I watched the tibia-proximal epiphysis after posting this question. It seems as though treating the femur in supine would be generally less effective since you can’t add the medial or lateral containment as easily. Perhaps a better way to ask the question above would be to ask ” when is it more advantageous to treat in the supine position?”
Putting the client in sidelying allows for a lot more flexibility of vectors. So, if you have treated the epiphysis while the client is supine, it would be a more general approach, Y axis on the diaphysis, and maybe x axis of the epihysis. However, even after you have cleared those, and you still find a primary restriction in the epihysis, and you have followed and treated according to the hierarchy, you may need to investigate different vectors of the distal epihysis of the femur or the proximal epiphysis of the tibia. Sidelying approach also allows you to combine vectors of both lateral and medial aspects of the epiphysis. You can also determine that possibly more treatment needs to be done in the epiphysis is by visual and palpatory assessment as well. One or both of the epiphysis may look and feel enlarged, and this would be a clue that perhaps you need to be more specific with vectors. Plus, there is a history of multiple and/or significant injuries to the knee. It is possible to be very specific with mechanical vectoring! Sometimes I find that I have to go back and forth between the medial and lateral condyles, and also the y axis of the long bone.