Vail health: Kneecap instability and dislocations can plague all ages (column)
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Patellar instability and dislocations can plague both children and adults. The patella, or kneecap, connects the muscles of the thigh to the tibia, or shinbone. The patella should sit within a groove at the end of the femur. As the knee bends and straightens with sitting and standing, the patella should glide smoothly up and down within the groove.
Unfortunately, sometimes the patella can slide partially out of the groove, called subluxation, or slide completely out of the groove, referred to as dislocation. When either of these occurs, pain, swelling and loss of function ensue.
There are many causes for why and how the patella can become unstable or dislocate. Individuals can have a shallow groove that can make them more prone. Additionally, some patients have looser ligaments, which can lead to patellar instability. Commonly, the patella dislocates due to a direct blow or fall on the knee.
Symptoms can vary from patient to patient with patellar instability and partial versus full dislocations. Patients often report feeling something in their knee shift out of place, as well as feelings of catching and popping within the knee. The knee then swells and is painful. Patellar instability can have more subtle symptoms, as well, such as pain while sitting, an increase in pain to the front of the knee with activity, swelling and clicking or cracking in the joint with movement.
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To make the proper diagnosis, we take a thorough history from the patient and do a physical exam of the knee. X-ray imaging is also very helpful to assess the bony structures and alignment of the knee joint, paying particular attention to the shape of the groove and where the patella sits in relationship to the groove. MRI scans are sometimes ordered, as well. These can help determine a better calculation of the trajectory of the patella in the groove and if there is any loose cartilage or bony fragments that could have been dislodged during a dislocation.
For patients who have suffered a first-time dislocation, we recommend nonsurgical treatment consisting of physical therapy with gentle range-of-motion exercises, as well as strengthening of knee and hip musculature.
In the Vail Valley, where we have a lot of skiers, bikers and runners, athletes tend to be quite strong in their quads and hip flexors but relatively weaker in their hamstrings and gluteus muscles. Physical therapy and personalized strengthening programs are helpful in addressing this issue. Bracing is another good option for treating a patellar dislocation. We fit patients with a special brace that helps hold the patella centered in the groove.
Unfortunately, if a patient has had several patellar subluxations and or dislocations, then he or she is more likely to continue to have these instability episodes. As a result, patients find they are unable to resume all of the activities they enjoy. In these cases of recurrent instability of the patella, surgery is usually required to stabilize the kneecap and allow patients to resume all of their sports.
Surgery consists of a medial patellofemoral ligament reconstruction. The reconstruction attaches the femur to the inner aspect of the patella, and its main purpose is to stabilize the patella within the groove. When the patella dislocates, there is full or partial thickness tearing of this ligament. In reconstruction surgery, we use a piece of donor tendon to tighten and reinforce the stretched out ligament, thus stabilizing the patella and preventing further dislocations. This is an outpatient surgery. A brace is required for four to six weeks after surgery. Physical therapy is started immediately after surgery. It can take fur months to fully recover and have a patient resume full activity.
Gretchen Meador is a physician assistant with Dr. Richard Cunningham, a knee and shoulder sports medicine specialist with Vail-Summit Orthopaedics. Cunningham is a physician for the U.S. Ski Team and president of Vail-Summit Orthopaedics. Do you have a sports medicine question you’d like him to answer in this column? Visit his website at http://www.vailknee.com to submit your topic idea. For more information about Vail-Summit Orthopaedics, visit http://www.vsortho.com.