broken-backed

adjectives

having the spine damaged
"a broken-backed book"; "a broken-backed old horse"
is similar to
harmed or injured or spoiled
"I won't buy damaged goods"; "the storm left a wake of badly damaged buildings"
(of a horse) having bones of the back united by a bony growth
is similar to
not in good physical or mental condition; out of condition
"fat and very unfit"; "certified as unfit for army service"; "drunk and unfit for service"
(of a ship) so weakened as to sag at each end