Thoracolumbar Burst Fracture: McCormack Load-sharing Classification Systematic Review and Single-arm Meta-analysis

Study Design. A systematic review and single-arm meta-analysis of randomized clinical trials. Objective. The aim of this study was to evaluate whether the load-sharing classification (LSC) is reliable to predict the best surgical approach for thoracolumbar burst fracture (TBF). Summary of Background Data. There is no previous review evaluating the efficacy of the use of LSC as a guide in the surgical treatment of burst fractures. Methods. On April 19(th), 2019, a broad search was performed in the following databases: EMBASE, PubMed, Cochrane, SCOPUS, Web of Science, LILACS, and gray literature. This study was registered on the International Prospective Register of Systematic Reviews. We included clinical trials involving patients with TBF undergoing posterior surgical treatment, classified by load-sharing score, and that enabled the analysis of the outcomes loss of segmental kyphosis and implant failure (IF). We performed random- or fixed-effects models meta-analyses depending on the data homogeneity. Heterogeneity between studies was estimated by I-2 and tau(2) statistics. Results. The search identified 189 references, out of which nine studies were eligible for this review. All articles presenting LSC up to 6 proved to be reliable in indicating that only posterior instrumentation is necessary, without screw failures or loss of kyphosis correction. For cases where the LSC was >6, only 2.5% of the individuals presented IF upon posterior approach alone. For loss of kyphosis correction, only 5% of patients had this outcome where LSC >6. For both outcomes together, we had 6% of postoperative problems (I-2 = 77%, tau(2) < 0.0015, P < 0.01). Conclusion. Load-sharing scores up to 6 are 100% reliable, only requiring posterior instrumentation for stabilization. For scores >6, the risk of implant breakage and loss of kyphosis correction in posterior fixation alone is low. Thus, other factors should be considered to define the best surgical approach to be adopted.