Long-term follow-up on disc renarrowing after anterior lumbar interbody fusion with autogenous tricortical iliac crest graft

Abstract

To have a retrospective review of the patients undergoing anterior lumbar interbody fusion (ALIF) with clinical and radiological assessment, and observe changing of graft after procedure and assess correlation between graft collapse and recurrence of radiculopathy. Sixty-seven consecutive patients undergoing ALIF only at L(4 - 5) with autologous iliac crest graft for intervertebral disc prolapse were followed-up for an average of 14 (2.5 - 32) years. The effect of the fusion was examined by the existence of radiolucent lines and bony continuity on plain radiographs and tomographs, or mobility on flexion-extension radiographs. The disc height was also measured. Lower limb radiculopathy was assessed based on the symptom and examination. Paired samples t-test was used for statistical analysis. Sixty-four patients with successful fusion were analyzed (fusion rate: 96%). All measurements in this study were completed by the same author, and the measurement error of more than 2 mm was statistically significant. According to this, graft collapse occurred in 55 patients (86%) and 9 patients (14%) had no graft collapse. In these 55 cases, the original disc height was (12.1 +/- 2.9) mm, increased immediately after the surgery to (16.2 +/- 1.9) mm, however re-narrowed to (12.9 +/- 2.7) mm at the first observation of solid fusion (a mean of 9 months, ranging from 5 to 14 months), which was not significant different compared to the original. There was no significant change in disc height after solid fusion and the disc space at the final follow-up was (12.6 +/- 2.3) mm. There was no radiculopathy observed in 52 cases (95%) during the follow-up. Disc space re-narrowing was observed in most cases after single level ALIF of L(4 - 5), however it was rarely less than the initial and unlikely to result in recurrence of radiculopathy.