Chronic pain is major public health problem, and is now of epidemic proportions . Medicare, social security, disability programs, workers’ compensation programs, and the private healthcare system all struggle to keep up with the never ending cost of chronic pain patients. Resulting in higher insurance premiums, loss of worker productivity, increased burdens on state and federal governments and a decrease in quality of life. Direct and indirect losses from chronic pain in the United States costs billions of dollars each year .
Chronic pain is defined as , “pain that extends beyond the expected period of healing or is related to a progressive disease. It is usually elicited by an injury or disease but may be perpetuated by factors that are both pathogenically and physically remote from the original cause. Because the pain persists, it is likely that environmental and psychological factors interact with the tissue damage, contributing to the persistence of pain and illness behavior.” Initially, general diagnosis’s such as cervical sprain / strain injury or acceleration / deceleration injury are appropriate when used within accepted guidelines. As the patient heals and time passes it is essential to obtain a specific anatomical diagnosis such as, a C5 cervical disc herniation or a right C5 cervical facet syndrome.
The scientific literature is very clear that cervical facet joints are the cause of chronic pain in 54% to 67% of chronic neck pain patients [3-9]. Despite the high prevalence of pain, the clinical diagnosis of the cervical facet joint as the primary source of pain is often overlooked .These undiagnosed patients typically go through unproductive treatment such as; physical therapy, chiropractic, injections, medications and other procedures to relieve their pain. With the proper diagnosis, these patients may benefit from specific interventions designed to manage cervical facet joint pain . The purpose of this chapter is to lay the ground work for the diagnosis of cervical facet pain in a clinical setting. A specific (I) history, (II) physical examination, (III) motion x-ray examination and / or (IV) a diagnostic facet block are instrumental in the diagnosis of chronic cervical facet joint dysfunction. With sound clinical judgment, a firm diagnosis can be made as to the probable level and structure of pain generation.
The cervical spine is generally separated into two distinct functional and structural parts: the upper cervical (Occiput to C2) and the lower cervical (C3-C7). The upper cervical spine has many muscle and ligamentous attachments, no intervertebral disc, and has uniquely shaped bones and joint surfaces. A typical lower cervical vertebra has a vertebral body, intervertebral disc, a right and left superior articular facet, and a right and left inferior articular facet. Facet joints are hinge-like structures that link the vertebrae together. They are located at the back of the spine and are true synovial joints. This means that each joint is surrounded by a thin ligamentous capsule of connective tissue, hyaline cartilage covers the articular surfaces, and synovial fluid nourishes as well as lubricates the joint.
Cervical facet joints have both mechanoreceptors and nociceptive (pain) nerve endings [10,11]. Within the joint are synovial folds, these folds are also pain sensitive . The facet joints are richly innervated by the medial branches of the segmental dorsal rami and the medial branches of the segments above and below [10,11]. This multilevel innervation of the facet joint is one of the reasons for the broad referral pattern . The facet joints are heavily innervated by nerves, but have poor blood supply. This poor blood supply impedes the healing process, which triggers scar tissue formation and adhesive capsulitis within the joint, resulting in chronic dysfunction and pain .
The multifidus are the deep muscles of the cervical spine and help to provide segmental stability. The multifidus are essential in a patient with facet pain because this muscle has been found to insert into the facet joint capsular ligaments. They have been found to cover 22.4 ± 9.6% of the facet joint capsule surface area . The multifidus muscle insertion into the cervical facet capsular ligament provides a mechanism for injury to this ligament and the facet joint as a whole [13,14]. This anatomical fact may also play a major role in rehabilitation of cervical facet joint injuries.
A recent study identified the, “facet articular cartilage, the synovial fold, and the facet capsule as structures at risk for injury during whiplash due to excessive facet joint compression or capsular ligament strain.” . It also found that, “facet joint components may be at risk for injury due to facet joint compression during rear-impact accelerations of 3.5g and above. Capsular ligament strains exceed the physiologic strains at 6.5g and were largest at the lower cervical spine.”. Therefore, relatively low impact collisions can cause facet injuries[13,14,16].
“It is consistent with known biological models that injuries to the osseous or soft tissues of a joint predispose that joint to premature, painful, osteoarthritic change.”. Long term, the facet joints will undergo degenerative changes characteristic of osteoarthritis as seen in other synovial joints . As the facet joint degeneration progresses the radiographic changes are more visible and often result in spinal stenosis, affecting both the nerve root and central canals .
Epidemiological studies, crash test studies and anatomical evidence all corroborate the reality that the cervical facet joints are prone to injury during a motor vehicle collision, have a rich nerve supply, heal poorly and are a source of pain [3-20]. Pain for prolonged periods of time can lead to reconditioning, neuroplastic changes and hyperexcitability of the nervous system .
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