Orthopaedics
Osteoarthritis and Inflammatory Arthritis
Joint disorders for MBBS and NEET-PG: osteoarthritis, rheumatoid arthritis, gout, pseudogout and seronegative spondyloarthropathies with crystal and imaging findings, mapped to NMC codes OR5.1 and OR6.1.
MedNext Academy | 3 min read
Osteoarthritis and Inflammatory Arthritis
Joint disorders for MBBS and NEET-PG: osteoarthritis, rheumatoid arthritis, gout, pseudogout and seronegative spondyloarthropathies with crystal and imaging findings, mapped to NMC codes OR5.1 and OR6.1.
This chapter covers the common non-infective joint disorders. It contrasts degenerative osteoarthritis with inflammatory disease such as rheumatoid arthritis, gout, pseudogout and the seronegative spondyloarthropathies, focusing on the clinical patterns, the crystal and serological findings, and the principles of management.
High-yield: Osteoarthritis and Inflammatory Arthritis
- Osteoarthritis is a degenerative disorder of cartilage that most commonly affects the knee, hip and hand.
- The four radiological hallmarks of osteoarthritis are joint space narrowing, subchondral sclerosis, osteophytes and subchondral cysts.
- Osteoarthritis pain is worse with activity and relieved by rest, and stiffness after inactivity is brief.
- Heberden nodes at the distal interphalangeal joints and Bouchard nodes at the proximal interphalangeal joints are signs of hand osteoarthritis.
- Management of osteoarthritis begins with weight loss, exercise and analgesia, with joint replacement reserved for advanced disease.
- Rheumatoid arthritis is a symmetrical inflammatory polyarthritis that typically spares the distal interphalangeal joints.
- Morning stiffness lasting more than an hour is characteristic of rheumatoid arthritis and other inflammatory arthritides.
- Rheumatoid arthritis causes ulnar deviation, swan neck and boutonniere deformities and a Z shaped thumb.
- Rheumatoid factor and anti-cyclic citrullinated peptide antibodies support the diagnosis of rheumatoid arthritis, and anti-CCP is the more specific.
- Rheumatoid arthritis is an important cause of atlantoaxial instability, which matters before any intubation or neck manipulation.
- Gout is caused by monosodium urate crystals that are needle shaped and negatively birefringent under polarised light.
- Pseudogout is caused by calcium pyrophosphate crystals that are rhomboid and positively birefringent, and chondrocalcinosis may be seen on x-ray.
- Ankylosing spondylitis is a seronegative spondyloarthropathy linked to HLA-B27 that causes a bamboo spine.
- The commonest joint affected by acute gout is the first metatarsophalangeal joint, known as podagra.
Osteoarthritis versus rheumatoid arthritis
- **Osteoarthritis:** Degenerative, asymmetrical, activity related pain, brief stiffness, distal interphalangeal Heberden nodes.
- **Rheumatoid arthritis:** Symmetrical inflammatory, prolonged morning stiffness, spares distal interphalangeal joints, positive anti-CCP.
- **Gout:** Needle shaped, negatively birefringent urate crystals, first metatarsophalangeal joint.
- **Pseudogout:** Rhomboid, positively birefringent pyrophosphate crystals, chondrocalcinosis.
NMC competencies in this chapter
- **OR5.1:** Osteoarthritis: clinical features, imaging and management
- **OR6.1:** Inflammatory arthritis: rheumatoid arthritis, gout and seronegative arthropathies
Frequently Asked Questions
How do you tell osteoarthritis from rheumatoid arthritis?
Osteoarthritis is degenerative, tends to be asymmetrical, hurts more with activity and involves the distal interphalangeal joints. Rheumatoid arthritis is symmetrical and inflammatory, has prolonged morning stiffness and spares the distal interphalangeal joints.
What are the radiological signs of osteoarthritis?
Joint space narrowing, subchondral sclerosis, osteophytes and subchondral cysts are the four classic features seen on plain x-ray.
How are gout and pseudogout crystals distinguished?
Gout crystals are needle shaped and negatively birefringent under polarised light, while pseudogout crystals are rhomboid and positively birefringent.
Why does atlantoaxial instability matter in rheumatoid arthritis?
Chronic inflammation can loosen the ligaments at the top of the neck, so the joint can subluxate. This must be checked before intubation or neck manipulation to avoid cord injury.
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