33-M/7   Metaphyseal, avulsion

Ligament avulsions are classified as M-fractures by convention, even when they occur in the epiphysis.

Medial, lateral, or bilateral avulsion fractures of the distal femur are classified as 33-M/7m, 33-M/7l, and 33-M/7, respectively.

These fractures are rare.

Twisting injuries may result in disruption of the medial or lateral collateral (MCL, LCL), anterior or posterior cruciate ligaments (ACL, PCL).

The MCL and ACL are most commonly injured.

Small avulsion fractures may represent markers of significant injuries, including knee dislocation and require MRI to determine the extent of the injury.

Injury of the medial collateral ligament at its femoral attachment can result in local pain and heterotopic ossification. This combination is referred to as the Pellegrini-Stieda lesion.