Facet joint arthropathy (zygapophyseal joint degeneration) is an important component of the spinal degenerative cascade and is responsible for 15-45% of axial low back pain. Facet joints are synovial joints of the posterior spinal elements with functions in segmental stability, load bearing, and motion restriction. Degenerative cascade: disc degeneration → segmental instability → increased load on facet joints → cartilage loss, subchondral sclerosis, osteophytes, capsular laxity, and synovial hypertrophy. CT is the best modality for bone details of the facet joint (osteophytes, subchondral sclerosis, vacuum phenomenon, facet morphology). MRI evaluates facet joint effusion (hyperintense fluid on T2) and synovial hypertrophy; contrast MRI shows active synovitis enhancement. Facet arthropathy frequently contributes to spinal stenosis: hypertrophic facets cause lateral recess and central canal narrowing, ligamentum flavum hypertrophy accompanies. Diagnostic facet block (medial branch block) is the most reliable diagnostic confirmation method. Treatment options: intra-articular steroid injection, medial branch block, and radiofrequency neurotomy (RFN). Surgery is considered only in presence of accompanying stenosis or instability.
Age Range
40-85
Peak Age
60
Gender
Equal
Prevalence
Very Common
Facet joints are true synovial joints: they contain hyaline cartilage-covered articular surfaces, synovial membrane, joint capsule, and synovial fluid. Degenerative process: disc degeneration leads to segmental height loss → increased load transferred to posterior elements → facet joint cartilage is overloaded → cartilage fibrillation and thinning → subchondral bone is stressed → sclerosis and cystic changes → osteophytes (bone remodeling) → capsular laxity → synovial inflammation and hypertrophy → joint effusion. Facet joint morphology affects degeneration: sagittally oriented facets (common at L4-5) are more prone to anterior slippage → degenerative spondylolisthesis; coronally oriented facets are more resistant to rotational stress. On MRI, effusion appears hyperintense on T2 because synovial fluid is free-water based → long T2 → bright signal. In active synovitis, synovial membrane vascularity increases → gadolinium accumulation → enhancement. Subchondral sclerosis appears hyperdense on CT because increased bone density raises X-ray attenuation. Ligamentum flavum is continuous with facet capsule, and facet degeneration triggers ligament hypertrophy → posterior canal narrowing.
Hyperintense fluid (effusion) in the facet joint space with hypertrophic facet joint morphology on T2-weighted MRI. Diagnostic combination of active degenerative facet arthropathy. Diagnosis is strengthened when bone changes on CT (sclerosis, osteophytes) are evaluated together with soft tissue changes on MRI (effusion, synovitis).
All components of facet joint degeneration are best imaged on CT: joint space narrowing (normal 2-4 mm → <2 mm), subchondral sclerosis (increased bone density), osteophytes (bony outgrowths at joint margins), subchondral cysts (subchondral bone erosion), vacuum phenomenon (intra-articular gas). Facet morphology (sagittal vs coronal orientation) and effect of hypertrophy on spinal canal are evaluated on axial sections.
Report Sentence
Joint space narrowing, subchondral sclerosis, and osteophytes in __[bilateral/left/right] facet joints at __ level on CT, consistent with degenerative facet arthropathy.
Hyperintense fluid collection in the facet joint space on T2-weighted MRI — facet joint effusion. Normal facet joint contains minimal synovial fluid; pathological effusion is defined as fluid accumulation >2 mm width. Effusion indicates active degeneration, synovitis, or instability. Bilateral effusion may be a predictor of degenerative spondylolisthesis. STIR sequence shows effusion more prominently with fat suppression.
Report Sentence
Facet joint effusion at __ level __[bilaterally/left/right] on MRI T2, suggesting active degenerative arthropathy.
Enhancement of thickened synovial membrane around the facet joint on contrast MRI — indicator of active synovitis. Synovial hypertrophy appears as isointense-mildly hyperintense thickened tissue on T1 and shows prominent enhancement after gadolinium. This finding helps assess activity of facet-related pain. Presence of enhancement may be a predictor of treatment response for patient selection for intra-articular steroid injection or medial branch block.
Report Sentence
Synovial enhancement in facet joints at __ level on contrast MRI, consistent with active synovitis.
Facet joint hypertrophy contributes to posterolateral canal narrowing and lateral recess stenosis. On axial CT, hypertrophic facets with osteophytes growing toward the spinal canal reduce lateral recess depth (normal >5 mm, stenosis <3 mm). Lateral recess stenosis affects the traversing nerve root. This finding usually coexists with disc bulging and ligamentum flavum hypertrophy, together forming the trefoil configuration.
Report Sentence
Facet joint hypertrophy and osteophytes at __ level __[bilaterally/left/right] contributing to lateral recess stenosis on CT with lateral recess depth measuring __ mm __[left/right].
Ligamentum flavum hypertrophy accompanying facet arthropathy: bilateral posterolateral T2 hypointense thickened band (>4-5 mm). Ligamentum flavum is continuous with facet capsule — facet degeneration triggers ligament hypertrophy. Hypertrophic ligament buckles toward spinal canal causing posterior narrowing. Facet hypertrophy + ligamentum flavum hypertrophy together are the main cause of posterolateral stenosis.
Report Sentence
Bilateral ligamentum flavum hypertrophy (__ mm) at __ level, contributing to posterolateral spinal canal narrowing together with facet arthropathy.
Criteria
Minimal joint space narrowing, minimal osteophytes, cartilage loss <50%, no or minimal effusion
Distinct Features
Usually asymptomatic or mild axial pain. Minimal contribution to spinal stenosis. Conservative treatment sufficient
Criteria
Marked joint space narrowing, prominent osteophytes, subchondral sclerosis/cysts, effusion present
Distinct Features
May be source of axial pain. Contributing to lateral recess stenosis. Facet block/steroid injection as treatment option
Criteria
Joint space obliterated, massive osteophytes, bone-on-bone contact, vacuum phenomenon, instability/subluxation
Distinct Features
Significant stenosis contribution. Risk of degenerative spondylolisthesis. Synovial cyst may develop. Surgery may be considered
Distinguishing Feature
Synovial cyst is a cystic structure originating from facet joint (T2 hyperintense cyst + rim enhancement); facet arthropathy is diffuse joint degeneration (effusion stays within joint, no cyst)
Distinguishing Feature
Spinal stenosis is the result of canal narrowing while facet arthropathy is one of the causes; stenosis involves contribution of multiple structures (disc + ligament + facet)
Distinguishing Feature
Degenerative spondylolisthesis may be an advanced consequence of facet arthropathy (facet sagittalization + instability → slippage); facet arthropathy without slippage is stable degeneration
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
12-monthFacet joint arthropathy is responsible for 15-45% of axial low back pain. Diagnostic facet block (medial branch block) is the most reliable diagnostic confirmation method — imaging findings alone cannot definitively establish pain source. Treatment steps: physical therapy + NSAIDs → diagnostic medial branch block → intra-articular steroid injection → radiofrequency neurotomy (RFN, provides longest pain control, 6-12 month effect). Surgery is considered only in presence of accompanying stenosis or instability. Advanced facet arthropathy is a risk factor for degenerative spondylolisthesis and synovial cyst development.
Facet joint arthropathy is an important source of axial back pain and is held responsible for 15-45% of mechanical back pain. Pain typically increases with extension and decreases with flexion. Diagnostic facet block (local anesthetic injection) is the most reliable confirmation method. Treatment: physical therapy, NSAIDs, intra-articular steroid injection, medial branch block, and radiofrequency neurotomy (long-term pain control). Facet arthropathy frequently contributes to spinal stenosis and may require decompression surgery.