The popping knee may be due to Discoid meniscus which is an abnormally shaped meniscus within the knee joint
The discoid meniscus can cause problems, usually a popping
sensation with pain over the outside part of the knee joint.
If there is a popping sensation, then conservative treatment consisting of exercises and stretching can be performed. If these treatments do not relieve the symptoms, arthroscopic surgery on the discoid meniscus would be helpful.