The knee extensor mechanism is the kinematic chain of quadriceps tendon, patella, and patellar tendon that transmits quadriceps force to the tibia. The patella functions as a sesamoid increasing the mechanical advantage (moment arm) of the quadriceps by approximately 30 percent. Disruption anywhere in this chain — quadriceps tendon, patellar fracture, or patellar tendon — produces loss of active knee extension.
Transmits quadriceps muscle force through the patella to the tibia for knee extension
Extensor mechanism disruption assessment requires the extension lag test — the inability to actively extend the knee fully against gravity. Patellar fractures disrupting the extensor mechanism (displaced fractures or those producing extension lag) require ORIF; undisplaced fractures with intact mechanism can be managed non-operatively.
Loss of active knee extension from quadriceps tendon, patellar fracture, or patellar tendon injury requiring identification of the disruption level and surgical repair.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
