Presentation
Fall onto concrete block, striking tibial tuberosity. Pain and swelling with difficulty weight bearing.
Patient Data
Lucent line through the posterior aspect of the proximal tibia on the lateral view, suspicious for a nondisplaced PCL avulsion fracture. Small joint effusion. No other finding of note. Further evaluation via noncontrast CT recommended.
Right knee joint is congruent. Small to moderate joint effusion. No lipohemarthrosis. Acute avulsion fracture of the posterior tibial spine at the insertion of the PCL with extension to the physis in keeping with a Salter-Harris 2 component. There is no anterior extension to involve the tibial tuberosity. Within the limits of CT, the PCL and ACL remain intact. There is mild edema of the surrounding soft tissues.
IMPRESSION:
Acute avulsion fracture of the posterior tibial spine at the insertion of the PCL with a small Salter-Harris 2 component.
Case Discussion
The PCL inserts on the posterior intercondylar area of the tibia. Avulsion fractures at its insertion are caused by posterior translation of the tibia, as occurred in this case with a fall with direct impact on the tibial tuberosity, likely with a flexed knee.