From Longman Dictionary of Contemporary Englishbad heart/leg/back etcbad heart/leg/back etcCONDITION/STATE OF somethinga heart, leg etc that is injured or does not work correctly I haven’t been able to do much because of my bad back. → bad
Examples from the Corpus
bad heart/leg/back etc• Medical deferment for a very bad heart.• He had a bad leg and they kept on at him to hurry up.• He had a bad back as well, you know, just like Rich.• For Joshua, at sixty-two, and suffering from a bad leg, distances had begun to take on an extraordinary significance.• A sweetheart, this little lady, not bad legs either.• The problems-from bad backs to carpal tunnel syndrome to headaches-have made the headlines of every health magazine in the country.• That coming from him who would go sick with a bad back whenever a job tired him. 