前路枕骨髁螺钉钢板系统的生物力学研究

Biomechanical study of anterior occipital condyle screw plate system

目的通过对前路枕骨髁螺钉钢板系统在枕颈融合中的生物力学研究,来探讨该技术应用于单纯前路枕颈融合手术的可行性。方法选取6具颈椎标本,男4具,女2具,死亡年龄(49±8)岁。对标本进行软组织剥离建立正常模型组,切除正常模型寰椎前弓、部分寰椎侧块、齿状突、齿突尖韧带、翼状韧带、寰椎横韧带,破坏关节囊,制作枕颈不稳模型,前路斜坡螺钉置钉建立斜坡螺钉固定模型,随后在原标本采用前路枕骨髁螺钉置钉建立枕骨髁螺钉固定模型。分别给予4组模型1.5 N·m的前屈、后伸、侧弯、旋转力矩,测量标本C_(0)-C_(1)与C_(0)-C_(2)的活动度(ROM)。最后进行拔出力试验,比较单双皮质固定对螺钉抗拔出力的影响。结果在C_(0)-C_(1)节段,斜坡螺钉组的前屈、后伸、侧弯及旋转活动度分别为6.46°±0.85°、5.14°±0.76°、2.73°±0.36°、1.12°±0.41°,枕骨髁螺钉组的活动度分别为5.92°±0.90°、4.16°±1.06°、2.86°±0.50°、1.05°±0.27°;在C_(0)-C_(2)节段,斜坡螺钉组的活动度分别为9.55°±1.99°、10.46°±2.03°、6.90°±1.29°、13.51°±1.37°,枕骨髁螺钉组的活动度分别为8.14°±1.38°、9.53°±1.55°、4.75°±1.06°、7.90°±1.68°,枕骨髁螺钉组较斜坡螺钉组的侧弯及旋转ROM明显下降,差异存在统计学意义(均P<0.05)。单皮质固定的枕骨髁螺钉最大拔出力为(408±28)N,双皮质固定最大拔出力为(439±33)N,两组差异有统计学意义(P<0.05)。结论前路枕骨髁螺钉钢板系统能够提供有效的生物力学稳定性,且在抗侧弯和抗旋转性能上比前路斜坡螺钉更具优势。

Objective To analyze the feasibility of anterior occipitocervical fusion biomechanical characteristic of craniovertebral reconstruction by anterior occipital condyle screw plate system.Methods Six cervical vertebra specimens including 4 males and 2 females were enrolled,whose mean age of death was(49.3±7.5)years.The normal models were established by soft tissue dissection,and the instability models were established by destroy bone and ligament structure including,anterior arch of the atlas,part of the lateral mass of the atlas,the odontoid process,the odontoid apical ligament,the pterygoid ligament,the transverse ligament of the atlas the joint capsule.The clivus screw fixation models were established by anterior clivus screw fixation,and then those models were performed by anterior occipital condyle screw fixation.All four groups were loaded with a 1.5 N·m continuous pure force in flexion-extension,lateral bending,and axial rotation.Then measured the range of motion of specimen C_(0)-C_(1) and C_(0)-C_(2).And the pull-out force test was conducted to compare the effects of unicortical and bicortical fixation on the pull-out force of screws.Results In the C_(0)-C_(1) segment,the range of motion in flexion-extension(forward and posterior),lateral bending and axial rotation in the clivus group was 6.46°±0.85°,5.14°±0.76°,2.73°±0.36°,1.12°±0.41°,respectively;and it was 5.92°±0.90°,4.16°±1.06°,2.86°±0.50°,1.05°±0.27°,respectively in the occipital condyle group.As for C_(0)-C_(2) segment,the range of motion in the clivus group was 9.55°±1.99°,10.46°±2.03°,6.90°±1.29°,13.51°±1.37°,respectively;and it was 8.14°±1.38°,9.53°±1.55°,4.75°±1.06°,7.90°±1.68°,respectively,in the occipital condyle group.The ranges of motion in the occipital condyle group were significantly lower than clivus group(all P<0.05).The maximum pull out force by bicortical fixation was significantly better than unicortical fixation((439±33)N vs(408±28)N,P<0.05).Conclusion The anterior occipital condyle screw plate system provides better stability especially in anti-bending and anti-rotation than the anterior clival screw fixation.