Typical sites of joint involvement in primary Osteoarthritis
What are the typical sites of joint involvement in primary (idiopathic) OA compared with secondary causes of noninflammatory, degenerative arthritis?
Primary (idiopathic) OA can cause noninflammatory, degenerative arthritic changes in the following joints:
- • Hands
- – DIPs
- – Proximal interphalangeal joints (PIPs)
- – First carpometacarpal joint (CMC) of thumb
- • Acromioclavicular joint of shoulder
- • Cervical, thoracic, and lumbosacral spine
- • Hips
- – Subchondral cysts (Egger’s cysts) in superior acetabulum are characteristic
- • Knees
- – Patellofemoral, medial, and lateral compartments
- • Feet
- – First metatarsophalangeal joint (MTP)
Secondary causes of degenerative arthritis can result in noninflammatory, degenerative changes in any joint (not just those for primary disease). Consequently, if a patient has degenerative changes in any of the following joints, you must consider secondary causes of OA:
- • Hands
- – MCPs
- Wrist
- • Elbow
- • Glenohumeral joint of shoulder (can be involved in primary OA also)
- • Ankle
- • Feet, other than first MTP
If the degenerative changes involve only one joint, consider traumatic arthritis. If multiple joints are involved, consider a metabolic or endocrine disorder that has caused the cartilage to degenerate in several joints. Note that the end stage of an underlying inflammatory arthritis that has destroyed the cartilage can result in degenerative changes superimposed on the inflammatory radiographic features.
