Intradiscal electrothermal therapy (IDET) for chronic low back pain in active-duty soldiers: 2-year follow-up

Background context: Intradiscal electrothermal therapy (IDET) is a new treatment option for chronic discogenic low back pain that is minimally invasive and has demonstrated success rates equal to or better than those for spinal fusion at short-term follow-up. Purpose: To report our experience with IDET in the management of chronic discogenic low back pain in active-duty soldiers. Study design: Consecutive case series at a US Army medical center. Outcome measures: The primary outcome measured was a reported 50% or greater reduction in pain at latest follow-up. Additional outcomes measured included analog pain scores, satisfaction, complications, duty status and subsequent spinal surgery. Methods: Between 1999 and 2001, 41 active-duty soldiers (34 men, 7 women) underwent IDET for chronic discogenic low back pain unresponsive to nonoperative therapy. Data were collected through clinic chart review and follow-up questionnaires. Success was defined as a stated "50% decrease in pain" from baseline. Results: During the study period, 36 of 41 patients underwent a single trial of IDET, and the remaining 5 underwent two trials of IDET. Only the results of the 36 patients who underwent one trial of IDET were used for statistical analysis. All 36 patients were available for follow-up at 6 months, whereas only 31 patients (86%) were reached for final follow-up (average, 29.7 months; range, 24 to 46). The success rate was 47% (17 of 36) at 6 months and 16% (5 of 31 patients) at latest follow-up. Although overall success rates were low, 20 of 31 soldiers (65%) had a persistent decrease in their analog pain score (average decrease of 2.5±1.6 on a 10-point scale), with 52% having 2-point or greater decrease. Nineteen of 31 soldiers (61%) were still on active duty at a minimum of 24 months after IDET. There were five transient complications (16%) from IDET, all reported within the first month. Seven of 31 soldiers (23%), all male, went on to spinal surgery within 24 months of failed IDET. Conclusions: IDET is not a substitute for spinal fusion in the treatment of chronic discogenic low back pain in active-duty soldiers. Our reasonable early results diminished with time and up to 20% of patients report worsening of baseline symptoms at final follow-up. IDET will prove its role in the treatment of chronic discogenic low back pain as more outcome data are obtained, but for now we consider it, at best, an antecedent rather than alternative to spinal fusion.