Patella dislocationWhat is a patella dislocation?

A patella dislocation is a fairly common sports injury. People often mistakenly described that they ‘dislocated their knee’.  This is not a true dislocation of the knee, but rather of the kneecap alone.   I seem to find this much more common in the younger athletic population rather than the college age or professional athlete. The injury usually occurs when the foot is planted to change directions suddenly. Typically, this is quite painful and results in swelling of the knee and difficulty walking.  If someone notices the kneecap is out of place, it can be put back in immediately on the field by straightening the leg, and occasionally using slight pressure on the kneecap.  Sometimes a reduction is performed in the emergency room if it is too painful and pain medications are needed.

More commonly, I see athletes whose kneecap subluxes out of place and then goes back in spontaneously.  The knee is usually quite swollen with tenderness along the sides of the kneecap.

Once in the office, the first imaging test is an X-ray.  While a fracture is unusual, these pictures may give some indication as to the susceptibility of the need to dislocate easily. Special views can be obtained that assess position of the patella with respect to the thigh bone.  An MRI study provides more information regarding the cartilage surface on the kneecap or thighbone.  As the kneecap comes out of place, it can scrape off cartilage from either the thigh bone or itself.

My greatest worry after this injury is that cartilage can be damaged on both the kneecap and the thigh bone.  Cartilage does not usually repair itself.  This can be the beginning of permanent damage to the cartilage and careful assessment is needed to prevent this.  While it can take years for the damage to show itself, it is very common.

Treatment for a patella dislocation

Treatment is typically nonoperative for an athlete’s (and non-athlete’s)  first-time dislocation.  Rest, ice, ibuprofen and elevation are helpful immediately.  An ACE wrap or knee brace may provide reassurance and stability for the first week, however after that, it is better to get the knee moving again to avoid stiffness. I like to use a physical therapist to help direct the rehabilitation with me.  The goals are to increase range of motion and strength over several weeks.  Most people need to use crutches for the first 10 days until the pain starts to decrease.  Rehab usually takes about 4 weeks.  My patients are typically up walking around without any braces within 2-3 weeks.  Young people are back to school right away (using crutches).  Full normal activities are allowed around 6 weeks out.

For people that develop recurrent dislocations or subluxations, surgical options are considered.  Depending on the situation, a number of different procedures can help to stabilize the patella and prevent further injury.

There are two primary surgical treatments.  The first involves repairing and tightening the tissues on the medial (inside) part of the patella.  This can either be done arthroscopically or with a small incision.

When this simple repair is not enough, the next step is a repair of the ligaments the hold the kneecap in place.  This is called a medial patellofemoral ligament reconstruction.  Thus procedure uses a tendon either taken from the patient or a donor to reconstruct this check-reign and prevent further dislocations.  Both are outpatient procedures and the rehab process starts right away.  Recovery is usually several months before one can safely return to sports and normal activities.

Dr. Scott Hacker is a Sports Medicine Orthopedic Surgeon in San Diego, CA, Team Surgeon to the US Olympic Team.  He specializes in sports medicine and sports injuries, knee and shoulder surgery.

If you have questions about patella dislocations, or recently had a patella dislocation, please feel free to contact me at Ask Dr. Hacker or through my office.

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