🦵 Joint Pain: Master the 4-Quadrant Approach for Quick Differential Diagnosis

“My knee is swollen and painful… maybe it’s just arthritis?”
Don’t be fooled—joint pain can be much more than just osteoarthritis.
The key to an accurate diagnosis lies in classifying the pain by onset (acute or chronic) and distribution (monoarticular or polyarticular).

In this article, we’ll walk you through a structured approach using the “Four-Quadrant Method,” which helps simplify your initial assessment. This is a high-yield topic for OSCEs and clinical rotations alike, covering everything from infectious arthritis to gout and rheumatoid arthritis.

📘 What You’ll Learn

• A simple classification method: How to approach joint pain using the “Four-Quadrant” model (Acute vs Chronic × Monoarticular vs Polyarticular)
• High-yield history-taking and physical exam tips: Tools to identify common and critical diagnoses such as septic arthritis, pseudogout, and RA
• Smart test selection: How and when to use labs, joint aspiration, and imaging—avoid unnecessary tests while ruling out red flags

🔍 Introductory Case: A Common Presentation of Joint Pain

【Doorway Information】
A woman in her 70s presents with:
Chief Complaint: Swelling and pain in her right knee (difficulty walking)
Vital Signs: BP 128/72 mmHg, HR 86/min, Temp 37.9°C, SpO₂ 98% (RA)

Patient’s Words:
“Doctor, my right knee suddenly got swollen since yesterday, and it hurts badly… I can barely walk. I also feel a bit feverish…”

🧭 How Should We Think About Joint Pain? — Start With Classification

In this case, several key points stand out: Acute onset, monoarticular, elderly patient, knee joint, and fever.
Together, these raise a red flag: “Acute monoarthritis with fever” must always prompt you to rule out infectious arthritis first.

“A hot, swollen knee… it could be crystal-induced, but we can’t afford to miss septic arthritis. That should be our top priority.”

🧩 Classify Using the “Four-Quadrant Approach”

Joint pain can be efficiently screened and approached by classifying it based on two axes:
Onset (Acute vs. Chronic) × Number of joints involved (Monoarticular vs. Polyarticular).

	Monoarticular	Polyarticular
Acute	Septic arthritis (emergency), Gout / Pseudogout, Trauma (fracture, sprain)	Viral arthritis, Reactive arthritis (post-diarrhea or UTI)
Chronic	Osteoarthritis (OA), Hemophilic arthropathy, Tumor-related lesions	Rheumatoid arthritis (RA), SLE, Psoriatic arthritis, Post-infectious arthritis

💡 Tip: The quadrants are based on the current clinical presentation, not the disease itself.
Some conditions evolve over time and move across quadrants:

• RA or SLE: May begin as monoarthritis but later become polyarticular
• Gout/Pseudogout: Initially acute, but may become chronic with recurrent flares
• OA: Can suddenly worsen if complicated by infection or crystal deposition

📌 Key point: Always assess the timeline and the bigger picture—don’t be confined to the quadrant you’re in now.

📍 The Location of Joint Pain Also Offers Critical Clues

The specific joint involved can significantly narrow your differential diagnosis.

Joint Involved	Suggestive Conditions
DIP joints	Osteoarthritis (Heberden’s nodes)
PIP and MCP joints	Rheumatoid arthritis (typically symmetric)
Shoulder in elderly	Rotator cuff tear, Calcific tendinitis
Sacroiliac joint	Ankylosing spondylitis, Infectious sacroiliitis

🩺 Column: Why Every Clinician Needs to Master Joint Pain Assessment

Joint pain is one of the most common symptoms seen across all clinical settings—outpatient clinics, emergency rooms, and inpatient wards.

Why it matters:

• A frequent reason for primary care and general internal medicine visits
• In elderly patients, joint pain can lead to loss of mobility and independence
• Underlying causes may include infection, autoimmune diseases, or even malignancy

Because it’s so common, joint pain can be underestimated—but beneath the surface, it often signals serious or systemic pathology. That’s why all healthcare professionals need a reliable and efficient way to assess it.

🔎 Topics: Uncommon but Important Joint Pain Diagnoses You Don’t Want to Miss

🦠 Tuberculous Arthritis

• Chronic monoarthritis
• Often lacks high fever or overt inflammation
• Commonly misdiagnosed as osteoarthritis or RA

🌫 Medically Unexplained or Functional Joint Pain

• Seen in somatoform disorders, menopause, or fibromyalgia
• Symptoms are often vague and migratory
• Pain may be out of proportion to physical findings

➡ Always keep a broad differential and consider less obvious causes, especially in atypical presentations.

