title: Spinal flexibility increase after chymopapain injection is dose dependent: a possible alternative to anterior release in scoliosis.
abstract: METHODS
  Experimental animal study.
  
  
  OBJECTIVE
  To investigate whether the increase in spinal flexibility after chymopapain injection is dose dependent and determine the "optimal" dosage of chymopapain to increase spinal flexibility in a rabbit model.
  
  
  BACKGROUND
  Spinal instability after chymopapain injection may result in severe back pain. However, this undesired mechanical effect in treating disc herniation may provide a safe minimally invasive approach for anterior spinal release in scoliosis correction.
  
  
  METHODS
  A total of 138 lumbar intervertebral discs from 46 New Zealand white rabbits were randomly injected with chymopapain at 6.25, 12.5, 25, 50, 75, and 100 picokatals (pKats)/0.05 mL/disc. The rabbits were killed 1 week after the injection, and the lateral bending stiffness of the spinal segments without posterior elements was determined.
  
  
  RESULTS
  The lateral bending spinal stiffness showed no significant change after injection of 6.25 and 12.5 pKats/0.05 mL/disc but reduced significantly following chymopapain injection of 25, 50, 75, and 100 pKats (all P < 0.05 by post hoc least significant difference tests). While the lateral bending stiffness was lowest at the 100-pKats dose, there were no significant differences between the four higher dosages.
  
  
  CONCLUSIONS
  The reduction in the lateral bending spinal stiffness after chymopapain injection is dose dependent, and an optimal dosage for spinal release existed; doses greater than the optimal dosage did not result in further significant decrease in lateral bending spinal stiffness.
authors.affiliation: Department of Orthopaedic Surgery, University of Hong Kong, Pokfulam.
authors.forename: D S
authors.initials: DS
authors.lastname: Lu
authors.forename: K D K
authors.initials: KD
authors.lastname: Luk
authors.forename: W W
authors.initials: WW
authors.lastname: Lu
authors.forename: K M C
authors.initials: KM
authors.lastname: Cheung
authors.forename: J C Y
authors.initials: JC
authors.lastname: Leong
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002917:Chymopapain / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007267:Injections; D007403:Intervertebral Disc / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D007404:Intervertebral Disc Chemolysis / Q000379:methods*; D008161:Lumbosacral Region; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D023421:Models, Animal; D018583:Pliability / Q000187:drug effects; D011817:Rabbits; D016059:Range of Motion, Articular / Q000187:drug effects; D012600:Scoliosis / Q000188:drug therapy; D013131:Spine / Q000187:drug effects* / Q000502:physiology*
chemical_list: D002917:Chymopapain