Sins Lauranne, Tétreault Patrice, Nuño Natalia, Hagemeister Nicola
Laboratoire de recherche en Imagerie et Orthopédie (LIO), CHUM Research Centre (CR-CHUM), Local R11.322, 900 St-Denis Street, Montréal, QC H2X 0A9, Canada e-mail:
Orthopaedics Surgery Department, Local DR-1118-16, Centre Hospitalier de l'Université de Montréal, Notre-Dame Hospital, 1560 rue Sherbrooke, Montréal, QC H2L 4M1, Canada e-mail:
J Biomech Eng. 2016 Dec 1;138(12). doi: 10.1115/1.4034654.
Prosthetic components' mismatch and subscapularis (SC) tear are determining factors for glenoid failure complication in nonconforming total shoulder arthroplasty (NC-TSA). Risk factors are linked to glenoid prosthetic loading. However, the mechanisms underlying the clinical observations remain unclear. This study assessed the combined impact of mismatch and subscapularis tear on glenoid loading. It was assumed that adequate glenoid loading was associated with minimal, but non-null, humeral head translations and contact pressure, as well as with maximal glenoid contact area, and that the center of pressure (COP) on the glenoid would have a centered displacement pattern. A numerical model was used to achieve two objectives. The first was to verify whether an optimum mismatch existed, for which failure risk would be minimal. The second was to explore the effect of subscapularis tear on the position of applied forces on the glenoid. A shoulder AnyBody musculoskeletal model was adapted to the arthroplasty context by introducing humeral head translations and contact between implants. Ten simulations were computed to compare combinations of varying mismatches (1.4 mm, 3.4 mm, 6.4 mm, 8.6 mm, and 9 mm) with two shoulder conditions (intact-muscle or subscapularis tear). Humeral head translations, center-of-pressure, contact area, contact pressure, and glenohumeral joint contact forces were numerically estimated. Mismatches between 3.4 mm and 6.4 mm were associated with the most minimal humeral translations and contact pressure, as well as with maximal contact area. Center of pressure displacement pattern differed according to shoulder condition, with an outward anterior tendency in presence of tear.
假体组件不匹配和肩胛下肌（SC）撕裂是非顺应性全肩关节置换术（NC-TSA）中导致关节盂失败并发症的决定性因素。风险因素与关节盂假体负荷有关。然而，这些临床观察结果背后的机制仍不清楚。本研究评估了不匹配和肩胛下肌撕裂对关节盂负荷的综合影响。假设适当的关节盂负荷与最小但非零的肱骨头平移和接触压力相关，以及与最大的关节盂接触面积相关，并且关节盂上的压力中心（COP）将具有居中的位移模式。使用数值模型来实现两个目标。第一个目标是验证是否存在最佳不匹配，即失败风险最小的情况。第二个目标是探讨肩胛下肌撕裂对关节盂上作用力位置的影响。通过引入肱骨头平移和植入物之间的接触，将一个肩部AnyBody肌肉骨骼模型应用于关节置换术的背景。计算了十次模拟，以比较不同不匹配（1.4毫米、3.4毫米、6.4毫米、8.6毫米和9毫米）与两种肩部状况（肌肉完整或肩胛下肌撕裂）的组合。通过数值估计肱骨头平移、压力中心、接触面积、接触压力和盂肱关节接触力。3.4毫米至6.4毫米之间的不匹配与最小的肱骨头平移和接触压力以及最大的接触面积相关。压力中心位移模式根据肩部状况而不同，在存在撕裂时具有向前外侧的趋势。
