Bilateral fracture of L5 pedicles in a patient with total disc replacement of L5-S1: a case report

Report of a rare complication - fracture of the pedicles - in a patient with total disc replacement of L5-S1, a surgical resolution, and a biomechanical explanation. To the authors' knowledge, there is only one previous report of bilateral fracture of the pedicles in the literature, as a complication in total disc replacement of the lumbar spine. In this case, no direct repair was made to the fracture site; instead intersomatic fusion was performed by the anterior approach. A 40-year-old male, a martial arts practitioner who had undergone L5-S1 (ProDisc(r)) disc replacement nine months earlier, with complete resolution of the preoperative symptoms and no complications, sudden pain during physical activity, without neurological symptoms. Computed axial tomography showed a fracture of the L5 pedicles and anterior luxation of the polyethylene insert. Surgery was performed by the posterior approach, with direct repair of the fractures and posterolateral fusion of L5-S1 with transpedicular screws (Schanz) and USS(r) internal fixator. A follow-up axial CT scan at 6 months after surgery showed complete consolidation of the fractures, and the patient was asymptomatic. Due to the alteration in weight transmission through the anterior part of the spine in the total replacement of the lumbar disc, which preserves the movement but not the absorption of forces, the pedicle becomes more susceptible to fracture. It is important to bear this complication in patients submitted to this procedure.

本报告旨在阐述1例L5-S1全椎间盘置换术后并发罕见并发症——椎弓根骨折的病例，附手术治疗方案及生物力学机制阐释。据作者所知，目前公开文献中仅报道过1例腰椎全椎间盘置换术后并发双侧椎弓根骨折的并发症病例。针对本次病例，临床未对骨折部位实施直接修复，而是采用前路入路完成椎体间融合术。本次病例的患者为40岁男性武术练习者，于9个月前接受L5-S1（ProDisc®）椎间盘置换术，术前症状已完全缓解且无术后并发症，此次在运动过程中突发疼痛，无神经功能受损症状。CT轴位扫描显示患者L5椎弓根骨折，聚乙烯衬垫向前脱位。手术采用后路入路，对骨折部位进行直接修复，并通过经椎弓根螺钉（Schanz螺钉）与USS®内固定器行L5-S1后外侧融合术。术后6个月的随访CT轴位扫描显示骨折完全愈合，患者无任何不适症状。腰椎全椎间盘置换术可保留脊柱活动度，但无法完成载荷吸收功能，改变了脊柱前部的重量传递路径，使得椎弓根的骨折易感性显著升高。对于接受该手术的患者，临床需警惕此类并发症的发生。