Patent ID: 8343156

Claim:
A mill head for attachment to a base, the base having a drive spindle, said mill head including: a housing, said housing having: a top shell; a bottom shell, said bottom shell being attached to and disposed under said top shell so that there is a space between said shells wherein, said shells are shaped to be attached to the base and shaped to cooperate with locking features integral with the base so that the locking features are capable of releasably holding said housing to the base; a housing first opening disposed in said top shell through which bone stock is introduced into said housing; a housing second opening in said bottom shell below the housing first opening; a housing third opening in said bottom shell that is separate from the housing second opening, the housing third opening being located inward from the housing second opening so as to be located closer to a centrally located longitudinal axis which passes through the top shell and the bottom shell of the housing than the housing second opening; and a housing ring that extends upwardly from an inner surface of said bottom shell around the housing third opening so as to form a barrier between the housing second opening and the housing third opening; a static impingement surface integral with said top shell adjacent the housing first opening; a cutting device disposed in said housing between said top shell and said bottom shell, said cutting device being mounted in said housing for rotational motion within said housing, said cutting device having: at least one cutting feature that is capable of pressing bone stock against the impingement surface to convert bone stock into bone chips; a cutting device opening through the cutting device through which the bone chips are capable of passing, wherein said cutting device opening is located outside of said housing ring that extends between the housing second opening and the housing third opening; and a cutting device coupling feature for connecting said cutting device to the base drive spindle so that, when said housing is attached to the base, the drive spindle engages said cutting device coupling feature, so that the drive spindle, when actuated, rotates said cutting device, said cutting device coupling feature being accessible through the housing third opening; and a catch tray separate from said housing that is removably attached to said bottom shell of said housing so as to extend below the housing second opening.