CincyKidsRad

Tibial spine avulsion fracture

Lateral radiograph of the knees shows an avulsion fracture (arrow) of the tibial spine. A small knee effusion is also present. Tibial spine avulsion fractures represent anterior cruciate ligament avulsion equivalent injuries. These injuries are unique to children due to the relative strength of the anterior cruciate ligament in relation to the bone. The avulsion fracture is typically treated with internal fixation.

Similar cases

Sagittal proton density weighted image shows an avulsion fracture of the posterior tibia epiphysis (arrow) and a moderate joint effusion with hemarthrosis (arrowhead). The posterior cruciate ligament is attached to the avulsed fragment. Posterior cruciate ligament avulsion fractures are uncommon. However, if a bone fragment is seen along the posterior tibial plateau, a PCL avulsion should be considered to be present. The posterior cruciate ligament provides stabilization to the knee and resists excessive posterior translation of the tibia.

Sagittal T2-W MRI shows the avulsion fracture (arrow) of the tibial spine and a large lipohemarthrosis (arrowhead). The lipohemarthrosis causes a parfait effect with blood layering most dependently (furthest from the arrowhead), effusion fluid in the middle, and fat floating on top. Tibial spine avulsion fractures are associated with anterior cruciate ligament (ACL) injuries. The ACL originates from the medial and anterior aspect of the tibial plateau and inserts on the lateral femoral condyle. Children are more likely to have tibial spine avulsions than an ACL rupture because the bone is weaker than the ligament.

AP (image 1) and lateral (image 2) radiographs of the knee show an avulsion fracture (arrow) of the medial tibial spine. This injury is an avulsion fracture of the anterior cruciate ligament insertion. Tibial spine avulsion fractures occur in children due to the greater tensile strength of the ligament compared to the underlying bone. Often, other internal derangement injuries are present.

AP and lateral radiographs of the knee show a small avulsion fragment along the lateral aspect of the tibial epiphysis and a large knee effusion. This type of fracture represents an avulsion of the lateral collateral ligament and is known as a Segond fracture. It is important to recognize as it is almost always associated with an ACL injury.