Prosthetic foot with tunable performance

• US 20030028256A1
• Filed: 10/04/2002
• Published: 02/06/2003
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: BioQuest Prosthetics LLC
• Original Assignee: BioQuest Prosthetics LLC
• Inventors: Townsend, Barry W., Claudino, Byron K.
• Granted Patent: US 7,226,485 B2
• Time in Patent Office: Days
• US Class Current: 623/52
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/66 Feet; Ankle joints
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/74 fluid , i.e. hydraulic or pneumatic
• CPC Class Codes: A61F 2/76 Means for assembling, fitting or testing prostheses, e.g. for measuring or balancing, e.g. alignment means
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/30462 retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61F 2002/5001 Cosmetic coverings
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers for implantable joints A61F2002/30563
• CPC Class Codes: A61F 2002/5006 Dampers, e.g. hydraulic damper
• CPC Class Codes: A61F 2002/5007 having elastic means different from springs, e.g. including an elastomeric insert elastic coating A61F2002/3007; springs A61F2002/5072; plate-like springs for feet A61F2002/6657
• CPC Class Codes: A61F 2002/5009 having two or more elastomeric blocks
• CPC Class Codes: A61F 2002/503 for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/5032 for adjusting fluid pressure
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/5075 Multiple spring systems including two or more helical springs
• CPC Class Codes: A61F 2002/5079 Leaf springs A61F2002/6657 takes precedence
• CPC Class Codes: A61F 2002/5083 modular
• CPC Class Codes: A61F 2002/607 Lower legs
• CPC Class Codes: A61F 2002/6614 Feet
• CPC Class Codes: A61F 2002/6621 : Toes
• CPC Class Codes: A61F 2002/6628 : Big toes
• CPC Class Codes: A61F 2002/6635 : Metatarsals
• CPC Class Codes: A61F 2002/6642 : Heels
• CPC Class Codes: A61F 2002/665 : Soles
• CPC Class Codes: A61F 2002/6657 : having a plate-like or strip-like spring element, e.g. an energy-storing cantilever spring keel
• CPC Class Codes: A61F 2002/6664 : Dual structures made of two connected cantilevered leaf springs
• CPC Class Codes: A61F 2002/6671 : C-shaped
• CPC Class Codes: A61F 2002/6678 : L-shaped
• CPC Class Codes: A61F 2002/6685 : S-shaped
• CPC Class Codes: A61F 2002/704 : computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/7615 : Measuring means for implanting artificial joints A61F2/4657
• CPC Class Codes: A61F 2220/0041 : using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2220/0075 : sutured, ligatured or stitched, retained or tied with a rope, string, thread, wire or cable
• CPC Class Codes: A61K 9/4816 : Wall or shell material

Abstract

A prosthetic foot incorporate a foot keel and a calf shank connected to the foot keel to form an ankle joint area of the prosthetic foot. The foot keel has forefoot and hindfoot portions and a relatively long midfoot portion extending between and upwardly arched from the forefoot and midfoot portions. The calf shank includes a downward convexly curved lower end which is attached at a portion thereof to the keel midfoot portion by way of an adjustable fastener arrangement. The foot has biplanar motion capability and, in a preferred form, also has high low dynamic response characteristics. The adjustable fastener arrangement permits adjustment of the alignment of the calf shank and the foot keel with respect to one another in the longitudinal direction of the foot keel for tuning the performance of the prosthetic foot.

Claims

1. A prosthetic foot comprising:

a longitudinally extending foot keel having a forefoot portion at one end, a hindfoot portion at an opposite end and a relatively long midfoot portion extending between and upwardly arched from said forefoot and hindfoot portions;

a releasable fastener;

an upstanding calf shank including a downward convexly curved lower end which is attached at a portion thereof to a proximate, posterior surface of said keel midfoot portion by way of said releasable fastener; and

means for adjusting the alignment of said calf shank and said foot keel with respect to one another in the longitudinal direction of said foot keel for tuning the performance of said prosthetic foot to be task specific.

2. The prosthetic foot according to claim 1, wherein said means for adjusting the alignment includes a longitudinally extending opening in at least one of said proximate, posterior surface of said keel midfoot portion and said downward convexly curved lower end of said calf shank, said releasable fastener extending through said opening to permit adjustably attaching said calf shank to said foot keel for adjusting said alignment.

3. The prosthetic foot according to claim 2, wherein each of said proximate, posterior surface of said keel midfoot portion and said downward convexly curved lower end of said calf shank are provided with a longitudinally extending opening through which said releasable fastener extends.

4. The prosthetic foot according to claim 1, further comprising a coupling element located between said lower end of said calf shank and said proximate, posterior surface of said keel midfoot portion, said coupling element extending along said attached portion of said calf shank and said proximate, posterior surface of said keel midfoot portion, and wherein said releasable fastener extends through an opening in said coupling element for attaching said calf shank to said foot keel.

