Rheumatology in Internal Medicine

Also written as Rheumatology, Musculoskeletal Medicine.

Rheumatologic diseases present with joint, muscle and systemic inflammation. In low‑resource African settings infections, HIV and endemic parasites are common triggers. Clinical reasoning focuses on pattern recognition, limited investigations and timely treatment.

Definition and diagnosis

Rheumatology covers disorders that cause inflammation, pain or deformity of joints, muscles, tendons and related organs. Diagnosis relies on history, pattern of joint involvement and basic labs.

• Joint aspiration: Is the effusion inflammatory, septic or crystal‑induced? Positive Gram stain or high neutrophils (>50 % polymorphs) suggests infection; needle‑shaped crystals point to gout.
• RF and anti‑CCP: Do they support rheumatoid arthritis? Positive anti‑CCP is highly specific; RF may be positive in infections or hepatitis.
• ESR/CRP: Are inflammatory markers elevated? Helps gauge activity but can be normal in early disease.

• Symmetrical small‑joint polyarthritis → consider rheumatoid arthritis
• Mono‑arthritis with fever → think septic arthritis
• Enthesitis + skin lesions → suspect psoriatic arthritis

Severity and staging

Severity guides treatment intensity. For rheumatoid arthritis, the DAS28 score (tender + swollen joint count, ESR/CRP, patient global) categorises remission, low, moderate or high disease activity.

• DAS28 ≤2.6 = remission
• 2.6 < DAS28 ≤3.2 = low activity
• 3.2 < DAS28 ≤5.1 = moderate activity
• DAS28 >5.1 = high activity

Causes, most likely first

Identify the most common aetiologies in East Africa before rare autoimmune diseases.

• Post‑streptococcal reactive arthritis (children)
• HIV‑associated arthritis
• Tuberculous arthritis
• Malaria‑related arthralgia
• Rheumatoid arthritis
• Systemic lupus erythematosus

How it presents

Key clinical patterns help narrow the differential.

• Symmetrical small‑joint swelling, morning stiffness >1 hour → rheumatoid arthritis
• Mono‑articular knee pain, fever, rapid onset → septic arthritis
• Low‑back pain with buttock tenderness, enthesitis → ankylosing spondylitis
• Joint pain with malar rash, photosensitivity → lupus

Investigations

Use affordable tests first; if unavailable, rely on clinical criteria.

• Plain radiograph: What structural changes are present? Joint space narrowing suggests rheumatoid arthritis; erosions indicate aggressive disease.
• Full blood count: Is there anaemia or leukocytosis? Anaemia of chronic disease supports inflammatory arthritis; neutrophilia may point to infection.
• HIV test: Is HIV infection a contributing factor? Positive result shifts management toward opportunistic infection screening.
• TB PCR on synovial fluid (if available): Does the patient have tuberculous arthritis? Positive result confirms need for anti‑TB therapy.

Red flags and complications

Recognise features that demand urgent action.

• Septic arthritis – rapid joint destruction, systemic sepsis
• Rapidly progressive renal failure in lupus
• Spinal cord compression from ankylosing spondylitis
• Severe anemia or thrombocytopenia in systemic disease

Management

Treat the underlying cause, control inflammation and prevent damage.

• Infection‑related arthritis – appropriate antimicrobial therapy; avoid steroids until infection cleared
• Rheumatoid arthritis – start disease‑modifying antirheumatic drug (DMARD) such as methotrexate; add low‑dose prednisolone for bridge therapy
• SLE – hydroxychloroquine first line; add steroids for organ involvement, avoid NSAIDs if renal disease present
• Ankylosing spondylitis – NSAID (e.g., ibuprofen) as first line; consider physiotherapy; avoid long‑term steroids

Follow‑up and prevention

Regular monitoring prevents irreversible damage.

• Assess disease activity every 3 months with DAS28 or clinical score
• Screen for drug toxicity: liver function for methotrexate, renal function for NSAIDs
• Vaccinate against influenza and pneumococcus; give TB prophylaxis if indicated
• Educate on joint protection and early physiotherapy

Often confused with

Distinguish common mimics.

• Septic vs. crystal arthritis – aspiration and Gram stain are decisive
• Rheumatoid vs. osteoarthritis – rheumatoid has morning stiffness, symmetrical small‑joint swelling; osteoarthritis shows crepitus and distal joint involvement
• Lupus vs. rheumatoid arthritis – lupus has malar rash, renal involvement, anti‑dsDNA positivity

Where results can mislead

Be aware of false‑negative or non‑specific findings.

• RF can be negative early in rheumatoid arthritis; rely on clinical pattern
• ESR may be normal in early lupus flares; check complement levels if suspicion remains
• Joint aspiration may be dry in early septic arthritis; repeat if clinical suspicion persists

Questions an examiner may ask

• A 28‑year‑old woman with symmetric hand swelling and morning stiffness >2 hours – what clinical features differentiate rheumatoid arthritis from osteoarthritis? — Look for small‑joint symmetric swelling, prolonged morning stiffness, systemic symptoms; osteoarthritis shows distal joint involvement, crepitus, no systemic signs.
• A patient with HIV presents with mono‑articular knee pain and fever – what is your immediate management? — Perform urgent joint aspiration, send for Gram stain and culture, start empirical antibiotics after samples; avoid steroids until infection ruled out.
• You have a limited lab set; how would you confirm rheumatoid arthritis? — Use clinical 2010 ACR/EULAR criteria (joint count, duration, serology if available, acute‑phase reactants, radiographs) and start DMARD based on high disease activity.
• A young man with low‑back pain, enthesitis and reduced chest expansion – which red flag prompts urgent referral? — Suspect spinal cord compression or severe ankylosing spondylitis; arrange urgent MRI and rheumatology input.
• Why is methotrexate preferred over long‑term NSAIDs in rheumatoid arthritis? — Methotrexate modifies disease course and prevents joint damage, whereas NSAIDs only relieve pain and have gastrointestinal/renal toxicity with chronic use.
• In a patient with lupus and proteinuria, why would you avoid high‑dose NSAIDs? — NSAIDs can worsen renal function and precipitate hypertension; renal‑protective agents and steroids are safer.
• How does the DAS28 score influence treatment decisions? — Scores >5.1 indicate high disease activity, prompting escalation to biologic DMARDs; ≤2.6 suggests remission, allowing tapering.
• What laboratory result could mislead you in early septic arthritis and how to overcome it? — A normal white‑cell count; repeat aspiration or rely on clinical signs and imaging if suspicion remains.

When to seek help

• Septic arthritis – severe pain, fever, inability to bear weight
• Rapidly progressive neurological deficit in ankylosing spondylitis
• Acute renal failure or pulmonary hemorrhage in lupus

Quick questions

Why is joint aspiration essential before starting steroids?

Steroids suppress immunity and can worsen an undiagnosed infection, leading to joint destruction.

Can rheumatoid arthritis be diagnosed without anti‑CCP?

Yes, using clinical criteria (symmetrical small‑joint swelling, morning stiffness, radiographic changes) when serology is unavailable.

What is the first step in a patient with suspected tuberculous arthritis?

Obtain synovial fluid for PCR or culture and start anti‑TB therapy once confirmed; surgical drainage may be needed.