import { HighYieldBox, ExamCheatSheet, Tabs, Tab, ComparisonTable, VivaScenario, ContentSection, SpecialTestCard, MedicalImage } from '@/components/content' # Knee Cruciate Ligament Examination The cruciate ligament examination is a fundamental orthopaedic skill. Examiners expect you to perform the Lachman test correctly (gold standard for ACL), recognize the importance of endpoint quality, and understand the posterior sag sign for PCL injuries. The pivot shift test demonstrates rotatory instability and correlates with functional symptoms. ## Quick Reference One-Pager ## ACL Examination ### Primary Tests **Endpoint Quality:** - **Firm endpoint** = ACL intact (even with some laxity may be constitutional) - **Soft/mushy endpoint** = ACL ruptured The endpoint is MORE IMPORTANT than the amount of translation for diagnosing ACL rupture. 1. **Less hamstring guarding** at 20-30° flexion 2. **ACL is more vertically oriented** at 20-30° (more anterior force on ligament) 3. **Easier to perform** with acute effusion 4. **Less pain** than testing at 90° flexion | Grade | Finding | |-------|---------| | 0 | Negative | | 1+ | Glide (subtle shift) | | 2+ | Clunk (clear reduction) | | 3+ | Gross shift with locking | **Clinical Correlation:** - Pivot shift correlates with functional instability (giving way during activities) - May be negative in awake patient due to guarding - Often becomes positive under anesthesia ### Additional ACL Tests ## PCL Examination ### Primary Tests **Critical Point:** Before performing posterior drawer, look for POSTERIOR SAG. If the tibia is already posteriorly subluxed, you may incorrectly interpret anterior translation during "anterior drawer" as positive - this is actually the tibia reducing to neutral! ## Combined Injuries **PCL + PLC (Posterolateral Corner):** - Most common combined injury with PCL - Dial test positive at 30° AND 90° - Increased varus at 30° (LCL component) **ACL + MCL:** - Common in valgus contact injury - Test valgus stress at 30° (MCL) - Valgus stress positive at 0° = combined ACL + MCL **Multiligament Injury (Knee Dislocation):** - ACL + PCL minimum - Always assess vascular status (popliteal artery) - CT angiography mandatory ## Grading System ## Summary Presentation ## Clinical Pearls **Acute ACL Injury:** - Hemarthrosis develops within 2 hours - 70% of acute hemarthroses have ACL injury - Lachman is more reliable than anterior drawer in acute setting **Chronic ACL Injury:** - May develop secondary meniscal tears - Quadriceps wasting - Pivot shift more easily elicited (less guarding) **PCL Injury Tips:** - Often missed - always look for posterior sag - Isolated PCL may not require surgery - Combined injuries need surgical consideration ## Examiner Tips