What is the recommended approach for a physical exam in a patient presenting with knee pain?

Physical Examination for Knee Pain

A systematic knee examination should include inspection for deformity/swelling/erythema, palpation of joint lines, documentation of flexion to 90 degrees, weight-bearing ability (at least 4 steps), range of motion testing, and special provocative tests to identify the pain source. 1

Inspection

• Observe for deformity, swelling, ecchymosis, and erythema to assess injury severity and identify urgent conditions requiring immediate referral 1
• Look for signs suggesting joint infection (fever, swelling, erythema, limited range of motion) which necessitates urgent evaluation 2
• Assess for visible effusion or asymmetry compared to the contralateral knee 2

Palpation

• Palpate joint line spaces systematically to localize tenderness, which has 83% sensitivity and 83% specificity for meniscal tears 3
• Examine for point tenderness over specific structures (patella, tibial tubercle, collateral ligaments, patellar tendon) 4
• Assess for warmth suggesting inflammatory or infectious processes 2

Range of Motion and Functional Testing

• Document the ability to flex to at least 90 degrees as this is a critical functional milestone 1
• Document weight-bearing ability by having the patient take at least 4 steps, as failure to document this results in incomplete assessment and influences management decisions 1
• Test both passive and active range of motion, comparing to the uninjured knee 4

Special Provocative Tests

• Perform valgus and varus stress testing to evaluate collateral ligament integrity 4
• Conduct the Lachman test and pivot shift test for anterior cruciate ligament assessment 4
• Use the posterior drawer and tibial sag tests to evaluate posterior cruciate ligament 4
• Perform the McMurray test (concurrent knee rotation and extension) which has 61% sensitivity and 84% specificity for meniscal tears 3
• Test for anterior knee pain during squatting, which is 91% sensitive and 50% specific for patellofemoral pain 3
• Consider the bounce test and Apley's grind test for additional meniscal evaluation 4

Critical Pitfall to Avoid

• Always assess for referred pain from hip or lumbar spine pathology before attributing all symptoms to the knee itself, as overlooking this is a common diagnostic error 5
• Never rush to imaging before completing the thorough clinical examination outlined above 5
• Always examine the uninjured knee first for comparison 4

Neurovascular Assessment

• Include neurovascular testing as part of the systematic examination to rule out vascular compromise or nerve injury 2

Documentation Requirements

• Failure to document weight-bearing ability and flexion to 90 degrees represents incomplete assessment and should be avoided 1
• Record all positive and pertinent negative findings to guide imaging decisions and management 2