You Never Have Just a Sprained Knee

When I was a sports medicine fellow a few years ago, my program director would not allow me to use the diagnosis of “knee sprain.” He did not believe in such a vague diagnosis, and after being trained that way I do not use that term, either. If there is a sprain in the knee, you must specifically define which ligament is sprained.

Now, as a sports medicine physician, “knee pain” in teens is one of the most common complaints that walks into my office. Outside of obvious injuries, there are a few common causes of knee pain — or the infamous sprain — that are usually related to activity instead of trauma. Four of the most common causes are discussed below.

Patellofemoral Syndrome (PFS), also known as “runner’s knee,” is the most common cause of knee pain. Even though PFS can be very painful, it is a very manageable condition. PFS causes pain on the front part of the knee, around the knee cap. PFS happens when the knee cap is not sliding in the groove that it’s supposed to move in. Weak leg muscles, flat feet, an increased Q angle (the angle of the thigh bone to the hip to the knee) and knock knees can all play a role in PFS. Treatment for PFS includes physical therapy, anti-inflammatories (such as ice) and, occasionally, a brace to help stabilize the knee cap.

Patellar tendonitis, or “jumper’s knee,” refers to pain on the front part of knee that is caused by stress or inflammation of the patellar tendon, which is the cord-like structure that attaches the bottom of the knee cap to the top part of the shin. This is caused by increased activity. It is associated most often with jumping sports but can also be seen in non-jumping sports. Pain is usually directly on the tendon itself and can be treated with ice, a tendon strap brace and rehab to focus on flexibility and strength.

Osgood Schlatter’s Disease is also pain on the front part of the knee, associated with a growth plate on the front part of shin. This is the area that the patellar tendon attaches to. This condition is commonly seen in kids around the age of 11 to 16 years old who hit a growth spurt, and it occurs because bones grow a lot faster than muscles and tendons do.  This leads to inflexibility and a pull on these growth areas, which in turn leads to inflammation and pain. Treatment focuses on cutting down inflammation, working on flexibility and using a tendon strap brace to take the stress off of the attachment on the growth plate.

Finally, OCD (no, not obsessive compulsive disorder!) or Osteochondritis Dissecansis a condition where there is a lack of blood supply to an area on the inner part of the knee, often the femur.  This leads to softening of the bone and, if not treated, can cause a part of the bone to break off. OCD can cause knee pain, sometimes with “locking” or “catching” and occasional swelling. Treatment for OCD is based on the location and extent of the injury as well as the age of the patient. Treatment can range from ceasing all activity to surgery.

So the next time you hear a diagnosis of a sprained knee, ask your doctor, “What exactly is sprained?”