Lenz Mark, Wahl Dieter, Zderic Ivan, Gueorguiev Boyko, Jupiter Jesse B, Perren Stephan M
AO Research Institute Davos, Clavadelerstrasse 8, CH-7270 Davos, Switzerland.
Department of Trauma, Hand and Reconstructive Surgery, University Hospital Jena, Germany.
J Orthop Res. 2016 Jun;34(6):949-52. doi: 10.1002/jor.23108. Epub 2015 Dec 10.
Polyaxial locking screws are increasingly applied in fracture fixation. To investigate the durability of the head-locking mechanism, the removal torque of variable angle (VA) and fixed angle (FA) stainless steel and titanium locking screws was investigated without and after a cyclic loading test. Stainless steel (St) and titanium (Ti) 2.4 mm orthogonally inserted FA screws and 2.4 mm VA screws inserted in different inclinations (0°-15°) (n = 6 per group) were locked at 0.8 Nm. Removal torque was determined without (W) and after (A) cyclic loading (sinusoidal load, 5 Hz, constant amplitude of 25 N, up to 10'000 cycles, or failure). Significant differences in-between the groups were detected by Student's t-test (p < 0.05). Except VA Ti in 0deg and FA, all groups exhibited a drop in removal torque below the insertion torque without and after cyclic testing. The removal torque was (St: FA W:0.81 Nm ± 0.04 A:0.72Nm ± 0.04; VA0deg W:0.73 Nm ± 0.04 A:0.65 Nm ± 0.05; VA15deg W:0.51 Nm ± 0.05 A:0.50 Nm ± 0.08; Ti: FA W:0.82 Nm ± 0.03 A:0.70 Nm ± 0.04; VA0deg W:0.80 Nm ± 0.02 A:0.72 Nm ± 0.05; VA15deg W:0.55 Nm ± 0.03 A:0.54 Nm ± 0.06). In all groups, the removal torque after cyclic testing did not drop below 16% of the removal torque without cyclic testing. No head loosening was observed after cyclic testing. Stainless steel and titanium 2.4 mm fixed and variable angle locking screws provide a stable and lasting head-locking mechanism. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:949-952, 2016.
多轴锁定螺钉在骨折固定中的应用越来越广泛。为了研究头部锁定机制的耐久性，我们对可变角度（VA）和固定角度（FA）的不锈钢和钛合金锁定螺钉在进行循环加载试验前后的拆除扭矩进行了研究。将不锈钢（St）和钛（Ti）材质的2.4毫米正交插入式FA螺钉以及以不同倾斜角度（0°-15°）插入的2.4毫米VA螺钉（每组n = 6）以0.8牛米的扭矩锁定。分别在未进行循环加载（W）以及进行循环加载后（A）（正弦载荷，5赫兹，恒定振幅25牛，最多10000次循环或直至失效）测定拆除扭矩。通过学生t检验检测组间的显著差异（p < 0.05）。除了0度的VA钛合金螺钉和FA螺钉外，所有组在未进行循环测试以及进行循环测试后，拆除扭矩均降至低于插入扭矩。拆除扭矩分别为（St：FA W：0.81牛米±0.04，A：0.72牛米±0.04；VA0度W：0.73牛米±0.04，A：0.65牛米±0.05；VA15度W：0.51牛米±0.05，A：0.50牛米±0.08；Ti：FA W：0.82牛米±0.03，A：0.70牛米±0.04；VA0度W：0.80牛米±0.02，A：0.72牛米±0.05；VA15度W：0.55牛米±0.03，A：0.54牛米±0.06）。在所有组中，循环测试后的拆除扭矩均未降至低于未进行循环测试时拆除扭矩的16%。循环测试后未观察到头部松动。不锈钢和钛合金材质的2.4毫米固定和可变角度锁定螺钉提供了稳定且持久的头部锁定机制。© 2015骨科研究协会。由威利期刊公司出版。《矫形外科学研究》34：949 - 952，2
