跟骨微创锁定接骨板联合螺钉辅助固定治疗Sanders Ⅱ型跟骨关节内骨折的三维有限元分析

Finite element analysis of treatment for Sanders type Ⅱ intra-articular calcaneal fracture by a minimally invasive calcaneal locking plate combined with additional screws fixation

目的:通过三维有限元分析评估跟骨微创锁定接骨板联合螺钉辅助固定治疗Sanders Ⅱ型跟骨关节内骨折的稳定性。方法:采用64排螺旋CT对1名正常成人的跟骨进行扫描及三维重建,将数据以DICOM格式导入Mimics软件,建立SandersⅡ型跟骨关节内骨折模型,然后分别模拟3种不同的微创固定方式:方式A单纯采用跟骨微创锁定接骨板固定;方式B采用跟骨微创锁定接骨板联合2枚从跟骨结节向跟骨前部置入的纵向螺钉进行辅助固定;方式C采用跟骨微创锁定接骨板结合1枚从跟骨结节外侧至跟骨前部,另1枚从跟骨结节内侧至内侧关节面方向置入的螺钉进行辅助固定。通过对距下关节面模拟加载640 N应力后进行三维有限元分析,记录各骨块、内置物最大移位及von Mises应力值,以评估不同微创固定方式的生物力学稳定性。结果:应力加载后,联合螺钉辅助固定后的各骨块及内置物最大移位均小于单纯微创锁定接骨板固定。3种固定方式的骨块最大移位均位于载距突处,且内置物最大移位亦位于载距突处。采用方式C固定后,关节面骨块最大移位均小于其他2种固定方式,且内置物最大移位亦最小。3种微创固定方式的内置物最大应力值均小于屈服强度,而采用方式C固定后的内置物最大应力值最小,且各骨块最大应力值亦均小于单纯接骨板固定。结论:联合螺钉辅助固定可能有助于提高SandersⅡ型跟骨关节内骨折微创固定的稳定性,而采用自跟骨结节外侧至跟骨前部及跟骨结节内侧至内侧关节面2枚螺钉进行辅助固定的生物力学效果可能更佳。

Objective:To evaluate the stability of a minimally invasive calcaneal locking plate combined with additional screws fixation for the treatment of Sanders type Ⅱ intra-articular calcaneal fractures using finite element analysis.Methods:The calcaneus of a healthy adult was scanned and reconstructed in three dimensions using a 64-row spiral CT.The scanning data was imported into Mimics software in DICOM format to establish a Sanders type Ⅱ intra-articular calcaneal fracture model.Subsequently,three different minimal invasive fixation methods were simulated:Method A involved solely utilizing a minimally invasive calcaneal locking plate for fixation;Method B included the utilization of a minimally invasive calcaneal locking plate along with two longitudinal screws inserted from calcaneal tuberosity towards the anterior part of the calcaneus for additional fixation;Method C encompassed the application of a minimally invasive calcaneal locking plate combined with one additional screw from the lateral aspect of the calcaneal tuberosity towards the anterior part of the calcaneus,and another one inserted from the medial aspect of the calcaneal tuberosity towards the direction of the medial articular surface for additional fixation.After simulation of 640 N loading on the subtalar joint,the maximum displacement and von Mises stress of each fragment and implants were recorded to evaluate the biomechanical stability of different minimally invasive fixation methods via finite element analysis.Results:After the stress loading,the maximum displacement values of fragments and implants were lower in the groups of plate with additional screws compared to those with sole fixation using a minimally invasive calcaneal locking plate.In three fixation methods,the maximum displacements of fragments were all located at the sustentaculum tali and the maximum displacements of implants also occurred at the screws near to the sustentaculum tali.Method C fixation yielded smaller maximum displacement values of facet fragments compared to the other two methods.Additionally,the maximum displacement value of implants was also the smallest.In all three minimally invasive fixation methods,the maximum stress values of implants were all below the yield strength.Similarly,Method C fixation exhibited the lowest maximum stress value of implants,with a lower maximum stress value of fragments compared to sole plate fixation.Conclusions:The combined screws for additional fixation may improve the stability of minimally invasive fixation for Sanders type Ⅱ intra-articular calcaneal fractures.Utilizing two screws from the lateral aspect of the calcaneal tuberosity towards the anterior part of the calcaneus and from the medial aspect of the calcaneal tuberosity towards the direction of the medial articular surface for additional fixation may achieve a better biomechanical effect.