Long-term outcome analysis of standard discectomy for lumbar disc protrusion and its influencing factors

Objective To appraise the long-term outcomes of standard discectomy for lumbar disc protrusion and to analyze the related factors. Methods We retrospectively studied 82 cases of nonspecific lumbar disc protrusion which involved single segment. All of them were treated with simple standard discectomy during February 1996-May 1999. The follow-up duration was 84-123 months, averagely (103. 3±11. 7) months. The following parameters was recorded: Body Mass Index(BMI) , occupation, diabetic history, pathological types of protruded lumbar disc and the number of recurrent disc protrusion at the final follow-up. Using X-ray and MRI techniques, we studied the disc-vertebra height ratio and the pathological types of protruded lumbar disc. The respective scales of Japanese Orthopedics Association(JOA) and VAS(low back pain/sciatica) before operation and at final follow-up and the modified Macnab's clinical outcomes were also recorded. Results The average scales before operation were as follow: JOA 6. 5±1. 3(5-9), VAS of low back pain 4. 8±0. 5(0-8), VAS of sciatica 7. 2±0. 5(4-10), at the final follow-up, the above parameters were 13. 2±1. 8(10-14), 1. 8±0. 3 (0-10) and 1. 2±0. 2(0-7), respectively. The average improvement rate of JOA scale was (78. 8±10. 3)%. Before operation, there were 62 cases of contained disc protrusion and 20 cases of uncontained disc protrusion at the MRI films. At the final follow-up, there were 7 cases of recurrent disc protrusion. At the first operation, all patients had disc protrusions at the final follow-up, 7 cases had recurrent disc protrusion, including 5 cases at L4-L5 , one each at L3-L4 and L5-S1 level, res- pectively. The final excellent rate was 80%(by modified Macnab method). Conclusions With strict surgical indication, good long-term outcomes could be expected with standard discectomy. The relative high BMI, strenuous work or sedentary posture, history of diabetes, early disc degeneration as well as the narrow disc height after operation can affect the long-term outcome. The post-operative improvement on sciatica is better than that on low back pain. Recurrent disc protrusion is found more at the L4-L5 level and /or in cases of disc protrusion. (Shanghai Med J, 2007, 30:336-339)