title: Safety of lumbar spine radiofrequency procedures in the presence of posterior pedicle screws: technical report of a cadaver study.
abstract: OBJECTIVE
  To determine whether the thermal energy associated with lumbar spine radiofrequency neurotomy (RFN) performed near titanium and stainless steel pedicle screws is conducted to the pedicle screws or adjacent tissues, or both, thus introducing potential for thermal damage to those tissues.
  
  
  METHODS
  Cadaver study.
  
  
  METHODS
  Cadaver laboratory equipped with fluoroscopy, surgical spine implements, and radiofrequency generator.
  
  
  METHODS
  No live human subject; a fresh frozen (and thawed) cadaver torso was used for the study.
  
  
  METHODS
  Titanium and stainless steel pedicle screws were placed in the lumbar spine of a fresh frozen cadaver torso with real-time fluoroscopic guidance. Conventional RFN cannula placement was performed at the level of pedicle screws and a control (nonsurgically altered) lumbar level. Neurotomy was performed with conventional radiofrequency lesioning parameters. Temperatures were recorded at multiple sites through thermistor probes.
  
  
  RESULTS
  Direct contact of the radiofrequency cannula with the pedicle screws during conventional RFN produced a substantial increase in temperature in the surrounding soft tissues. A small increase in temperature occurred at the same sites at the control level.
  
  
  CONCLUSIONS
  Titanium and stainless steel pedicle screws are capable of sustaining large increases in temperature when the radiofrequency probe comes in contact with the screw. These results are suggestive that pedicle screws could serve as a possible source of tissue heating and thermal injury during RFN.
authors.affiliation: Division of Pain Medicine.
authors.forename: Halena M
authors.initials: HM
authors.lastname: Gazelka
authors.affiliation: Department of Anesthesiology.
authors.forename: Tasha L
authors.initials: TL
authors.lastname: Welch
authors.affiliation: Division of Orthopedic Spine Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Nassr
authors.affiliation: Division of Pain Medicine.
authors.forename: Tim J
authors.initials: TJ
authors.lastname: Lamer
mesh_terms: D001863:Bone Screws; D002102:Cadaver; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D003714:Denervation / Q000009:adverse effects / Q000379:methods; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*
keywords: Facet Radiofrequency; Pedicle Screws; Radiofrequency; Radiofrequency Neurotomy; Spine Instrumentation