What history and physical examination steps should be performed for a patient presenting with knee pain?

Physical Assessment of Knee Pain

All patients presenting with knee pain require a systematic history and physical examination that includes specific pain characteristics, mechanism of injury, mechanical symptoms, joint effusion assessment, and targeted provocative maneuvers to identify ligamentous, meniscal, or patellofemoral pathology. 1

Essential History Components

Pain Characteristics

• Onset, quality, intensity, distribution, duration, and course of the pain, including both sensory and affective components 1
• Exacerbating and relieving factors, particularly relationship to weight-bearing, stairs, squatting, or specific activities 1, 2
• Timing of symptom onset: acute traumatic versus gradual/chronic onset helps differentiate ligamentous injury from degenerative conditions 2, 3

Mechanical Symptoms

• Locking (true inability to extend versus pseudo-locking from pain) suggests meniscal tear or loose body 2, 3
• Popping or clicking during movement indicates possible meniscal pathology or patellofemoral instability 4, 3
• Giving way or instability suggests ligamentous injury (particularly anterior cruciate ligament) or patellar subluxation 5, 3

Joint Effusion History

• Timing of swelling: immediate (within 2 hours suggests hemarthrosis from ligament tear), delayed (6-24 hours suggests meniscal injury or synovitis) 2, 3
• Amount and recurrence of effusion 3

Additional Critical History

• Age: patients ≥45 years with activity-related pain and <30 minutes morning stiffness have 95% sensitivity for osteoarthritis 6
• Previous diagnostic tests, therapies, and current medications including substance use 1
• Medical, surgical, family, and social history 1
• Impact on activities of daily living and functional limitations 1

Systematic Physical Examination

Inspection

• Compare both knees for symmetry, swelling, erythema, muscle atrophy (particularly quadriceps wasting), and deformity 5, 2
• Observe gait pattern for antalgic gait, inability to bear weight, or compensatory movements 1, 2
• Assess alignment for varus or valgus deformity 2

Palpation for Point Tenderness

• Medial and lateral joint lines: 83% sensitive and 83% specific for meniscal tears when tender 6
• Patellar borders and facets: isolated patellar tenderness warrants radiography per Ottawa rules 1, 3
• Tibial tubercle: tenderness suggests Osgood-Schlatter disease in adolescents 1, 7
• Head of fibula: tenderness requires radiography per Ottawa rules 1, 3
• Pes anserine bursa, iliotibial band, and patellar tendon for bursitis or tendinopathy 2, 8

Joint Effusion Assessment

• Ballottement test (patellar tap) for moderate to large effusions 2, 3
• Bulge sign or stroke test for small effusions 2, 3
• Presence of effusion with normal radiographs indicates need for MRI to evaluate soft-tissue pathology 1, 4

Range of Motion Testing

• Active and passive flexion/extension: normal knee flexes 0° to 135°; inability to flex to 90° requires radiography per Ottawa rules 1, 3
• Compare to contralateral knee for baseline 5, 3
• Note crepitus during motion suggesting chondromalacia or osteoarthritis 2, 3

Ligamentous Stability Testing

Collateral Ligaments

• Valgus stress test at 0° and 30° flexion for medial collateral ligament integrity 5, 2
• Varus stress test at 0° and 30° flexion for lateral collateral ligament integrity 5, 2

Anterior Cruciate Ligament

• Lachman test (most sensitive): knee at 20-30° flexion with anterior tibial translation 5, 2
• Pivot shift test: combined rotation and valgus stress during extension 5, 2
• Anterior drawer test at 90° flexion (less sensitive than Lachman) 5, 2

Posterior Cruciate Ligament

• Posterior drawer test: posterior tibial translation at 90° flexion 5, 2
• Tibial sag test (gravity test): observe for posterior tibial displacement with knee flexed 5, 2

Meniscal Testing

• McMurray test: knee rotation (internal for lateral meniscus, external for medial) during extension from full flexion; 61% sensitive, 84% specific 5, 6
• Apley grind test: compression with rotation in prone position 5, 3
• Bounce test: resistance to full extension suggests meniscal tear 5, 3
• Joint line tenderness combined with mechanical symptoms increases diagnostic accuracy 3, 6

Patellofemoral Assessment

• Patellar apprehension test: lateral displacement of patella with knee at 30° flexion reproduces instability 2, 3
• Patellar grind test (Clarke sign): compression of patella during quadriceps contraction 2, 3
• Decline squat test: anterior knee pain during single-leg squat on decline is 91% sensitive for patellofemoral pain 7, 6
• Patellar mobility assessment: hypermobility suggests instability risk 7, 2

Neurovascular Examination

• Motor function: assess quadriceps, hamstrings, ankle dorsiflexion/plantarflexion 1, 2
• Sensory testing: evaluate for dermatomal deficits suggesting radiculopathy 1, 2
• Distal pulses and capillary refill: critical in trauma to exclude vascular injury 2

Additional Assessments

• Hip examination with range of motion: hip pathology commonly refers pain to the knee 1, 4, 9
• Lumbar spine assessment: radiculopathy can mimic knee pain 4, 9
• Psychosocial evaluation: assess impact on mood, sleep, function, and presence of anxiety or depression in chronic pain 1

Common Pitfalls to Avoid

• Do not skip examination of the contralateral knee for comparison; asymmetry provides critical diagnostic information 5, 3
• Do not attribute knee pain solely to local pathology without examining the hip and spine, as referred pain is common 1, 4, 9
• Do not overlook red flags requiring urgent evaluation: severe pain with inability to bear weight, fever with joint swelling/erythema (septic arthritis), acute neurovascular compromise, or severe instability 2, 6
• Do not order MRI before obtaining plain radiographs in patients with chronic pain; approximately 20% inappropriately receive early MRI 7, 4
• Do not assume mechanical symptoms (clicking, locking) always require surgery; degenerative meniscal tears with mechanical symptoms respond to conservative treatment 6

Indications for Radiography (Ottawa Knee Rules)

Obtain knee radiographs if any of the following criteria are met in patients ≥18 years with acute knee pain: 1, 3

• Age ≥55 years
• Isolated patellar tenderness (no other bone tenderness)
• Tenderness at head of fibula
• Inability to flex knee to 90°
• Inability to bear weight immediately after injury and in emergency department (4 steps)

When to Proceed to Advanced Imaging

• MRI without contrast is indicated when radiographs are normal or show only effusion but pain persists, particularly with mechanical symptoms suggesting meniscal or ligamentous injury 1, 4
• MRI is appropriate for chronic pain (≥6 weeks) with mechanical clicking and effusion to detect repairable meniscal tears before they become degenerative 4
• Reserve MRI with contrast for suspected infection, tumor, or inflammatory arthropathy—not for isolated mechanical symptoms 4