Medical leave was a term in Starfleet which described shore leave at medical order. According to Starfleet regulations, an officer taking medical leave could select their rehabilitation facility.
Although shore leave can be ordered by medical personnel for a crewmember's well-being, a medical leave may be specifically for those who suffered physical or psychological injury in the line of duty.
In 2375 Ensign Nog was ordered to take medical leave by Starfleet Command after he lost a leg in the battle of AR-558. Upon his return to Deep Space 9 Captain Benjamin Sisko read the orders from a PADD and told Nog that his medical leave is granted except his participation for his welcome home party in the wardroom. (DS9: "It's Only a Paper Moon")