Knee braces for patellar syndrome are designed to control the knee cap. The knee cap can cause pain in several ways. It can slide out of place, it can tilt, it can become broken, or the tendon holding it in place can become swollen or torn.
Patella stabilizers are designed to either force the knee cap into a certain postion, or to prevent it from moving. Knee cap control is achieved with a buttress. The buttress can be either static or dynamic. A static buttress should prevent the knee cap from moving. A dynamic buttress applies pressure to force the knee cap into a desired position.
Patella stabilizers only need hinges when some measure of protection and stability is required, like with a meniscus tear or ligament injury. If the knee problem is only related to the knee cap, hinges are probably more than you need.