Affliction of the bone and muscle. Degenerative.
Every planet that's been terraformed for human life has its own little quirks. In the Georgia system, the air down underground in the mines, mixed up with the ore processors is a recipe for Bowden's, and everybody on the planet eventually contracts it: miners, dumpers, even people who've never set foot in a mine.
Treatable with a drug called Pescaline "D" (see Cortex Lexicon).