Reducing a dislocated patella

How to Reduce a Dislocated Patella

A dislocated patella typically occurs when a force is applied to the medial side of the patella forcing it laterally out of the femoral groove in which it rides. The patella is held in place inferiorly by the patella tendon and supported on the sides by the medial and lateral patella femoral ligaments.

The patella almost always dislocates laterally. When this occurs, the patient will be in significant pain with their knee flexed and the patella displaced laterally. As with most dislocations, the longer the patella remains out of joint, the more swelling there will be in and around the joint. This swelling makes it harder to reduce. So, the sooner the joint can be reduced back into normal anatomical position, the better.

Treatment:

Examine closely

Palpate the patella for fractures

Gently check the stability of the knee

To reduce the patella:

With one hand grasp the ankle. Place the other hand on the lateral aspect of the knee with the fingers in the popliteal space and the thumb against the lateral aspect of the patella.

As you push against the patella with your thumb, slowly straighten out the leg with the hand that is on the ankle. As the leg extends, the patella will reduce back into normal anatomical position.

Once reduced, wrap the knee with a 6” ace wrap for gentle compression and to minimize swelling, then splint the leg straight. Because of the risk that the medial patella ligament has been partially torn and there may be other ligamentous damage, the knee has to be splinted straight. Once the knee is wrapped and splinted, the patient may try to walk with the leg stiff and straight. If the injury was only a dislocated patella and ligamentous sprain, walking should be pain free.

Please note: in the event that the patella does not reduce, splint the leg in the position found and transport in a litter.

For more information see the Sept/Oct 2004 issue of the Wilderness Medicine Newsletter.

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