Is Kambin's Triangle Safe or Not for Percutaneous Endoscopic Transforaminal Oblique Fixation from the Posterior Corner in the Lumbar Spine: A Neuroimaging Anatomic Assessment.

BACKGROUND:Nerve root injury and dural tears are important complications in endoscopic spine techniques. Whether Kambin's triangle is safe or not is unknown for percutaneous endoscopic transforaminal oblique fixation from the posterior corner (PETOFPC) in lumbar spine. This study aimed to verify neural safety of PETOFPC and to define and evaluate the ideal operating target and actual safe working area in Kambin's triangle for PETOFPC. METHODS:Lumbar magnetic resonance imaging was performed in 60 outpatients. The distances from the working targets to exiting nerve roots and dural sac/traversing nerve roots in the coronal and sagittal planes (c1-c6, s1-s6) and the distances from the exiting roots to the dural sac/traversing nerve roots in the upper and lower endplate planes (d1 and d2) were measured and statistically analyzed. RESULTS:All coronal planes (c1-c6) first increased and then decreased; they gradually increased from L1-2, maximized in L4-5, and decreased slightly in L5-S1. In L1-2 through L5-S1, d1 and d2 gradually increased (F = 249.7, P < 0.0001; F = 511.7, P < 0.0001), d2 > d1 (P < 0.05). Values of d1 and d2 were smallest in L1-2 (6.71 ± 2.10 mm and 11.89 ± 2.55 mm) and largest in L5-S1 (13.37 ± 4.09 mm and 22.05 ± 3.96 mm). With the outward shift of the targets in the sagittal plane, both s1, s3, s5 and s2, s4, s6 gradually decreased (s1 > s3 > s5, s2 > s4 > s6). CONCLUSIONS:We calculated the ideal operating target and actual safe area and further proved that Kambin's triangle is safe enough for PETOFPC. PETOFPC is a promising technology and may have great clinical significance.