What is Sinding-Larsen-Johansson disease?
Sinding-Larsen-Johansson disease, or enthesitis of the apex patellae, is a painful condition at the lower edge – the tip – of the patella (kneecap). Together with Osgood-Schlatter disease, it is the most common reason adolescents visit a paediatric orthopaedic specialist for knee problems. The strongest muscle in the human body, the quadriceps femoris, extends the knee. It originates from several attachment points on the pelvis and attaches via a common tendon to the upper edge of the patella. The force of the quadriceps then passes over the patella and the patellar ligament to the shin bone (tibia), specifically to a bony prominence on its front surface, the tibial tuberosity. Sinding-Larsen-Johansson disease develops as a result of repeated microtrauma from stretching and pulling at the origin of the patellar ligament on the tip of the patella. As with Osgood-Schlatter disease, it occurs during the adolescent growth spurt; however, unlike Osgood-Schlatter disease, which is more common in boys, it occurs equally in both sexes.
How is Sinding-Larsen-Johansson disease diagnosed?
In Sinding-Larsen-Johansson disease, children complain of pain at the front of the knee, at the tip of the patella. There is usually no history of trauma; instead, the pain develops gradually and worsens after sports activities. The pain is often bilateral. No swelling is found on clinical examination, but palpation always elicits marked tenderness over the tip of the patella. To properly elicit patellar tenderness, the patella needs to be gently tilted upward with the other hand during examination so that its tip is more accessible to palpation. A lateral knee X-ray shows a characteristic finding – a faint shadow, or osteolysis, over the tip of the patella – although an X-ray is not essential at the first visit. Pain beside the patella, only on the inner side of the knee, can be caused by a thickened medial plica, which children usually describe as hurting right from the start of activity.
How is Sinding-Larsen-Johansson disease treated?
Treatment of Sinding-Larsen-Johansson disease is conservative, using physical therapy. Jumping and landing should definitely be stopped, as this is when the forces are greatest. Sports activities are modified, and cycling is encouraged. It is most important to start stretching the thigh muscles, which are usually shortened. Persistent muscle stretching should be combined with stretching of the muscle fascia using a foam roller. Since Sinding-Larsen-Johansson disease occurs more often in young athletes who jump, they should be advised on correct jumping technique. The condition usually resolves with physical therapy. In children whose pain does not settle after prolonged physical therapy, orthopaedic insoles with a supination wedge can be fitted. However, in some children, knee arthroscopy is needed to examine the tip of the patella and, if necessary, refresh the origin of the patellar ligament with a needle.
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