This classic discusses the original publication of Dr Stieda: Über eine typische Verletzung am unteren Femurende, published in 1908, on the ossified post-traumatic lesion at or near the medial collateral ligament (MCL), adjacent to the margin of the medial femoral condyle which is nowadays known as the Pellegrini-Stieda lesion. One of the presumed mechanisms of injury is an avulsion fracture at the MCL origin. Most patients are asymptomatic, in case of pain, however it is called a Pellegrini-Stieda syndrome. Recently, there are signs directing towards a muscular lesion, in particular the insertion of the adductor magnus muscle. In 1908, Alfred Stieda described a case series of an ossification on the medial side of the knee, which was treated operatively. During this operation, the origin to his belief was an avulsion from the medial epicondyle by the medial head of the gastrocnemius muscle. Although the theory that it concerned an avulsion fracture of the epicondyle is no longer accepted, the part of his findings that it concerned a muscle/tendon ossification at the insertion of the medial head of the gastrocnemius is interesting. Treatment is only indicated in symptomatic cases. When confronted with an ossification on the medial side of the knee, one should be aware that the MCL, the insertion of the adductor magnus or the gastrocnemius muscle might be involved. The first known publication was by Köhler in 1903. Historically, this entity should therefore be named the Köhler-Pellegrini-Stieda lesion.