In rheumatoid arthritis, which is the most common site of joint involvement?
A. Distal interphalangeal joints of the hands
B. Large joints of the lower limbs (knees and hips)
C. Cervical spine and temporomandibular joints
D. Proximal interphalangeal and metacarpophalangeal joints of the hands
Explanation
Most Common Sites of Joint Involvement in RA
Key Point
The proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the hands are the most frequently affected joints in rheumatoid arthritis, occurring in >90% of patients with established disease.
Pattern of Joint Involvement
Table
Joint Site
Frequency
Characteristics
PIP and MCP joints (hands)
>90%
Bilateral, symmetrical; early and persistent involvement
DIP joints (hands)
<10%
Rare; more typical of osteoarthritis
Wrists
80%
Common; causes carpal tunnel syndrome
Knees, ankles, feet
60–80%
Later involvement; weight-bearing joints
Cervical spine
20–30%
Late complication; atlantoaxial subluxation risk
TMJ, shoulders
<20%
Uncommon; late manifestation
Clinical Significance
High-YieldNEET PG
The symmetric polyarticular pattern affecting small joints of the hands is a hallmark diagnostic feature of RA and distinguishes it from other arthritides.
Clinical Pearl
The characteristic swan-neck deformity (hyperextension of PIP joint with flexion of DIP joint) and boutonniere deformity (flexion of PIP with hyperextension of DIP) develop from chronic PIP and MCP joint inflammation and destruction.
Why Small Joints First?
1.
High concentration of synovial tissue and inflammatory cells
2.
Greater exposure to immune complexes and autoantibodies
3.
Mechanical factors: frequent movement and stress
4.
Synovial hyperplasia begins in small joints before spreading proximally
