Comparison of anterior- and posterior-approach instrumented lumbar interbody fusion for spondylolisthesis.

OBJECT The purpose of this study was to compare the imaging and clinical outcomes obtained in patients with lumbar spondylolisthesis who have undergone either instrumented anterior lumbar interbody fusion (ALIF) or instrumented posterior LIF (PLIF), especially with regard to the development of adjacent-segment degeneration (ASD). METHODS Forty-eight patients with preoperative spondylolisthesis and minimal ASD who underwent instrumented L4-5 fusion were divided into two groups according to the surgical approach. After ensuring the two groups' comparability, the following variables were evaluated: postoperative segmental and lumbar lordosis, postoperative percentage of vertebral slippage, reduction rate, incidence of ASD, and clinical outcomes. RESULTS Adjacent-segment degeneration was found in 44.0% of the patients in the ALIF group and in 82.6% of those in the PLIF group (p = 0.008). Clinical success rates were 92.0 and 87.0% in the ALIF and PLIF groups, respectively. There were no statistically significant intergroup differences in the postoperative segmental and lumbar lordosis, postoperative percentage of slippage, reduction rate, Japanese Orthopaedic Association score, and success rate. CONCLUSIONS Both ALIF and PLIF can produce good outcomes in treating lumbar spondylolisthesis, but ALIF is more advantageous in preventing the development of ASD.