The quantitative analysis of tissue injury markers after mini-open lumbar fusion

Study Design. A prospective and comparative analysis of tissue injury after mini-open lumbar fusion and conventional technique. Objective. To evaluate the tissue injury quantitatively after mini-open lumbar fusion. Summary of Background Data. The advantages of minimally invasive techniques demonstrated by clinical reports have been a smaller scar, lesser pain, and rapid rehabilitation. It has not been established, however, that the minimally invasive technique has less tissue injury and less systemic response than the conventional spine surgery. Methods. Twenty patients who had undergone posterior decompression and the fusion of the L4-L5 segment for spinal stenosis were studied prospectively. Ten patients that had the conventional posterior decompression and posterior lumbar interbody fusion (PLIF) at L4-L5 were enrolled in a control group. The remaining 10 patients who underwent MISS techniques (paramedian mini-open approach using a tubular retractor) were enrolled in a study group. The serum enzymes representing skeletal muscle injury (creatinine kinase and aldolase), pro-inflammatory cytokines (IL-6, IL-8), and anti-inflammatory cytokines (IL-10, IL-1 receptor antagonist) were analyzed with ELISA techniques. They were checked on the day before operation and 1, 3, 7, and 14 days after operation. Results. Serum creatinine kinase and most of the inflammatory cytokines were significantly high in the control group on postoperative days 1 and 3 and returned to the normal level on postoperative day 7. Serum aldolase was significantly high on postoperative day 1, and IL-8 remained elevated until postoperative day 7 in the control group. Conclusion. Mini-open lumbar fusion may significantly contribute to the reduction of muscle injury and systemic inflammatory reactions during the acute postoperative period. This study suggests that mini-open lumbar fusion may also play an important role in preventing medical morbidity after spinal surgery.