Purpose This study aimed to determine the mid-and longterm success and complication rates of radiofrequency ablation (RFA) in treatment of osteoid osteoma (OO). Furthermore we were interested in the value of bone biopsy when using a core-drill before the radiofrequency ablation. Methods We retrospectively analysed data of 33 patients (33 osteoid osteomas, 22 males, 11 females) who underwent computed-tomography (CT) guided radiofrequency ablation between 1998 and 2005. The patients had a mean age of 20 years (range, five to 50 years). They were monitored for a mean follow-up of 92 months (range, 60-121 months). Results Lesions were located as follows: 11 cases in the proximal femur, five in the femoral shaft, six in the tibia, one in the calcaneus, two in the metatarsals (second and fourth metatarsals), one in the os cuneiforme mediale, six in the humeral and one in the ulnar shaft. Within the presented time frame 32 of 33 patients were successfully treated and had no more complaints. In one of 33 patients relapse occurred after 28 months and RFA was repeated. There were no complications associated with the procedure. Biopsy obtained prior to thermocoagulation with the help of a core-drill was able to prove diagnosis in all patients (100%). Conclusions These results indicate that the presented technique of CT guided RFA combined with the use of a core-drill for biopsy prior to RFA treatment is a highly effective, efficient, minimally invasive and safe method for the treatment of OO, yielding a success rate of 97% combined with a 100% histological verification of the diagnosis after a minimum follow-up period of five years.

In a randomized, parallel group study, we evaluated the efficacy of a 4-day versus an 8-day course of indomethacin (50 mg, 3 times per day), given as prophylaxis against heterotopic ossification after cementless total hip arthroplasty in 209 patients with arthrosis. Patients receiving the prophylaxis for 8 days had less (p = 0.03) severe heterotopic bone formation.