Sinding-Larsen-Johansson Syndrome (distal patella apophysitis) is irritation and inflammation of the growth plate (apophysis) at the bottom of the patella (kneecap), where the patella tendon inserts. In a child, the bones grow from areas called growth plates. The growth plate is made up of cartilage cells, which are softer and more vulnerable to injury than mature bone. Sinding-Larsen-Johansson is most often seen in children between the ages of 10 and 15 and usually appears during a period of rapid growth.
Sinding-Larsen-Johansson Syndrome is caused by increased tension and pressure on the growth center. This pressure usually results from overuse of the knee (repetitive running and jumping). Having tight quadriceps muscles (in the front of the thigh) also puts pressure on this growth center and may make this condition more likely to occur. Tight muscles are more common during a growth spurt.
Your child will complain of a pain at the bottom of the kneecap. They may have swelling at this location, and this pain may limit their activities.
Your doctor will do a physical examination of the knee and review your child’s symptoms. X-rays may show irregular bone edges or fragments at the bottom end of the kneecap but are not generally required to make the diagnosis.
Your child will need rest from painful activities to take the pressure off the growth center and allow the inflammation to resolve. Ice packs should be applied to the knee for 15-20 minutes every 2-4 hours for 2-3 days or until the pain goes away. Your child’s doctor may prescribe a strap to support the kneecap and recommend stretches for tight muscles.
The goal is to return your child to his or her sport as quickly and safely as possible. If your child returns to sports or activities too soon or pushes through pain, the injury may worsen, which could lead to chronic pain and difficulty with sports. Everyone recovers from injury at a different rate. Return to sport or activity will be determined by how soon your child’s knee recovers, not by how many days or weeks it has been since the injury occurred.
Your child may return safely to sports or activities when each of the following is true (Begin at the top of the list and progress to the bottom):
The most important thing to do is to have your child limit activity as soon as he or she notices the pain at the bottom of the kneecap. Warming up before activity and quadriceps stretching after activity may also help to prevent Sinding-Larsen-Johansson Syndrome.