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OBJECTIVE The purpose of this study was to describe the genesis of the AO Spine Sacral and Pelvic Classification System in the context of historical sacral and pelvic grading systems. METHODS A systematic search of MEDLINE, EMBASE, Google Scholar, and Cochrane databases was performed consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all existing sacral and pelvic fracture classification systems. RESULTS A total of 49 articles were included in this review, comprising 23 pelvic classification systems and 17 sacral grading schemes. The AO Spine Sacral and Pelvic Classification System represents both the evolutionary product of these historical systems and a reinvention of classic concepts in 5 ways. First, the classification introduces fracture types in a graduated order of biomechanical stability while also taking into consideration the neurological status of patients. Second, the traditional belief that Denis central zone III fractures have the highest rate of neurological deficit is not supported because this subgroup often includes a broad spectrum of injuries ranging from a benign sagittally oriented undisplaced fracture to an unstable “U-type” fracture. Third, the 1990 Isler lumbosacral system is adopted in its original format to divide injuries based on their likelihood of affecting posterior pelvic or spinopelvic stability. Fourth, new discrete fracture subtypes are introduced and the importance of bilateral injuries is acknowledged. Last, this is the first integrated sacral and pelvic classification to date. CONCLUSIONS The AO Spine Sacral and Pelvic Classification is a universally applicable system that redefines and reorders historical fracture morphologies into a rational hierarchy. This is the first classification to simultaneously address the biomechanical stability of the posterior pelvic complex and spinopelvic stability, while also taking into consideration neurological status. Further high-quality controlled trials are required prior to the inclusion of this novel classification within a validated scoring system to guide the management of sacral and pelvic injuries.

Object Despite promising early clinical results, the long-term outcome of the use of expandable titanium cages to reconstruct the anterior column after traumatic burst fractures is still unknown. The purpose of this prospective study was to assess the clinical and radiological outcomes of the use of expandable titanium cages 5 years postoperatively. Methods Eighty patients with traumatic thoracolumbar burst fractures (T4–L5) underwent posterior stabilization followed by anterior corpectomy and reconstruction using expandable titanium cages with or without additional anterior plating. After 5 years, fusion was evaluated by means of plain radiographs and CT scans, and the patients' scores on the Oswestry Disability Index (ODI), their neurological status, and clinical results were assessed. Results Forty-five (56%) of the 80 patients could be examined after 5 years. There was a relatively high rate of complications related to thoracotomy (26%), but there were no complications directly related to the cages. Revision surgery was required in 1 case. The average postoperative loss of correction was only 2.4° due to minimal subsidence of the cages. No cage showed a radiolucent line or instability in flexion-extension views. Bony fusion, as assessed by CT scan, was achieved in 41 patients (91%). On clinical examination, 96% of all patients were ambulatory and showed minimal restriction of spinal range of motion; 71% did not need analgesic medication at all; and 67% were able to work. The average ODI score was 12. Thirty-one percent of patients complained of some kind of anterior approach–related complications. Conclusions Combined anteroposterior stabilization of thoracolumbar burst fractures with expandable titanium cages is a relative safe procedure with satisfactory radiological and clinical long-term outcome. High fusion rates can be achieved, with only minor loss of correction, typically occurring in the 1st year. However, open thoracotomy carries the risks of additional complications and development of post-thoracotomy syndrome.