I have a c5-7 incomplete sci, i can walk with a walker, my rt leg is weaker, but despite going through lots of therapy, i still cannot bend my right knee. are there any bionic knee surgeries/mechanical knee operations? adaptiveexercise/equipment?

You need advice from an interdisciplinary team which includes a neurologist, a physiotherapist and an orthopedist besides your primary care doctor as the coordinator. Good luck.

Although it would be expected that you would suffer spasticity in the right leg from the spinal cord injury, it would be prudent to also exclude knee joint damage if significant loss of range of motion is present. Loads of possible therapeutic approaches, but would start with an orthopedic surgical consultation. A physiatrist would be the next step.