🧠 Clinical Reasoning with FPH: Structure Your Thought Process

Use the FPH framework — Fact, Problem, Hypothesis — to translate patient complaints into diagnostic reasoning.

🔍 Fact

• 70s female
• Sudden onset of right knee swelling and pain since yesterday
• Difficulty walking, feels febrile (Temp 37.9°C)
• Stable vital signs (BP 128/72, HR 86, SpO₂ 98%)

🧠 Problem

Acute monoarthritis with fever in an elderly patient
→ Must prioritize ruling out septic arthritis

💭 Hypothesis

Priority	Condition	Reason
🟥 High	Septic arthritis	Needs urgent exclusion — could be limb- or life-threatening
🟧 Medium	Pseudogout (CPPD)	Common in elderly, especially affecting the knee
🟨 Low	Gout	Atypical in elderly women; still possible post-menopause
🟫 Low	Acute exacerbation of OA	Fever is uncommon—makes OA less likely
⬛ Rare	Hematologic or neoplastic disease	Usually chronic, with systemic symptoms

💡 Clinical Pearl:
“Any hot, swollen joint is septic arthritis until proven otherwise.”
— BMJ Best Practice

🗣️ Step 1: History Taking — Capture the Full Picture with OPQRST + PAM HITS FOSS

Accurate history is critical—not just “where does it hurt?” but what’s behind the pain.
Use the dual framework of OPQRST (for symptom characterization) and PAM HITS FOSS (for background factors).

🔹 OPQRST: Seven Key Questions to Define the Pain

Letter	What to Ask	Clinical Relevance
O (Onset)	When did it start? Sudden or gradual?	Sudden onset suggests infection or crystals
P (Provocation/Palliation)	What makes it better or worse?	Better with rest → mechanical; better with movement → inflammatory
Q (Quality)	What does it feel like?	Sharp, dull, catching → structural clues
R (Region/Radiation)	Where is the pain? Does it spread?	Helps localize intra-articular vs periarticular pain
S (Severity)	Pain scale 0–10	For monitoring response to treatment
T (Time course)	Is it worse at any particular time of day?	Morning → inflammatory; evening → mechanical (e.g., OA)

💡 Tip:

• Relieved by rest → mechanical (OA, overuse)
• Improved by movement → inflammatory (RA, PsA, ankylosing spondylitis)
• Morning stiffness >30 min → inflammatory arthritis
• Evening worsening → degenerative or mechanical cause

🔸 PAM HITS FOSS: Uncover Underlying Risk Factors

Letter	Item	Clinical Connection
P	Past medical history	RA, OA, gout, diabetes—important red flags
A	Allergy	NSAID or colchicine intolerance may limit treatment options
M	Medications	Steroids or immunosuppressants increase infection risk
H	Hospitalization	Recent stay → concern for bacteremia/septic arthritis
I/T	Injury/Trauma	Recent fall or impact → fracture or traumatic arthritis
S	Surgery	Artificial joints → risk for prosthetic joint infection
F	Family history	RA, psoriasis, lupus — genetic susceptibility
O	OBGYN	Postmenopausal status may influence gout or osteoporosis
S	Sexual history	STI risk → gonococcal arthritis, reactive arthritis
S	Social history	Smoking, alcohol, activity level, occupation — key lifestyle clues

🟦 Column: What Can Be Learned from History Alone?

It’s often said that “80% of diagnoses come from history alone.”
In joint pain, this is especially true.

• “Sudden knee swelling and fever” → Think septic arthritis first
• “Severe toe pain at night after drinking” → Classic gout attack
• “Morning hand stiffness lasting over 30 minutes” → Suggestive of RA or SLE
• “Knee pain 2 weeks after diarrhea” → Consider reactive arthritis

By exploring the timeline, distribution, triggers, systemic signs, and underlying risk, a clear diagnostic direction emerges—often without any labs or imaging.

💡 Tip: Joint Pain Often Hides in Daily Life

Don’t just focus on the joint itself—ask what kind of forces are acting on it in daily life.

• Occupation: Long-standing work → knee OA / plantar fasciitis
• Heavy lifting or caregiving: Shoulder/lower back strain
• Desk jobs: Elbow/wrist stress, cervical spondylosis
• Hobbies: Running/hiking → knee & ankle overuse
• Sports: Tennis/golf → wrist & elbow stress; swimming → shoulder
• Lifestyle: Sitting on floor → hip/knee pressure; soft bedding → posture-related pain

These everyday factors may hold the key to understanding “invisible” causes of joint pain—especially in primary care or OSCE settings.

