Serviço de Ortopedia e Traumatologia Prof. Nova Monteiro, Hospital Municipal Miguel Couto, Rio de Janeiro, RJ, Brazil.
Laboratório de Biomateriais em Ortopedia, Faculdade de Ciências Médicas, Universidade de Campinas (UNICAMP), Campinas, SP, Brazil.
PLoS One. 2019 Jul 30;14(7):e0220523. doi: 10.1371/journal.pone.0220523. eCollection 2019.
The purpose of this study was to evaluate the role of a non-locking plate applied to the anteromedial surface of the proximal humerus on loads at the implant-bone interface of non-locking and locking lateral plate fixation of proximal humeral fractures with a medial gap.
Twenty synthetic humeri models were used. In fifteen, the proximal portion of the humerus was osteotomized to create a two-part surgical neck fracture, with a 10-mm medial gap and a 5-mm lateral gap; five models were controls. In the osteotomized humeri, five models were stabilized with a locking lateral plate (group L), five with a locking lateral plate and an anteromedial non-locking plate (group L+T), and five with a non-locking lateral plate and a non-locking anteromedial plate (group T+T). All humeri were tested under axial loading until catastrophic failure, which was characterized as complete closure of the medial gap. Stiffness was calculated using force vs. displacement curves. The data were analyzed via descriptive and inferential studies, at a 5% significance level.
Statistically significant differences were seen among all the constructions. The combination of a lateral locking plate with an anteromedial non-locking plate (group L+T) was the stiffest construction, while the combination of a non-locking lateral plate with a non-locking anteromedial plate (group T+T) was the least stiff, even in comparison with a single locking lateral plate (p = 0.01). When the two groups which utilized a lateral locking plate (groups L+T and L) were compared, the group with additional anteromedial support demonstrated greater stiffness (p = 0.03), and stiffness values for the control group comprised of intact humeri models were even higher (p = 0.01).
Combining a lateral locking plate with a non-locking anteromedial plate provides a stiffer construction for fixation of unstable two-part proximal humerus fractures with a medial gap. Mechanical benefits of medial support with a second non-locking antero-medial plate seems to be related with better construct stability in terms of strength and fatigue, potentially reducing the risk of varus collapse of the humerus head and fracture healing disturbances.
本研究旨在评估在存在内侧间隙的不稳定二部分肱骨近端骨折中，应用于肱骨近端前内侧表面的非锁定钢板对非锁定和锁定外侧钢板固定的植入物-骨界面负荷的作用。
使用二十个合成肱骨模型。在十五个模型中，肱骨近端被切开以创建两部分外科颈骨折，有 10mm 的内侧间隙和 5mm 的外侧间隙；五个模型为对照组。在切开的肱骨中，五个模型用锁定外侧钢板（组 L）固定，五个模型用锁定外侧钢板和前内侧非锁定钢板（组 L+T）固定，五个模型用非锁定外侧钢板和非锁定前内侧钢板（组 T+T）固定。所有肱骨均在轴向加载下进行测试，直至灾难性失效，其特征为完全关闭内侧间隙。使用力与位移曲线计算刚度。通过描述性和推论性研究分析数据，置信水平为 5%。
所有结构之间均存在统计学显著差异。外侧锁定钢板联合前内侧非锁定钢板（组 L+T）的组合结构最坚固，而外侧非锁定钢板联合前内侧非锁定钢板（组 T+T）的组合结构最不坚固，甚至与单个锁定外侧钢板相比也是如此（p=0.01）。当比较使用外侧锁定钢板的两组（组 L+T 和 L）时，具有额外前内侧支撑的组显示出更高的刚度（p=0.03），而由完整肱骨模型组成的对照组的刚度值甚至更高（p=0.01）。
将外侧锁定钢板与非锁定前内侧钢板相结合，可为存在内侧间隙的不稳定二部分肱骨近端骨折提供更坚固的固定。使用第二个非锁定前内侧钢板进行内侧支撑的机械优势似乎与强度和疲劳方面的更好的结构稳定性有关，从而降低肱骨头内翻塌陷和骨折愈合障碍的风险。
