Knee Dislocation
Basics
Description
Description
- Defined by the position of the tibia in relation to the distal femur:
- Anterior dislocation:
- Most common
- Hyperextension mechanism
- Disruption of the posterior capsule, posterior cruciate ligament (PCL), and often the anterior cruciate ligament (ACL)
- Posterior dislocation:
- Second most common
- Direct blow to the anterior tibia with the knee flexed at 90 degrees, “dashboard injury”
- Medial dislocation:
- Varus stress causing tear to the ACL, PCL, and lateral collateral ligament (LCL)
- Lateral dislocation:
- Valgus stress causing tear to the ACL, PCL, and medial collateral ligament (MCL)
- Rotatory
- PCL remains intact as the tibia rotates around the femur
- Anterior dislocation:
- Associated injuries:
- Popliteal artery injury:
- Associated with up to 40% of dislocations
- High rates of arterial disruption due to anatomic tethering, proximally and distally
- Disruption leads to intimal tears or transection and often delayed thrombosis
- Very high rate of limb loss if vascular repair is delayed >8 hr
- Peroneal nerve injury:
- Associated with 25% of dislocations
- Tethered proximally and distally to fibular neck
- Injury due to traction or transection, most often with medial or rotatory dislocations
- Permanent footdrop in >50% of patients, partial recovery another 25%
- Popliteal artery injury:
Etiology
Etiology
- High energy:
- Fall from height, motor vehicle crashes, and auto vs. pedestrian accidents
- Low energy:
- Athletic injury (most often football), trampoline fall
- Ultra-low energy:
- Obese individuals
- Routine walking
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Citation
Schaider, Jeffrey J., et al., editors. "Knee Dislocation." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307064/all/Knee_Dislocation.
Knee Dislocation. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307064/all/Knee_Dislocation. Accessed December 12, 2024.
Knee Dislocation. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307064/all/Knee_Dislocation
Knee Dislocation [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 December 12]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307064/all/Knee_Dislocation.
* Article titles in AMA citation format should be in sentence-case
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