According to the CPT Asst:
"Code 29874 describes a surgical knee arthroscopy performed to remove foreign bodies or loose bodies of the bone or cartilage within the knee joint. It may be necessary to enlarge the entry portal when large loose or foreign bodies need to be removed.
Please note that if a knee arthroscopy for removal of loose or foreign bodies (29874) is performed in the same knee compartment as procedures described by codes 29875-29881, then code 29874 should not be reported separately as this is considered to be an inclusive component of codes 29875-29881.
However, if a knee arthroscopy for removal of loose or foreign bodies (29874) is performed in a different knee compartment as the knee arthroscopy procedure codes 29875-29881, then code 29874 may be reported separately with modifier -59, Distinct Procedural Service, appended. For example, when smoothing down the cartilage and/or drilling holes to create microfractures is also performed in addition to removal of foreign bodies or loose bodies of the bone or cartilage within the knee joint, code 29879 may be reported in addition to code 29874 only if performed in a separate knee compartment. Modifier -59 should be appended to indicate that a separate compartment was involved."
I've always found that if there's a really big one, the dr mentions the size. Mostly they wind up inclusive to a debridement or other codes.
-Bruce
