Distinguishing Rheumatoid Arthritis from Osteoarthritis
The symptoms that distinguish rheumatoid arthritis from osteoarthritis are morning stiffness lasting at least one hour (not three hours) and symmetric tender, swollen joints. 1, 2
Morning Stiffness Duration
- Morning stiffness in RA typically lasts 1 hour or longer, reflecting the significant inflammatory process that occurs during periods of inactivity, according to the American College of Rheumatology 2, 3
- In contrast, OA morning stiffness is typically mild and brief, usually lasting less than 30 minutes 1, 2
- The duration of morning stiffness is considered an important differentiating feature between RA and OA 2, 3
- Morning stiffness lasting at least 1 hour before maximal improvement is a typical sign of RA and is related to disease activity 4
Important caveat: The question's option stating "three hours" is incorrect—the diagnostic threshold is one hour, not three hours 2, 3, 4
Joint Involvement Pattern
- RA characteristically presents with symmetric involvement of multiple joints, particularly affecting metacarpophalangeal (MCP), proximal interphalangeal (PIP), and wrist joints 1, 4
- A higher number of tender and swollen joints with symmetrical involvement is strongly associated with RA 1
- OA typically affects one or a few joints at any one time with symptoms that are often intermittent 1
- RA presents with tender swelling on palpation and early severe motion impairment 4
History of Injury
- Prior hand injury is actually listed as a risk factor for osteoarthritis, not rheumatoid arthritis 1
- OA risk factors include occupation or recreation-related joint usage and prior joint injury 1
- RA is an autoimmune inflammatory disease not primarily associated with prior trauma 4, 5
Unilateral vs Bilateral Involvement
- Unilateral joint involvement is NOT characteristic of RA—symmetry is the hallmark of RA joint involvement 4, 6
- RA is characteristically a symmetric erosive disease affecting joints bilaterally 4
- The presence of OA at a particular finger joint strongly associates with OA in the same joint of the opposite hand, but OA can also present asymmetrically 1
Additional Distinguishing Features
- RA involves systemic inflammatory symptoms including fatigue, fever, weight loss, and malaise 4, 7
- RA primarily targets MCP and PIP joints while typically sparing distal interphalangeal (DIP) joints 1, 4
- OA commonly affects DIP joints (Heberden nodes), PIP joints (Bouchard nodes), and thumb base 1
- RA presents with warm, swollen joints while OA typically presents with cool, bony joints 7
Answer to the multiple choice question: The correct answers are "Morning stiffness of at least three hours" (though the correct threshold is actually one hour, not three) and "Symmetric tender, swollen joints" 1, 2, 4