Facet Injections in the Treatment of Low Back Pain

General Principles
Although injections may be helpful in confirming a diagnosis, they should be used primarily after a specific presumptive diagnosis has been established. Injections should not be used in isolation, but rather in conjunction with a program stressing muscle flexibility, strengthening, and functional restoration. Proper follow-up after injections to assess the patient's treatment response and ability to progress in the rehabilitation program is essential. A limited number of injections can be tried to reduce pain, but careful monitoring of the response is required prior to a second or third injection.

These injections are an adjunct treatment, which facilitates participation in an active exercise program and may assist in avoiding the need for surgical intervention. All physiatrists who perform injections should be aware of the indications, contraindications, and complications of therapeutic injections, and fully inform patients of the potential risks.

Facet Injections
The therapeutic benefit of facet injections remains controversial. The controversy begins with the poor correlation of the history and examination with true facet mediated low back pain.

Many patients will complain of back and often lower extremity pain with standing, walking, and extension-type activities. The neurologic examination is normal, and provocative tests for nerve root inflammation are usually negative. Many patients will have increased pain on passive extension, and/or extension and rotation; less often patients will complain of pain with flexion.

In addition, radiographic and bone scan imaging has not been helpful in selecting appropriate patients for facet injections. The primary role of facet injections remains diagnostic. There is less support for the therapeutic effect of intra-articular corticosteroid injections or ablations of the nerves innervating the lumbar facet joints.

Facet injections should be used for patients who have failed a directed non-operative treatment program which incorporates various manipulation/mobilization techniques. They are not indicated in the first four to six weeks of treatment and, when utilized, should be done under fluoroscopic guidance using contrast medium to assure proper placement.

The goal of facet injections is to verify the diagnosis and perhaps assist with pain reduction in order to facilitate an active physical therapy program. If prior injections were helpful and there is a recurrence of pain, they can be repeated; however, repeat injections should be limited. Those patients who have reliably demonstrated a therapeutic analgesic response to injected anesthetics of varying half-lives and have failed conservative care may be candidates for therapeutic radiofrequency denervation procedures. This procedure should be used only in those failing a comprehensive program and in no way should be considered in the initial management of an episode of acute low back pain.