1):17. doi: 10.1186/s12938-022-00988-7.
This study aims to analyze the effects of a novel dual-bearing shoulder prosthesis and a conventional reverse shoulder prosthesis on the deltoid and rotator cuff muscle forces for four different arm motions. The dual-bearing prosthesis is a glenoid-sparing joint replacement with a moving center of rotation. It has been developed to treat rotator cuff arthropathy, providing an increased post-operative functionality.
A three-dimensional musculoskeletal OpenSim® model of an upper body, incorporating a natural gleno-humeral joint and a scapula-thoracic joint developed by Blana et al. (J Biomech 41: 1714-1721, 2008), was used as a reference for the natural shoulder. It was modified by integrating first a novel dual-bearing prosthesis, and second, a reverse shoulder prosthesis into the shoulder joint complex. Four different arm motions, namely abduction, scaption, internal and external rotation, were simulated using an inverse kinematics approach. For each of the three models, shoulder muscle forces and joint reaction forces were calculated with a 2 kg weight in the hand.
In general, the maximal shoulder muscle force and joint reaction force values were in a similar range for both prosthesis models during all four motions. The maximal deltoid muscle forces in the model with the dual-bearing prosthesis were 18% lower for abduction and 3% higher for scaption compared to the natural shoulder. The maximal rotator cuff muscle forces in the model with the dual-bearing prosthesis were 36% lower for abduction and 1% higher for scaption compared to the natural shoulder. Although the maximal deltoid muscle forces in the model with the dual-bearing prosthesis in internal and external rotation were 52% and 64% higher, respectively, compared to the natural shoulder, the maximal rotator cuff muscle forces were 27% lower in both motions.
The study shows that the dual-bearing shoulder prosthesis is a feasible option for patients with rotator cuff tear and has a strong potential to be used as secondary as well as primary joint replacement. The study also demonstrates that computer simulations can help to guide the continued optimization of this particular design concept for successful clinical outcomes.
本研究旨在分析新型双轴承肩假体和传统反式肩假体对四种不同手臂运动的三角肌和肩袖肌肉力量的影响。双轴承假体是一种保留关节盂的关节置换术，具有移动的旋转中心。它是为治疗肩袖关节炎而开发的，可提供术后更高的功能。
采用 Blana 等人（J Biomech 41: 1714-1721, 2008）开发的包含自然盂肱关节和肩胛胸关节的三维肌肉骨骼 OpenSim®上身模型作为自然肩部的参考。通过将新型双轴承假体和反式肩假体集成到肩关节复合体中，对其进行了修改。使用逆运动学方法模拟了四种不同的手臂运动，即外展、内收、内旋和外旋。对于每个模型，在手内施加 2kg 重量的情况下计算了肩部肌肉力和关节反作用力。
总体而言，在所有四种运动中，两种假体模型的最大肩部肌肉力和关节反作用力值都在相似范围内。双轴承假体模型的三角肌最大力在外展时降低 18%，在内收时升高 3%，与自然肩部相比。双轴承假体模型的肩袖最大力在外展时降低 36%，在内收时升高 1%，与自然肩部相比。尽管双轴承假体模型在内部和外部旋转时的最大三角肌力分别比自然肩部高 52%和 64%，但在这两种运动中，最大肩袖肌肉力都降低了 27%。
该研究表明，双轴承肩假体是肩袖撕裂患者的可行选择，具有作为二次和原发性关节置换的强大潜力。该研究还表明，计算机模拟可以帮助指导这一特定设计概念的持续优化，以实现成功的临床结果。
