12/05/2025
Clinical Assessment of Chronic Knee Instability involves a structured and systematic approach combining history, physical examination, and functional testing to evaluate ligamentous integrity and biomechanical dysfunction. Below is a detailed explanation:
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1. History Taking (Subjective Assessment)
A. Main Complaints:
Recurrent episodes of "giving way" or buckling of the knee, especially during pivoting or walking on uneven ground.
Sensation of instability, not necessarily pain.
Associated clicking, locking, or catching, if meniscal injury is present.
Activity avoidance: patients may avoid running, sports, stairs.
B. Trauma History:
Initial injury mechanism (valgus, varus, hyperextension, pivoting).
Was there a pop sound at the time of injury?
Swelling: immediate swelling may indicate ACL injury (hemarthrosis).
C. Functional Status:
Level of activity (Tegner Activity Scale).
Any limitation in ADLs (Activities of Daily Living), stairs, squatting, sports.
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2. Inspection & General Observation
Gait assessment: Look for quadriceps avoidance gait (common in ACL-deficient knee).
Observe muscle wasting, particularly of the quadriceps.
Swelling, effusion, scars from previous surgeries.
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3. Palpation
Joint line tenderness suggests meniscal injury.
Medial or lateral joint line gap may indicate MCL or LCL laxity.
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4. Range of Motion (ROM)
Assess both active and passive flexion and extension.
Painful or limited range may reflect secondary joint pathology.
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5. Ligament-Specific Tests
A. Anterior Cruciate Ligament (ACL)
Lachman Test: Most sensitive (performed at 20–30° flexion).
Anterior Drawer Test: Less sensitive, done at 90° flexion.
Pivot Shift Test: Reproduces instability (anterolateral rotary instability); highly specific but less sensitive.
B. Posterior Cruciate Ligament (PCL)
Posterior Drawer Test: Best for PCL integrity (at 90° flexion).
Sag Sign / Gravity Sign: Observe posterior tibial sag when the knee is flexed at 90°.
C. Medial Collateral Ligament (MCL)
Valgus stress test at 0° and 30° flexion.
Laxity at 30° = isolated MCL; at 0° = combined injury (MCL + ACL/PCL).
D. Lateral Collateral Ligament (LCL)
Varus stress test at 0° and 30°.
Laxity at 30° = isolated LCL; at 0° = posterolateral corner (PLC) injury.
E. Posterolateral Corner (PLC)
Dial test: compare external rotation at 30° and 90° of knee flexion.
Posterolateral drawer test.
Reverse pivot shift test.
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6. Meniscal Evaluation (often co-existing)
McMurray Test.
Thessaly Test.
Apley's Compression Test.
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7. Functional Tests
Hop tests (single-leg hop for distance, triple hop, crossover hop).
Step-down tests for dynamic control.
Balance and proprioception assessment, often using Y-balance test.
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8. Imaging Correlation (as part of full assessment)
While not part of the physical exam, consider:
MRI: gold standard for soft tissue integrity (ACL, PCL, menisci).
Stress X-rays: for quantifying instability under varus/valgus/anterior-posterior stress.
