Patella (knee cap) is a protective bone attached to the quadriceps muscles of the thigh by quadriceps tendon. Patella attaches with the femur bone and forms a patellofemoral joint. Patella is protected by a ligament which secures the kneecap from gliding out and is called as medial patellofemoral ligament (MPFL).
Dislocation of the patella occurs when the patella moves out of the patellofemoral groove, (called as trochlea) onto a bony head of the femur. If the knee cap partially comes out of the groove, it is called as subluxation and if the kneecap completely comes out, it is called as dislocation (luxation). Patella dislocation is commonly observed in young athletes between 15 and 20 years and commonly affects women because of the wider pelvis which creates lateral pull on the patella.
Some of the causes for patellar dislocation include direct blow or trauma, twisting of the knee while changing direction, muscle contraction, and congenital defects. It also occurs when the MPFL is torn. The common symptoms include pain, tenderness, swelling around the knee joint, restricted movement of the knee, numbness below the knee, and discoloration of the area where the injury has occurred.
Your doctor will examine your knee and suggest diagnostic tests such as X-ray, CT scan, and MRI scan to confirm the condition and provide treatment.
Medial patellofemoral ligament reconstruction – In this procedure, the torn MPF ligament is removed and reconstructed using grafting technique. Grafts are usually harvested from the hamstring tendons, located at the back of the knee and are fixed to the patella tendon using screws. The grafts are either taken from the same individuals (autograft) or from a donor (allograft). This procedure is also performed using an arthroscope.
After the surgery, your doctor will suggest you use crutches for a few weeks, prescribe medications to control pain and swelling, and recommend physical therapy which will help you to return to your sports activities at the earliest.