Review Question - QID 211436

This football player is presenting with knee instability and a proximal lateral tibia avulsion fracture (Segond fracture), which is pathognomonic for an anterior cruciate ligament (ACL) injury. In ACL injuries, MRI will often demonstrate the classic bone bruising pattern observed in the middle third of lateral femoral condyle and posterior third of proximal tibia (Figure D).

The anterolateral ligament (ALL) of the knee has been identified as a separate capsuloligamentous structure originating on the lateral femoral epicondyle and inserting on the anterolateral tibia. The presence of a Segond fracture (bony avulsion of the ALL) is associated with ACL injuries, and correlates with the anterior tibial translation event that occurs during acute ACL injuries. This same anterior translation and abutment of the posterolateral tibia against the middle third of the lateral femoral condyle is responsible for the classic bone bruising pattern observed on MRI in 50% of acute ACL injuries.

Claes et al. investigated the relationship of the Segond fracture with the ALL of the knee in a cadaveric study. They identified that in all the cadavers, the ALL was a distinct ligamentous structure connecting the lateral femoral epicondyle with the anterolateral proximal tibia. They concluded that as the ALL inserts in the region of the proximal tibia from where Segond fractures consistently avulse, the Segond fracture is a bony avulsion of the ALL itself.

Lubowitz et al. reviewed the ALL of the knee in an editorial. They reported the ALL to be a distinct ligamentous structure of the anterolateral aspect of the knee, with its origin proximal and posterior to the popliteus tendon insertion on the lateral femoral epicondyle, and its insertion on the anterolateral aspect of the proximal tibia, and has firm attachments to the lateral meniscus. They concluded that from a surgical standpoint, ACL reconstruction alone may fail to control knee rotational instability, and patients undergoing ACL reconstruction may benefit from concomitant reconstruction of the ALL.

Figure A is a knee radiograph demonstrating a Segond fracture. Figure B demonstrates a horizontal medial meniscus tear. Figure C demonstrates the "double PCL sign" which signifies a displaced bucket-handle meniscus tear. Figure D demonstrates the classic bone bruising pattern in ACL injuries (middle third of lateral femoral condyle and posterior third of proximal tibia). Figure E demonstrates a posterior cruciate ligament (PCL) injury. Figure F demonstrates a lateral collateral ligament (LCL) injury. Illustration A is a cadaveric dissection demonstrating the ALL.

Incorrect Answers:
Answer 1: While medial meniscus tears may be seen in chronic ACL injuries, the Segond fracture is more commonly associated with an acute ACL injury.
Answer 2: An ACL injury is more likely to be observed in the presence of a Segond fracture than a displaced bucket-handle meniscus tear.
Answer 4: The Segond fracture has not been shown to be associated with a PCL tear.
Answer 5: A bony avulsion fracture of the fibular head (not the anterolateral tibia) is associated with LCL and posterolateral corner (PLC) injuries.