Garcés Gerardo L, Martel Oscar, Yánez Alejandro, Cuadrado Alberto
Department of Medical and Surgical Sciences, University of Las Palmas de Gran Canaria, Edificio de Ciencias de la Salud, Campus Universitario de San Cristobal, Trasera del Hospital InsularC/ Doctor Pasteur s/n, 35016, Las Palmas, Spain.
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Edificio de Ingenierías, Campus de Tafira, 35017, Las Palmas, Spain.
BMC Musculoskelet Disord. 2019 Feb 8;20(1):60. doi: 10.1186/s12891-019-2435-1.
The purpose of this study was to compare the biomechanical behaviour of two bioabsorbable interference screws with different geometries.
Two different pitch (2.5 and 5 mm) bioabsorbable interference screws, both 9 × 30 mm, were tested. Tests were performed with forty bovine digital extensor tendons and skeletally mature porcine tibiae. Two protocols of cyclic tests at 1 Hz were performed: 1000 cycles from 50 to 250 N, and 5000 cycles from 100 to 300 N (n = 10 for each type of test and screw). After the cyclic loading, a final ramp displacement until failure at 0.5 mm/s was applied.
The stiffness after the cyclic phase of the tests was not statistically different between the two screws (1000th cycle: 2.5 mm pitch 280.3 ± 56.4 N/mm, 5 mm pitch 275.2 ± 65.0 N/mm, P = .965; 5000th cycle: 2.5 mm pitch 281.3 ± 66.4 N/mm, 5 mm pitch 286.1 ± 79.4 N/mm, P = .814). The yield load was not significantly different between the screws (1000 cycle tests: 2.5 mm pitch 482.2 ± 120.2 N, 5 mm pitch 495.9 ± 131.3 N, P = .508; 5000 cycle tests: 2.5 mm pitch 476.4 ± 65.3 N, 5 mm pitch 494.3 ± 39.2 N, P = .391). No correlation was found between the insertion torque and yield load (1000 cycle tests, R = 0.013; 5000 cycle tests, R = 0.006).
The pitch of bioabsorbable interference screws does not seem to affect fixation strength. Also, the authors recommend not to use insertion torque alone to estimate the fixation strength.
本研究的目的是比较两种不同几何形状的可吸收加压螺钉的生物力学行为。
测试了两种不同螺距（2.5和5毫米）的9×30毫米可吸收加压螺钉。对40条牛趾背伸肌腱和骨骼成熟的猪胫骨进行测试。进行了两种1赫兹的循环测试方案：从50至250牛进行1000次循环，以及从100至300牛进行5000次循环（每种测试类型和螺钉各n = 10）。循环加载后，以0.5毫米/秒的速度施加最终斜坡位移直至失效。
两种螺钉在测试循环阶段后的刚度无统计学差异（第1000次循环：2.5毫米螺距280.3±56.4牛/毫米，5毫米螺距275.2±65.0牛/毫米，P = 0.965；第5000次循环：2.5毫米螺距281.3±66.4牛/毫米，5毫米螺距286.1±79.4牛/毫米，P = 0.814）。螺钉之间的屈服载荷无显著差异（1000次循环测试：2.5毫米螺距482.2±120.2牛，5毫米螺距495.9±131.3牛，P = 0.508；5000次循环测试：2.5毫米螺距476.4±65.3牛，5毫米螺距494.3±39.2牛，P = 0.391）。未发现插入扭矩与屈服载荷之间存在相关性（1000次循环测试，R = 0.013；5000次循环测试，R = 0.006）。
可吸收加压螺钉的螺距似乎不影响固定强度。此外，作者建议不要仅使用插入扭矩来估计固定强度。
