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🦴 Mastering the Musculoskeletal System: Clinical Examination from Basic to Advanced

Based on Harrison's Principles of Internal Medicine 22E (2025) and Sabiston Textbook of Surgery

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PART 1 — How to Think & Read Efficiently

The Core Philosophy: Examine First, Investigate Second

1. What structure is involved? (joint, periarticular, bone, muscle, nerve)
2. What is the nature of pathology? (inflammatory vs. mechanical vs. referred)
3. What are the functional consequences?
4. Are there systemic/extraarticular clues?

How to Read MSK Efficiently

Practical tip: Learn anatomy through clinical scenarios — not in isolation. Every time you read about rotator cuff, ask: "How do I test each muscle?"

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PART 2 — The Universal MSK Examination Framework

LOOK (Inspection)

• Standing: alignment, posture, muscle wasting, deformity
• Gait: antalgic (pain), Trendelenburg (hip abductor weakness), steppage (foot drop)
• Skin: erythema (inflammation/infection), pallor/ecchymosis (vascular/fracture), psoriatic plaques, tophi, nodules
• Swelling: location — articular (within joint line) vs. periarticular (beyond joint margins)

FEEL (Palpation)

• Temperature: warmth = active inflammation or infection
• Tenderness: locate precisely — joint line vs. ligament vs. tendon insertion (enthesis) vs. bursa
• Swelling character:
  • Fluctuant → synovial effusion (fluid)
  • Boggy/compressible like grapes → synovial hypertrophy (proliferative inflammation, e.g., RA)
  • Hard as a nut → bony hypertrophy (OA)
• Crepitus: fine = normal; coarse = cartilage degeneration (OA)
• Muscle: atrophy, tenderness, trigger points

MOVE (Range of Motion)

• Active ROM first — what the patient can do voluntarily
• Passive ROM — what you can do when patient is relaxed
• Key rule: If passive > active → periarticular cause (tendon rupture, tendinitis, myopathy)
• Use a goniometer for accurate documentation
• Always compare contralaterally

Muscle Strength Grading (MRC Scale)

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PART 3 — Regional MSK Examination

🖐️ HAND & WRIST

1. Make a fist → tests all finger flexors
2. Thumbs-up → thumb abduction + extension (APL, EPB)
3. A-OK sign → thumb opposition + intrinsic function

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💪 SHOULDER

• Acromioclavicular (AC) joint — top of shoulder
• Bicipital groove (anterior) — biceps tendon
• Greater tuberosity — supraspinatus insertion
• Coracoid process — anterior, just below clavicle

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🦵 KNEE

• Bulge sign (small effusion): Milk fluid from medial pouch proximally, tap lateral side → medial bulge visible
• Patella Ballottement (large effusion): Press patella downward — it "bounces" back

• Clarke's test: Press patella distally while patient contracts quads → pain = chondromalacia patellae
• J-sign: Watch patellar tracking during knee extension — lateral deviation = maltracking

• Prepatellar bursa: Anterior to patella ("housemaid's knee")
• Infrapatellar bursa: Below patellar ligament
• Pes anserine bursa: Medial proximal tibia — often missed; tender in obese patients + OA + fibromyalgia

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🦴 HIP

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🔙 SPINE (Low Back)

• Inspect: loss of lordosis, scoliosis, muscle spasm
• Palpate: spinous processes, paraspinal muscles, SI joints
• ROM: flexion (touch toes), extension, lateral flexion, rotation

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PART 4 — Articular vs. Periarticular: The Critical Distinction

Rule: If passive ROM is full and pain-free but active ROM is limited/painful → the problem is periarticular (tendon, bursa, muscle). Investigations for joint pathology will be unhelpful.

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PART 5 — Inflammatory vs. Mechanical: The Second Key Distinction

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PART 6 — When to Investigate (and When NOT to)

Investigate ONLY when the exam cannot answer the question:

Do NOT investigate when:

• Clinical exam clearly identifies a periarticular cause (tendinitis, bursitis) → treat first
• Chronic mechanical low back pain without neurological signs → imaging rarely changes management
• Effusion is small and clearly reactive → aspirate only if septic arthritis cannot be excluded

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PART 7 — The 28-Joint Count (For Inflammatory Arthritis)

• 10 PIPs (fingers 2–5, bilateral)
• 10 MCPs (fingers 1–5, bilateral)
• 2 Wrists
• 2 Elbows
• 2 Shoulders
• 2 Knees

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PART 8 — Study Roadmap (Basic → Advanced)

LEVEL 1 (Basic)
├── Anatomy: bones, joints, muscles per region (Gray's)
├── Screening: GALS (Gait, Arms, Legs, Spine) screen
└── Vocabulary: articular vs. periarticular, mono vs. poly, acute vs. chronic

LEVEL 2 (Intermediate)
├── Regional examination: Hand, Shoulder, Knee, Hip, Spine
├── Special tests: learn 2-3 per joint with sensitivity/specificity
└── Pattern recognition: which diseases affect which joints

LEVEL 3 (Advanced)
├── Combined maneuvers + clinical reasoning
├── Neurological correlation (nerve roots, entrapments)
├── Systemic MSK disease (RA, SpA, crystal arthropathies, vasculitis)
└── Functional assessment + outcome measures (VAS, HAQ, DAS28)

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Quick Reference: Red Flags in MSK

• Hot, swollen, single joint → Septic arthritis until proven otherwise (arthrocentesis)
• Back pain + night sweats + weight loss → Malignancy / TB spine
• Hip pain in child + fever + limp → Septic arthritis / Perthe's disease
• Acute joint pain after intercourse in young adult → Gonococcal arthritis
• Jaw claudication + scalp tenderness + ESR >50 → Giant cell arteritis (temporal arteritis)

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