Power operated dermatome with shielded rotary knife blade

1. A combination of an annular rotary knife blade and a blade housing assembly for a power operated dermatome, the blade housing assembly supporting the annular rotary knife blade for rotation with respect to the blade housing assembly, the combination comprising: the annular rotary knife blade supported for rotation about an axis of rotation by the blade housing assembly, the annular rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the annular rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and the blade housing assembly including a blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the annular rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to the axis of rotation of the annular rotary knife blade, and a blade housing cover extending from the blade housing into the interior region of the annular rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the annular rotary knife blade inner wall and having an inner surface adjacent to and continuing the lower material-directing surface of the annular rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second lower end of the blade housing adjacent the outer wall of the blade housing.

2. The combination of claim 1 wherein the shield of the blade housing cover extends into the radially recessed upper portion of the annular rotary knife blade inner wall.

3. The combination of claim 1 wherein the blade housing assembly includes a blade lock ring removably attached to the blade housing to secure the rotary knife blade to the blade housing assembly.

4. A combination of a rotary knife blade and a blade housing assembly for a power operated dermatome, the blade housing assembly supporting the rotary knife blade for rotation about an axis of rotation with respect to the blade housing assembly and the combination defining a material-directing surface for tissue cut by the rotary knife blade, the combination comprising: the rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end having a cutting edge defining a cutting plane substantially orthogonal to the axis of rotation, the inner wall defining an interior region of the rotary knife blade and including a material-directing surface adjacent the cutting edge and a radially-recessed upper portion; and the blade housing assembly including a blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to the axis of rotation of the rotary knife blade, and a blade housing cover extending from the blade housing into the interior region of the rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the rotary knife blade inner wall and having a material-directing inner surface adjacent to and continuing the material-directing surface of the rotary knife blade inner wall, the material-directing surface of the rotary knife blade and the material-directing inner surface of the blade housing cover shield comprising the material-directing surface of the combination, a lower end of the material-directing inner surface of the shield extending below the second lower end of the blade housing adjacent the outer wall of the blade housing.

5. The combination of claim 4 wherein the shield of the blade housing cover extends into the radially recessed upper portion of the rotary knife blade inner wall.

6. The combination of claim 4 wherein the blade housing assembly includes a blade lock ring removably attached to the blade housing to secure the rotary knife blade to the blade housing assembly.

7. A head assembly for a power operated dermatome, the head assembly comprising: a frame body supporting a gear train, an annular rotary knife blade, a blade housing assembly supporting the annular rotary knife blade for rotation about an axis of rotation with respect to the blade housing assembly, the annular rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the annular rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and the blade housing assembly including a blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the annular rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to the axis of rotation of the annular rotary knife blade, and a blade housing cover extending from the blade housing into the interior region of the annular rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the annular rotary knife blade inner wall and having an inner surface adjacent to and continuing the lower material-directing surface of the rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second lower end of the blade housing adjacent the outer wall of the blade housing.

8. The head assembly of claim 7 wherein the shield of the blade housing cover extends into the radially recessed upper portion of the annular rotary knife blade inner wall.

9. The head assembly of claim 7 wherein the blade housing assembly includes a blade lock ring removably attached to the blade housing to secure the annular rotary knife blade to the blade housing assembly.

10. A combination of a power driven rotary knife blade and a blade housing assembly supporting the power driven rotary knife blade for rotation with respect to the blade housing assembly, the combination comprising: the power driven rotary knife blade supported for rotation about an axis of rotation by the blade housing assembly, the power driven rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the power driven rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and the blade housing assembly including a blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the power driven rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to the axis of rotation of the power driven rotary knife blade, and a blade housing cover extending from the inner wall of the blade housing into the interior region of the power driven rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the power driven rotary knife blade inner wall and having an inner surface adjacent to and aligned with the lower material-directing surface of the power driven rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second lower end of the blade housing.

11. The combination of claim 10 wherein the shield of the blade housing cover extends into the radially recessed upper portion of the power driven rotary knife blade inner wall.

12. The combination of claim 10 wherein the blade housing assembly includes a blade lock ring removably attached to the blade housing to secure the power driven rotary knife blade to the blade housing assembly.

13. A power operated dermatome comprising: a rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and a blade housing assembly supporting the rotary knife blade for rotation with respect to the blade housing assembly, the blade housing assembly including a blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to an axis of rotation of the rotary knife blade, and a blade housing cover extending from the inner wall of the blade housing into the interior region of the rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the rotary knife blade inner wall and having an inner surface adjacent to and aligned with the lower material-directing lower surface of the rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second lower end of the blade housing.