🖐️ Step 2: Physical Examination — Identify the True Nature of the Pain

After history-taking, the next step is physical examination to determine whether the pain is due to infection, inflammation, or structural abnormality.

✅ 1. General Assessment

• Fever, tachycardia → Consider septic arthritis or sepsis
• Skin rash, conjunctivitis → Think autoimmune or reactive arthritis
• Lymphadenopathy, splenomegaly → Possible hematologic disease
• Weight loss, fatigue → Suggest systemic illness

✅ 2. Local Joint Examination (Inspection, Palpation, ROM)

Finding	Interpretation
Redness	Infectious or crystal-induced arthritis
Warmth	Infection or inflammation
Swelling	Synovitis or joint effusion
Spontaneous or passive pain	Suggests intra-articular pathology
Restricted ROM	Due to swelling, pain, or mechanical block
Tenderness	Indicates inflammation of synovium, tendons, or bone

✅ 3. Check Other Joints

• Is it truly monoarthritis? Look for subtle signs in other joints
• DIP/PIP/MCP involvement and symmetry help differentiate OA from RA

✅ 4. Extra-articular Signs

• Skin: Psoriatic plaques, purpura → PsA, vasculitis
• Eyes: Conjunctivitis, uveitis → ReA, ankylosing spondylitis
• Mouth: Ulcers → Behçet’s disease, SLE
• Nails: Pitting, paronychia → Psoriatic arthritis

✅ 5. Use of Adjunct Tools (e.g., Ultrasound)

• POCUS: Assess effusion, synovial thickening, blood flow
• Identify active inflammation (via power Doppler)
• Dynamic testing → Diagnose motion-induced pain in real time
• Evaluate bursa/tendons for bursitis or tendinitis

🟨 Topics: Don’t Miss These Joint-Specific Clues

Condition	Site	Key Tests	Common Background
Tennis elbow (lateral epicondylitis)	Lateral elbow	Cozen’s test	PC work, racket sports
Golfer’s elbow (medial epicondylitis)	Medial elbow	Pain on wrist flexion resistance	Manual work, cleaning
Trigger finger	MP joint	Clicking during flexion-extension	Middle-aged women, diabetes
De Quervain’s tenosynovitis	Thumb tendons	Finkelstein test	Childcare, smartphone use
Little leaguer’s elbow	Medial elbow	Valgus stress test	Repetitive throwing
Jumper’s knee	Patellar tendon	Pain with resisted extension	Jumping sports
Osgood-Schlatter disease	Tibial tuberosity	Tenderness, pain on motion	Adolescent boys
Frozen shoulder	Shoulder joint	Apley scratch test, limited abduction	Night pain, difficulty dressing
Rotator cuff tear	Shoulder joint	Drop arm test, weak external rotation	Elderly, often asymptomatic

🟦 Column: Shoulder Motion Depends on Four Key Muscles — the Rotator Cuff

The rotator cuff stabilizes the shoulder joint and enables precise movement.

Muscle	Name	Main Action
棘上筋	Supraspinatus	Abduction (initial)
棘下筋	Infraspinatus	External rotation
小円筋	Teres minor	External rotation
肩甲下筋	Subscapularis	Internal rotation

Other key shoulder motions:

• Abduction: Supraspinatus + middle deltoid
• Flexion: Anterior deltoid + biceps
• Internal rotation: Subscapularis, teres major, latissimus dorsi
• External rotation: Infraspinatus, teres minor

Understanding these anatomical roles helps target the physical exam and interpret special tests accurately.

🔬 Step 3: Labs and Imaging — Visualize the Hidden Pathology

After forming a hypothesis through history and physical exam, lab and imaging studies are crucial to confirm or refute your suspicions—especially to distinguish between infection, crystal deposition, or systemic disease.

