Correlation of reduction and clinical outcome in patients with degenerative spondylolisthesis.

STUDY DESIGN: Prospective cohort study. INTRODUCTION: Operative treatment is increasingly implemented for the treatment of degenerative lumbar listhesis, with lumbar fusion the most common intervention. Prediction of clinical outcomes after such procedures is of ongoing relevance, and the correlation of radiologic parameters with clinical outcome remains controversial. In particular, clinical studies have not determined conclusively whether reduction of slipped vertebrae is beneficial. METHODS: We performed a monocenter prospective analysis of a comprehensive set of quality of life scores (QLS) (Core Outcome Measure Index, Oswestry Low Back Pain Disability Index, SF-36) of 40 patients, who underwent a standardized PLIF procedure for symptomatic, Spondylolisthesis. Follow-up was 24 months. The correlations between the radiologic parameters (degree of slippage, sagittal rotation) and the clinical scores before surgery as well as 12 and 24 months post-operatively were examined. RESULTS: All QLS showed a statistically significant improvement after 12 and 24 months post-operatively (p < 0.05). The mean amount of the anterior slippage was 34.2 ± 14.7 % (minimum 12 %, maximum 78 %). After 12 months, there was an average 19.1 % decrease to 15.1 ± 8.3 % (minimum 2 %, maximum 38 %, p < 0.000) and after 24 months it was decreased by 18.0-16.2 ± 9.0 % (minimum 2.9 %, maximum 40 %, p < 0.000). Average sagittal rotation measured 67.3° ± 16.6° initially (minimum 35°, maximum 118) and decreased by 4.3° to an average of 63.0° ± 15.2° at 12 months post-surgery (minimum 15°, maximum 101°, p = 0.065,), and by 5.7° to an average of 61.6° ± 13.0° at 24 months (minimum 15°, maximum 90°, p = 0.044). The data show positive correlations between the amount of reduction of the slipped vertebra as well as the amount of correction of the sagittal rotation and the improvement of the clinical outcomes(r = 0.31-0.54, p < 0.05). CONCLUSION: The current study indicates a modest advantage for the best possible reposition in respect of the clinical outcome.