General Session: Tumor, Trauma, Infection, Image
Presented by: H. Aono - View Audio/Video Presentation (Members Only)
H. Aono(1), K. Ishii(2), H. Tobimatsu(1), S. Takenaka(1), Y. Nagamoto(1), M. Iwasaki(3)
(1) Osaka National Hospital, Orthopedic Surgery, Osaka, Japan
(2) University of California, San Francisco Orthopedic Trauma Institute, Orthopedic Surgery, San Francisco, CA, United States
(3) Osaka Rosai Hospital, Orthopedic Surgery, Sakai, Japan
Introduction: Thoracolumbar burst fractures are the most common type of spine fracture treated surgically. Management for these fractures remains a matter of discussion. We had presented successful results of temporary short-segment fixation without augmentation for thoracolumbar burst fractures previously (annual meeting of Eurospine, ASIA, and ISSLS). In these previous presentations, vertebral body itself was reduced and maintained after surgery and correction loss occurred at disc level after implant removal. In this study, we investigated the risk factor for kyphotic change and revealed limitation of this surgical procedure.
Methods: This multicenter study included 58 consecutive patients with thoracolumbar burst fracture (T11-L3) who underwent surgery by ligamentotaxis procedure using Schanz screws. There were 40 men and 18 women, with an average age of 39 years and they were followed at least one year after implant removal (range, 2-7 years). Twenty-five patients were treated with vertbroplasty and 33 were treated without vertebroplasty. Their implants were removed around 1 year after initial surgery after confirming union of the fracture. We measured the vertebral body angle (VBA), which was measured between the superior and inferior endplates of the injured vertebra, and the superoinferior endplate angle (SIEA), which was measured between the superior endplate of the intact vertebra cephalad to the fracture and the inferior endplate of the intact vertebra caudad to the fracture before and just after operation, approximately 1 year after initial operation and final follow up. Multiple logistic regression analysis was performed to identify the risk factors for postoperative correction loss. We defined correction loss more than 10° in SIEA as major kyphotic change. The factors we evaluated were age, gender, operation time, blood loss, combination of vertebroplasty, load-sharing score(M&G score), AO classification(typeA3 or B), preoperative SIEA, and preoperative canal compromise ratio.
Results: VBA was corrected 12.1° after operation and loss of correction was 0.5° before removal and deteriorated 0.2° after removal in average (total correction loss 0.7°). SIEA was corrected 11.8° after operation and loss of correction was 3.4° before removal and deteriorated 6.7° after removal in average (total correction loss 9.1°). Kyphosis was advanced due to loss of disc height mainly after implant removal though vertebral body itself was reduced and maintained. Multiple logistic regression analysis revealed preoperative SIEA(P=0.48) and preoperative canal compromise ratio(P=0.11) were risk factors of postoperative kyphotic change.
Discussion: To the best of our knowledge, there was no report which focused on risk factors for correction loss in temporary short-segment fixation for thoracolumbar burst fracture. In the current study, the load-sharing score, which evaluate total destruction of vertebra, was not included in risk factors. However, canal compromised ratio, which represent destruction of vertebra in axial plane, was one of the risk factors. Concerning preoperative SIEA, reduction and distraction force during surgery was applied not only injured vertebra but also adjacent discs, and as a result, correction loss might have occurred at disc level mainly after implant removal.
Conclusion: Fractured vertebrae were reduced and maintained after surgery with temporary short-segment fixation. Kyphotic change was observed due to loss of disc height mostly after implant removal. Preoperative SIEA and canal compromise ratio were the risk factors for postoperative kyphotic deformity.