You can start Physiotherapy treatment immediately after removal of pop cast if any, or if surgical manage than you can start exercises as early as possible.

If your had immobilized your patellar fracture for 8 weeks., or should have healed well. Nevertheless, it's high time to go for exercises. If not stiffness will ensue. With physio you must get full range of flexion and extension with adequate muscle strength. Hope you already had visited some physio..

Hi, Goals for physical therapy post patellar fracture are increasing weight bearing as tolerated, restoration of normal tissue relationships to improve motion, strength and the ability to perform functional activities of daily living. Manual Therapeutic Technique (MTT): hands on care including soft tissue massage, and joint mobilization by a physical therapist to modulate pain and reduce any soft tissue or tendon irritation and restore normal joint mechanics and range of motion.......Therapeutic Exercises (TE) including exercises to improve range of motion, strength and performance of the knee and surrounding muscles.