Patellar Sleeve Avulsion


  • Acute traumatic condition representing chondral or osteochondral avulsion injury at the inferior pole of the patella (the proximal attachment of the patellar tendon)
  • Usually occurs between the age of —8 to 12 years of age, when patellar ossification is nearly complete
  • The mechanism is usually a powerful contraction of the quadriceps muscle applied to a flexed knee


  • Pain and swelling around the inferior pole of the patella
  • Inability to straight leg raise
  • On x-ray (lateral)
    • Will likely have “—Patella Alta” (high riding patella) where the the distance between the patella and the tibial tubercle is greater than 1.1*patella vertical height (green arrows)
    • —On a true lateral (not the Horizonal Beam view), with knee slightly flexed,  Blumensaat’s line (red line) should point to the inferior pole of the patella
    • MRI may be necessary if x-ray is normal (as the injury may only be cartilaginous)




















  • Treatment is surgical – injury is NOT TO BE MISSED!