(637) Intradiskal Electrothermal Anuloplasty (IDET) to Treat Discogenic Low Back Pain: Preliminary Results of a Multi‐Center Prospective Trial

Authors: F. Todd Wetzel, University of Chicago Spine Center; Gunnar Andersson; Casey Lee; Hansen Yuan; Ralph Rashbaum; John Peloza; Frank Phillips Mechanical low back pain on the basis of degenerative disc disease remains difficult to treat. Conservative care, with varying reports of efficacy, is limited to pharmacotherapy and physical therapy. Invasive options have traditionally been limited to spinal arthrodesis. While newer techniques such as laparoscopic arthrodesis have made this alternative less invasive, a substantial gap in the treatment continuum exists nonetheless. Application of thermal energy to the disc may alter collagen structure, and, theoretically, biomechanics, and perform a functional deafferentation on the disc. A percutaneous extradual catheter technique utilizing this principle has been developed. It is the purpose of this study to report the preliminary results of this new technique, Intradiskal Electrothermal Anuloplasty (IDET), to treat patients with intractable low back pain, who otherwise would have been candidates for spinal fusion. Materials and Methods: A total of 74 patients were entered in a prospective multi‐institution study. Criteria for entrance included failure of conservative care, at least 3 months of back pain, and symptomatic degenerative disc disease as suggested by MRI and confirmed by provocative discography. Patients with prior surgery were excluded. Patients with greater than 2‐level disease were excluded. All patients have had axial pain as their primary complaint, although most did have components of nonradicular referred pain. All patients underwent MRI, or had MRI within 3 months of study enrollment. All revealed degenerative disc disease without evidence of significant disc prolapse or central canal stenosis. Discograms were graded according to morphology and pain production. Stringent concordance with presenting pain complaints were required for a discogram to be graded positive. All patients were taken to the Operating Room, and under monitored anesthesia care, intradiskal electrotheramal anuloplasty performed. Standard Indices were used for postoperative evaluation. At 6 months, complete data were present on 65 patients. It is this subset that will be reported. Major parameters analyzed included adverse events, pain, quality of life (as determined by American Academy of Orthopedic Surgery Questionnaire), sitting ability, working ability, and medication use. Minor parameters included findings on clinical examination and procedural information. Results: 120 levels were treated in 65 patients. 32 patients received 2‐level treatment with 33 receiving 1‐level treatment. The average intradiskal temperature achieved was 88.3°F with a range of 75°F to 95°F. Average procedure time was 69.5 minutes with a range of 15–160 minutes. Four adverse outcomes may have been related to the catheter technique. All involved posttreatment lower extremity pain different in character from that experienced preoperatively. In two cases this may have been related to catheter position (3%). Additionally, there were 8 failures of treatment (12.3%). Four of these patients went on to interbody fusion, and one to a DAS drug infusion system; one patient was not able to be followed up due to noncompliance. Mean VAS preoperatively was 6.2; this decreased to 4.0 postoperatively ( P <.05). At 6 months, 69% of patients were working, versus 58% at time 0. Patients also reported less interference with work due to pain. Sitting ability (0 = unable, to 100 = no restriction) increased from 46 to 64 ( P <.05). Walking ability also increased at 6 months following IDET, with 85% noting no limitations in walking ability (vs 26 % pretreatment, <.05). Discussion: Preliminary results of the intradiskal electrothermal anuloplasty seem to support a positive role for this procedure in the treatment of discogenic low back pain. The initial rate of failure is 12.3%. Improvement in sitting scores, which would be expected in the successful treatment of discogenic low back pain tend to support efficacy. Additionally, the apparent functional benefit in terms of ability to work suggests a positive therapeutic affect. The specific mechanism of action (biomechanical, deafferentation, or a combination) remains imprecisely delineated. The complication rate appears to be acceptable. Further follow‐up, in order to refine selection criteria, and define efficacy is required.