Friday Quiz # 11 Answer | Figure 1

CincyKidsRad

Cincinnati Children's Radiology

Friday Quiz # 11 Answer

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.

Similar cases

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.](https://app.figure1.com/case-detail/2f22daa0-f41d-41ae-a25f-13b79f44c26b)

A rupture of the deltoid ligament. A fracture of the posterior malleolus of the tibia and a rupture of the syndesmosis.](https://app.figure1.com/case-detail/34504aca-e74a-4676-b937-cf0e55f0b643)

Three avulsion fractures are present in this case. The vertically oriented fragment along the lateral tibia (pink) is known as a Segond fracture and has a high association with ACL tears. It is classically described as an avulsion of the lateral capsular ligament, though this is debated. The tibial intercondylar eminence avulsion fracture (yellow) lies at the distal ACL attachment and is more common in skeletally immature patients. The very uncommon fracture at the medial condyle (green) is due to avulsion of the meniscofemoral component of the deep MCL. #FridayQuizDay](https://app.figure1.com/case-detail/523577a3-2dd1-40cd-9100-92722193446d)

Lateral radiograph of the knee (image 1) shows an avulsion fracture (arrow) of the posterior aspect of the tibia epiphysis and a large knee effusion (arrowhead). Sagittal CT image (image 2) shows the avulsion fragment (arrow). Sagittal T2 weighted MRI (image 3) highlights the avulsion fragment (arrow) and the large hemarthrosis (arrowhead). The proton density MRI (image 4) highlights that the avulsion fracture is connected to the posterior cruciate ligament (arrow). Posterior cruciate ligament avulsion fractures are uncommon. They typically occur after motor vehicle collision. However it can also occur as a jumping injury where the individual lands on a plantarflexed foot with the knee in flexion.](https://app.figure1.com/case-detail/584c6df9-b13d-4ae6-b131-aabb42bd1518)