14. The power operated dermatome of claim 13 wherein the shield of the blade housing cover extends into the radially recessed upper portion of the rotary knife blade inner wall.

15. The power operated dermatome of claim 13 wherein the blade housing assembly includes a blade lock ring removably attached to the blade housing to secure the rotary knife blade to the blade housing assembly.

16. The combination of claim 1 wherein a lower portion of the inner wall of the blade housing includes a bearing surface extending radially inwardly into the inner wall.

17. The combination of claim 4 wherein a lower portion of the inner wall of the blade housing includes a bearing surface extending radially inwardly into the inner wall.

18. The head assembly of claim 7 wherein a lower portion of the inner wall of the blade housing includes a bearing surface extending radially inwardly into the inner wall.

19. The combination of claim 10 wherein a lower portion of the inner wall of the blade housing includes a bearing surface extending radially inwardly into the inner wall.

20. The power operated dermatome of claim 13 wherein a lower portion of the inner wall of the blade housing includes a bearing surface extending radially inwardly into the inner wall.

21. A combination of an annular rotary knife blade and a blade housing assembly for a power operated dermatome, the blade housing assembly supporting the annular rotary knife blade for rotation with respect to the blade housing assembly, the combination comprising: the annular rotary knife blade supported for rotation about an axis of rotation by the blade housing assembly, the annular rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the annular rotary knife blade and including a lower material-directing surface and a recessed upper portion; and the blade housing assembly including a blade housing and a blade lock ring coupled to the blade housing, the blade housing having a first upper end and an axially spaced apart second lower end and an inner wall and a radially spaced apart outer wall, the first end of the annular rotary knife blade positioned between the first upper end and the second lower end of the blade housing as viewed with respect to the axis of rotation of the annular rotary knife blade, the blade housing including a blade housing cover extending from the blade housing into the interior region of the annular rotary knife blade, the blade housing cover including a shield extending along the recessed upper portion of the annular rotary knife blade inner wall and having an inner surface adjacent to and continuing the lower material-directing surface of the annular rotary knife blade inner wall, the blade lock ring including an inner surface and a radially spaced apart outer surface and an upper surface and an axially spaced apart lower surface, the inner surface of the blade lock ring including a bearing surface adjacent the upper surface of the blade lock ring, the blade housing including a bearing surface extending axially upwardly into a second lower end of the blade housing, the bearing surface of the blade lock ring and the bearing surface of the blade housing in axial alignment defining a bearing race of the blade housing assembly.

22. The combination of an annular rotary knife blade and a blade housing assembly of claim 21 wherein the bearing surface of the blade housing comprises an arcuate bearing surface and the bearing surface of the blade lock ring comprises an arcuate bearing surface.

23. A combination of a power driven rotary knife blade and a blade housing assembly supporting the power driven rotary knife blade for rotation with respect to the blade housing assembly, the combination comprising: the power driven rotary knife blade supported for rotation about an axis of rotation by the blade housing assembly, the power driven rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the power driven rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and the blade housing assembly including a blade housing having a central body including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the first end of the power driven rotary knife blade positioned between the first end of the central body of the blade housing and the second end of the central body of the blade housing as viewed with respect to the axis of rotation of the power driven rotary knife blade, the blade housing including a blade housing cover extending from the inner wall of the central body of the blade housing into the interior region of the power driven rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the power driven rotary knife blade inner wall and having an inner surface adjacent to and continuing the lower material-directing surface of the power driven rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second end of the central body of the blade housing adjacent the outer wall of the central body of the blade housing.

24. A power operated dermatome comprising: a rotary knife blade including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the second end defining a cutting edge, the inner wall defining an interior region of the rotary knife blade and including a lower material-directing surface adjacent the cutting edge and a radially recessed upper portion; and a blade housing assembly supporting the rotary knife blade for rotation with respect to the blade housing assembly, the blade housing assembly including a blade housing having a central body including a first end and an axially spaced apart second end and an inner wall and a radially spaced apart outer wall, the first end of the rotary knife blade positioned between the first end of the central body of the blade housing and the second end of the central body of the blade housing as viewed with respect to the axis of rotation of the rotary knife blade, the blade housing including a blade housing cover extending from the inner wall of the blade housing into the interior region of the rotary knife blade, the blade housing cover including a shield extending along the radially recessed upper portion of the rotary knife blade inner wall and having an inner surface adjacent to and continuing the lower material-directing lower surface of the rotary knife blade inner wall, a lower end of the inner surface of the shield extending below the second end of the central body of the blade housing adjacent the outer wall of the central body of the blade housing.