目的 比较长型PHILOS接骨板（Synthes公司, 瑞士）扭转成螺旋形前后的生物力学特性，为临床治疗肱骨中上段骨折提供生物力学依据。方法 12例Synbone人工骨（SYNBONE公司，瑞士）的右侧肱骨平均分为两组，对照组（n=6）采用10孔的长型PHILOS接骨板固定，实验组（n=6）采用相同的接骨板扭转成螺旋形后固定。肱骨中上段骨折造模后，利用万能力学试验机分别检测并比较两组接骨板固定后的整体构件在轴向拉伸和压缩、同向和反向扭转、前后及内外向三点弯曲6种加载方式下的生物力学特性。结果 在100~500 N拉伸和压缩载荷下，实验组骨折断端位移分别较对照组增加约95%和58%；在0.6~3 N?m反向扭矩下，实验组扭转角度始终明显小于对照组，减少幅度达到55%~64%；在0.6 ~3 N?m的同向扭矩和1.5 ~7.5 N?m的前后向弯矩下，实验组的扭转角度和桡度均大于对照组，差异有显著性意义（P＜0.05）；当内外向弯矩为1.5、3 N?m时，实验组与对照组的桡度差别无显著性意义（P＞0.05），而内外向弯矩为4.5、6、7.5 N?m时，实验组的桡度较对照组小20%~30%。实验组与对照组构件相比，拉伸和压缩刚度分别低49%和36%，同向和反向扭转刚度分别低19%和高150%，内外向和前后向弯曲刚度分别高18%和低70%，差异均有显著性意义（P＜0.05）。结论 长型PHILOS接骨板扭转成螺旋形后固定肱骨中上段骨折的总体力学性能有所改善，可以满足临床对该类骨折的手术固定和术后康复需要。结合微创手术的优势，该技术有望在临床得到广泛应用。
Objective To compare biomechanical properties of the helical and straight long PHILOS (proximal humerus internal locking system) plates (Synthes Inc., Switzerland), so as to provide some biomechanical evidence for treating proximal metaphyseal-diaphyseal humeral shaft fractures in clinic. Methods Twelve Synbone artificial bones of right humerus (SYNBONE Inc., Switzerland) were divided into two groups. In control group (n=6), the humerus was fixed with the 10 hole long straight PHILOS plate, while in experimental group (n=6), the humerus was fixed with the same long PHILOS plate which was precontoured for moulding (i.e. helical PHILOS plate). After the proximal metaphyseal-diaphyseal humeral shaft fractures were made in all artificial bones, the biomechanical properties of the specimens in two groups under 6 loading modes (i.e., axial tension and compression, torsion in the same and reverse direction, medial-lateral and anterior-posterior three-point bending) were tested en bloc and compared. ResultsCompare with control group, under 100-500 N tensile and compressive loads, the axial displacement at the fractured end in experimental group increased by about 95% and 58%, respectively. Under 0.6-3 N?m torsional moment in reversed direction, the tensional angle in experimental group was obviously smaller than that in control group, with a decrease of 55%-64%. Under medial-lateral bending moment of 1.5 and 3 N?m, no significant difference was found in deflection of the experiment and control group, while under medial-lateral bending moment of 4.5, 6 and 7.5 N?m, the deflection in experimental group decreased by 20% 30% as compared to control group. Under 0.6-3 N?m torsional moment in the same direction and 1.5-7.5 N?m anterior-posterior bending moment, both the torsional angle and the deflection in experimental group were larger than those in control group, with a significant difference (P＜0.05). Compared with control group, the tensile stiffness and compressive stiffness decreased by 49% and 36%, the torsional stiffness in the same direction decreased by 19% and that in reversed direction increased by 150%, three-point bending stiffness in medial lateral direction increased by 18% and that in anterior posterior direction decreased by 70% in experimental group, all with a significant difference (P＜0.05). ConclusionsCompared with the long straight PHILO plate, the long helical PHILOS plate has better biomechanical properties, which can meet the clinical need of proximal metaphyseal-diaphyseal humeral shaft fracture fixation and postoperative rehabilitation. This surgical technique is expected to be widely applied in clinic, especially with the advantage of minimal invasive surgery.