The following is the summary of “Biomechanics of Transforaminal Endoscopic Approaches” published in the December 2022 issue of spine by Farshad,  et al.

Research on the mechanics of dead bodies. This research set out to assess transforaminal endoscopic approaches versus open decompression procedures for their efficacy. Even though endoscopic decompression is beneficial in numerous clinical studies, its biomechanical effects (both with and without disk injury) have not been investigated until now. In a load-controlled endoscopic transforaminal approach study, biomechanical testing was performed on 12 spinal segments taken from 4 fresh-frozen cadavers. Endoscopic approach segmental ROM was compared to microsurgical decompression with unilateral laminotomy and midline decompression with bilateral laminotomy. Segments were subjected to flexion-extension (FE), lateral shear (LS), lateral bending (LB), anterior shear (AS), and axial rotation (AR) loading in their natural state and after decompression.

When comparing the 2 endoscopic transforaminal techniques, the range of motion(ROM) of the vertebral segments was similar. There was, however, a trend toward a larger ROM after accessing from the inside-out: There was no statistically significant difference between the means (FE+3% vs. +7%, P=0.484; LS+1% vs. +12%, P=0.18; LB+0.6% vs. +9%, P=0.18), means (AS+2% vs. +11%), or probabilities (AR4% vs. +5%, P=0.18). No statistically significant difference in range of motion (ROM) of vertebral segments was observed between transforaminal vertebral segments’ the endoscopic approaches and open unilateral decompression. 

Vertebral segment ROM was significantly smaller with the transforaminal endoscopic approaches compared with midline decompression for almost all loading scenarios: FE: +4% versus +17%, P=0.005; AS: +6% versus 21%, P=0.007; AR: 0% versus +24%, P=0.002. The transforaminal endoscopic intracanal technique preserves the native ROM of lumbar vertebral segments and shows a trend toward relative biomechanical superiority over the inside-out technique and open decompression procedures.