5. The prosthetic foot according to claim 4, wherein said releasable fastener connects said coupling element to said foot keel and another releasable fastener connects said coupling element to said calf shank for attaching said calf shank to said keel hindfoot portion.

6. The prosthetic foot according to claim 5, wherein said releasable fastener and said another releasable fastener are spaced from one another in said coupling element in a direction along said longitudinal direction of said foot keel.

7. The prosthetic foot according to claim 6, wherein said another releasable fastener is more posterior than said releasable fastener.

8. The prosthetic foot according to claim 1, wherein said curved lower end of said calf shank is in the shape of a parabola with the smallest radius of curvature of said parabola located at said lower end and extending upwardly in said parabola shape.

9. The prosthetic foot according to claim 1, wherein said calf shank is S-shaped with a lower portion of said S-shape forming said curved lower end of said calf shank.

10. The prosthetic foot according to claim 1, wherein said calf shank is J-shaped with a lower portion of said J-shape forming said curved lower end of said calf shank.

11. The prosthetic foot according to claim 1, wherein each of two vertically spaced ends of said calf shank are convexly rounded into respective free ends extending in the same direction along said longitudinally extending foot keel with a relatively straight upstanding portion of said calf shank joining said rounded ends on a side thereof opposite that of said free ends.

12. The prosthetic foot according to claim 1, wherein said convexly curved lower end of said calf shank extends upward anteriorly from said lower end.

13. The prosthetic foot according to claim 1, wherein each of said forefoot portion and said hindfoot portion are upward concavely curved.

14. The prosthetic foot according to claim 1, wherein said midfoot portion of said foot keel is upward convexly curved over the entire longitudinal extent between said forefoot and hindfoot portions.

15. The prosthetic foot according to claim 1, wherein said midfoot portion of said foot keel includes a posterior, upwardly facing concavity in which said curved lower end of said calf shank is attached to said foot keel by way of said releasable fastener.

16. The prosthetic foot according to claim 1, wherein said hindfoot portion includes a heel with a posterior lateral corner which is more posterior and lateral than the medial corner of the heel to encourage hindfoot eversion during initial contact phase of gait.

17. The prosthetic foot according to claim 1, wherein the plantar surface of the midfoot portion of said foot keel has a longitudinal arch concavity with a medial aspect larger in radius than a lateral aspect thereof.

18. The prosthetic foot according to claim 1, wherein a dorsal aspect of said midfoot portion and forefoot portion of said foot keel is formed with an upwardly facing concavity which mimics in function the fifth ray axis of motion of a human foot, said concavity having a longitudinal axis which is oriented at an angle of 20°

to 35°

to the longitudinal axis of the foot keel with the medial being more anterior than the lateral to encourage fifth ray motion in gait as in the oblique low gear axis of rotation of the second to fifth metatarsals in the human foot.

19. The prosthetic foot according to claim 1, wherein the posterior of the forefoot portion of said keel includes medial and lateral expansion joint holes extending through said forefoot portion between dorsal and plantar surfaces thereof, and expansion joints extending forward from respective ones of said holes to the anterior edge of the forefoot portion to form medial, middle and lateral expansion struts which create improved biplanar motion capability of the forefoot portion of said foot keel.

20. The prosthetic foot according to claim 19, wherein said expansion joint holes are located along a line in the transverse plane which extends at an angle of 25 to 35°

to the longitudinal axis of the foot keel with the medial expansion joint hole more anterior than the lateral expansion joint hole.

21. The prosthetic foot according to claim 19, wherein said expansion joint holes as projected on a sagittal plane are inclined at an angle of 45°

to the transverse plane with the dorsal aspect of the holes being more anterior than the plantar aspect.

22. The prosthetic foot according to claim 19, wherein the distance from the releasable fastener to the lateral expansion joint hole is shorter than the distance from the releasable fastener to the medial expansion joint hole such that the lateral portion of the prosthetic foot has a shorter toe lever than the medial for enabling midfoot high and low dynamic response.

23. The prosthetic foot according to claim 1, wherein the anterior end of said forefoot portion is shaped in an upwardly curved arc to simulate the human toes being dorsiflexed in the heel rise toe off position of the late stance phase of gait.

24. The prosthetic foot according to claim 1, wherein the posterior of the forefoot portion of said keel includes at least one expansion joint hole extending through said forefoot portion between dorsal and plantar surfaces thereof with an expansion joint extending forward from said expansion joint hole to the anterior edge of the forefoot portion to form plural expansion struts which create improved biplanar motion capability of the forefoot portion of said foot.

25. The prosthetic foot according to claim 1, wherein said forefoot, midfoot and hindfoot portions of said keel are formed of a single piece of resilient material.

