If you suspect an occult knee dislocation, immediately consult orthopedics as revascularization within six to eight hours of popliteal artery injury is recommended to prevent ischemic complications.

Occult Knee Dislocation Take-Home

Don’t send home patients who tell you that it felt like their knee shifted out of place and they have a big swollen knee with laxity in multiple directions on exam until you’re sure they haven’t had a vascular injury related to a spontaneously reduced knee dislocation. Even if they have palpable peripheral pulses and a normal ABI, speak to your orthopedic surgeon, considering a CT angiogram to rule out a popliteal injury, and admit. Remember to have a high index of suspicion in any obese person with even a low-force mechanism.

A special thanks to Dr. Arun Sayal and Dr. Hossein Mehdian for their participation in the EM Cases podcast on which this article is based.

Dr. Helman is an emergency physician at North York General Hospital in Toronto. He is an assistant professor at the University of Toronto, Division of Emergency Medicine, and the education innovation lead at the Schwartz/Reisman Emergency Medicine Institute. He is the founder and host of Emergency Medicine Cases podcast and website.