Morphometric analysis of the working zone for endoscopic lumbar discectomy.
OBJECTIVE
Our study's purpose was to analyze the working zone for the current practice of endoscopic discectomy at the lateral exit zone of the intervertebral foramen (IVF) and to define a safe point for clinical practice.


METHODS
One hundred eighty-six nerve roots of the lumbar IVFs of cadaveric spines were studied. Upon lateral inspection, we measured the distance from the nerve root to the most dorsolateral margin of the disc and to the lateral edge of the superior articular process of the vertebra below at the plane of the superior endplate of the vertebra below. The angle between the root and the plane of the disc was also measured.


RESULTS
The results showed that the mean distance from the nerve root to the most dorsolateral margin of the disc was 3.4 +/- 2.7 mm (range 0.0-10.8 mm), the mean distance from the nerve root to the lateral edge of the superior articular process of the vertebra below was 11.6 +/- 4.6 mm (range 4.1-24.3 mm), and the mean angle between the nerve root and the plane of the disc was 79.1 degrees +/- 7.6 degrees (range 56.0-90.0 degrees ).


CONCLUSIONS
The values of the base of the working zone have a wide distribution. Blind puncture of annulus by the working cannula or obturator may be dangerous. The safer procedure would be the direct viewing of the annulus by endoscopy before annulotomy; the working cannula should be inserted into the foramen as close as possible to the facet joint.
Min
Jun-Hong
JH
Department of Neurosurgery, College of Medicine, Korea University, Seoul, Korea.
Kang
Shin-Hyuk
SH
Lee
Jang-Bo
JB
Cho
Tai-Hyoung
TH
Suh
Jung-Keun
JK
Rhyu
Im-Joo
IJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001837:Body Weights and Measures; D017587:Diskectomy, Percutaneous / Q000379:methods / Q000592:standards*; D004724:Endoscopy / Q000379:methods / Q000592:standards*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000033:anatomy & histology* / Q000473:pathology / Q000601:surgery; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control; D008159:Lumbar Vertebrae / Q000033:anatomy & histology* / Q000473:pathology / Q000601:surgery; D008297:Male; D008488:Medical Illustration; D008875:Middle Aged; D013126:Spinal Nerve Roots / Q000033:anatomy & histology / Q000601:surgery; D021801:Zygapophyseal Joint / Q000033:anatomy & histology / Q000601:surgery