Roberts Jason W, Grindel Steven I, Rebholz Brandon, Wang Mei
Department of Orthopaedic Surgery, Medical College of Wisconsin, Milwaukee, WI 53226-0099, USA.
J Hand Surg Am. 2007 Sep;32(7):971-5. doi: 10.1016/j.jhsa.2007.05.019.
Compression plating is a commonly accepted technique for treating diaphyseal forearm fractures. The purpose of this study was to evaluate the stabilizing effects of two hybrid fixations that replace the end screws of a locked unicortical fixation with bicortical (locked or unlocked) screws and to compare these hybrid fixations to an unlocked bicortical fixation.
Sixteen composite radius sawbones were equally divided into 4 groups. We performed a midshaft osteotomy and plate fixation on the volar surface with 1 of 4 different constructs: 3 unlocked bicortical screws on each side (unlocked bicortical), 3 locked unicortical screws on each side (locked unicortical), or with 2 unicortical locked screws near the fracture and 1 bicortical unlocked (unlocked hybrid) or locked (locked hybrid) screw distant from the fracture on each end (LCP system, Synthes USA, Paoli, PA). Specimens were tested in nondestructive 4-point bending and torsion on a servo-hydraulic material testing system. The construct stiffness was obtained from the linear portion of the load-displacement curves after 3 cycles of preconditioning. The results from all groups were compared using analysis of variance and post hoc Bonferroni tests.
Under torsional loads, replacing the end screws of a locked unicortical configuration with bicortical screws significantly improved the construct stiffness: 57.6% increase for the locked screws and 51.6% increase for the unlocked. In anteroposterior (AP) bending, the highest improvement over the locked unicortical configuration came from the locked hybrid constructs (42.9% increase). When compared with the unlocked bicortical configuration, both hybrid constructs provide equivalent stability in torsion but superior stability in AP bending.
Replacing a single set of unicortical locked screws with locked or unlocked bicortical screws distant from the fracture site improves torsional stability of the construct by more than 50%, giving stability equal to standard unlocked plating. The hybrid fixation, however, with locked bicortical end screws has the best stability in AP bending.
加压钢板内固定术是治疗尺骨干骨折普遍认可的技术。本研究旨在评估两种混合固定方式（用双皮质（锁定或非锁定）螺钉替代锁定单皮质固定的端螺钉）的稳定效果，并将这些混合固定方式与非锁定双皮质固定进行比较。
将16个合成桡骨锯骨标本平均分为4组。我们在掌侧进行骨干截骨并用以下4种不同结构之一进行钢板固定：两侧各3枚非锁定双皮质螺钉（非锁定双皮质）、两侧各3枚锁定单皮质螺钉（锁定单皮质），或在骨折部位附近用2枚单皮质锁定螺钉，两端各用1枚远离骨折部位的非锁定（非锁定混合）或锁定（锁定混合）双皮质螺钉（LCP系统，美国辛迪思公司，宾夕法尼亚州波利）。在伺服液压材料测试系统上对标本进行无损四点弯曲和扭转试验。在进行3个循环的预处理后，从载荷-位移曲线的线性部分获得结构刚度。使用方差分析和事后邦费罗尼检验比较所有组的结果。
在扭转载荷下，用双皮质螺钉替代锁定单皮质结构的端螺钉可显著提高结构刚度：锁定螺钉提高57.6%，非锁定螺钉提高51.6%。在前后（AP）弯曲中，相对于锁定单皮质结构，最大的改善来自锁定混合结构（提高42.9%）。与非锁定双皮质结构相比，两种混合结构在扭转时提供同等稳定性，但在AP弯曲时具有更好的稳定性。
用远离骨折部位的锁定或非锁定双皮质螺钉替代一组单皮质锁定螺钉可使结构的扭转稳定性提高50%以上，其稳定性与标准非锁定钢板固定相当。然而，带有锁定双皮质端螺钉的混合固定在AP弯曲中具有最佳稳定性。
