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Knee Dislocation: Pearls and Pitfalls

Knee dislocation is an infrequent but serious limb-threatening injury that is traditionally associated with high-velocity injuries. The true frequency of knee dislocations is unclear as up to 50% of injuries self-reduce before presenting to the ED. The knee sits encapsulated by a dense supportive shell of ligaments and tendons; therefore, a significant blunt force is usually needed to disrupt the joint.

However, there have been some rare reports of low-energy mechanisms resulting in dislocation; these were usually associated with a twisting / rotational action (often from athletic injury) and in obese individuals (1). Complications vary from ligamentous and meniscal injuries to more…

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  Core EM

Only patients with bilateral strong peripheral pulses should undergo pre-reduction imaging, reduction of suspected knee dislocation should not be delayed if there is any sign of vascular impairment.

 FOAMcast

Most worrisome sequelae = popliteal artery disruption. Of patients with popliteal disruption, the amputation rate rises to 90% 8 hours after the injury without surgical intervention.

 Ortho Bullets

Emergent closed reduction followed by vascular assessment/consult.

Articles of Interest

High risk, can’t miss!

Knee dislocation (KD) is an uncommon injury with the potential for grave consequences if not recognized and appropriately managed.

A Review of Knee Dislocations

Prompt recognition of this injury and proper care combined with an extensive rehabilitation program can greatly improve the prognosis for the patient. Neurovascular integrity should be assessed routinely for several days after the injury to ensure that complications do not develop.

Knee dislocation: Lessons for EMS

True knee dislocations have a high incidence of vascular injury, even if they are "reduced." Normal distal pulses won't rule out a vascular injury however.

Resources

WikEM

Popliteal artery injury is common, about 25% of cases. Neurologic deficit may indicate vascular injury. Spontaneous reduction common. About 50% self-reduce, usually en route to ED.