锁定螺钉在骨质疏松性骨中的“杂交”钢板结构固定中增加了多少固定？

How much do locked screws add to the fixation of "hybrid" plate constructs in osteoporotic bone?

机构信息

Excelen Center for Bone and Joint Research and Education, Minneapolis, MN, USA.

出版信息

J Orthop Trauma. 2010 Mar;24(3):163-9. doi: 10.1097/BOT.0b013e3181d35c29.

DOI:10.1097/BOT.0b013e3181d35c29

PMID:20182252

Abstract

BACKGROUND

Hybrid locked plating has become a commonly used technique for treating complex fractures and nonunions, but information is lacking to direct the specific application of this fixation method. The purpose of this study was to determine the effect of the number and location of locked screws on the mechanical properties of hybrid plate constructs in an osteoporotic bone model.

METHODS

A synthetic commercial composite model of osteoporotic bone with a 5-mm simulated fracture gap was fixed with a 12-hole plate. Seven different constructs (n=5/construct) were tested including 2 unlocked and 5 hybrid configurations. All constructs used bicortical screws tightened to 4 N.m torque. Cyclic (sinusoidal) testing was performed with a peak torsional load of +/-8 N.m for 100,000 cycles. Torsional stiffness of each construct was measured in 10,000 cycle increments, and the maximum removal torque of each screw was measured at the conclusion of torsional testing.

RESULTS

Stiffness of the constructs at each testing interval was most affected by the number of screws; stiffness increased at least 33% when 4 screws were used on each side of the fracture versus 3 per side. Among the constructs with 4 screws in each fragment, no difference was observed when 1 or 2 unlocked screws were replaced with locked screws on each side of the simulated fracture. In contrast, replacement of 3 unlocked screws with locked screws increased the torsional stiffness of the construct by another 24% (P<0.001). Compared with baseline (pretesting) values, postcycling screw removal torque was similar for locked screws at all positions (average 50% of peak removal), but removal torque of unlocked screws furthest from the fracture was increased by 274% if they were placed immediately adjacent to a locked screw (P<0.001).

CONCLUSIONS

At least 3 bicortical locked screws on each side of a fracture are needed to increase the torsional stiffness in an osteoporotic bone model. Locked screws placed between the fracture and unlocked screws protect the unlocked screws from loosening and may have some clinical utility in improving fatigue life of the construct.

LEVEL OF EVIDENCE

Biomechanical level 1.

摘要

背景

混合锁定接骨板已成为治疗复杂骨折和骨不连的常用技术，但缺乏指导这种固定方法具体应用的信息。本研究旨在确定骨质疏松骨模型中锁定螺钉的数量和位置对混合钢板结构力学性能的影响。

方法

使用具有 5mm 模拟骨折间隙的合成商业复合材料骨质疏松骨模型固定 12 孔钢板。测试了 7 种不同的结构（n=5/结构），包括 2 种未锁定和 5 种混合配置。所有结构均使用双皮质螺钉拧紧至 4N.m 扭矩。进行了正弦波测试，峰值扭转负载为 +/-8N.m，持续 100,000 次循环。在每个 10,000 次循环的增量测量每个结构的扭转刚度，并在扭转测试结束时测量每个螺钉的最大去除扭矩。

结果

每个测试间隔的结构刚度受螺钉数量的影响最大；与每侧使用 3 个螺钉相比，在骨折的每侧使用 4 个螺钉时，刚度至少增加了 33%。在每侧用锁定螺钉替换 1 或 2 个未锁定螺钉的 4 个螺钉的结构中，在骨折侧之间没有观察到差异。相比之下，用锁定螺钉替换 3 个未锁定螺钉会使结构的扭转刚度再增加 24%（P<0.001）。与基线（预测试）值相比，所有位置的锁定螺钉的循环后螺钉去除扭矩相似（平均为峰值去除扭矩的 50%），但如果将未锁定螺钉放置在锁定螺钉的最靠近骨折处，则去除扭矩增加了 274%（P<0.001）。