Imaging abnormalities that correlate with joint pain.
Imaging abnormalities don't always correlate to joint pain. However, MRI can visualise and identify many structures, some of which are innervated and sensitive to pain. This review explores which MRI features are most directly linked to pain in knee joint osteoarthritis (OA):
- Bone marrow lesions (and bone attrition) reflect trauma, fibrosis and necrosis within the bone and are correlated to pain. They appear under the cortical bone, in weight-bearing areas, and are linked to varus or valgus malalignments, often seen in knee OA (82%).
- Synovitis is an inflammation, proliferation and hypertrophy of the synovium, and is present in about 50% of knee OA. Patients with synovitis are 4.8x more likely to experience pain.
- Large joint effusions may distend the articular capsule (which contains nociceptive fibres) and may be associated with pain in knee OA.
- Some other abnormalities are not directly correlated to knee OA pain (chronic meniscal tears, chronic ACL tears, Baker's cysts, pes anserine bursitis).
- Cartilage is not innervated and is an unlikely source of pain. However, when it is worn out, bone is more vulnerable to damage or injury.
Most of these MRI findings often co-occur in patients with knee OA. Targeting these structural findings (especially bone marrow lesions and synovitis) might help reduce pain and stabilize osteoarthritis progression. > From: Felson, Br J Sports Med 45 (2011) 289–291. All rights reserved to BMJ Publishing Group Ltd.
The Pubmed summary of the article can be found here.