体外锁定加压钢板内侧与外侧固定肱骨中下段骨折稳定性分析

Stability analysis of medial and lateral fixation of middle and lower humeral fractures with external locking compression plate

目的以生物力学指标评价体外以锁定加压钢板(locking compression plate,LCP)内侧、外侧固定肱骨中下段骨折的效果,为临床肱骨中下段骨折内固定治疗提供生物力学指标。方法12个人工仿生肱骨,用摆锯在肱骨干髓端髁上距鹰嘴窝20 mm处行横形截骨模拟肱骨中下段横形骨折,随机分为肱骨中下段骨折内侧和外侧以锁定加压钢板固定各6个。分别在固定器固定部位边缘粘贴电阻应变片,以静态电阻应变仪测量各组标本在压缩载荷下各测点的应变值,以单向虎克定律计算各测点的应力值。最后通过比较应力、应变指标评估体外锁定加压钢板内侧、外侧固定肱骨中下段骨折的稳定性。结果在相同载荷作用下,肱骨中下段横形骨折外侧固定组各测点应力、应变大于肱骨中下段横形骨折内侧固定组,差异显著(P<0.05)。结论体外锁定加压钢板内侧、外侧内固定肱骨中下段横形骨折后,在载荷作用下应力、应变均发生了变化,锁定加压钢板内侧固定组应力、应变改变较小,具有较好的稳定性。

Objective To evaluate the effect of locking compression plate(LCP)on medial and lateral fixation of middle and lower humeral fractures in vitro.Methods Twelve artificial bionic humerus were used to simulate the transverse fracture of the middle and lower humerus.The transverse osteotomy was performed with a swing saw at the part of the humeral shaft 20 mm from the olecranon fossa.They were randomly divided into 2 groups:the medial fixation group and the lateral fixation group.In the medial fixation group,the inner side of the middle and lower humeral fracture was fixed with LCP and in the lateral fixation group,the outer side of the middle and lower humeral fracture was fixed LCP.The resistance strain gauges were pasted on the edges of the fixed parts of the fixator.Under compressive loads,the static resistance strain gauges were used to measure the strain values at each measurement point of the specimens of each group.The one-way Hooke’s law was used to calculate the stress values at each measurement point.Finally,by comparing the stress and strain indicators,the stability of the medial and lateral fixation of the middle and lower humerus fractures with external LCP was evaluated.Results Under the same loads,the stress and strain of each measuring point in the lateral fixation group of transverse fracture of middle and lower humerus were significantly higher than those in the medial fixation group of transverse fracture of middle and lower humerus(P<0.05).Conclusions After the transverse fracture of the middle and lower humerus is fixed with the LCP in vitro,the stress values and strain values changed under loads.With good stability,the medial fixation group has less changes in stress and strain.