
This illustration arrow shows the anterior cruciate ligament in the front, and the posterior cruciate ligament can be visualised behind it.
The word 'cruciate' means 'crossed', and in the knee the term relates to the cruciate ligaments right in the middle of the knee. Page updated June 2024 by Dr Sheila Strover (Clinical Editor)

This illustration arrow shows the anterior cruciate ligament in the front, and the posterior cruciate ligament can be visualised behind it.
The crossed structure of the two cruciate ligaments allows bending and straightening of the knee, while keeping the knee stable and preventing the two big bones from moving front- and backwards, or rotating excessively, in relation to one another.
"....The anterior cruciate ligament resists the combined motions of anterior tibial translation and internal tibial rotation, which defines the concept of rotational stability...."
Being born without cruciate ligaments is "....extremely rare, with a prevalence of 0.017 per 1000 live births....[Orthopaedic surgeons] suggest conservative treatment for asymptomatic patients.....For those who are symptomatic, in order to regain knee stability and function, most clinicians are reported to proceed with cruciate ligament reconstruction or orthopaedic surgery"