How long will a fractured knee cap take to hear?

6-8 weeks. Generally bones heal in about 6-8 weeks. Various factors can affect the healing process, such as diabetes and smoking, both of which can increase the healing time. A fractured patella (knee cap) generally will heal in about 6-8 weeks (whether it undergoes surgery or not).
6-12 weeks. Fractures anywhere take aproimately 6-8 weeks to heal. Since the knee cap is the main fulcrum for extending and flexing your knee itdespite the bone being healed in might take extra time to heal or rehabilitate the quad muscle. It also is intraarticular fracture andas such may result in arthritis.