Adoption of Intraoperative Mechanomyography as a Spinal Decompression Endpoint: A Single-Surgeon Comparison by Era

ABSTRACT Background Intraoperative adequacy of spinal decompression is typically judged by visual inspection and tactile assessment rather than objective physiologic confirmation, leaving no objective endpoint for completion. We compared outcomes before and after a single surgeon adopted routine intraoperative mechanomyography (MMG). Methods In this retrospective single-surgeon, single-institution, era-based cohort, 600 consecutive adult spinal decompression patients were analyzed: 300 before adoption and 300 after stable 100% MMG utilization. The pre-adoption era used visual and tactile assessment; the post-adoption era used MMG threshold-guided decompression targeted at ≤2.0 mA. The primary endpoint was 90-day unplanned return to the operating room (RTOR); confirmatory endpoints were incidental durotomy and 3-month pain. Adjusted regression controlled for demographic and procedural covariates; a post hoc classification distinguished decompression-related from non-decompression RTOR, with sparse subcategories analyzed by Fisher exact tests and a multinomial interaction test. Results RTOR decreased from 29/300 (9.7%) to 8/300 (2.7%; adjusted OR 0.245, 95% CI 0.106–0.566, p=0.001). Decompression-related RTOR decreased from 4.7% to 1.0% (p=0.012) and non-decompression RTOR from 5.0% to 1.7% (p=0.038); the differential reduction was not significant (interaction p=0.590). Durotomy decreased from 9.7% to 2.3% (adjusted OR 0.246, p=0.002), mean 3-month pain from 4.91 to 1.93 (adjusted β −3.09, p<0.001), and treatment non-response from 45.7% to 7.3%. Conclusions Routine MMG adoption was associated with lower RTOR, durotomy, pain, and treatment non-response. Because non-decompression RTOR also decreased and case volume doubled between eras, causal attribution to MMG alone is not possible. These findings are hypothesis-generating and support prospective multicenter validation with patient-level threshold capture.