title: Comparison of the invasiveness of conventional discectomy and microendoscopic discectomy for lumbar disc herniation: Differences in the methods of approach.
abstract: BACKGROUND
  The aim of this study was to investigate whether differences in the methods of approach to the vertebral arch influence the invasiveness of conventional discectomy and microendoscopic discectomy (MED).
  
  
  METHODS
  In this study, 41 Wistar rats were divided into four groups: controls (no surgery) (n = 10), shams (skin incision only) (n = 11), MED (n = 10), and conventional discectomy (n = 10). We performed ethological and blood biochemical examinations for three of the groups, excluding the control group, and a histological examination for three of the groups, excluding the sham group. In the ethological examination, we measured the threshold of postoperative pain using the von Frey test. In the blood chemical examination, we measured blood creatine phosphokinase and inflammatory cytokines, and compared the severity of tissue damage by histological examination using hematoxylin-eosin and immunohistochemical staining.
  
  
  RESULTS
  The conventional discectomy group showed a significantly lower threshold of postoperative pain, compared with the MED group (P < 0.05). Blood biochemical investigation revealed that the creatine phosphokinase (P < 0.05) and tumor necrosis factor-α levels (P < 0.05) of the conventional discectomy group were significantly higher than those in the MED group. In the histological examination, it was found that a wide range of paraspinal muscle damage occurred in the conventional discectomy group (P < 0.05) and that the damage was mostly confined to the periosteum and nearby nerve endings.
  
  
  CONCLUSIONS
  MED was found to be less invasive than conventional discectomy based on ethological, blood biochemical, and histological examinations.
authors.affiliation: Department of Orthopaedic Surgery, Toho University School of Medicine, Tokyo, Japan.
authors.forename: Manabu
authors.initials: M
authors.lastname: Hara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Yuichirou
authors.initials: Y
authors.lastname: Yokoyama
authors.forename: Akihito
authors.initials: A
authors.lastname: Wada
authors.forename: Keiji
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Iida
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D017586:Diskectomy / Q000379:methods*; D004724:Endoscopy / Q000379:methods*; D007405:Intervertebral Disc Displacement / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery; D008297:Male; D008866:Microsurgery / Q000379:methods*; D011183:Postoperative Complications; D051381:Rats; D017208:Rats, Wistar
keywords: Conventional discectomy; microendoscopic discectomy; operative invasiveness