I've been diagnosed with arthritis in my right knee and advised to build muscle. I have an aeropilates machine with rebounder and the pilates exercises have done wonders for my knee once I got serious about consistency, etc. I want to do more cardio and do not belong to a gym, so bike, elliptical, etc. are out. I have an Urban Rebounder, which may still be too much for my knee, but would the cardio tramp be OK? I have a feeling the jump board would be better since it's a more stable surface, but the aeropilates system only makes the tramp accessory.