The National Institute for Clinical Excellence is examining computed tomography (CT)-guided thermocoagulation of osteoid osteoma and will publish guidance on its safety and efficacy to the NHS in England and Wales. The Institute's Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about CT-guided thermocoagulation of osteoid osteoma.

This document has been prepared for public consultation. It summarises the procedure and sets out the provisional recommendation made by the Advisory Committee.

Note that this document is not the Institute's formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that the Institute will follow after the consultation period ends is as follows.

• The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
• The Advisory Committee will then prepare the Final Interventional Procedure Document (FIPD) and submit it to the Institute.
• The FIPD may be used as the basis for the Institute's guidance on the use of the procedure in the NHS in England and Wales.

For further details, see the Interim Guide to the Interventional Procedures Programme, which is available from the Institute's website (www.nice.org.uk/ip).

Closing date for comments: 23 December 2003

Target date for publication of guidance: March 2004

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.

Current evidence on the safety and efficacy of computed tomography (CT)-guided thermocoagulation of osteoid osteoma appears adequate to support its use, provided that the normal arrangements are in place for consent, audit and clinical governance.

Osteoid osteomas are benign, bone-forming tumours that occur most frequently in the legs, especially the femur and tibia.

Almost all patients have pain as a result of the tumour. Other symptoms include growth disturbances, bony deformity, scoliosis and, if located within a joint, swelling, synovitis, restricted movement and contracture. This condition may regress spontaneously, but the resolution of symptoms is unpredictable and may take months or years.

Standard treatment initially focuses on pain management using non-steroidal anti-inflammatory drugs. Patients who continue to have pain or who experience other tumour-related complications are offered surgical excision. Surgery requires a hospital stay of several days and the patient cannot undertake weight-bearing activity for a substantial period of time. Aggressive resection carries the risk of postoperative fracture, infection and haematoma.

In recent years several minimally invasive techniques using imaging, such as percutaneous resection and radiofrequency ablation, have been introduced in patients with osteoid osteoma in order to achieve removal or destruction of the tumour without the subsequent morbidity of standard surgical treatment.

In this procedure, the lesion is located using computed tomography (CT) and an entry hole is created through the bone. The core of the lesion is then removed for biopsy; CT is used to monitor needle progress and placement. A radiofrequency electrode probe is introduced into the centre of the osteoma and heated. The electrode is then removed and a CT scan is done to assess the outcome of the procedure.

Resolution of pain was the main outcome reported in the studies. In a case series of 97 consecutive patients with a mean follow up of 41 months, 76% of patients (74/97) reported a good response after one treatment session and 92% (89/97) reported a good response after one or two sessions. In the smaller studies, resolution of symptoms was reported by 82-95% of patients at final follow up. For more details, refer to the sources of evidence (see Appendix).

The Specialist Advisors considered that this was an established procedure with no concerns or uncertainties about its efficacy. One advisor stated that the procedure was better than open surgery as there is less risk of recurrence. One Advisor questioned whether the procedure worked.

Few complications were observed in the studies. Five out of 239 patients (2%) experienced complications, including three who experienced superficial burns. For more details, refer to the sources of evidence (see Appendix).

The Specialist Advisors noted transient pain as the most common complication of the procedure. Infection was also listed, but described as a rare adverse event. It was noted that if the tumour is in a difficult area, adjacent structures may be at risk from inappropriate positioning of the electrode, but Advisors commented that the procedure is still safer than surgery in similar situations.

The Advisory Committee noted that this procedure may not be appropriate for patients with spinal lesions. In such cases careful patient selection is particularly important.

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making it's provisional recommendations.

• Interventional Procedure Overview of Computed tomography-guided thermocoagulation of osteoid osteoid, May 2003

Available from: www.nice.org.uk/ip221overview