Sinding-Larsen-Johansson Syndrome (Patellar Apophysitis)

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Sinding-Larsen-Johansson Syndrome (Patellar Apophysitis)

Sinding-Larsen-Johansson Syndrome (Patellar Apophysitis) is an overuse injury causing anterior knee pain that is localized to the inferior pole of the patella. Apophysitis is a chronic traction injury of the immature osteotendinous junction. Sinding-Larsen-Johansson Syndrome affects the patellar tendon at its attachment to the inferior aspect of the patella. The condition arises from repetitive contraction of the quadriceps muscles, leading to damage at the attachment of the patellar tendon to the inferior pole of the patella and resulting in apophysitis. It presents in a similar fashion to Osgood-Schlatter disease and shares the same pathogenesis.

Sinding-Larsen-Johansson Syndrome is typically diagnosed in adolescents between the ages of 10 and 15 and is more common in males. It is associated with sports that involve running, jumping, or kicking such as track and field, football, soccer, basketball, volleyball, and field hockey. It often arises after a significant increase in activity (e.g., training for an upcoming competition). Risk factors include muscle imbalances, being overweight, and poor physical condition. It is also particularly common in children with Cerebral Palsy. The diagnosis for Sinding-Larsen-Johansson Syndrome is typically clinical, with patients presenting with tenderness and swelling at the inferior pole of the patella, and pain on resisted knee extension.

• Pain and swelling at the inferior pole of the patella (typically seen in active adolescents between the ages of 10 and 15)
• Pain that is aggravated by running, jumping, kicking, climbing stairs, kneeling, or squatting
• Pain that is relieved by rest
• May present with a painful limp

• Pain, swelling, and tenderness at the inferior pole of the patella
• Pain on forceful extension of the knee (e.g., pain on squatting)
• Pain on resisted extension of the knee

Plain radiography may demonstrate soft tissue swelling, enlargement of the inferior pole of the patella, or adjacent osseous fragments. However, early changes may be absent or subtle.

Diagnostic ultrasound demonstrates thickening of the deeper fibers of the patellar tendon adjacent to the inferior pole of the patella and may also reveal tearing of fibers and cartilage inflammation.

MRI can also demonstrate the presence of Sinding-Larsen-Johansson Syndrome by identifying thickening of the tendon. However, due to its cost and availability, it is most likely to be used if other knee pathologies are suspected.

The following are examples of “red flags” for patients presenting with knee pain:

• History of a significant injury
• Severe pain
• Unrelenting pain
• Nocturnal pain
• Unexplained weight loss
• Fever
• Deformity
• Significant swelling
• Leg pain arising after a prolonged period of immobility or bed rest
• Presence of tingling, numbness, burning, or other neurological impairment
• Loss of distal leg pulses
• Significant loss of range of motion
• Severe tenderness on palpation or severe pain with any examination procedure

If any “red flags” are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

• Inform the patient and their parents that Sinding-Larsen-Johansson Syndrome is self-limiting and generally resolves within a few months, provided the aggravating activities are curtailed.
• Recommend replacing their sporting activity with a low-impact activity (e.g., swimming or cycling) while they heal. This will help them to cope better with being deprived of playing their chosen sport.
• When the condition has resolved, and before the patient returns to their regular sports training, recommend that the parents discuss the condition with their child’s coach to ensure that excessive high-impact exercises are avoided.

Differential Diagnosis

Osgood-Schlatter Disease – Osgood-Schlatter Disease is considered to be a traction apophysitis of the tibial tuberosity. It presents in children and adolescents with a 4:1 predominance in males. In males, the condition usually presents between the ages of 12 and 15. In females, the condition presents earlier between the ages of 8 and 12. The condition is bilateral in approximately 25% of cases. Osgood-Schlatter Disease is associated with and experienced after activities that involve a forceful extension of the knee, such as jumping (e.g., in basketball and volleyball), kicking (e.g., in soccer), running, and gymnastics. Kneeling is also an exacerbating factor. Pain is usually mild and intermittent in the early stages but can become severe and more continuous. Physical examination findings in Osgood-Schlatter Disease include local tenderness and prominence of the tibial tuberosity, as well as pain on resisted knee extension. Osgood-Schlatter Disease is a self-limiting disorder, with 90% of cases making a full recovery (although kneeling may continue to remain uncomfortable). After the condition has been resolved, a non-tender but variously enlarged tibial tuberosity may remain present.

Hoffa Disease – Hoffa Disease is an inflammation of the infrapatellar fat pad due to its impingement caused by forceful hyperextension of the knee or by direct impact to the patella. It causes anterior knee pain, which is made worse with resisted knee extension and is characterized by tenderness and swelling immediately below the patella. Hoffa’s test involves using both thumbs to apply pressure to the sides of the patellar tendon while the patient extends their bent knee. Pain or apprehension during this test is considered to be evidence of the presence of Hoffa Disease.

Plica Syndrome – Plica Syndrome is an inflammation of a synovial fold which is a remnant of fetal tissue that sometimes persists into adulthood. It can become inflamed due to direct trauma or overuse caused by repetitive and strenuous knee flexion and extension activities. It most typically results in anteromedial knee pain and can present like a meniscal injury or Patellofemoral Pain Syndrome. Examination reveals tenderness on the medial side of the patella above the medial tibiofemoral joint line.

Osteosarcoma – Osteosarcoma is a neoplasia that classically targets the metaphysis of a bone, with a preference for the knee and shoulder. It is the second most common primary bone malignancy and the most common type in adolescents and young adults. It is most prevalent in the 10 to 25-year age group and has a 2:1 predominance in males. One subtype of osteosarcoma is called periosteal osteosarcoma. It has a preference for the posterior surface of the distal femur and the anterior surface of the upper tibia (where a palpable prominence and tenderness could mimic Osgood-Schlatter Disease).