Osteoarthritis of the spine: the facet joints

Abstract

Osteoarthritis (OA) of the spine involves the facet joints, which are located in the posterior aspect of the vertebral column and, in humans, are the only true synovial joints between adjacent spinal levels. Facet joint osteoarthritis (FJ OA) is widely prevalent in older adults, and is thought to be a common cause of back and neck pain. The prevalence of facet-mediated pain in clinical populations increases with increasing age, suggesting that FJ OA might have a particularly important role in older adults with spinal pain. Nevertheless, to date FJ OA has received far less study than other important OA phenotypes such as knee OA, and other features of spine pathoanatomy such as degenerative disc disease. This Review presents the current state of knowledge of FJ OA, including relevant anatomy, biomechanics, epidemiology, and clinical manifestations. We present the view that the modern concept of FJ OA is consonant with the concept of OA as a failure of the whole joint, and not simply of facet joint cartilage.

Figure 1

Facet joint and intervertebral disc anatomy. At every spinal level, the paired facet joint and the intervertebral disc make up the ‘three-joint complex’, or the spinal ‘motion segment’. a | Sagittal view of a cervical disc–facet unit. b | Axial view of a cervical disc–facet unit. The cervical facet joint space cannot be seen in cross-section owing to the orientation of the joint in the cervical region. c | Sagittal view of a lumbar disc–facet unit. The lumbar facet joint space cannot be seen in cross-section owing to the orientation of the joint in the lumbar region. d | Axial view of a lumbar disc–facet unit.

Figure 2

Normal facet joints and advanced facet joint osteoarthritis. The intervertebral disc is shown in blue and nerves in yellow. a | T2-weighted axial MRI image of normal facet joints with no joint-space narrowing (white arrow), and no osteophytes or articular process hypertrophy (white arrowheads). b | Normal facet joints. c | T2-weighted axial MRI image of osteoarthritic facet joints with joint-space narrowing (yellow arrow), osteophytes and articular process hypertrophy (yellow arrowhead). Facet joint osteoarthritis, disc-bulging, and a facet joint synovial cyst (green arrowhead) in combination lead to stenosis of the central canal and lateral recesses. d | Osteoarthritic facet joints.

Figure 3

Cervical and lumbar facet joint pain referral patterns. a | Distributions of pain referred from the cervical facet joints. b | Distributions of pain referred from the lumbar facet joints. This is a composite map of lumbar facet joint pain referral locations from multiple studies.^– The lumbar and low lumbar/gluteal regions are the most common locations of pain. Although not depicted here, referral of pain distal to the knee can also occur, but is relatively rare. Part a adapted with permission from Lippincott Williams & Wilkins © Dwyer, A. et al. Cervical zygapophyseal joint pain patterns. I: A study in normal volunteers. Spine (Phila Pa 1976) 15, 453–457 (1990).

Figure 4

Relationship between age and prevalence of low back pain attributed to lumbar facet joints. Prevalence of lumbar facet-mediated pain as determined by double-blind, comparative block techniques in different clinical populations.^,,,,– A higher prevalence of facet-mediated pain is seen in samples of older adults as compared to younger adults. Each point represents a group rather an individual; ecological correlations could underestimate the variability seen on an individual level.