The aim of our retrospective study was to evaluate the efficacy of interstitial laser photocoagulation for the treatment of osteoid osteomas and to identify the factors leading to failure of the procedure.

Thirty-five patients received interstitial laser photocoagulation treatment. A minimum of 3months follow-up was required. The laser fibre was positioned within the nidus under CT guidance, and energy between 500 and 1800J was delivered at a power of 2 Watts/s. Follow-up was by outpatient appointment and through a questionnaire sent to the patients.

Thirty patients replied to the questionnaire. Mean follow-up was 40months. The technical success rate was 100%. The primary success rate (no pain at 1month) was 94.3%. The rate of recurrence was 6%. The rate of complications was 11.4% (a skin burn, patellar enthesopathy, a broken item of material, sacro-iliac fibrous alterations). Factors likely to favour failure of the procedure are the size of the nidus (P=0.04) and poor positioning of the laser fibre (P=0.03).

Interstitial laser photocoagulation is an effective and safe treatment for osteoid osteomas.