Tibial Tubercle Avulsion


  • Avulsion fracture of the tibial tubercle, usually by sudden violent muscle contraction
  • Can often also take off the whole anterior part of the tibia (not just the tubercle)


  • Pain and swelling around the tibial tubercle
  • With a displaced fracture, it is unlikely that the patient is able to straight leg raise
  • Usually unable to weightbear (if the fracture is displaced, the quadriceps mechanism is not intact and the leg would not be able to be supported)

X-ray Features

  • Displacement (or at least significant irregularity) of the tibial tubercle
  • If the fracture is displaced:
    • The fibres of the patellar tendon will appear wavy instead of straight (lateral x-ray)
    • The distance between the patella and the tibial tubercle (or where it should be) will be MORE than 1.1* the vertical height of the patella (lateral x-ray)
    • Blumensaat’s line will not point to the inferior pole of the patella (lateral x-ray)


  • If displaced, requires surgical management
  • If undisplaced and stable (can straight leg raise), can often be managed in a knee extension (Zimmer) splint