Nalbone L, Adelfio R, D'Arienzo M, Ingrassia T, Nigrelli V, Zabbara F, Paladini P, Campi F, Pellegrini A, Porcellini G
Clinica Ortopedica e Traumatologica del Policlinico, 'Paolo Giaccone' Università degli Studi di Palermo, Palermo, Italy.
Musculoskelet Surg. 2014 Aug;98(2):135-42. doi: 10.1007/s12306-013-0274-z. Epub 2013 May 30.
Total reverse shoulder arthroplasty is becoming more and more the standard therapeutic practice for glenohumeral arthropathy with massive lesions of the rotator cuff. The biomechanical principle of this prosthesis is represented by the reversion of the normal anatomy of the shoulder joint. This non-anatomical prosthesis leads to a medialization of the rotation centre of the glenohumeral joint and also to a distalization of the humeral head. All that causes a deltoid tension increasing so allowing a larger abduction of the arm. Main complications of the reverse shoulder prosthesis are due to the joint instability, the scapular notching and the wear of the polyethylene insert.
The main goal of the present work is to study the effect of the positioning of the humeral component on the intrinsic stability of the reverse shoulder prosthesis. In particular, through finite element method simulations, the variation of the stability ratio of the shoulder joint has been calculated for both vertical and horizontal dislocating loads depending on the humeral stem version angle. Moreover, in order to estimate the wear of the polyethylene cup, some analyses have been developed to calculate the pressures on the polyethylene insert.
The obtained results demonstrate the dislocation of a shoulder prosthesis and the wear of the polyethylene insert can be prevented or limited by conveniently varying the version angle of the humeral component.
对于伴有肩袖巨大损伤的盂肱关节病，全肩关节置换术越来越成为标准的治疗方法。这种假体的生物力学原理表现为肩关节正常解剖结构的反转。这种非解剖型假体导致盂肱关节旋转中心向内侧移位，同时肱骨头向远侧移位。所有这些都会导致三角肌张力增加，从而使手臂能够更大程度地外展。反肩关节假体的主要并发症是关节不稳定、肩胛切迹和聚乙烯衬垫磨损。
本研究的主要目的是研究肱骨部件的定位对反肩关节假体固有稳定性的影响。特别是，通过有限元方法模拟，根据肱骨干旋转角度，计算了垂直和水平脱位载荷下肩关节稳定性比值的变化。此外，为了估计聚乙烯杯的磨损情况，还进行了一些分析来计算聚乙烯衬垫上的压力。
所得结果表明，通过适当改变肱骨部件的旋转角度，可以防止或限制肩关节假体的脱位和聚乙烯衬垫的磨损。
