A safety scalpel, comprising: a handle having a first end and a second end and having a longitudinal axis that extends between the first end and the second end, and a cartridge assembly detachably and slideably mounted onto at least a portion of the handle parallel to or along the longitudinal axis, comprising: a blade guard having a first end and second end and a locking aperture defined near the first end, the blade guard defining a hollow cavity, wherein the blade guard slideably mounts onto the second end of the handle; a blade holder slideably mounted within the cavity of the blade guard; a blade keyed to cooperatively mate with the blade holder, such that as the blade holder slides within the cavity of the blade guard, the blade, extends from or retracts within the second end of the blade guard, characterised in that: the blade holder having at least one front leg and at least one rear leg, wherein the at least one rear leg has a pair of front feet (522, 524) and a pair of back feet (526, 528), the pair of back feet (526, 528) being spring loadable and receivable within the locking aperture of the blade guard. a handle having a first end and a second end and having a longitudinal axis that extends between the first end and the second end, and a cartridge assembly detachably and slideably mounted onto at least a portion of the handle parallel to or along the longitudinal axis, comprising: a blade guard having a first end and second end and a locking aperture defined near the first end, the blade guard defining a hollow cavity, wherein the blade guard slideably mounts onto the second end of the handle; a blade holder slideably mounted within the cavity of the blade guard; a blade keyed to cooperatively mate with the blade holder, such that as the blade holder slides within the cavity of the blade guard, the blade, extends from or retracts within the second end of the blade guard, characterised in that: the blade holder having at least one front leg and at least one rear leg, wherein the at least one rear leg has a pair of front feet (522, 524) and a pair of back feet (526, 528), the pair of back feet (526, 528) being spring loadable and receivable within the locking aperture of the blade guard. a blade guard having a first end and second end and a locking aperture defined near the first end, the blade guard defining a hollow cavity, wherein the blade guard slideably mounts onto the second end of the handle; a blade holder slideably mounted within the cavity of the blade guard; a blade keyed to cooperatively mate with the blade holder, such that as the blade holder slides within the cavity of the blade guard, the blade, extends from or retracts within the second end of the blade guard, characterised in that: the blade holder having at least one front leg and at least one rear leg, wherein the at least one rear leg has a pair of front feet (522, 524) and a pair of back feet (526, 528), the pair of back feet (526, 528) being spring loadable and receivable within the locking aperture of the blade guard. the blade holder having at least one front leg and at least one rear leg, wherein the at least one rear leg has a pair of front feet (522, 524) and a pair of back feet (526, 528), the pair of back feet (526, 528) being spring loadable and receivable within the locking aperture of the blade guard.