Good looking model.
You seem to be using relatively advanced techniques to produce quite basic features. Are you adapting knowledge of a different CAD system?
There doesn't seem to be anything preventing the upper part sliding forwards and back on the middle part. Is this intentional?

Hi Aled, I'n not adapting from a different CAD system, to be honest I just know how to use solidworks, but since I learn to work with it by myself I try to use the fixtures that allow me to work as quick as I can. About your second question, yes it is intentional, the middle part exists only to reduce drag, allowing the patient to walk normally.It will be the pattela preventing the knee to bend in the wrong direction, and of course a lot of physiotherapy.

Can you please give me the 2 dimensional sheet of this model.