Atrofia paraespinal postoperatoria. ¿El abordaje importa?

OBJECTIVE: To compare the level of post-op muscle atrophy related to the different approaches used in segmental lumbar fusion for degenerative disease (midline vs. Wiltse vs. MIS TLIF). MATERIALS AND METHODS: An observational, cross sectional, multicenter, descriptive and retrospective study was performed including a series of patients undergoing surgery for lumbar degenerative disease. We analyzed 45 patients (24 females), with a mean age of 58.7 years, undergoing surgery in 5 surgical centers between 2015 and 2018. A one-level instrumented fusion, from L3 to S1 was performed (7 cases L3-L4, 25 cases L4-L5 and 13 cases L5-S1). In 15 cases, a midline approach was used; in 15, a Wiltse approach was used, and in 15 cases, an MIS TLIF approach was used. All the patients were studied preoperatively and for at least 6 months after surgery (mean follow-up 14.6 months) with magnetic resonance imaging. The images were analyzed by three specialists in spine surgery. Two variables were considered to compare the level of atrophy before and after surgery: cross-sectional area (CSA) of the multifidus muscle (MM) and spinal erector muscles (SEM) and the fat infiltration level (FI) using the Kjaer visual classification. The analyses were conducted using the RStudio (1.1.383 version) statistical software, and the P values obtained were compared using the Wilcoxon rank-sum test. RESULTS: No significant differences were found between the approaches in terms of MM atrophy. The comparison of P for CSA and the SEM evidenced differences between MIS TLIF versus midline (P = 0.018) and midline versus Wiltse (P = 0.027). CONCLUSION: The minimally invasive approaches used for decompression and lumbar monosegmental arthrodesis had more impact on the EMs than on the MM. Randomized controlled trials might be useful to validate the results of this investigation.