Knee Examination

Overview – Knee Examination

The knee examination is a core component of musculoskeletal OSCEs and clinical assessment of joint pain, trauma, swelling, or instability. It is especially relevant for evaluating patients with ligament injuries, meniscal tears, inflammatory arthritis, or effusions. This guide provides a systematic and high-yield approach to knee examination, from inspection and palpation to special tests that help differentiate pathologies such as anterior cruciate ligament (ACL) tears, meniscal injuries, and gout.

Preparation

  • Wash hands, introduce yourself, confirm patient identity and age.
  • Explain procedure and gain consent.
  • Patient should be in shorts, lying with bed at 45°.
  • Inspect surroundings for walking aids.

Inspection

General Inspection

  • Compare both knees.
  • Begin with patient standing to assess:
    • Gait:
    • Deformities:
      • Varus (bow-legged) → osteoarthritis
      • Valgus (knock-knees) → arthritis
      • Flexion deformity → inability to fully extend the knee

Local Signs

  • Scars:
    • Small incisions (arthroscopy/meniscectomy)
    • Midline incision (total knee replacement)
  • Swelling & erythema → inflammation or infection
  • Wasting of quadriceps:
    • Measure 15 cm above superior pole of patella
  • Baker’s cyst:
  • Psoriatic plaques: especially over extensor surfaces

Palpation

  • Temperature: Use back of hand to compare above both knees
  • Tenderness sites (flex knee to 90°):
    • Popliteal fossa → Baker’s cyst
    • Medial/lateral joint lines → meniscus or collateral ligament injury
    • Patellar borders
    • Tibial tuberosity → tibial apophysitis (Osgood-Schlatter)
    • Femoral condyles

Effusion Tests

Patellar Tap (for large effusions)

  • Compress suprapatellar pouch downward
  • Press down patella with fingers
  • Positive = floating or bouncing patella

Bulge Sign (for small effusions)

  • Stroke upwards on medial aspect of knee
  • Then swipe downward on lateral side
  • Positive = bulge appears on medial side
Knee Exam - Patellar tests

Range of Motion (ROM)

Compare active vs passive movements, feel for crepitus:

  • Flexion: up to 140° (biceps femoris, semitendinosus)
  • Extension: full extension expected
  • Hyperextension: up to 10° in some individuals

Special Tests

Ligament Stability

Anterior Drawer Test – ACL tear

  • Knee flexed at 90°, sit on foot
  • Pull tibia forward → excessive movement = ACL tear

Posterior Drawer Test – PCL tear

  • Same position as above
  • Push tibia backward

Lachman’s Test – ACL

  • One hand stabilizes femur
  • Other pulls tibia forward → test for anterior laxity

Collateral Ligament Test

  • Flex knee to 30°
  • Apply valgus stress (medial) and varus stress (lateral)
  • Positive if excessive movement
Knee Exam - Anterior & Posterior Drawer Tests
Knee Exam - Collateral Ligaments

Meniscal Injury

McMurray’s Test

Lateral meniscus:

  • Flex hip and knee to 90°
  • Internally rotate foot, apply varus stress, extend knee
  • Pain/click = positive

Medial meniscus:

  • Externally rotate foot, apply valgus stress, extend knee
  • Pain/click = positive

Grind Test (Optional):

  • Compress and rotate tibia over femur → meniscal damage
McMurray's Test

Patellar Instability

Patellar Apprehension Test

  • Push patella laterally while observing for pain or guarding
    → Suggestive of patellar dislocation or patellofemoral syndrome
Knee Apprehension Test

To Complete the Exam

  • Examine hip and ankle (joint above and below)
  • Neurovascular exam of the limb

Clinical Correlations

Gout

  • Affects 1st MTP and lower limb joints (e.g. knee)
  • Triggers: alcohol, red meat, diuretics
  • Symptoms:
    • Monoarthritis
    • Swollen, erythematous, tender joint
    • Fever in acute attacks
  • Investigations:
    • Uric acid, WCC
    • Joint aspiration: needle-shaped, negatively birefringent crystals
  • Treatment:
    • Acute: NSAIDs, colchicine, steroids
    • Long-term: Allopurinol (watch for rash), probenecid, pegloticase

Pseudogout

Septic Arthritis

  • Organism: Staphylococcus aureus
  • Risk factors: joint injections, prosthetic joints, immunosuppression
  • Features:
    • Fever, monoarthritis, erythema, effusion
  • Investigations:
    • Synovial fluid: purulent, ↑WCC, gram stain
    • Bloods: ↑CRP, ↑WCC
  • Treatment: Joint drainage + IV antibiotics

Ligament Injuries

ACL

  • Mechanism: Hyperextension or twisting injury
  • Audible “pop”, rapid swelling, instability
  • Common in athletes
  • Unhappy triad: ACL + MCL + medial meniscus

PCL

  • Mechanism: Dashboard injury or hyperflexion

Collateral Ligaments

  • Mechanism: Direct blow to the lateral/medial knee
  • Medial (MCL) injuries more common than lateral

Meniscal Tears

  • Mechanism: Twisting of flexed, weight-bearing knee
  • Signs:
    • Delayed effusion
    • Joint line tenderness
    • Locking or clicking sensation
    • Quadriceps wasting

Summary – Knee Examination

The knee examination is a core OSCE skill that helps differentiate between ligamentous, meniscal, inflammatory, or degenerative knee conditions. With structured inspection, palpation, ROM testing, and special manoeuvres like McMurray’s and drawer tests, clinicians can pinpoint pathologies such as ACL tears, osteoarthritis, or gout. For a broader context, see our OSCE Prep Overview page.

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