Clinical outcomes of combined anterior and posterior spinal fusion for dystrophic thoracolumbar spinal deformities of neurofibromatosis-1: fate of nonvascularized anterior fibular strut grafts

Abstract

Study design: Retrospective study.

Objective: To analyze the clinical outcomes of anterior and posterior spinal fusion (APSF) using a fibular strut autograft (FSAG) and to investigate the morphological changes in the reconstructed spinal column of dystrophic deformities in neurofibromatosis (NF)-1.

Summary of background data: APSF is desirable for dystrophic deformities in NF-1 with more than 50° of dystrophic kyphosis. There are few reports regarding the clinical outcomes of APSF in which the morphological changes over time of the anterior strut graft have been investigated.

Methods: The clinical and radiographic outcomes of APSF with FSAG were investigated in 10 consecutive patients with dystrophic deformity in NF-1. For qualitative and quantitative analyses, the chronological changes in the FSAG configuration, length, and diameter were evaluated.

Results: The mean follow-up period was 9 years, 9 months (range, 1-30 years). Graft bone erosion and postoperative curve progression were not observed in any patient. In quantitative analyses of the anterior strut, the mean ratio of the latest and immediately postoperative FSAG lengths was 0.98 (0.93-1.09). The mean central/peripheral ratios of the FSAG diameter (central portion/[upper end + lower end]/2) were 1.02 (0.92-1.10) immediately after surgery, and 1.01 (0.92-1.07) at the latest follow-up, with no significant change between these 2 time points (P = 0.937). The mean preoperative cross-sectional area of the apical vertebral body and its mean virtual cross-sectional area at the final follow-up were 3.80 (1.83-5.43) and 4.87 (2.46-7.00) cm(2), respectively, with a significant difference between these 2 parameters (P = 0.0078). The mean final/preoperative ratio was 1.31 (1.10-1.43).

Conclusion: APSF with FSAG for dystrophic deformity in NF-1 successfully reconstructed a reliable spinal column with a rich bone stock. The FSAG and surrounding vertebral bodies were free from postoperative erosion due to dystrophic changes and maintained their stability for a long time.