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Patellar Instability – (Medial Patellofemoral Ligament Reconstruction)

What is patellar instability?

When the knee is functioning properly, the kneecap runs smoothly in a groove of the femur called the trochlear groove. 

If the kneecap slides out of this groove, the kneecap will become unstable, increasing the risk of dislocation, chondral damage and arthritis.  

Anatomic anomalies like shallow or uneven grooves may cause the kneecap to slide out, or an injury such as a heavy fall or sharp blow to the kneecap may also cause it to dislocate. 

Bracing and strengthening exercises treat single episode dislocations while surgery is advised to correct multiple dislocation injuries.

What are the symptoms of patellar instability?

– Knee pain and swelling 
– Giving way or instability 
– Cracking or grinding sounds in the knee when you climb stairs or when you bend the knee 
– Certain conditions contribute to knee instability including Ehlers-Danlos Syndrome where the ligaments are loose. 

How is patellar instability diagnosed? 

X-rays can help Dr Herald see if the kneecap is out of place or misaligned. 

An MRI can help Dr Herald rule out other injuries such as MPFC ligament tears, chondral damage or loose fragments. 

Non-surgical solutions include bracing for several weeks, and using crutches, anti-inflammatory drugs, rest, elevation and icepacks and physical therapy. 

More chronic or severe instability will require surgery that is usually done via a knee arthroscopy procedure as a day procedure. 

Nearly half of all people who dislocate their knee who have non-surgical treatments will dislocate the knee again. 

What does surgery for patellar instability involve?

–     Persistent pain should not be ignored as recurrent dislocations can cause damage to the delicate chondral surfaces of the knee joint and predispose to arthritis.

–     There are a number of surgical procedures that may help in this situation depending on your anatomy.

–     A Medial Patellofemoral Ligament Reconstruction (MPLF) is a surgical procedure indicated in patients with more severe patellar instability.

–     An MPFL reconstruction will reconstruct and tighten loose medial ligaments; a lateral release will release tight lateral structures; while a tibial ubercle transfer will realign the whole extensor mechanism by breaking the bone that the patella tendon is attached to and moving it with the patella into a more suitable position.

–     Knee joint replacement is sometimes used to treat severe arthritis and recurrent dislocations that exacerbate patellar instability.

–     Dr Herald will work with you to find the most appropriate surgery and rehabilitation for you.