26. The prosthetic foot according to claim 25, wherein said resilient material is a semi-rigid plastic.

27. The prosthetic foot according to claim 1, wherein said midfoot portion is formed of a semi-rigid material with a longitudinal arch shaped to create a dynamic response capability of said foot in gait such that the medial aspect of the longitudinal arch has a relatively higher dynamic response capability and the lateral aspect of said longitudinal arch has a relatively lower dynamic response capability.

28. The prosthetic foot according to claim 1, wherein the posterior end of said hindfoot portion is shaped in an upwardly curved arc that reacts to ground reaction forces during heel strike by compressing for shock absorption.

29. The prosthetic foot according to claim 25, wherein the anterior of the hindfoot portion of said keel includes an expansion joint hole extending through said hindfoot portion between dorsal and plantar surfaces thereof with an expansion joint extending posteriorly from said expansion joint hole to the posterior edge of the hindfoot portion to form plural expansion struts which create improved biplanar motion capability of the hindfoot portion of said foot.

30. A prosthetic foot comprising:

a longitudinally extending foot keel having a forefoot portion at one end, a hindfoot portion at an opposite end and a relatively long midfoot portion extending between and upwardly arched from said forefoot and hindfoot portions;

a calf shank including a downward convexly curved lower end; and

an adjustable fastening arrangement attaching said curved lower end of said calf shank to said midfoot portion of said keel to form an ankle joint area of said prosthetic foot; and

wherein said adjustable fastening arrangement permits adjustment of the alignment of said calf shank and said foot keel with respect to one another in the longitudinal direction of said foot keel for tuning the performance of said prosthetic foot.

31. The prosthetic foot according to claim 30, wherein said adjustable fastening arrangement includes at least one releasable fastener and a coupling element located between said calf shank and said keel, said coupling element and said at least one releasable fastener attaching said calf shank to said foot keel.

32. The prosthetic foot according to claim 31, wherein said adjustable fastening arrangement includes a longitudinally extending opening in each of said calf shank and said foot keel which receive respective releasable fasteners and permit said calf shank and said keel to be slid relative to one another in said longitudinal direction over a range of adjustment for tuning the performance of said prosthetic foot.

33. The prosthetic foot according to claim 30, wherein said convexly curved lower end of said calf shank extends upward anteriorly from said lower end.

34. A foot keel for a prosthetic foot which can be tuned for improved performance for a specific task, said foot keel comprising a longitudinally extending, semi-rigid, resilient member having a forefoot portion at one end, a hindfoot portion at an opposite end and a relatively long midfoot portion extending between and upwardly arched from said forefoot and hindfoot portions, and wherein a posterior surface of said keel midfoot portion is provided with a fastening arrangement permitting a calf shank to be adjustably aligned with respect to said foot keel in the longitudinal direction and attached to said foot keel for tuning the performance of the prosthetic foot formed thereby.

35. The foot keel according to claim 34, wherein said fastening arrangement includes a longitudinally extending opening in said midfoot portion along which a fastener for connecting said foot keel and a calf shank can be slid.

36. The foot keel according to claim 34, wherein each of said forefoot portion and said hindfoot portion are upward concavely curved.

37. The foot keel according to claim 34, wherein said midfoot portion is upward convexly curved over its entire longitudinal extent between said forefoot and hindfoot portions.

38. The foot keel according to claim 34, wherein said midfoot portion includes a posterior, upwardly facing concavity for receiving the curved lower end of a calf shank to be attached to said foot keel by way of a releasable fastener at said fastening arrangement.

39. The foot keel according to claim 34, wherein said hindfoot portion includes a heel with a posterior lateral corner which is more posterior and lateral than the medial corner of the heel to encourage hindfoot eversion during initial contact phase of gait.

40. The foot keel according to claim 34, wherein the plantar surface of the midfoot portion of said foot keel member has a longitudinal arch concavity with a medial aspect larger in radius than a lateral aspect thereof.

41. The foot keel according to claim 34, wherein a dorsal aspect of said midfoot portion and forefoot portion of said foot keel member is formed with an upwardly facing concavity which mimics in function the fifth ray axis of motion of a human foot, said concavity having a longitudinal axis which is oriented at an angle of 20°

to 35°

to the longitudinal axis of the foot keel with the medial being more anterior than the lateral to encourage fifth ray motion in gait as in the oblique low gear axis of rotation of the second to fifth metatarsals in the human foot.

42. The foot keel according to claim 34, wherein a dorsal aspect of said midfoot portion and forefoot portion of said foot keel member is formed with an upwardly facing concavity, said concavity having a longitudinal axis which is oriented parallel to the frontal plane of the foot keel.

