Centre for Biomedical Engineering, Institute of Orthopaedics and Musculoskeletal Science, University College London, Stanmore, HA7 4LP, UK.
J Orthop Res. 2012 Jun;30(6):998-1003. doi: 10.1002/jor.22015. Epub 2011 Nov 16.
Loosening of glenoid components in TSA is a main cause of failure. In reverse anatomy TSA designs used for unstable joints, fixation is particularly demanding. Strains developed around the glenoid rim of biomechanical sawbone scapulae implanted with (a) the original fixed-fulcrum Bayley-Walker glenoid prosthesis in current clinical use, and (b) a revised version with conical cross-section, were compared. The conical shape of the revised design was hypothesized to produce greater strains in the glenoid rim than the original tapered screw design. The 2D strain field at three accessible locations around the rim of each scapula was measured with three-element rosette strain gauges for two types of simulated cancellous bone fill under applied physiologically relevant loads. The average strain energy densities around the rim for the conical design were greater than for the original design by a factor of 1.55-2.25 for all loading conditions. Results indicate that a significantly greater proportion of load was directed toward cortical bone in the conical design, thus promoting cortical bone loading.
在 TSA 中，肩胛盂部件松动是失败的主要原因。在用于不稳定关节的反向解剖 TSA 设计中，固定的要求特别高。在植入（a）当前临床使用的原始固定支点 Bayley-Walker 肩胛盂假体和（b）具有锥形横截面的改良版本的生物力学锯肩胛骨的肩胛盂边缘周围，比较了发展的应变。假设改良设计的锥形形状会在肩胛盂边缘产生比原始锥形螺钉设计更大的应变。在每个肩胛骨边缘的三个可访问位置，使用三元件花键应变计测量二维应变场，模拟在施加生理相关载荷下两种类型的松质骨填充。对于所有加载条件，锥形设计的边缘周围的平均应变能密度比原始设计大 1.55-2.25 倍。结果表明，在锥形设计中，更大比例的载荷被引导到皮质骨，从而促进了皮质骨的载荷。
