A prosthesis (30) is disclosed that comprises a support member (32) configured to be implanted on the femur outside the knee joint capsule to displace a target tissue in a lateral direction away from the knee when implanted. The target tissue includes at least one associated muscle or connective tissue of the knee. In particular examples, the support member is configured to redirect or realign forces exerted on the lateral and medial compartments of the knee by the target tissue so as to reduce loading in the medial compartment of the knee. The support member may have a spanning section between a displacement portion (33) and a fixation portion (34), with a bearing surface in the displacement portion configured to atraumatically engage and displace the target tissue. The fixation portion can be configured and dimensioned to be secured to the femur outside the knee joint capsule； and the displacement portion is in an example dimensioned to displace the target tissue in said lateral direction away from the knee.
