经关节斜坡螺钉内固定技术的生物力学研究

Biomechanical evaluation of posterior atlanto-occipital clivus screw fixationtechniques

目的通过对后路经寰枕关节-斜坡螺钉内固定系统的生物力学研究,探讨其生物力学特性,并为临床应用提供理论依据。方法选取8具健康成人新鲜尸体的8个枕颈标本,男5例,女3例,年龄(50.8±6.4)岁(范围35~60岁),身高(170.6±10.2)cm(范围155~180 cm)。将8具解剖结构完整且未行手术操作的标本建立为正常模型;将8具枕寰枢复合体的关节囊、韧带等连接结构破坏并锯断齿状突的标本建立为枕颈不稳模型;将8具安装经寰枕关节斜坡螺钉内固定系统的标本建立为内固定模型。分别给予正常和内固定模型1.5 N·m的屈伸、侧弯和轴向旋转扭矩,并测量标本C_(0)~C_(1)和C_(0)~C_(2)节段的活动范围(rang of motion,ROM),比较分析枕颈区正常模型和内固定模型的活动度变化情况,评价后路经寰枕关节斜坡螺钉内固定系统的力学特性。结果正常模型C_(0)~C_(1)节段的屈伸、侧弯、轴向旋转活动范围分别为23.85°±2.43°、4.74°±0.55°、5.77°±0.75°,C_(0)~C_(2)节段上分别为30.6°6±3.05°、9.09°±1.37°、70.97°±9.48°;内固定模型C_(0)~C_(1)节段的屈伸、侧弯、轴向旋转活动范围分别为0.71°±0.24°、0.24°±0.06°、0.34°±0.09°,C_(0)~C_(2)节段上分别为3.09°±0.82°、0.74°±0.07°、1.22°±0.10°。在疲劳测试组上,C_(0)~C_(1)节段的屈伸、侧弯和轴向旋转活动范围分别为0.86°±0.27°、0.30°±0.06°、0.42°±0.11°,C_(0)~C_(2)节段上分别为4.07°±0.86°、0.81°±0.12°、1.52°±0.13°,同正常模型比较,疲劳测试后的内固定模型在各个方向上的活动范围均显著减少,活动度削减比均达90%以上。结论后路经寰枕斜坡螺钉内固定系统能有效减少枕颈部在屈伸、侧弯及旋转上的活动范围,具有安全可靠的生物力学稳定性。

Objective To provide a theoretical basis for the clinical application of the posterior route through atlas occipital articular slope screw internal fixation system through the biomechanical study.Methods Eight cadavers of healthy adults aged 35-60 years and 155-180 cm in height were selected.The specimens with complete anatomical structure and without surgical operation were established as normal models.The model of occipito-atlantoaxial complex was established by breaking the articular capsule,ligament and other connecting structures and cutting the dentate process.The device was established as an internal fixation model through the specimen of atlantooccipital joint slope screw internal fixation system.Given normal model and internal fixation of 1.5 N·m in the moment of flexion,lateral bending and axial rotation and to measure the specimen C_(0)-C_(1) and C_(0)-C_(2) segment of the range(range of motion,ROM),comparative analysis of pillow neck area within the normal model and fixed model changes the range of movement,after the evaluation through the slope between atlas and the occipital screw internal fixation system of mechanical properties.Results In the normal model,the flexion,flexion and extension,lateral bend and axial rotation ranges of C_(0)-C_(1) segments were 23.85°±2.43°,4.74°±0.55°,5.77°±0.75°,respectively;the corresponding activity ranges of C_(0)-C_(2) segments were 30.66°±3.05°,9.09°±1.37°,70.97°±9.48°,respectively;in the internal fixation model,the flexion and extension,lateral bend and axial rotation ranges of C_(0)-C_(1) segments were 0.71°±0.24°,0.24°±0.06°,0.34°±0.09°,respectively.The corresponding activity range of C_(0)-C_(2) segment was 3.09°±0.82°,0.74°±0.07°,1.22°±0.10°,respectively.Compared with the normal model,the range of activity of the internal fixation model in all directions was significantly reduced(<3°),and the reduction ratio of activity was more than 90%.Conclusion The posterior route through pillow slope screw internal fixation system can effectively reduce the range of motion of the occipital neck in flexion,extension,lateral bending and rotation,and has safe and reliable biomechanical stability.