There are three possible forms of patellar tendon rupture.
The first form of rupture is a complete tear.
In a complete tear, the tendon separates completely from the top of the tibia which results in the inability to straighten one’s leg. When the tendon tears, it can break a piece of the bone off of the kneecap.
The second form of rupturing the patellar tendon is a partial tear.
A partial tear is when some of the fibers of the patellar tendon are torn but the majority of the tendon is still attached to the soft tissue located at the posterior end of the patella bone.
The third form of rupture is caused by patellar tendonitis (“jumper’s knee”).
Patellar tendinitis causes the tendon to be torn in the middle due to the tissue damage it has been acquiring from over-use. Patellar tendonitis is inflammation of the tendon which results in the weakening of the tendon. Tendonitis is caused by excessive jumping or running without sufficient rest.
The tell-tale sign of a ruptured patella tendon is the movement of the patella further up the quadriceps. When rupture occurs, the patella loses support from the tibia and moves toward the hip when the quadriceps muscle contracts, hindering the leg’s ability to extend. This means that those affected cannot stand, as their knee buckles and gives way when they attempt to do so.