Patellar Instability

Kneecap (patella) dislocations are more common in younger athletes.  Most often, the kneecap will slide out of its groove to the outside of knee. Sometimes, the kneecap will spontaneously relocate into its normal position. Otherwise, a medical professional may need to maneuver the patella into its groove.

A patellar dislocation may be a one-time event, triggered by a fall, direct blow to the knee, or other injury. Young, athletic females and individuals who have family members with patellar dislocations are predisposed to this condition.  Weak leg muscles, ligament laxity, and certain anatomic features can make you more susceptible to recurrent events as well.

After a patellar dislocation, you may notice knee swelling and bruising, pain under the kneecap, stiffness, or sensation that the knee will buckle or give out.

X-rays of the knee will help determine if there is a concomitant fracture.  MRIs are often ordered to determine if there is cartilage damage or ligament tears as a result of the injury.

If the knee cartilage appears to be intact after the first dislocation, your medical provider may prescribe physical therapy to help regain motion and strengthen the muscles around your knee and recommend wearing a brace.

A knee arthroscopy may be recommended if there are problems with the kneecap cartilage.  Your surgeon will try to reattach the loose piece of cartilage or will remove it.  Tissue may be released to inhibit the kneecap from being pulled off track.

In cases where a ligament is torn and does not heal, or you continue to have kneecap instability, a larger surgical procedure may be required.

Some patients may benefit from a medial patellofemoral ligament (MPFL) repair, where the surgeon will reattach the ligament to help stabilize the kneecap.  If the MPFL is damaged or weak, he or she may supplement or recreate the structure with allograft tissue (graft from a donor).

Patients who have severe alignment problems and continued patellar dislocations may be candidates for an anterior medialization of the tibial tubercle (AMZ) procedure where the bony patellar tendon attachment is moved so the kneecap can track appropriately.