title: Laparoscopic assisted fusion of the lumbosacral spine. A biomechanical and histologic analysis of the open versus laparoscopic technique in an animal model.
abstract: METHODS
  An animal model for laparoscopic lumbosacral fusion.
  
  
  OBJECTIVE
  To compare the biomechanical and histologic results of open to laparoscopic lumbosacral discectomy and fusion in an animal model.
  
  
  BACKGROUND
  Early clinical reports of laparoscopic lumbosacral fusions are encouraging, but animal experiments have not been reported.
  
  
  METHODS
  Ten pigs (50-80 kg) were divided into two groups. Group 1 underwent an open anterior lumbosacral discectomy and fusion at L7-S1 using autologous bone graft and a titanium MOSS (DePuy Motech) cage. Group 2 was identical to Group 1 except that a laparoscopic technique was used. The animals were killed at 3 months, and the lumbosacral spines were harvested for biomechanical and histologic testing.
  
  
  RESULTS
  Estimated blood loss and average length of operation, respectively, for the two groups were: Group 1, 50 mL, 2 hours 50 minutes; and Group 2, 40 mL, 3 hours 40 minutes. There were no perioperative or postoperative complications in either group. Motion analysis results showed less motion in lateral bending, flexion, and extension than in the intact specimen in both groups. Tensile testing showed that the stiffness was significantly greater in the open group than in the laparoscopic group (P < 0.004). Histologic examination showed a less extensive discectomy and less bone growth in the implant in the laparoscopic group. Inadequate decortication of end-plates occurred in two animals who underwent laparoscopy.
  
  
  CONCLUSIONS
  Although lumbosacral discectomy and implant insertion can be performed using the laparoscopic technique, the construct may not have the same biomechanical strength as that attained with the open procedure. Laparoscopic-assisted lumbosacral fusion surgery requires additional investigation before it is widely used in clinical situations.
authors.affiliation: Department of Orthopaedic Surgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Riley
authors.forename: J C
authors.initials: JC
authors.lastname: Eck
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: J M
authors.initials: JM
authors.lastname: Toth
authors.forename: C
authors.initials: C
authors.lastname: Nguyen
authors.forename: T H
authors.initials: TH
authors.lastname: Lim
authors.forename: L M
authors.initials: LM
authors.lastname: McGrady
mesh_terms: D000818:Animals; D016063:Blood Loss, Surgical; D016025:Bone Transplantation; D017586:Diskectomy / Q000379:methods*; D007403:Intervertebral Disc / Q000473:pathology; D010535:Laparoscopy; D008159:Lumbar Vertebrae / Q000473:pathology / Q000601:surgery*; D019736:Prostheses and Implants; D012447:Sacrum / Q000473:pathology / Q000601:surgery*; D013123:Spinal Fusion / Q000379:methods*; D013314:Stress, Mechanical; D013552:Swine; D013997:Time Factors