Broken bones, like a clavicle or scapula, that can't really be splinted or immobilised beyond securing the affected limb in a sling and being very cautious not to move or jar the shoulder of the injured side; no rigid security of an encasing cast or splint like that for a broken wrist- the shoulder-blade or collarbone are reliant on the surrounding bodily structures to guard and support them throughout the gradually-healing pain of being fractured and the injured character is moving with the utmost gingerness.
this is one of my favorite injuries to give to whumpees because basically no matter what the basic situation is, they're completely fucked.
getting captured, manhandled by angry hands? pain.
getting tied up or chained up and thrown in a cell? pain.
getting drafted into fighting a battle because the good guys are short-staffed that day? pain.
getting a hug from an overeager loved one who missed them very much? pain.
trying to make themselves breakfast or drive a car or sit at a desk? pain.
it's just such a great affecting injury, love it a lot.