RADIOGRAPHIC RESTORATION OF LUMBAR ALIGNMENT AFTER TRANSFORAMINAL LUMBAR INTERBODY FUSION

OBJECTIVE: Restoration of lumbar lordosis is a critical factor in long-term success after lumbar fusions. Transforaminal lumbar interbody fusion (TLIF) is a popular surgical technique in the lumbar spine, but few data exist on change in spinal alignment after the procedure. METHODS: Eighty patients who underwent TLIF surgery were retrospectively reviewed (minimum follow-up period, 2 years). Standing x-rays were assessed for changes in focal and segmental kyphosis, and restoration of lumbar lordosis. Improvement in spondylolisthesis, sagittal balance, and scoliosis were also assessed. Fusion was assessed as well. RESULTS: Eighty operations were performed at 107 levels. Mean presenting lumbar Cobb angle measurement (L1-S1) was 36.3 +/- 4.5 degrees (range, 12-77 degrees). Forty patients (50%) had sagittal imbalance. Mean postoperative Cobb angle (L1-S1) was 55.1 +/- 6.6. Thirty-three of 36 patients with segmental kyphosis (92%) had restoration of lordosis. Improvement in alignment was most prominent at the surgical level (mean increase in lordosis, 20.2 +/- 4.2 degrees). The improvement in lumbar lordosis among patients undergoing multilevel TLIFs (27.3 +/- 3.4 degrees) was significantly higher compared with patients undergoing single-level operations (17.4 +/- 4.4) (Student's t test, P = 0.0004). Thirty of the 40 patients with sagittal imbalance (75%) achieved immediate restoration of normal sagittal balance. The ability to restore normal sagittal balance was correlated with a sagittal imbalance of less than 10 cm (P = 0.0001). Spondylolisthesis was completely corrected at the TLIF site in 90 of 99 levels (91%). Three patients (4%) required reoperation, 2 for implant disengagement and 1 for worsening kyphoscoliosis above the original surgical levels. Two of the 80 patients had pseudoarthrosis; hence, the rate of pseudoarthrosis was 2.5%. CONCLUSION: The TLIF operation is highly effective in improving spinal alignment in patients with degenerative spinal disorders when the appropriate surgical technique is implemented.