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

Abstract

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.

Adjacent Bi-level bilateral pedicle stress fractures after instrumented posterolateral lumbar fusion—a case report and review of the literature

“…Load distribution is absorbed mainly by the intervertebral disc in the anterior segment. In the posterior segment, the load passes through the facet joints and is distributed among the posterior elements (pars interarticularis, laminae, and pedicles), the pars being the most susceptible to injury, followed by the pedicles [26]. A stress fracture of the lumbar pedicle is rare but can occur, especially in conditions in which the load on the neural arch is abnormally distributed.…”

The Role of Vertebral Porosity and Implant Loading Mode on Bone-Tissue Stress in the Human Vertebral Body Following Lumbar Total Disc Arthroplasty

“…Despite evidence that lumbar total disc arthroplasty (TDA) can improve clinical outcomes relative to fusion in some patients, 1,2 TDA is narrowly indicated and has not been widely adopted 3–6 . Complications such as implant subsidence, migration, and vertebral fracture may be related to the bone biomechanics in the vertebral body supporting an implant 7–18 . However, the bone biomechanics for this class of implant are not fully understood; for example, it remains unclear how the stresses that develop in the underlying bone tissue depend on the implant's loading mode ( e.g.…”