Wheeler D L, Colville M R
Orthopaedic Research Laboratory, Oregon Health Sciences University, Portland, USA.
J Orthop Trauma. 1997 Jul;11(5):363-7. doi: 10.1097/00005131-199707000-00012.
The purpose of this study was to investigate the mechanical strength and durability of intramedullary nailing (IM) and percutaneous pinning (PP) for fixation of three-part proximal humeral fractures using a cadaveric model.
Three-part surgical neck fractures were created in paired embalmed cadaveric humeri. Fractures were fixed with IM and PP fixation. The fixation stiffness and durability was assessed under cyclic rotational loading (infraspinatus) ramping from 0.1 to 1.25 Newton-meters for 10,000 cycles. The specimen were then torsionally loaded to failure.
Mechanical testing was performed using a servohydraulic test system (MTS, Minneapolis, MN, U.S.A.).
PP fixations were accomplished using standard multiplane techniques. IM fixation was attained using an 11.0-millimeter-diameter curved rod interlocked proximally with three splayed 5.0-millimeter cancellous screws and distally with three 3.5-millimeter cortical screws.
During cyclic loading the reconstruction stiffness, angular migration, and angular displacement per cycle were measured and compared between fixation methods. The ultimate torque at failure, absolute angular migration, and reconstruction stiffness during failure were recorded and compared between fixation methods during destructive testing.
The intramedullary device had greater stiffness and less angular displacement of fragments during cyclic loading. When loading the reconstructions to failure, the intramedullary device proved to have greater failure torques, stiffness, energy absorbed, and angular displacement before failure.
This biomechanical study showed that the IM device provided a stronger, more stable, and durable fixation option than did PP fixation for large-fragment multipart proximal humeral fractures with minimal comminution.
本研究旨在使用尸体模型，调查髓内钉固定术（IM）和经皮穿针固定术（PP）治疗三部分肱骨近端骨折的机械强度和耐久性。
在成对的防腐处理尸体肱骨上制造三部分外科颈骨折。骨折采用IM和PP固定。在0.1至1.25牛顿米的循环旋转负荷（冈下肌）下递增负荷10000次循环，评估固定刚度和耐久性。然后对标本进行扭转负荷直至破坏。
使用伺服液压测试系统（美国明尼阿波利斯市的MTS公司）进行力学测试。
PP固定采用标准多平面技术完成。IM固定使用一根直径11.0毫米的弯棒，近端与三根呈扇形分布的5.0毫米松质骨螺钉锁定，远端与三根3.5毫米皮质骨螺钉锁定。
在循环负荷期间，测量并比较两种固定方法之间的重建刚度、角度移位和每循环角度位移。记录并比较破坏试验期间两种固定方法之间的破坏时极限扭矩、绝对角度移位和破坏时重建刚度。
在循环负荷期间，髓内装置具有更大的刚度，骨折块的角度位移更小。当对重建结构加载直至破坏时，髓内装置被证明具有更大的破坏扭矩、刚度、吸收能量和破坏前角度位移。
这项生物力学研究表明，对于粉碎程度最小的大骨折块多部分肱骨近端骨折，IM装置比PP固定提供了更强、更稳定和更持久的固定选择。
