Military Veteran Suffers From Frost Bite Both Feet And Now

Military Veteran suffers from frost bite both feet and now has knee and back problems, because he was a paratrooper with the 101st. Airborne division Screaming eagles, parachuting from planes. He is compensated for frostbite for his feet, which are his primary disability, would the knees and back be secondary disability to his primary, would this be a presumptive disability since it is as a result of military service?