Hello!
The thick structure which lies along the lateral border of the patella, (the knee cap) and represents the confluence of many structures is the lateral retinaculum and it is part of the soft tissue, fascia.
The lateral retinaculum can be excessively tight. In this situation, the patella is laterally tilted and or laterally displaced. There is a chicken and the egg situation with respect to whether a tight lateral retinaculum causes a tilted/displaced patella or whether a tilted/displaced patella leads to a tight lateral retinaculum.
It may be necessary to perform lateral retinacular release to allow proper patellar tracking & prevent patellar subluxation or dislocation.
This can be done arthroscopically a small incision in the knee joint and this is called arthroscopic lateral retinacular replacement.
Take care!