The Schenck classification is categorizing knee dislocation based on the pattern of ligament tears. The four major ligamentous stabilizers are the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and the lateral collateral ligament (LCL) complex.
Five patterns of major injuries are seen in knee dislocations (KD), each designated by a Roman numeral, from I to V.
- KD I: involvement of the ACL or PCL
KD II: injury to both ACL and PCL, with both collaterals intact
KD III: injury to both ACL and PCL, and MCL or LCL - not both - torn
- KDIIIM (if MCL torn)
- KDIIIL (if LCL torn)
KD IV: all 4 ligaments torn
- highest rate of vascular injury (5-15%)
KD V: multiligamentous injury with periarticular fracture
- i.e. knee fracture-dislocation
Additional letter designators indicate the presence of neurovascular injury:
- C: popliteal artery injury
- N: peripheral nerve injury
It is important if tendinous injuries, avulsions of the biceps femoris, tibial tubercle, and/or quadriceps tendon tears are present, in which cases additional descriptor(s) is/are documented.