CT-guided obturator nerve block via the posterior approach

Objective: To describe the technique of obturator nerve block under CT guidance via the posterior approach, and to evaluate the efficacy of the procedure in the short-term and mid-term relief of chronic hip pain. Design and Patients: Consecutive patients referred for obturator nerve block were prospectively enrolled in this study. Under CT-guidance, via a posterior approach through the pelvis, local anaesthetic and steroid were infiltrated around the obturator nerve using a 22G spinal needle. Fifty-one patients (19 male, 32 female), mean age 54 years, with hip pain refractory to conventional therapy underwent the procedure. Visual Analogue Scale pain scores were recorded before the procedure and at 30 minutes, 24 hours, 1 week and 3 months thereafter. Results: Pain scores within 30 minutes showed a decrease from a mean +/- SD score of 8.41 +/- 1.22 pre-procedure to 2.86 +/- 2.1, p < 0.001. At 24 hours, the mean pain score was 2.06 +/- 1.76, a decrease of 76% from pre-procedural score, p < 0.001. Sustained pain relief at 1 week and 3 months was attained in 92% (mean pain score 2.41 +/- 2.2, p < 0.001) and 82% (mean pain score 3.80 +/- 2.94, p < 0.001) of cases respectively. Follow-up data was complete for all 51 patients. No serious side-effects were reported. Conclusions: In patients with hip pain refractory to conventional pain control measures, CT-guided obturator nerve block can provide relief from pain in the short to medium term. The posterior approach offers safe, reliable and effective access to the nerve, in a procedure which is well-tolerated by the patient.