How do i know if i have sprained my popliteus muscle?

MRI: Mri is the only way to confirm it. I suspect there is something else going on. The popliteus unlocks the knee from full extension and provides little functionality over that role. A twisting injury to the knee may cause a popliteal strain, but rotational stability of the knee is provided by the cruciate ligaments and more susceptible to injury over the popliteus tendon.

Difficult to know: As it is a tiny muscle and tendon on the posterior lateral aspect of your knee. Usually if you have torn or sprained it, it is associated with another injury such as an lcl sprain, acl sprain or posterior lateral corner injury.