1540 THE BONE & JOINT JOURNAL  ONCOLOGY Radiofrequency ablation in the treatment of cartilaginous lesions in the long bones RESULTS OF A PILOT STUDY E. F. Dierselhuis, P. J. M. van den Eerden, H. J. Hoekstra, S. K. Bulstra, A. J. H. Suurmeijer, P. C. Jutte From Department of Orthopaedic Surgery, University Medical Center Groningen, The Netherlands  E. F. Dierselhuis, MD, Orthopaedic Resident Department of Orthopaedic Surgery  P. J. M. van den Eerden, MD, Radiologist Department of Radiology  H. J. Hoekstra, MD, PhD, Professor of Surgical Oncology Department of Surgery  S. K. Bulstra, MD, PhD, Professor of Orthopaedic Surgery  A. J. H. Suurmeijer, MD, PhD, Professor of Pathology, Department of Pathology  P. C. Jutte, MD, PhD, Orthopaedic Surgeon Department of Orthopaedic Surgery University Medical Center Groningen, Postbus 30.001, 9700 RB Groningen, The Netherlands. Correspondence should be sent to P. C. Jutte; e-mail: p.c.jutte@umcg.nl ©2014 The British Editorial Society of Bone & Joint Surgery doi:10.1302/0301-620X.96B11. 33544 $2.00 Bone Joint J 2014;96-B:1540–5. Received 4 December 2013; Accepted after revision 17 July 2014 Atypical cartilaginous tumours are usually treated by curettage. The purpose of this study was to show that radiofrequency ablation was an effective alternative treatment. We enrolled 20 patients (two male, 18 female, mean age 56 years (36 to 72) in a proof-of- principle study. After inclusion, biopsy and radiofrequency ablation were performed, followed three months later by curettage and adjuvant phenolisation. The primary endpoint was the proportional necrosis in the retrieved material. Secondary endpoints were correlation with the findings on gadolinium enhanced MRI, functional outcome and complications. Our results show that 95% to 100% necrosis was obtained in 14 of the 20 patients. MRI had a 91% sensitivity and 67% specificity for detecting residual tumour after curettage. The mean functional outcome (MSTS) score six weeks after radiofrequency ablation was 27.1 (23 to 30) compared with 18.1 (12 to 25) after curettage (p < 0.001). No complications occurred after ablation, while two patients developed a pathological fracture after curettage. We have shown that radiofrequency ablation is capable of completely eradicating cartilaginous tumour cells in selective cases. MRI has a 91% sensitivity for detecting any residual tumour. Radiofrequency ablation can be performed on an outpatient basis allowing a rapid return to normal activities. If it can be made more effective, it has the potential to provide better local control, while improving functional outcome. Cite this article: Bone Joint J 2014;96-B:1540–5. The mainstay of treatment for primary bone tumours is surgery. Central atypical cartilagi- nous tumours (ACT - formerly known as chon- drosarcoma grade I) are generally treated by curettage: previously, treatment consisted of wide resection or amputation. 1 In general, the treatment of chondroid tumours can be prob- lematic, since they are relatively resistant to irradiation and chemotherapy. It can also be difficult to differentiate ACT from its benign counterpart (enchondroma) and grade II tumours. 2,3 In contrast to higher grade chon- drosarcoma, ACTs grow slowly and do not metastasise, unless upgrading or dedifferentia- tion occurs. 4,5 Although curettage causes less morbidity than more extensive surgery, it still has a negative impact on functional outcome. 1 Local recurrence (LR) occurs in up to 7.7 % of patients after curettage. 6 In the event of LR, a repeat operation is often needed, exposing the patient to the additional risks of common peri-operative complications such as infection or fracture. In addition, prophylactic hardware is sometimes needed. 7 All these measures have a negative effect on a patient’s quality of life. Although the adage ‘life before limb’ remains true for ACT, the relatively mild nature of these tumours in the long bones might justify less aggressive treatment. Therefore, a new treatment strategy is needed that improves local control and functional out- come, while lowering the rate of complications. Moreover, follow-up must be sufficient to eval- uate the effect of such treatment. A minimally- invasive approach using radiofrequency abla- tion (RFA), monitored by gadolinium-enhanced magnetic resonance imaging (G-MRI), might be capable of meeting these requirements. For nearly two decades, RFA has been used as a minimally-invasive surgical technique in orthopaedics. With RFA, a high-frequency alternating current heats tissue to approxi- mately 80°C, causing it to necrose. 8 Initially, RFA was used to treat osteoid osteoma. 9,10 With increasing clinical experience, bone metastases and chondroblastomas have also been success- fully treated. 11,12 Complications are rare, although local adverse events such as cellulitis or burns of the surrounding skin have been reported. 9,10 When more challenging sites, such