MSD Manual

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Extending the Knee
Extending the Knee

Extending the knee involves several structures, which can be injured when people try to straighten their knee and are blocked from doing so. These injuries include

A tear (rupture) in the quadriceps tendon, which attaches the main muscle in the thigh (quadriceps) to the kneecap (patella)

A tear in the patellar tendon, which attaches the kneecap to the shinbone (tibia)

Fracture of the kneecap or top of the shinbone

In these topics
Knee Extensor Injuries