An avulsion is a tearing away of the normal attachment of an anatomical structure.
Avulsions may occur where muscles are attached to bone, where the tendinous muscle attachment tears off the bone, often taking with it a small bony fragment.
Open Reduction and Internal Fixation of Isolated Posterior Cruciate Ligament Avulsion Fractures: Clinical and Functional Outcome. Joshi S, Bhatia C, Gondane A, Rai A, Singh S and Gupta S. Knee Surg Relat Res. 2017 Sep; 29(3): 210–216.
All-arthroscopic treatment of tibial avulsion fractures of the posterior cruciate ligament. Gwinner C, Hoburg A, Wilde S, Schatka I, Krapohl B and Jung TM. GMS Interdiscip Plast Reconstr Surg DGPW. 2016; 5: Doc02.