Schuhli锁定螺母加强钢板治疗骨质疏松肱骨骨折的生物力学研究

A biomechanical comparison of Schuhli nuts for plating of osteoporotic humeral fractures

目的:评价骨质疏松肱骨骨折中Schuhli锁定螺母替代骨水泥增强钢板内固定稳定性的效果。方法:分别用Schuhli锁定螺母配标准螺钉和骨水泥加强螺钉对骨质疏松的肱骨干骨折模型行钢板内固定,在3种加载模式下测试其内固定的强度和稳定性,并与标准固定组进行对比。再在4.5N m扭矩下将肱骨干循环扭转1000次,在同样模式下测试内固定的强度和稳定性。结果:循环扭转前后,锁定螺母组和骨水泥加强组在扭转加载模式下的内固定稳定性均明显高于标准固定组(循环前高出6～14倍,循环后高出3～3.6倍);而两组组间比较,在各加载模式下的内固定稳定性差异均不明显(P>0.05)。在轴压和四点弯曲模式下,两组循环扭转前的内固定稳定性与标准固定组比较亦无明显差异(P>0.05)。结论:使用Schuhli锁定螺母可获得与骨水泥加强同样的稳定性,还可避免水泥外渗和骨质热坏死的发生而影响骨折的愈合。

Objective： To evaluate the effects of Schnhli locking nuts on enhancing fixation stability for plating of osteoporotic humeral fractures as an alternative to cement augmented screws. Methods： This study compared the fixation strength and stability of plate constructs using Schnhli locking nuts with standard screws and cement augmented screws for fixation of simulated humeral shaft fractures in a test model with osteoporosis. The constructs were tested in 3 testing modalities to determine fixation stability. The humeri were cycled in torsion （4.5 Nm） for 1000 cycles to simulate upper extremity use during the early postoperative period and retested for stability. Results： The Schnhli locking nuts and cement augmented screws had significantly greater fixation stability than the standard screws before （range, 6-14 times greater） and after cycling in torsional loading （range, 3-3.6 times greater）. Compared with Schuhli fixation, cement augmented screws showed no significant difference in fixation stability in all loading modes however （P〉0.05）. Compared with the standard screws in axial and 4-point bending before cycling, increasing of fixation stability in cement augmented screws and Schuhli augmentation was not significant （ P〉0.05 ）. Conclusions： Schuhli locking nuts offer the stability of cement augmentation while avoiding its potential adverse effects on fracture healing with extravasation and thermal necrosis.