CT-guided obturator nerve block for diagnosis and treatment of painful conditions of the hip

Obturator nerve blocks (ONB) have been performed by anaesthesiologists mainly to eliminate the obturator reflex during transurethral resections. An effect on hip pain has also been described. However, being a time-consuming and operator-dependent procedure if performed manually, it has not been widely used for chronic hip pain. The purpose of this pilot study was to check whether CT guidance could improve reproducibility of the block (= immediate effect) and to test its potential value for treatment of chronic hip pain. Fifteen chronically ill patients with osteoarthritis underwent a single ONE. Sixteen millilitres of Lidocaine 1% mixed with 2 ml Iopramide was injected into the obturator canal. The patients were followed up to 9 months after the intervention. With a single injection pain relief was achieved for 1-8 weeks in 7 of 15 patients. Excellent pain relief for 3-11 months was achieved in another 4 patients. Reasons for a midterm or even long-term effect based on a single injection of local anaesthetic are not exactly known. The CT-guided ONE is a fast, easy and safe procedure that may be useful for mid-term (weeks) and sometimes even long-term (months) treatment of hip pain.