No it is Fabella...
( I had never heard of it either and I actually had orthopedists who were not on the lookout for this problem.) I went to several doctors before getting the correct diagnosis.

Fabella Bone
The fabella is a small sesamoid bone found in some mammals embedded in the tendon of the lateral head of the gastrocnemius muscle behind the lateral condyle of the femur. It is an accessory bone.