43. The foot keel according to claim 34, wherein the posterior of the forefoot portion of said keel member includes medial and lateral expansion joint holes extending through said forefoot portion between dorsal and plantar surfaces thereof, and wherein expansion joints extend forward from respective ones of said holes to the anterior edge of the forefoot portion to form medial, middle and lateral expansion struts which create improved biplanar motion capability of the forefoot portion of said foot keel member.

44. The foot keel according to claim 43, wherein said expansion joint holes are located along a line in the transverse plane which extends at an angle of 35°

to the longitudinal axis of the foot keel with the medial expansion joint hole more anterior than the lateral expansion joint hole.

45. The foot keel according to claim 44, wherein said expansion joint holes are located along a line parallel to the frontal plane of the foot keel.

46. The foot keel according to claim 43, wherein said expansion joint holes as projected on a sagittal plane are inclined at an angle of 45°

to the transverse plane with the dorsal aspect of the holes being more anterior than the plantar aspect.

47. The foot keel according to claim 43, wherein the distance from said fastening arrangement to the lateral expansion joint hole is greater than the distance from the releasable fastening arrangement to the medial expansion joint hole such that the lateral portion of the prosthetic foot keel has a shorter toe lever than the medial for enabling midfoot high and low dynamic response.

48. The foot keel according to claim 34, wherein the anterior end of said forefoot portion is shaped in an upwardly curved arc to simulate the human toes being dorsiflexed in the heel rise toe off position of the late stance phase of gait.

49. The foot keel according to claim 34, wherein the posterior of the forefoot portion of said keel includes at least one expansion joint hole extending through said forefoot portion between dorsal and plantar surfaces thereof with an expansion joint extending forward from said expansion joint hole to the anterior edge of the forefoot portion to form plural expansion struts which create improved biplanar motion capability of the forefoot portion of said foot.

50. The foot keel according to claim 34, wherein said midfoot portion is formed with a longitudinal arch shaped to create a dynamic response capability in a prosthetic foot in gait such that the medial aspect of the longitudinal arch has a relatively higher dynamic response capability and the lateral aspect of said longitudinal arch has a relatively lower dynamic response capability.

51. The foot keel according to claim 34, wherein the posterior end of said hindfoot portion is shaped in an upwardly curved arc that reacts to ground reaction forces during heel strike by compressing for shock absorption.

52. The foot keel according to claim 34, wherein the anterior of the hindfoot portion of said keel includes an expansion joint hole extending through said hindfoot portion between dorsal and plantar surfaces thereof with an expansion joint extending posteriorly from said expansion joint hole to the posterior edge of the hindfoot portion to form plural expansion struts which create improved biplanar motion capability of the hindfoot portion in a prosthetic foot in gait.

53. The foot keel according to claim 34, wherein the anterior end of the foot keel is parallel to the frontal plane of the foot keel.

54. The foot keel according to claim 34, wherein the posterior terminal heel area is parallel to the frontal plane of the foot keel.

55. A calf shank for a prosthetic foot comprising:

an elongated, semi-rigid, resilient member having an outward convexly curved portion at one end of said member for attachment to a foot keel to form an ankle area of the prosthetic foot, an opposite end of said member having means for connecting said calf shank to a supporting structure on an amputee'"'"'s leg, and wherein said convexly curved portion at said one end of said member is provided with a fastening arrangement permitting the calf shank to be adjustably aligned with respect to the foot keel in the longitudinal direction of the foot keel and attached to the foot keel for tuning the performance of the prosthetic foot formed by the foot keel and said calf shank.

56. The calf shank according to claim 55, wherein said fastening arrangement includes a longitudinally extending opening in said convexly curved portion of said member along which a fastener for connecting said calf shank to a foot keel can be slid.

57. The calf shank according to claim 55, wherein said convexly curved portion is in the shape of a parabola.

58. The calf shank according to claim 55, wherein said calf shank is S-shaped.

59. The calf shank according to claim 55, wherein said calf shank is J-shaped.

60. The calf shank according to claim 55, wherein each of said one end and said opposite end of said calf shank member are convexly rounded to respective free ends of said member in the same direction, and wherein a relatively straight portion of said member joins said rounded ends on a side of said member opposite that of said free ends.

61. A method of tuning the performance of a prosthetic foot to be task specific, wherein said prosthetic foot comprises a longitudinally extending foot keel having a forefoot portion at one end, a hindfoot portion at an opposite end and a relatively long midfoot portion extending between and upwardly arched from said forefoot and hindfoot portions, and a calf shank including a downward convexly curved lower end attached at a portion thereof to said keel midportion by way of an adjustable fastening arrangement to form an ankle joint area of said prosthetic foot, said method comprising adjusting the alignment of said calf shank and said foot keel with respect to one another in the longitudinal direction of said foot keel, and securing said calf shank and said foot keel to one another in the adjusted position with said fastening arrangement.