Genicular Nerve Block & RF Neurotomy of Knee Joint Chronic osteoarthritis pain of the knee is often not effectively managed with non-pharmacological or pharmacological treatments. Radiofrequency (RF) neurotomy, when applied to articular nerve branches (genicular nerves), provides a therapeutic alternative for effective management of chronic pain associated with osteoarthritis of the knee. Although surgery is generally effective for patients with advanced disease, some older individuals with comorbidities may not be appropriate surgical candidates. In addition some patients do not wish to consider surgery and prefer non- surgical options. In these patients, radiofrequency (RF) neurotomy of the genicular nerves might be a successful alternative to surgery. This procedure is based on the theory that cutting the nerve supply to a painful structure may alleviate pain and restore function. Indications for genicular nerve blocks • Patients with chronic knee pain secondary to osteoarthritis • Patients with failed knee replacement • Patients unfit for knee replacement • Patients who want to avoid surgery Diagnostic genicular nerve blocks These injections are performed under fluoroscopy guidance. A small amount of local anaesthetic (1-2ml) of lidocaine or bupivacaine is injected around the superior lateral (SL), superior medial (SM) and the inferior medial (IM) branches. A response is considered positive if there is at least 50% reduction in pain in the 24hrs following injection. Cooled radiofrequency of genicular nerves Patients with a positive response are offered either cooled or conventional radiofrequency neurotomy for a more sustained response. The procedure is usually done on an outpatient basis. The procedure is performed under fluoroscopic guidance to ensure accuracy of needle placement. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that there may need repeated injections. Radiofrequency treatment is a two-step procedure. The first step is diagnostic, involving injection of local anaesthetic around the genicular branches innervating the knee joint, as described above. Patients who experience good pain relief following diagnostic injections are offered radiofrequency denervation treatment. This involves creating a heat lesion around the genicular nerves carrying painful impulses from the knee joint. Successful treatment can result in pain relief lasting several months. Either conventional radiofrequency treatment (70-80°c) or cooled radiofrequency treatment (60°c) can be used. Cooled radiofrequency allows creation of larger-volume, spherical lesions compared to conventional radiofrequency. Treatment is performed under local anaesthetic and can take 4 to 6 weeks to work. Complications Complications are rare, particularly if injections are performed using a precise needle-positioning technique. Septic arthritis can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. Post-procedural pain flare-up is not uncommon, and may be treated with painkillers. Neurological complications including paraesthesias and numbness have been described but are extremely rare. Radiofrequency treatment can cause patchy numbness of the over lying skin. Incidence of infection is low as the procedure is performed under strict aseptic conditions and the injections are extra articular.
Posted on: Sat, 20 Dec 2014 11:50:31 +0000
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