Locking of the knee joint : summary

Locking of the knee joint

•      Medial rotation of the femur on tibia during terminal phase of extension (last 30° of extension )

•      It is brought about by quadriceps femoris

•      Locked knee becomes absolutely rigid

•      All ligaments are taut

•      Function: locking of the joint bring the joint into close packed

•      Clinical anatomy :

•      True Knee Locking: True locking at the knee is where the knee gets physically stuck and you physically can't move the knee for a period of time.

•      True knee locking is caused by a mechanical block where something gets caught inside the joint, preventing movement.  Cause: menisci tear , loose body

•      True locking is fairly rare and typically occurs as you move the knee into full extension, i.e. towards being fully straight.

•      Pseudo Knee Locking: Pseudo knee locking is much more common than true locking.

•      Here, knee movement is limited by temporary by muscle spasming as the body tries to protect itself in response to pain. Ex: inflammation , swelling etc

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