Preoperative Pelvic Incidence Minus Lumbar Lordosis Mismatch in Repeat Posterior Lumbar Interbody Fusion Induces Subsequent Corrective Long Fusion.

ABSTRACT

OBJECTIVE: Only a few studies have addressed clinical outcomes of revision surgery for adjacent segment disease. The purpose of this study was to elucidate clinical outcomes of second (repeat) posterior lumbar interbody fusion (PLIF) by focusing on the relationship between clinical outcomes and spinopelvic parameters and predisposing factors requiring subsequent corrective long fusion after repeat PLIF. METHODS: We analyzed the data of 47 patients ≥40 years old who underwent repeat PLIF after single-segment PLIF owing to adjacent segment disease. The correlation between clinical outcomes and radiographic parameters was investigated. Patient demographics and radiographic parameters were compared between patients with and without subsequent corrective long fusion. RESULTS: Japanese Orthopaedic Association score at final follow-up was 13.4, and the recovery rate was 37.2%. All sagittal parameters except pelvic tilt and C7-central sacral vertical line at final follow-up showed weak to moderate (|r| = 0.30-0.56) correlation with clinical scores. Finally, 11% of patients required subsequent long corrective fusion. Pelvic incidence minus lumbar lordosis (PI-LL) mismatch (cutoff value of 27.5°) and thoracic kyphosis (cutoff value of 12.5°) before repeat PLIF were identified as predisposing factors for subsequent long corrective fusion. CONCLUSIONS: The clinical outcomes of repeat PLIF were inferior to outcomes of primary PLIF. Once PI-LL mismatch occurs after initial PLIF, it will be difficult to resolve the PI-LL mismatch during the second PLIF. To stop the chain of reoperations in patients whose preoperative PI-LL exceeds 27.5° before repeat PLIF, corrective long fusion may be a surgical option to consider.