Patellar instability (the kneecap going out of joint) is a relatively common problem, especially in young athletes and dancers. In some patients treatment without surgery results in ongoing dislocations, weakness, diminished knee function and fear of using the knee. In many of these cases the main problem causing the symptoms (patellar instability) is injury to the medial patellofemoral ligament (MPFL).
The indication for surgical reconstruction of the MPFL is recurrent instability (the kneecap continues to go out of joint). The chance of this happening if you have had only one dislocations is less than 50%. Unless you are an elite athlete the literature does not support an immediate operation. I usually recommend surgery in the acute setting only when a loose body or other joint damage is identified. Some high level athletes also tear their MCL and vastus medialis obliquus (VMO) which should all be repaired. If clinical examination and xrays show that the kneecap is still sitting out of alignment after several weeks of physiotherapy then surgery is worthwhile.
As a general rule the knee is kept fully straight for 3 weeks. You can take your full weight on the leg during this time. Bending of the knee is then allowed and increased over about a month. It typically takes 3 months to restore the knee to full function after dislocating your patella. Some patients are not able to restore function to their knee and require surgery.
Not all patients will need an MRI but proper xrays views are essential. This includes a true lateral, a true weight bearing AP, a skyline or merchant view and sometimes stress xrays. Emergency department xrays are rarely adequate so most of the time I will arrange these xrays when I meet you.
MPFL reconstruction surgery canbe combined with a lateral retinacular release, tibial tuberosity medialization (Elmslie-Trillat osteotomy) or anteromedialization (Fulkerson osteotomy). This is determined by a detailed clinical assessment of your Q-Angle and J-sign and xray measurement of your tibial tubercle to trochlear groove (TT-TG) distance. If the kneecap is too high then a moving the tibial tubercle downwards may be enough to correct the instability.
During the operation, the attachment between the knee cap and inside part of the thigh bone (medial epicondyle of the femur), is recreated with another tendon. I usually use one of your hamstrings to do this but there are many graft oprtions which we can discuss.MPFL reconstruction is not a common operation but works very well for the right patient.