What is the recommended approach for a knee physical assessment in a patient presenting with knee pain or limited mobility, regardless of age or medical history, including previous knee injuries, surgeries, or conditions such as osteoarthritis?

Knee Physical Assessment

Begin the physical examination on the uninjured knee first for comparison, then systematically evaluate the injured knee through inspection, palpation, range of motion testing, and specific provocative maneuvers tailored to the suspected pathology based on patient age and presentation. 1

Structured Assessment Framework

The EULAR guidelines recommend evaluating these core components in sequence: 1

• Pain characteristics and location - Document onset, quality, aggravating/relieving factors 1
• Functional limitations - Assess activities of daily living, work/leisure participation, and mobility restrictions 1
• Lower limb joint status - Examine alignment, effusion, and joint line tenderness 1
• Strength and proprioception - Test muscle strength and postural control 1
• Comorbidities - Screen for weight issues, sleep quality, fatigue, and mood disturbances 1

Systematic Physical Examination Technique

Inspection and Palpation

• Effusion assessment is essential - Presence indicates inflammation, trauma, or underlying pathology requiring further investigation 1
• Isolated patellar tenderness suggests patellofemoral pathology 1
• Fibular head tenderness may indicate lateral collateral ligament injury or fracture 1
• Joint line tenderness is 83% sensitive and 83% specific for meniscal tears 2

Range of Motion Testing

Perform both passive and active range-of-motion testing: 3

• Inability to flex knee to 90 degrees is a red flag requiring radiographic evaluation per Ottawa Knee Rules 4
• Limited range of motion with crepitus suggests osteoarthritis, particularly in patients over 45 years 5

Ligamentous Stability Testing

• Lachman test is more sensitive and specific than the drawer sign for anterior cruciate ligament evaluation (74% sensitive, 95% specific) 2, 6
• Posterior drawer and tibial sag tests evaluate posterior cruciate ligament integrity (81% sensitive, 95% specific) 3, 2
• Valgus and varus stress testing assesses collateral ligament integrity 3

Meniscal Testing

The physical examination for meniscal injury is moderately accurate: 2, 6

• McMurray test (concurrent knee rotation and extension) is highly specific (97%) but less sensitive (52%) 2, 6
• Joint line tenderness is sensitive (75-83%) but not specific (27-83%) 2, 6
• Apley's grind test and bounce test provide additional diagnostic information 3

Age-Specific and Presentation-Specific Approaches

Patients ≥45 Years with Activity-Related Pain

Clinical criteria alone are highly accurate for osteoarthritis diagnosis (89% sensitive, 88% specific) without requiring radiographs initially: 1, 2, 6

• Age >45-50 years with activity-related joint pain 1, 2
• Morning stiffness <30 minutes 2, 6
• Crepitus on examination 5, 6
• Bony enlargement 6

Critical pitfall: Focus on functional limitations and pain rather than crepitus alone, as meniscal tears are often asymptomatic in elderly patients, with the majority over 70 having incidental tears 1, 7

Patients <40 Years with Anterior Knee Pain

Suspect patellofemoral pain syndrome: 1, 2

• Anterior knee pain during squat is 91% sensitive and 50% specific 1, 2
• Hip and knee strength evaluation is essential as weakness contributes to pathology 1
• Lifetime prevalence approximately 25% in physically active individuals 2

Acute Trauma Patients

Apply Ottawa Knee Rules to determine need for radiography (100% sensitive for fractures): 4

• Age ≥55 years 4
• Isolated patellar tenderness 4
• Fibular head tenderness 4
• Inability to flex knee to 90° 4
• Inability to bear weight immediately or take 4 weight-bearing steps 4

Do not apply decision rules if: gross deformity, palpable mass, penetrating injury, prosthetic hardware, multiple injuries, altered mental status, neuropathy, or increased fracture risk 4

Functional Performance Testing

For patients requiring objective functional assessment: 1

• Single Leg Hop Test has high to moderate quality evidence for reliability and validity 1
• Crossover Hop Test has moderate quality evidence for reliability and construct validity 1

Critical Pitfalls to Avoid

Always consider alternative pain sources: 1, 7

• Hip pathology can present as knee pain - examine hip if knee findings are unremarkable 1, 7
• Lumbar spine pathology may cause referred knee pain 1, 7
• Avoid overreacting to crepitus or incidental MRI findings without correlating to symptoms, as approximately 20% of chronic knee pain patients undergo MRI without recent radiographs 1, 7

Integration with Treatment Planning

The assessment should directly inform individualized management: 1

• Tailor treatment based on risk factors, pain intensity, inflammation signs, and structural damage severity 1
• Non-pharmacological interventions (education, exercise, weight loss, assistive devices) should be core components for all patients 1, 7
• For osteoarthritis, first-line management includes exercise therapy, weight loss if overweight, and self-management programs 2
• Progressive functional decline (difficulty with stairs, rising from chairs, walking) indicates clinically significant pathology requiring intervention 7