Facet Capsulitis

A doctor holds a model of the spine and points to a structure.
A doctor holds a model of the spine and points to a structure. Mary Kate Denny/The Image Bank/Getty Images

Facet Capsulitis

Capsulitis is inflammation of any anatomical capsule. In the body, an anatomical capsule is a structure, generally made of fibrous tissue, that encases a part or parts. For example, the facet joints at the back of the spinal column are enclosed in capsules known aptly as facet joint capsules. 

Perhaps the most well-known form of capsulitis is adhesive capsulitis, or frozen shoulder.

Types of Capsulitis Found in the Spine

Capsulitis is often found at the sacroiliac joints of people who have an inflammatory arthritic disease such as spondylitis. In these cases, capsulitis is considered to be an active inflammatory lesion. For people with spondylitis, an MRI using one of several specialized techniques is generally necessary to find evidence of capsulitis as well as other active inflammatory lesions.  

Other types of active inflammation include osteitis,  enthesitis and synovitis.  All (including capsulitis) are early signs of sacroiliitis or spondylitis.  The difference between them lies in the location of the inflammation.  For example, synovitis is inflammation of the synovial lining inside a joint, osteitis is inflammation of the bone, and so forth.

RelatedOsteitis and Spondylitis

To learn more about active inflammation, check out this article:  Types of Active Inflammation.

Facet Capsulitis

In the facet joint, the capsule is known as a "pain generator," which means it is one of a number of  structures that making up the facet joint that may be responsible for back pain and/or dysfunction.

The facet capsule is made of fibrous connective tissue that surrounds the whole joint.

 Inside the capsule and joint is a synovial lining that secretes synovial fluid.  The job of synovial fluid is to lubricate the surfaces of the joints so that movement can occur smoothly and painlessly.  You might think of synovial fluid as the joint's WD-40.  Just as the facet joint capsule can become inflamed, so can the synovial lining and fluid (collectively called the synovium.)

Facet Joint Arthritis

According to Gellhorn, Katz and Suri, in their article entitled, "Osteoarthritis of the spine: the facet joints," which was published in the May 7, 2014 issue of the journal Nature Reviews Rheumatology, the capsule is one of several structures whose "failure" can cause facet arthritis - even though most experts think of facet joint arthritis as a bone and cartilage condition.  

How does your doctor or physical therapist know when your facet joint capsule is inflamed?  One way is by evaluating the "capsular pattern."  An inflamed facet joint tends to stretch the fibers of the capsule, which causes pain as well as movement limitation, specifically, side bending, rotation and extension, - with flexion unimpeded.

Other areas affected by facet arthritis include ligaments, synovium, muscles and the disc.

 The authors say that the disc tends to degenerate along with the facet joint, which means the two adjacent structures are both implicated in degenerative disc disease.


Gellhorn, A., Katz, J., Suri, P. Osteoarthritis of the spine: the facet joints. Nat Rev Rheumatol. May 7 2014. Accessed Feb 2016 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4012322/#BX2

Hermann KGA, Bollow M. Magnetic Resonance Imaging of Sacroiliitis in Patients with Spondyloarthritis: Correlation with Anatomy and Histology. Fortschr Röntgenstr 2014.https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0033-1350411

Sudoł-Szopinska1, Iwona, Urbanik, Andrzej. Diagnostic imaging of sacroiliac joints and the spine in the course of spondyloarthropathies.