F. Todd Wetzel, MD, Gunnar B.J. Andersson, MD, Chicago, IL, USA; John H. Peloza, MD, Dallas, TX, USA; Ralph F. Rashbaum, MD, Plano, TX, USA; Casey K. Lee, MD, Roseland, NJ, USA; Hansen A. Yuan, MD, Syracuse, NY, USA; Frank M. Phillips, MD, Howard S. An, MD, Chicago, IL, USAIntroduction: Low back pain on the basis of degenerative disc disease is difficult to treat. No particular conservative strategy has been shown to be effective. Invasive options have been limited to spinal arthrodesis. Application of the thermal energy to the disc alters collagen structure and may perform a functional deafferentation on the disc. The technique of Intradiscal Electrothermal Therapy (IDET; ORATEC Interventions, Inc.) uses this principle to treat patients with intractable low back pain. This multicenter, prospective cohort study was initiated in 1998 to evaluate the effectiveness of IDET on patients who otherwise would have been fusion candidates. This is a report of the 2-year outcomes associated with this study.Materials and methods: A total of 78 patients were entered in the intent-to-treat group in a prospective multiinstitution cohort study. The inclusion criteria were predominant low back pain, persistence of symptoms for more than 3 months and failure of at least 6 weeks of conservative care. Exclusion criteria were sequestered disc herniation, greater than two levels of symptomatic degenerative disc disease, spinal stenosis, spondylolisthesis or previous surgery at the treated level. All patients underwent a standard clinical evaluation, including physical examination, planar X-rays, magnetic resonance imaging (MRI) or had MRI within 6 months of study enrollment. All patients underwent provocative discography. Discograms were graded according to morphology and pain production. Procedures were performed on an outpatient basis under monitored anesthesia and biplanar fluoroscopy. Thermal treatment was administered according to standardized protocols. Standard, validated indexes were used for pre- and postoperative evaluations: a Visual Analog Scale (VAS), the American Academy of Orthopaedic Surgeons lumbar spine instrument and the SF-36 Health Survey. Patients were assessed before treatment and at 1 month, 3 months, 6 months, 1 year and 2 years after treatment. Matched-pair statistical testing was used to assess the changes in patient outcomes from pretreatment to each posttreatment.Results: Two patients were withdrawn from the study for various reasons. Seventy-five percent were available for 2-year follow-up. Among these patients, who were originally fusion candidates, only 18% required additional back surgery. Seventy-four percent had a single disc treated, and 26% had two levels treated. At 2 years posttreatment, 88% of the patients reported they would “definitely” or “probably” choose the same treatment for their back surgery. Sixty-one percent of the patients reported they were performing 100% of their job at 2 years after IDET compared with 23% before treatment. A total of 8.7% reported they were performing 50% or less of their job at 2 years after treatment compared with 38% before treatment (Tables 1 and 2)Table 1OutcomePre-IDET12 monthsChange from pre-IDETp ValueVAS5.3 ± 2.33.3 ± 2.7−2.3 ± 2.9.0071SF-36Physical Function4.0 ± 23.666.4 ± 24.522.0 ± 23.7.0008Bodily Pain30.5 ± 15.953.0 ± 23.022.8 ± 24.3.0007Role Physical24.1 ± 38.854.9 ± 41.036.8 ± 56.7.0111Role Emotional60.9 ± 41.577.2 ± 40.112.3 ± 52.4.3202Social Function55.4 ± 26.977.0 ± 20.923.0 ± 37.6.0155General Health72.6 ± 18.679.4 ± 23.66.6 ± 13.1.0415Mental Health64.4 ± 20.173.3 ± 13.711.7 ± 15.4.0039Vitality40.8 ± 22.756.2 ± 23.016.1 ± 23.0.0009Table 2OutcomePre-IDET24 monthsChange from pre-IDETp ValueVAS5.3 ± 2.32.5 ± 2.626 ± 2.5<.0001SF-36Physical Function4.0 ± 23.672.1 ± 27.027.5 ± 25.2<.0001Bodily Pain30.5 ± 15.963.1 ± 25.030.8 ± 21.0<.0001Role Physical24.1 ± 38.870.0 ± 41.741.7 ± 45.2.0002Role Emotional60.9 ± 41.584.7 ± 34.011.1 ± 49.8.2857Social Function55.4 ± 26.983.3 ± 26.224.5 ± 28.7.0004General Health72.6 ± 18.67.4 ± 24.35.7 ± 16.8.1130Mental Health64.4 ± 20.175.0 ± 22.89.2 ± 17.5.0169Vitality40.8 ± 22.763.3 ± 23.210.8 ± 25.3.0009.Conclusion: Within the limitations of study design, these data support that IDET may be a viable treatment for patients with degenerative disc disease previously thought to be fusion candidates. Improvements in pain, physical function and overall quality of life is observed at 12 months after IDET and maintained through 24 months.