What treatment is used for medial patellar partial retinaculum tear. How long must I wait until resuming normal activities?

Depends. The severity of your knee injury that caused the tear of the medial patellar retinaculum tear will determine the length of your recovery. Physical therapy can be very beneficial to aid your recovery and speed your return to "normal" activities. If you have not seen an orthopaedic surgeon yet, it would probably be worthwhile for you.