Shiley Center for Orthopaedic Research and Education at Scripps Clinic, La Jolla, CA, USA.
Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, CA, USA.
J Shoulder Elbow Surg. 2014 Mar;23(3):347-54. doi: 10.1016/j.jse.2013.06.008. Epub 2013 Sep 3.
This study undertook a computational analysis of a wedged glenoid component for correction of retroverted glenoid arthritic deformity to determine whether a wedge-shaped glenoid component design with a built-in correction for version reduces excessive stresses in the implant, cement, and glenoid bone. Recommendations for correcting retroversion deformity are asymmetric reaming of the anterior glenoid, bone grafting of the posterior glenoid, or a glenoid component with posterior augmentation. Eccentric reaming has the disadvantages of removing normal bone, reducing structural support for the glenoid component, and increasing the risk of bone perforation by the fixation pegs. Bone grafting to correct retroverted deformity does not consistently generate successful results.
Finite element models of 2 scapulae models representing a normal and an arthritic retroverted glenoid were implanted with a standard glenoid component (in retroversion or neutral alignment) or a wedged component. Glenohumeral forces representing in vivo loading were applied and stresses and strains computed in the bone, cement, and glenoid component.
The retroverted glenoid components generated the highest compressive stresses and decreased cyclic fatigue life predictions for trabecular bone. Correction of retroversion by the wedged glenoid component significantly decreased stresses and predicted greater bone fatigue life. The cement volume estimated to survive 10 million cycles was the lowest for the retroverted components and the highest for neutrally implanted glenoid components and for wedged components.
A wedged glenoid implant is a viable option to correct severe arthritic retroversion, reducing the need for eccentric reaming and the risk for implant failure.
本研究通过计算分析楔形肩胛盂假体来矫正后倾的肩胛盂关节炎畸形，以确定是否楔形肩胛盂假体设计与内置的矫正版本减少了植入物、水泥和肩胛盂骨的过度应力。矫正后倾畸形的建议包括前肩胛盂的不对称扩孔、后肩胛盂的植骨或带有后增强的肩胛盂假体。偏心扩孔具有去除正常骨、减少对肩胛盂假体的结构支撑以及增加固定钉穿透骨的风险的缺点。为了矫正后倾畸形而进行植骨并不能始终产生成功的结果。
用标准的肩胛盂假体（后倾或中立对齐）或楔形假体植入代表正常和关节炎后倾的两个肩胛盂模型的有限元模型。施加代表体内负荷的盂肱关节力，并计算骨、水泥和肩胛盂假体中的应力和应变。
后倾的肩胛盂假体产生了最高的压缩应力，并降低了小梁骨的循环疲劳寿命预测。楔形肩胛盂假体矫正后倾显著降低了应力并预测了更大的骨疲劳寿命。估计能存活 1000 万次循环的水泥体积对于后倾组件最低，对于中立植入的肩胛盂组件和楔形组件最高。
楔形肩胛盂假体是矫正严重关节炎后倾的可行选择，可以减少偏心扩孔的需要和植入物失效的风险。
