What physical examination tests are recommended for an adult or older adult patient presenting with knee joint issues, possibly with a history of trauma or osteoarthritis?

Physical Examination Tests for Knee Joint Assessment

For acute knee trauma, perform the Ottawa Knee Rule criteria assessment first, followed by specific ligamentous and meniscal tests based on mechanism of injury; for chronic knee pain, focus on joint line tenderness, range of motion, crepitus, and effusion assessment. 1

Initial Assessment Framework

For Acute Trauma Patients

Apply the Ottawa Knee Rule to determine imaging needs: 1, 2

• Age ≥55 years
• Isolated patellar tenderness on palpation
• Tenderness at the head of the fibula
• Inability to flex knee to 90 degrees
• Inability to bear weight for 4 steps immediately after injury or in the emergency department

Critical red flags requiring immediate evaluation: 3, 4

• Palpable gap in tendon (suggests complete rupture)
• Gross deformity
• Inability to bear weight at all
• Fever with joint effusion (septic arthritis emergency)

For Chronic Knee Pain or Osteoarthritis

Essential examination components: 1, 5

• Joint line tenderness (75% sensitive for meniscal tears but only 27% specific)
• Crepitus in patellofemoral compartment
• Limited range of motion
• Varus or valgus alignment assessment
• Presence and size of joint effusion

Specific Physical Examination Tests

Ligamentous Injury Assessment

Anterior Cruciate Ligament (ACL): 6, 7, 2

• Lachman test (most sensitive and specific - 74% sensitive, 95% specific) - preferred over anterior drawer sign
• Pivot shift test
• Always examine with knee at 20-30 degrees flexion

Posterior Cruciate Ligament (PCL): 6, 7

• Posterior drawer test (81% sensitive, 95% specific)
• Tibial sag test

Collateral Ligaments: 6, 7

• Valgus stress test (medial collateral ligament)
• Varus stress test (lateral collateral ligament)

Meniscal Injury Assessment

Key meniscal tests with performance characteristics: 6, 2, 8

• Joint line tenderness: 75% sensitive but only 27% specific - useful for screening but not diagnostic alone
• McMurray test: 97% specific but only 52% sensitive - when positive, highly suggestive of meniscal tear
• Apley's grind test: additional confirmatory test
• Bounce test: assess for mechanical block to extension

Patellar Assessment

For suspected patellar instability or dislocation: 1

• Palpate for medial patellar tenderness
• Assess for small osseous fragments along medial patellar margin
• Evaluate patellofemoral tracking

Critical Examination Pitfalls

Timing considerations: 3

• Excessive swelling and pain can limit examination accuracy for up to 48 hours after acute injury
• Re-examination after 3-5 days is important if initial exam is limited or partial tears are suspected
• Delayed examination improves diagnostic accuracy once acute swelling subsides

Always examine the uninjured knee first for comparison. 6, 8

Do NOT apply clinical decision rules in these situations: 1

• Gross deformity present
• Palpable mass
• Penetrating injury
• Prosthetic hardware
• Multiple injuries limiting reliable examination
• Altered mental status (head injury, intoxication, dementia)
• Neuropathy (paraplegia, diabetes)
• History suggesting increased fracture risk

Examination Sequence Algorithm

Step 1: Visual Inspection

• Alignment (varus/valgus deformity)
• Swelling/effusion
• Ecchymosis
• Gross deformity 8

Step 2: Palpation

• Joint line tenderness (medial and lateral)
• Patellar tenderness
• Fibular head tenderness
• Palpable gaps in tendons 3, 8

Step 3: Range of Motion

• Active and passive flexion/extension
• Document inability to flex to 90 degrees (Ottawa criterion)
• Assess for crepitus during motion 5, 8

Step 4: Effusion Assessment

• Ballottement test
• Bulge sign
• If significant effusion with fever: urgent aspiration required to rule out septic arthritis 4

Step 5: Stability Testing

• Perform ligamentous tests based on mechanism of injury
• Lachman test for ACL (most important)
• Valgus/varus stress for collaterals
• Posterior drawer if dashboard injury or hyperextension 6, 7, 2

Step 6: Meniscal Testing

• McMurray test (high specificity when positive)
• Joint line tenderness (high sensitivity for screening)
• Apley's grind test 6, 2

Step 7: Functional Assessment

• Ability to bear weight for 4 steps
• Gait pattern
• Single leg stance if able 1, 2

Special Population Considerations

Adolescents with knee pain and inability to bear weight: 9

• Consider slipped capital femoral epiphysis (SCFE) presenting as referred knee pain
• Requires hip examination and imaging even without direct knee trauma

Patients >50 years with chronic symptoms: 5, 2

• Clinical features for osteoarthritis: age >50 years, morning stiffness <30 minutes, crepitus, bony enlargement (89% sensitive, 88% specific)
• Degenerative meniscal tears common - McMurray test may cause pain but doesn't necessarily indicate acute tear requiring surgery