Radiofrequency ablation (RFA) refers to a technique where an electical current is passed through body tissue to heat it up and destroy it. There are a number of ways to perform RFA such as monopolar, bipolar, and cooled. It is a precision technique, which produces discrete lesions with generally little or no damage to surrounding tissues, and is the treatment of choice for destroying tissue volumes ranging from the size of a drop of water to the size of a small egg.
Monopolar RFA involves the insertion of a probe into the body with the current being dispersed through an earth electrode which is generally a self-adhesive pad placed elsewhere on the body. A monopolar RFA electrode will be insulated along most of its length but it will have an exposed tip of several millimetres. When current is passed through the probe an elliptical or spherical shaped lesion will be formed around the tip of the needle, generally of roughly the same diameter as the length of the exposed tip. The temperate and duration of the lesion are precisely controlled to destroy only the target tissue around the tip of the electrode. Monopolar RFA is the technique generally used for the destruction of small nerves such as those that supply spinal facet joints, so this is the technique used for radiofrequency facet joint denervation.
Bipolar RFA involves the insertion of either a single probe with two electrically insulated electrodes at its tip, or two parallel probes separated by a small distance. When radiofrequency energy is passed through a bipolar probe the lesion is created between the two electrodes and the same parameters of temperature and time can be used. It, too, creates lesions of specific size and shape. Bipolar RFA is generally used for the destruction of benign or malignant soft tissue tumours.
Cooled RFA, like bipolar RFA, can be used to produce larger lesions. As tissue becomes destroyed using non-cooled RFA the thermal “reach” of the technique becomes limited. Cooling the RFA probe can extend its reach, allowing larger lesions to be created. Bipolar and Cooled RFA are generally used for tumour ablation.
RFA is the NICE approved treatment of choice for osteoid osteomas.
Palliation for metastatic skeletal tumours from malignant cancers can also be achieved with one or more of the following – RFA, cryoablation (freezing rather than heating), or by PMMA cement augmentation (eg. vertebroplasty, balloon kyphoplasty, cementoplasty).