Posterior Knee Dislocation Injury
Specifically, POSTERIOR KNEE DISLOCATIONS can have significant associated injury that needs unique approach and workup.
SPONTANEOUS REDUCTION: can occur up to 50% prior to ER arrival, and thus suspicion needed with mechanism of injury.
POSTERIOR DISLOCATION: ~25% cases. Neurologic deficit can signal vascular injury.
ASSOCIATED INJURIES: 1.Popliteal artery injury-->Cannot rule out based on normal distal pulses and Ankle Brachial Index (ABI) > 0.9 Requires definitive vascular imaging or serial exams 2. Neurologic injuries 3. Common peroneal nerve injury (25%) TEST FOR: Sensation in 1st dorsal web space, Dorsiflexion of foot, Toe extension, Tibial nerve injured (less common) 4. Fractures-> Femur and tibia most common. Check hip and ankle joints for associated fracture. Avulsion fractures common 5. Compartment syndrome risk high with vascular compromise.
CLINICAL: instability with lachmans, posterior drawers, and special ligament/meniscus testing. Obtain full neurovascular eval w/ doppler. Evaluate compartments and consider compartment syndrome.
WORK UP: obtain x-rays, vascular assessments (ABIs: Ankle-Brachial-Index). Consider CT. If suspicious of posterior dislocation or vascular injury---> CT with angiography. Also, think of tibial plateau injury.
SEGOND FRACTURE: Avulsion fracture (small) of the lateral surface of the lateral tibial condyle. Usually results from excessive internal rotation and varus stress--->>>> LINK TO ACL TEARS.
Consider trauma/vascular/orthopedic consult for these types of injury. Rapid reduction needed for neuro/vasc compromise.
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