Criteria for surgery in degenerative lumbar disc disease

Purpose of the study To determine predictive factors allowing to improve the results of fusion i n low back pain treatment. Material and method Fifty six patients were retrospectively reviewed. Average age at surgery wa s 42. In 29 cases, discectomy or nucleolysis had been previously performed. All patients were treated by anterior lumbar interbody fusion. Functional results were assessed by the Beaujon index, with determination of a relativ e improvement rate. Results were analyzed according to clinical symptoms, f used level, previous surgery, association to posterior osteosynthesis and M RI changes. MRI changes were classified according to Medic types. Results The average relative improvement rate was 66 per cent. Pain topography, pre vious surgery, fused level, association with posterior osteosynthesis had n ot statistical effect on the functional result. Inversely, a close relation was observed between pre-operative MRI changes and the result of surgery: best results were observed in Medic I changes on adjacent vertebral end pla tes, with decreased signal of T1 and increased signal on T2 weighted images , suggesting inflammatory changes; poor results were observed in isolated disc degeneration without vertebral end-plates changes; poor results were observed in Medic II changes with increased signal on bot h T1 and T2 weighted images, suggesting degenerative changes; but among 5 n on unions, 3 were observed in Medic II changes. Discussion The authors identify a lumbar disc dysfunction syndrome characterized by me chanical pain, with disc narrowing and anterior condensation of the vertebr al plates on MRI (Modic I changes). This syndrom should be differentiated f rom common degenerative disc disease, without vertebral plates abnormalitie s (the "black disc" on MRI). Conclusion Anterior fusion is effective for the treatment of low-back pain due to dege nerative disc disease, when associated to vertebral plate changes; as the p athology is mainly anterior. We prefer an anterior mini-invasive approach; furthermore, posterior elements are intact and canal exploration is unneces sary. However, an additional posterior osteosynthesis is preferable in Medi c type II, as non union rate is increased by fatty degenerative involution.