title: Disc volume reduction with percutaneous nucleoplasty in an animal model.
abstract: METHODS
  We assessed volume following nucleoplasty disc decompression in lower lumbar spines from cadaveric pigs using 7.1Tesla magnetic resonance imaging (MRI).
  
  
  OBJECTIVE
  To investigate coblation-induced volume reductions as a possible mechanism underlying nucleoplasty.
  
  
  METHODS
  We assessed volume following nucleoplastic disc decompression in pig spines using 7.1-Tesla MRI. Volumetry was performed in lumbar discs of 21 postmortem pigs. A preoperative image data set was obtained, volume was determined, and either disc decompression or placebo therapy was performed in a randomized manner. Group 1 (nucleoplasty group) was treated according to the usual nucleoplasty protocol with coblation current applied to 6 channels for 10 seconds each in an application field of 360°; in group 2 (placebo group) the same procedure was performed but without coblation current. After the procedure, a second data set was generated and volumes calculated and matched with the preoperative measurements in a blinded manner. To analyze the effectiveness of nucleoplasty, volumes between treatment and placebo groups were compared.
  
  
  RESULTS
  The average preoperative nucleus volume was 0.994 ml (SD: 0.298 ml). In the nucleoplasty group (n = 21) volume was reduced by an average of 0.087 ml (SD: 0.110 ml) or 7.14%. In the placebo group (n = 21) volume was increased by an average of 0.075 ml (SD: 0.075 ml) or 8.94%. The average nucleoplasty-induced volume reduction was 0.162 ml (SD: 0.124 ml) or 16.08%. Volume reduction in lumbar discs was significant in favor of the nucleoplasty group (p<0.0001).
  
  
  CONCLUSIONS
  Our study demonstrates that nucleoplasty has a volume-reducing effect on the lumbar nucleus pulposus in an animal model. Furthermore, we show the volume reduction to be a coblation effect of nucleoplasty in porcine discs.
authors.affiliation: Clinic and Outpatient Clinic for Orthopedics and Orthopedic Surgery, Greifswald University Medicine, Greifswald, Germany. richard.kasch@uni-greifswald.de
authors.forename: Richard
authors.initials: R
authors.lastname: Kasch
authors.forename: Birger
authors.initials: B
authors.lastname: Mensel
authors.forename: Florian
authors.initials: F
authors.lastname: Schmidt
authors.forename: Sebastian
authors.initials: S
authors.lastname: Ruetten
authors.forename: Thomas
authors.initials: T
authors.lastname: Barz
authors.forename: Susanne
authors.initials: S
authors.lastname: Froehlich
authors.forename: Rebecca
authors.initials: R
authors.lastname: Seipel
authors.forename: Harry R
authors.initials: HR
authors.lastname: Merk
authors.forename: Ralph
authors.initials: R
authors.lastname: Kayser
mesh_terms: D000818:Animals; D017587:Diskectomy, Percutaneous / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D023421:Models, Animal; D015233:Models, Statistical; D009985:Orthopedics / Q000379:methods; D010919:Placebos; D013552:Swine; D016896:Treatment Outcome
chemical_list: D010919:Placebos