Classic Presentation
Sinding-Larsen-Johansson Syndrome (SLJ) is specific to pediatric athletes, usually in the age range of 7 to 12 years, on average. Athletes will usually complain of pain over the front of the knee at the end of a practice or end of a school day. The pain will specifically be at a growth plate on the most inferior portion of the knee cap called the lower pole. Pain typically will resolve with rest However, more severe cases can be painful enough to cause a limp. Also, the pain can be ongoing for weeks to months prior to seeking care, due to instances where pain resolves with rest. For clarification purposes, Sinding-Larsen-Johansson Syndrome is simply a an overuse injury that occurs due to pull on the growth plate at the lower portion of the knee cap.
Evaluation
Athletes can have a variety of physical presentations of this condition. Some will have notable swelling over the lower knee cap only. On the other hand, some athletes will have no visible signs of injury, yet have significant tenderness over the lower pole of the patella. Keep in mind that mild cases of Sinding-Larsen-Johansson may only cause pain with activity and therefore the physical exam can be normal. Sinding-Larsen-Johansson Syndrome can be confused with patella tendonitis or Osgood Schlatter Disease, which is typically more common in older patients. In general, x-rays are not needed, but in the photo below you will see the presence of the lower pole of the patella growth plate that is sometimes confused for a fracture. Of note, fragmentation of the growth plate can be normal, therefore a fragmented growth plate with an asymptomatic patient would not be consistent with the diagnosis of Sinding-Larsen-Johansson Syndrome.
X-ray Evaluation
Treatment
In general, Sinding-Larsen-Johansson Syndrome will improve over time, although athletes can see flare-ups depending upon their volume of activity. The flare-ups should subside once the growth plate has closed. Relative rest and icing is a good first step when in pain. Stretching and improving flexibility of the hamstring and quadriceps muscles can be helpful to prevent return of pain once it is under control. In general a patella strap that is typically not as helpful as in Osgood Schlatter Disease.
Return to Play
Mild Sinding-Larsen-Johansson Syndrome does not require restriction from activities, as the athlete can usually participate on an as tolerated basis. Moderate pain may require restriction from activities for several weeks to a month, until the pain is better under control and flexibility of the hamstring and quadriceps muscles have improved. In rare cases, the athlete may need to be placed in a straight leg knee immobilizer and crutches to completely remove tension from the patella and allow it to heal appropriately.
Sports Considerations
An athlete should consider cross training and conditioning in a sport with less impact, such as swimming or biking.