BackgroundOsteoid osteoma (OO) is a readily treatable, painful benign bone tumor that preferentially afflicts young patients. Computed tomography (CT)-guided percutaneous radiofrequency ablation (RFA) treatment has been accepted since 1992 as a noticeably safe and minimally invasive treatment option for OO.ObjectiveTo prospectively analyze the factors that may affect time to pain relief post CT-guided percutaneous RFA treatment of OO. These factors include patient’s age, sex, amount of sclerosis surrounding the nidus, the relation to nearby joint and the number of muscles that have to be traversed.Materials and methodsThis study was conducted on 30 patients diagnosed to have OO on the basis of clinical and radiological criteria. All patients were treated by CT-guided percutaneous RFA. Pain was evaluated after the procedure daily for one week using a visual analogue scale (VAS) with 0 denoting no pain and 10 the worst pain imaginable. Moreover, time to pain relief was analyzed in relation to patient’s age and sex, the amount of sclerosis surrounding the nidus, the relation to nearby joint and the number of muscles that have to be traversed to reach the lesion.ResultsThere was a highly significant statistical difference (p=0.001) between the mean time to pain relief in OOs with variable amount of sclerosis surrounding the nidus. On the contrary, there was no significant statistical difference considering patient’s sex (p=0.654), relation to nearby joint (p=1.0) or number of muscles that have to be traversed (p=0.108) in relation to time to pain relief. Considering patient’s age, there was a significant positive correlation (p=0.013) and (r=0.446) between patient’s age and time to pain relief. In addition, there was a highly significant positive correlation (p=0.0001) and (r=0.636) between the amount of sclerosis surrounding the nidus and time to pain relief. Eventually, the amount of sclerosis surrounding the nidus was shown to be a highly significant independent factor affecting time to pain relief.ConclusionThe amount of sclerosis surrounding the nidus of osteoid osteoma is the most effectual factor for time to pain relief post CT-guided percutaneous radiofrequency ablation treatment