✅ 1. Define the Purpose of Testing

• Rule out serious conditions (septic arthritis, malignancy)
• Support your working diagnosis (e.g. crystals, autoimmune markers)
• Visualize disease extent and guide referral or management

✅ 2. Blood Tests — For Screening and Narrowing Down

Test	Purpose	Notes
WBC / CRP	Detect infection or inflammation	Normal results don’t completely rule out septic arthritis
Uric acid	Evaluate for gout	May be low during acute flare
Calcium / Magnesium / Phosphate	Evaluate for pseudogout (CPPD)	Low magnesium can trigger crystal formation
RF / Anti-CCP	Support RA diagnosis	Negative doesn’t rule out RA
ANA / ANCA	Evaluate SLE or vasculitis	Always interpret with clinical symptoms

✅ 3. Joint Aspiration — The Decisive Test

Parameter	Findings	Interpretation
Appearance	Purulent, bloody, or clear yellow	Purulence → high suspicion of infection
WBC in synovial fluid	> 50,000 /μL	Suggests infection (can also be high in crystal arthritis)
Crystal analysis	Needle-shaped (urate), rhomboid (CPPD)	Use polarized microscopy
Gram stain / Culture	Positive confirms septic arthritis	Negative does not fully exclude it

✅ 4. Imaging — Assess Depth and Spread

Modality	Findings	Useful For
X-ray	Erosions, calcifications, joint space narrowing	OA, RA, CPPD, infection
Ultrasound (POCUS)	Synovial thickening, joint effusion, hyperemia	Crystal arthritis, infection, RA
MRI	Synovitis, bone marrow edema, tumor	Useful for difficult or atypical cases

🟨 Topics: Radiologic Clues by Disease

Disease	Modality	Typical Findings	Notes
Pseudogout (CPPD)	X-ray	Calcification in cartilage or meniscus	Also look for crowned dens sign (cervical spine)
Gout	X-ray	“Overhanging edge” erosions	Seen in chronic cases
RA	X-ray	Erosions + joint space narrowing (symmetric)	MCP, PIP are classic sites
OA	X-ray	Osteophytes, joint space narrowing, sclerosis	Common at DIP joints
Ankylosing spondylitis	X-ray	Bamboo spine	Look for sacroiliac joint fusion
Psoriatic arthritis	X-ray	Pencil-in-cup deformity	DIP involvement with bone destruction
Septic arthritis	X-ray	Joint destruction, bone erosion	Late finding
Tuberculous arthritis	X-ray/CT	Phemister triad (erosion + sclerosis + joint space narrowing)	Classic for TB joint infection
Vertebral compression fracture	X-ray	Wedge deformity	Early MRI is better for diagnosis
Spinal metastasis	X-ray	Winking Owl Sign (pedicle loss)	Suggests bone involvement by tumor

🟦 Topics: Assessing RA Disease Activity

After diagnosis, assessing disease activity helps guide therapy and predict prognosis. CRP and RF alone aren’t enough—use composite scores:

Score	CRP?	Components	Interpretation
DAS28-CRP	Yes	28 joints (tender + swollen) + CRP + VAS	>5.1 = high activity / <2.6 = remission
SDAI	Yes	Tender + swollen joints + physician/patient global + CRP	Simple to calculate
CDAI	No	Same as SDAI without CRP	Useful if CRP not available

💡 Tip:
These scores help determine whether the current symptoms require escalation or modification of treatment.

🔁 Case Review: Applying the Diagnostic Steps to Our Introductory Patient

🟢 Recap of the Case

Patient: Woman in her 70s
Chief Complaint: Acute swelling and pain in the right knee
Vitals: Temp 37.9°C, BP 128/72, HR 86, SpO₂ 98%
Onset: Since yesterday
Function: Difficulty walking

🧠 Step 1: History Review (Fact → Problem → Hypothesis)

Patient’s Description:
“My right knee suddenly became swollen and very painful since yesterday. I feel a bit feverish and can barely walk.”

▶ OPQRST

• O: Sudden onset yesterday
• P: Worse with walking, slightly relieved at rest
• Q: Throbbing-type pain
• R: Right knee only, no radiation
• S: 7 out of 10 pain severity
• T: Persistent throughout the day, bothersome at night

▶ PAM HITS FOSS

• P: No known OA or RA history
• A: No known allergies
• M: On antihypertensives only; no steroids
• H: No recent hospitalization
• I/T: No obvious trauma
• S: No joint replacement history
• F: No family history of RA or gout
• O: Postmenopausal
• S: No high-risk sexual history
• S: Independent lifestyle, non-smoker

🔍 Fact

• 70s female
• Acute, unilateral knee pain and swelling
• Low-grade fever, difficulty walking

🧠 Problem

Acute monoarthritis in an elderly patient with fever → Rule out septic arthritis first

💭 Hypothesis

• 🟥 Septic arthritis – must be excluded urgently
• 🟧 Pseudogout (CPPD) – elderly, knee, acute onset
• 🟨 Gout – possible but less typical (female, knee)
• 🟫 OA flare-up – fever makes it atypical
• ⬛ Hematologic or neoplastic disease – low likelihood in this setting

