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This unfortunate injury is associated with sports that involve repetitive running, jumping, or kicking such as soccer and rugby.

The patella (kneecap) is a loose bone that sits in your quadriceps and patella tendons. It glides up and down a groove (the trochlea groove of the femoral condyle) as you bend and straighten your knee.

Patellar dislocation occurs when the patella is displaced from this groove, most commonly laterally (towards the outside of the knee). This may either be caused by something traumatic especially where there is a history of a traumatic force to the kneecap or it can occur in the absence of trauma as is the case in young girls with associated ligamentous laxity

The stabiliser in your kneecap that protects against displacement is the medial patellofemoral ligament. Anatomically it acts as a passive check to prevent the patella from extreme lateral displacement which is why we find that in the majority of dislocation cases it is disrupted.

Patients usually complain of the knee suddenly giving way while jumping or running/twisting and the subsequent development of severe pain. A feeling of something “moving out of place” or “popping” is quite common. Often the dislocation reduces spontaneously with knee extension. But, swelling develops almost immediately.

It is common to mistake this injury for an Anterior Cruciate Ligament ( ACL)  rupture as both conditions have similar mechanisms of injury with an audible “pop” and giving way of the leg as well as a quick development of swelling. But, on examination of a patellar dislocation there is usually gross swelling, marked tenderness over the medial (inside) border of the patella and when attempting to push the patella in a lateral direction the patient experiences pain or apprehension. Quadriceps muscle contraction aggravates the pain.

Most first-time dislocations are treated without surgery, with pain relief medication, immobilization of your knee with an extension splint for 2-3 weeks. During this time period you should be using crutches, and be following a rehabilitation program.

The most important aim of rehabilitation after such an injury is to reduce the chances of a recurrence. Hence the rehab program is lengthy and emphasizes core stability, vastus medialis obliquus strength, and stretching of the lateral structures when tight.

Surgery is indicated for second dislocations, or in patients not improving with appropriate rehabilitation (the re-dislocation rate after primary patellar dislocation managed non-operatively is anywhere between 15-44%). Medial patellofemoral surgery has become the surgery of choice.

So if you find yourself “buckled at the knees”, follow the RICE principle in the acute stage (Rest, Ice, Compression and Elevation) and seek treatment from your physiotherapist and/or orthopaedic doctor.

Andrew@PhysioPRO