Passive artificial knee

Patent metadata

Field	Value
Publication number	US-10405997-B2
Application number	US-201615571027-A
Country	US
Kind code	B2
Filing date	May 4, 2016
Priority date	May 5, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A passive artificial knee includes a knee hinge assembly defining a knee axis, a locking hinge assembly defining a locking axis, and a post linking the knee hinge assembly and the locking hinge assembly. A ground reaction force applied to the artificial knee posterior to the locking axis causes an interfering relation by compression of the locking hinge assembly and the knee hinge assembly during heel strike at early-stance gait phase of an individual wearing the artificial knee, thereby locking rotation of the post about the knee axis. Shifting of ground reaction force anterior to the locking axis during a mid-stance to late-stance gait phase of the individual causes rotation of the post about the locking axis, thereby unlocking rotation of the post about the knee axis and enabling flexion and subsequent swing phase extension of the passive artificial knee joint. The artificial knee is a passive joint that can be fabricated and maintained at low expense.

First claim

What is claimed is:

1. An artificial knee, comprising:
a) a knee hinge assembly defining a knee axis, the knee hinge assembly including (i) a head plate, (ii) an early-stance flexion hinge at the head plate defining an early-stance flexion axis, the head plate having an anterior end and a posterior end that together define a head plate axis normal to the early-stance flexion axis, the early-stance flexion axis being between the anterior end and the posterior end, (iii) a knee hinge collinear with the knee axis at a post, the post having a first end and a second end that together define a major longitudinal axis, the knee axis intersecting and being normal to the major longitudinal axis, and (iv) a linking member that links the early-stance flexion hinge to the knee hinge and defines a first surface that contacts a locking hinge assembly during compression of the locking hinge assembly and the knee hinge assembly;
b) the locking hinge assembly defining a locking axis;
c) the post linking the knee hinge assembly and the locking hinge assembly, wherein a ground reaction force applied to the artificial knee posterior to the locking axis causes an interfering relation at a point between the locking hinge assembly and the knee hinge assembly during heel strike and early stance gait phases of an individual wearing the artificial knee, whereby rotation of the locking hinge assembly causes radial compression of the knee hinge assembly at the point of interfering relation, thereby locking rotation of the post about the knee axis, and wherein shifting of the ground reaction force anterior to the locking axis during a mid-stance gait phase of the individual causes rotation of the post about the locking axis, thereby unlocking rotation of the post about the knee axis; and
d) a spring between the head plate and the linking member biasing rotation of the linking member about the early-stance flexion axis to thereby direct the knee hinge and the first end of the post toward the head plate.

2. The artificial knee of claim 1 , wherein the locking hinge assembly includes:
a) a foot plate having a latch, the latch defining a second surface that contacts the first surface of the knee hinge assembly at or posterior to the major longitudinal axis during compression of the locking hinge assembly and the knee hinge assembly; and
b) a locking hinge collinear with the locking axis and linking the foot plate to the second end of the post.

3. The artificial knee of claim 2 , wherein the locking axis is normal to and intersects a line that is parallel to the major longitudinal axis.

4. The artificial knee of claim 3 , wherein, when the major longitudinal axis of the post is normal to the head plate axis, the line parallel to the major longitudinal axis intersects the head plate axis on a side of the knee axis opposite that of the early-stance flexion hinge axis.

5. The artificial knee of claim 4 , wherein the spring spans the head plate and the linking member at the posterior end of the head plate, and wherein the early-stance flexion axis is between the spring and the anterior end of the head plate.

6. The artificial knee of claim 5 , further including a differential damping system at the knee hinge, wherein the differential damping system includes:
a) a first damper at one side of the knee hinge, the first damper engaging the post and the linking member;
b) a second damper at an opposite side of the knee hinge, the second damper engaging the post and the linking member; and
c) a one-way clutch that engages the second damper only during flexion of the artificial knee.

7. The artificial knee of claim 6 , wherein the second damper provides more resistance to rotation of the post about the knee axis than does the first damper.

8. The artificial knee of claim 1 , wherein:
a) the knee hinge assembly further defines a first locking surface that lies in and includes an endpoint of a secant line of a first circle defined by rotation of the post about the knee axis, wherein the secant line is normal to a radial line extending from the knee axis to the first circle;
b) the locking hinge assembly further defines a second locking surface that lies in a second circle defined by rotation about the locking axis; and
c) the locking hinge assembly defines an arc at the second locking surface by rotation of the post about the knee axis, the knee axis intersecting the secant line at the first locking surface, whereby rotation of the second locking surface about the locking axis causes the radial compression of the knee hinge assembly at a given point between the first locking surface and the knee axis, thereby causing the interfering relation between the first locking surface and the second locking surface that locks the post and prevents rotation of the post about the knee axis.

9. An artificial knee, comprising:
a) a head plate, having an anterior end and a posterior end defining a head plate axis, and an early-stance flexion hinge between the anterior end and the posterior end defining an early-stance flexion axis that is normal to the head plate axis;
b) a post having
i) a first end and a second end together defining a major longitudinal axis,
ii) a knee hinge defining a knee axis at the first end of the post, wherein the knee axis is normal to and intersects the major longitudinal axis, and
iii) a locking hinge defining a locking axis at the second end of the post, wherein the locking axis is normal to and intersects a line parallel to the major longitudinal axis;

c) a linking member linked to the head plate at the early-stance flexion hinge and linked to the post at the knee hinge, wherein, when the major longitudinal axis of the post is normal to the head plate axis, the line parallel to the major longitudinal axis intersects the head plate axis on a side of the knee axis opposite to that of the early-stance flexion axis;
d) a spring between the head plate and the linking member biasing rotation of the linking member about the early-stance flexion axis to thereby direct the knee hinge and the first end of the post toward the head plate; and
e) a foot plate linked to the post at the locking hinge, the foot plate including a latch that is in an interfering relation at a point between the latch and the linking member during heel strike and early stance gait phases of an individual wearing the artificial knee, whereby the latch will be engaged with the linking member thereby causing radial compression of the knee hinge assembly at the point of interfering relation, and preventing rotation of the post about the knee axis, and whereby, during a mid-stance gait phase of the individual, when a ground reaction force applied to the artificial knee is anterior to the locking axis, the foot plate will rotate about the locking axis and consequently disengage the latch from the linking member, thereby enabling the post to rotate about the knee axis.

10. The artificial knee of claim 9 , wherein the interfering relation between the latch and the linking member during heel strike and early-stance gait phases is posterior to the major longitudinal axis.

11. The artificial knee of claim 10 , wherein the spring spans the head plate and the linking member at the posterior end of the head plate, and the early-stance flexion axis is between the spring and the anterior end of the head plate.

12. The artificial knee of claim 11 , further including a differential damping system at the knee hinge, wherein the differential damping system includes:
a) a first damper at one side of the knee hinge, the first damper engaging the post and the linking member;
b) a second damper at an opposite side of the knee hinge, the second damper

Assignees

• Massachusetts Inst Technology

Inventors

• Arelekatti Venkata Narayana Murthy
• Winter Amos G
• Dorsch Daniel Scott

Classifications

• A61F2002/6854

  for locking or unlocking a joint · CPC title

• A61F2002/5003

  having damping means, e.g. shock absorbers · CPC title

• A61F2002/5073

  Helical springs, e.g. having at least one helical spring · CPC title

• A61F2005/0162

  when weight is applied · CPC title

• A61F2/64 Primary

  Knee joints · CPC title