🖐️ Step 2: Physical Exam Review

• Inspection: Redness, swelling, warmth in the right knee
• Palpation: Pain with passive ROM, significant tenderness
• Other joints: No abnormalities—clear monoarticular case
• Systemic signs: No rash, oral ulcers, conjunctivitis, or weight loss
• POCUS: Joint effusion and synovial thickening → Indication for aspiration

🔬 Step 3: Lab and Imaging Review

• Blood tests: WBC and CRP moderately elevated; no strong infection markers
• Joint fluid: Cloudy, mildly elevated WBCs, CPPD crystals detected
• Gram stain & culture: Negative
• X-ray: Chondrocalcinosis (calcium deposits) in the knee

🟩 Final Impression

No convincing signs of septic arthritis. Crystal analysis and imaging support pseudogout (CPPD).

Treatment: Start NSAIDs; consider colchicine if symptoms persist.

📤 Referral: When and What to Communicate to a Specialist

Now that the initial workup is complete, the next step may be referral. But when should you refer? And what should you include?

🟥 Urgent Referrals — Red Flags You Can’t Miss

Clinical Situation	Suspected Condition	Action
High fever, intense pain, limited ROM + monoarthritis	Septic arthritis	Immediate orthopedic referral; joint aspiration and culture needed ASAP
Polyarthritis + bleeding tendency, rash, altered mental status	Hematologic disease, autoimmune disease, sepsis	Urgent internal medicine or rheumatology consult
Rapid joint deformity or tumor-like swelling	Metastasis, vascular tumor, malignancy	Refer to orthopedics or surgical oncology for workup

🟡 Referral During Outpatient Follow-up

Clinical Scenario	Possible Diagnosis	Suggested Department
Persistent inflammation, synovial thickening despite treatment	Early RA or autoimmune disease	Rheumatology
Symptoms persist but no crystals detected	Chronic joint degeneration or OA	Orthopedics
Recurrent attacks of gout or pseudogout	Metabolic or renal issues	Rheumatology or nephrology

🔍 Before You Refer: Complete These First

• Joint aspiration: To rule out infection or crystal-induced arthritis
• Imaging (X-ray or ultrasound): Assess for structural changes and synovitis
• Blood tests: WBC, CRP, uric acid, RF, anti-CCP, ANA, Ca, Mg, P, etc.
• Full-body check: Look for rash, oral ulcers, uveitis, other joint involvement

💡 Tip: Clearly state the reason for referral.
Not just “I can’t figure it out,” but “Suspect RA; initial tests done; requesting further evaluation and management.”
This makes it easier for specialists to act on your findings.

🟨 Topics: Don’t Miss These — Reactive Arthritis and Gout Management

🔹 Reactive Arthritis (ReA)

Reactive arthritis is a sterile arthritis that develops after an infection, most commonly gastrointestinal or genitourinary.

• Common in young men and HLA-B27 positive individuals
• GI pathogens: Salmonella, Shigella, Campylobacter, Yersinia
• STI-related: Chlamydia trachomatis (often asymptomatic)

Classic Triad (Reiter’s Syndrome)

• Asymmetric arthritis (especially lower limbs)
• Conjunctivitis or uveitis
• Urethritis

Treatment

• NSAIDs: First-line for pain and inflammation
• Oral steroids: For persistent cases
• DMARDs (e.g. sulfasalazine): In refractory or chronic cases
• Antibiotics: Only if underlying infection is active or confirmed

---

🔹 Gout — Acute Management and Long-term Prevention

🩺 Acute Flare Treatment

• NSAIDs: First choice (caution for GI side effects)
• Colchicine: Effective if given within 24 hours; diarrhea is common side effect
• Steroids: Oral or intra-articular if NSAIDs/colchicine are contraindicated

⚠ Do NOT initiate uric acid-lowering therapy during an acute attack.

🎯 Uric Acid-Lowering Therapy (for Prevention)

Type	Drug	Indication
Production Inhibitors	Allopurinol, Febuxostat	Overproduction of uric acid
Excretion Enhancers	Benzbromarone, Probenecid	Underexcretion of uric acid

Target uric acid level: Below 6.0 mg/dL (5.0 mg/dL if recurrent flares)

🏃 Lifestyle Modification

• Avoid high-purine foods: organ meats, fish roe, alcohol
• Limit fructose and sweetened beverages
• Ensure adequate hydration
• Manage comorbidities: hypertension, CKD, obesity

💡 Tip: Gout requires a dual strategy — acute management and long-term prevention.

