Osgood-Schlatter disease

Osgood-Schlatter disease (OSD) is a traction apophysitis that occurs where the patellar tendon attaches to the tibial tuberosity. It is an overuse injury typically seen in children aged 9–14 years of age who regularly engage in athletics. OSD is characterized by progressive anterior knee pain that is exacerbated by activity (typically jumping, kneeling, running, or squatting). On examination, there is usually focal swelling and tenderness over the tibial tuberosity. Diagnosis is clinical. Imaging is reserved for ruling out differential diagnoses of OSD if there is diagnostic uncertainty. Treatment is usually conservative, involving NSAIDs, ice, and physical therapy. Surgery is reserved for refractory cases in patients with a closed growth plate.

• Age
  • Adolescents; on average 9–14 years old
  • Commonly develops shortly after growth spurts
• Sex: ♂ > ♀ (3:1)

Epidemiological data refers to the US, unless otherwise specified.

• Overuse (especially sports involving sprinting and jumping) during the ossification period (adolescence) → excessive strain and repeated avulsion of the patellar ligament on the tibial tuberosity → inflammation → traction apophysitis
• Chronic inflammation of the patellar ligament can disrupt the secondary ossification of the tibial tuberosity → detachment of the apophysis → subsequent callus formation during the healing process → persistently prominent tibial tuberosity ^[1]

Symptoms ^[2][3]

• Progressive anterior knee pain
  • Exacerbated by activity, e.g., jumping, kneeling, running, squatting
  • Relieved by rest (within minutes to hours after activity)
• Often unilateral ^[3]

Examination findings ^[2][3]

• Focal swelling and tenderness of the tibial tuberosity ^[3]
• Pain is reproduced by knee extension against resistance.
• Tightness of the quadriceps and hamstrings

OSD is usually a clinical diagnosis; imaging is indicated to rule out differential diagnoses of OSD if there is diagnostic uncertainty. ^[4]

Imaging ^[4][5]

Modalities ^[4]

• X-ray (first-line): AP, lateral, and tangential patella views ^[1][4][5]
• MRI without IV contrast: Consider if initial radiographs are normal.
• Ultrasound: not routinely indicated ^[4][6]

Findings

In acute disease, imaging shows signs of inflammation (e.g., soft tissue swelling); in subacute and chronic (> 3 months) disease, abnormalities are seen in the bones and/or tendons. ^[3][7]

• Findings common to all modalities ^[5][8]
  • Anterior soft tissue swelling
  • Prominent tibial tuberosity over the tibial shaft ^[9]
  • Irregular or fragmented tibial tuberosity ^[9][10]
  • Formation of free ossicles
  • Calcification and thickening of the patellar tendon
• Specific findings by modality
  • X-ray: blurred margins of the patellar tendon ^[5]
  • MRI ^[3]
    • Edema around the tibial tuberosity
    • Partial tears in the apophysis
    • Infrapatellar bursitis ^[9]
  • Ultrasound: hypoechoic thickening of the patellar tendon ^[3][7]

• Bursitis, e.g., of the infrapatellar bursa or prepatellar bursa
• Patellofemoral syndrome
• Multipartite patella
• Osteochondritis dissecans of the patella
• Patellar stress fracture (a high-risk stress fracture)
• Avulsion fraction of the tibial tubercle ^[2]
• Quadriceps or patellar tendonitis
• Fat pad impingement (Hoffa disease)
• Tumors (osteosarcoma, osteoid osteoma, Ewing sarcoma)
• Infections (septic arthritis, osteomyelitis)

Sinding-Larsen-Johansson disease ^[2][3]

• Definition: traction apophysitis of the inferior patellar pole
• Epidemiology: most common in adolescent athletes 10–13 years of age ^[10][11]
• Clinical features
  • Anterior knee pain exacerbated by activity (e.g., jumping, running)
  • Swelling and tenderness of the inferior patella
• Diagnostics
  • Usually a clinical diagnosis; imaging (e.g., x-ray, MRI, and/or ultrasound) may be obtained to rule out other diagnoses.
  • Imaging findings include: ^[3][8]
    • Prominence and possible fragmentation of the inferior patellar pole ^[9]
    • Soft tissue swelling
    • Calcification and thickening of the patellar tendon
    • Infrapatellar bursitis
• Treatment: similar to treatment of OSD

The differential diagnoses listed here are not exhaustive.

Most cases of OSD (> 90%) respond to conservative management and resolve once full bone maturity is reached. ^[5]

Approach ^[2][3][5]

• All patients: Start conservative management.
• If symptoms are severe or persist despite conservative management, consider:
  • Immobilizing with a brace, strap, or cast for 3–6 weeks ^[12]
  • Imaging to exclude differential diagnoses of OSD ^[6]
• If symptoms are refractory and the growth plate has closed, refer for surgical management.

Conservative management ^[2][3][5]

• Relative rest: Avoid painful activity, while engaging in physical activity as tolerated. ^[11]
• NSAIDs (e.g., ibuprofen )
• Ice
• Physical therapy focusing on flexibility and strengthening of the quadriceps and hamstrings

If symptoms are severe or persist despite conservative management, consider immobilizing with a brace, strap, or cast for 3–6 weeks. ^[12]

Avoid steroid injections because of the risk of weakening the patellar tendon. ^[3][5]

Surgical management ^[3][5]

• Indication: symptoms refractory to conservative management in patients with a closed growth plate
• Method: excision of persistently prominent tibial tuberosity and/or ossicles that have formed in the patellar tendon ^[11]

• Genu recurvatum (rare): knee joint deformity characterized by hyperextension in the tibiofemoral joint ^[13]
  • Etiology
    • Congenital causes include connective tissue disorders (e.g., Marfan syndrome, Ehlers-Danlos syndrome), physeal arrest, arthrogryposis multiplex congenita, and conditions that affect muscles involved in knee stability (e.g., muscular dystrophy)
    • Acquired causes include poliomyelitis and proximal tibial growth plate damage (e.g., due to Osgood-Schlatter disease, osteomyelitis, trauma) ^[12]
  • Clinical features: manifests with knee pain, leg-length discrepancy, poor proprioceptive control, and/or gait disturbances (e.g., extension gait pattern)
  • Treatment
    • Conservative: taping, knee bracing, gait, and functional training
    • Surgical: anterior opening-wedge proximal tibial osteotomy with or without postoperative external fixation with progressive distraction
• Persistently prominent tibial tuberosity ^[3]
• Ossicle formation in the patellar tendon ^[11]
• Chronic pain

We list the most important complications. The selection is not exhaustive.