I'm a physio, so I see a lot of these. Rarely is the continuing pain due to the cartilage itself or what's been done to it during the op, so try not to worry about that. Wobbleboard is just a circle of timber with 1/2 a sphere underneath. When u stand on it, you have to work all the muscles to retain your balance. Balance is lost temporarily after ops like this and needs retraining. Another way to retrain it is to use a minitramp. Various exercises - u may want to get some guidance for these.