💡 Tips & Clinical Pearl

🎤 History-Taking Tips

• Always clarify location and time course of joint pain
• Use classification: Acute vs. Chronic / Monoarticular vs. Polyarticular
• Ask about timing and triggers:
  • Morning stiffness → RA
  • Pain improves with movement → Psoriatic or inflammatory arthritis
• Explore lifestyle and occupational history:
  • Repetitive activities → Think tennis elbow, swimmer’s shoulder, etc.

🖐️ Physical Exam Tips

• Always compare affected and unaffected sides
• Use POCUS to observe joint fluid and synovium dynamically
• Don’t miss periarticular structures: tendons, bursae, ligaments
• Use provocative tests wisely: e.g., Drop Arm Test, Finkelstein Test

🧠 Clinical Pearl

“If you hear hoofbeats, think horses — not zebras.”
— Theodore Woodward, MD

Meaning: When approaching a differential diagnosis, always consider the most common conditions first.
In joint pain, focus on the “horses” like OA, crystal arthritis, or septic arthritis.
Zebras (rare diseases) should be considered only after excluding the likely and dangerous ones.

💡 Remember: The best clinicians balance probability and severity in their thinking.

🗣️ OET Speaking Session – Joint Pain

👥 Scenario

You are a doctor in a general practice clinic. A 72-year-old woman presents with sudden onset of right knee pain and swelling since yesterday. She can barely walk and feels slightly feverish.

You suspect pseudogout (CPPD), but it’s important to rule out septic arthritis.

🎯 Your Task

• Explain the likely diagnosis and what may have caused it
• Discuss the need for joint aspiration
• Reassure the patient and respond to emotional cues
• Provide information about the plan for follow-up and referral

💬 Common Patient Cues & Sample Doctor Responses

🧠 Challenging Questions & Sample Doctor Responses

✉️ OET Writing Task – Sample Referral Letter

Today’s Date

Dr. Andrew Green
Rheumatology Department
Westside Medical Centre

Re: Mrs. Elizabeth Sanders, 72 years old

Dear Dr. Green,

I am writing to refer Mrs. Elizabeth Sanders, a 72-year-old woman, for further evaluation and management of suspected pseudogout affecting her right knee. Septic arthritis has not been excluded at this point.

Mrs. Sanders presented to my clinic today with sudden-onset pain, swelling, and reduced mobility in her right knee since yesterday morning. She reports difficulty bearing weight and a low-grade fever (37.9°C), but no recent trauma or constitutional symptoms. Notably, she experienced a similar, self-limited episode in the same joint approximately eight months ago, which resolved spontaneously.

Her past medical history includes hypertension and stage 2 chronic kidney disease. She is currently on amlodipine and is not taking any anticoagulants. She has no personal or family history of rheumatoid arthritis or gout.

Joint aspiration has been arranged today to investigate for crystal-induced arthritis and to exclude infection. I would appreciate your assessment regarding diagnosis confirmation, further imaging, and long-term management options.

Please do not hesitate to contact me if you require any further information.

Yours sincerely,

Dr. [Your Name]
General Practitioner

🧾 Summary

Joint pain is a common and often complex complaint encountered across all clinical settings — from outpatient practice to emergency care. A structured approach that includes careful history-taking, focused examination, and appropriate investigations is crucial for timely diagnosis and intervention.

In this article, we explored the differential diagnosis of monoarthritis with an emphasis on practical bedside clues and red flags. We also included OET-based communication tasks, designed to help internationally minded clinicians build confidence in explaining, reassuring, and referring patients with joint-related complaints.

Whether you are preparing for OSCEs, managing patients in primary care, or training for international exams like OET or USMLE, the ability to assess joint pain thoroughly and communicate clearly remains an essential skill.

🔗 Related Articles

• Approach to Fever in Clinical Practice
• How to Assess and Manage Back Pain
• Differentiating Limb Weakness in Primary Care
• 日本語版はこちら：関節痛へのアプローチ

📚 References

1. Bijlsma JWJ, et al. EULAR evidence-based recommendations for the diagnosis of joint disorders. Ann Rheum Dis. 2016;75(1):3–15.
2. Rosenthal AK, Ryan LM. Calcium Pyrophosphate Deposition Disease. N Engl J Med. 2016;374:2575–2584.
3. Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet. 2019;393(10182):1745–1759.
4. OET Official Guide for Medicine (Cambridge Boxhill Language Assessment, 2021 Edition).