Indication of posterior lumbar interbody fusion for lumbar disc herniation

OBJECTIVE: To examine whether lumbar disc herniation with massive extrusion and/or segmental instability can be an indicator for spinal fusion or not, by comparing the outcome of posterior lumbar interbody fusion (PLIF) and discectomy alone. METHODS: One hundred seventy-four patients with PLIF and 177 patients with discectomy were retrospectively analyzed. We hypothesized two criteria for fusion: massive herniation and segmental instability. The patients were divided into four groups according to our original criteria: group F-F (n = 96) consisted of the patients who fulfilled the criteria for fusion and underwent PLIF; group nF-F (n = 78) consisted of those who did not fulfill the criteria but had PLIF; group F-nF (n = 30) consisted of those who fulfilled the criteria but underwent discectomy; group nF-nF (n = 147) comprised those who did not fulfill the criteria and underwent discectomy. Each patient was evaluated clinically and radiologically at 5 years after operation. RESULTS: Groups F-F and nF-F had significantly superior results on low back pain compared with group F-nF (F-F vs F-nF, P < 0.05; nF-F vs F-nF, P < 0.01). The frequency of additional operation at the involved level was significantly higher in group F-nF (10.0%) than in group F-F (2.0%) (P < 0.05). Postoperative instability of the adjacent segment developed in 15 cases (8.6%) in groups F-F and nF-F and in 3 cases (1.7%) in groups F-nF and nF-nF (P < 0.01). CONCLUSION: Lumbar disc herniation with massive herniation or segmental instability can be well treated with PLIF.