The Use of Microwaves Ablation in the Treatment of Epiphyseal Osteoid Osteomas

This study was designed to demonstrate the feasibility and the reliability of microwave ablation (MWA) of epiphyseal osteoid osteomas (OO).

From February to November 2012, 7 patients (4 males and 3 females; age range 16–30 years) with epiphyseal OOs were treated with MWA. The treatment was performed with 16 G antennas with a power of 20 W for 2 min. The OOs were approached by using coaxial needles inserted with hammer or with automatic drill. All patients underwent spinal anaesthesia, with posttreatment 6–8 h observation before discharging. We treated epiphyseal OOs placed away from nervous and vascular nontarget structures, located in: femoral head (n = 2), femoral lesser trochanter (n = 2), femoral neck (n = 2), and proximal tibial epiphysis (n = 1). CT was used to visualize the nidus and to insert the needle for thermal ablation and for postprocedure control. Technical success was considered the positioning of the antenna in the nidus, while the efficacy of treatment was clinically evaluated as the complete remission of pain after the procedure by using the visual analogue score (VAS). Follow-up was performed by using VAS score 1 day, 1 week, and 1, 3, and 6 months after the procedure, whereas MRI examination was performed immediately after the procedure, at 1 month, and in any case of recurrence. Complications were also recorded.

All patients experienced resolution of the symptomatology (VAS = 0) in ~1 week until the last follow-up, with residual VAS < 2 points occurring only from 1 to 7 days after the procedure. No intraprocedural complication was noted, whereas one patient had back pain for 2 months after the procedure, likely due to spinal analgesic injection.

In our experience, MWA can be safely performed with excellent results without complications in selected cases of epiphyseal OOs; however, the clinical significance of this report is limited because there were only few patients included in this study. Thus, these data must be confirmed by further and larger studies.