Boots – shoes – and leggings – Orthopedic boot or shoe with corrective element – Arch support
Reexamination Certificate
2001-03-16
2004-06-08
DeMille, Danton D. (Department: 3764)
Boots, shoes, and leggings
Orthopedic boot or shoe with corrective element
Arch support
C036S180000
Reexamination Certificate
active
06745501
ABSTRACT:
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates generally to orthotic foot appliances, and more particularly to an improved orthotic device for treatment of gait cycle disorders which frequently develop in patients suffering from diabetes, rheumatoid arthritis and certain other conditions.
b. Background
Relevant to the background of the present invention, there will now be a discussion of the following: i) the main components or parts of the human leg and foot; ii) the proper gait cycle which a person goes through in a normal walking motion; and iii) the abnormal gait cycle which develops from diabetes, rheumatoid arthritis or other conditions which impair proper transfer of weight onto the forefoot when walking, and which is corrected by the present invention.
a) The Main Components or Parts of the Human Leg and Foot
With reference to
FIGS. 1-3
, there is shown a typical human foot
10
, and the lower part
12
of the leg
14
. The two lower bones of the leg
14
are the tibia
16
and the fibula
18
. Below the tibia
16
and fibula
18
, there is the talus
20
(i.e., the “ankle bone”). Positioned below and rearwardly of the talus
20
is the calcaneus
22
(i.e., the “heel bone”). Positioned moderately below and forward of the talus
20
are the navicular
24
and the cuboid
26
. Extending forwardly from the navicular
24
are the three cuneiform bones
28
. Extending forwardly from the cuneiform bones
28
and from the cuboid
26
are the five metatarsals
30
. Forwardly of the metatarsals
30
are the phalanges
32
which make up the five toes
34
.
The movement of the talus
20
relative to the tibia
16
and fibula
18
is such that it enables the entire foot to be articulated upwardly and downwardly (in the motion of raising or lowering the forward part of the foot). However, the talus
20
is connected to the tibia
16
and fibula
18
in such a way that when the entire leg
14
is rotated about its vertical axis (i.e., the axis extending the length of the leg), the talus
20
rotates with the leg
14
.
With regard to the relationship of the talus
20
to the calcaneus
22
, these move relative to one another about what is called the “subtalar joint” indicated at
36
. The subtalar joint
36
can be described generally as a hinge joint about which the talus
20
and calcaneus
22
articulate relative to one another. The hinge axis extends upwardly and forwardly at an angle of about 42° from the horizontal, and also slants forwardly and inwardly at a moderate angle (e.g., about 16° from a straightforward direction). There is also the midtarsal joint
38
, which is in reality composed of two separate joints, the talo-navicular and the calcaneal-cuboid.
b) Gate Cycle of a Normal Foot
During the normal walking motion, the hip (i.e., the pelvis) moves on a transverse plane. Also, the femur (i.e., the leg bone between the knee joint and the hip) and the tibia rotate about an axis parallel to the length of the person's leg. This rotation of the leg about its vertical axis is interdependent with the pronating and supinating of the foot during the gait cycle. There is also flexion and extension of the knee and the ankle joint.
At the beginning of the normal gait cycle the heel of the forwardly positioned leg strikes the ground, after which the forward part of the foot rotates downwardly into ground engagement. The leg then continues through its walking motion to extend rearwardly and the person pushes off from the ball of the foot as the other leg comes into ground engagement.
The phases that make up the gait cycle can be seen in FIG.
4
. When the leg is swung forwardly and makes initial ground contact, at the moment of ground contact the leg is rotated moderately to the outside (i.e., the knee of the leg is at a more outward position away from the centerline of the body) so that the foot is more toward the supinated position. However, as the person moves further through the gait cycle toward the 25% position, the leg rotates about its vertical axis in an inside direction so that the subtalar joint is pronating. The effect of this is to rotate the heel of the foot so that the point of pressure or contact moves forwardly from an outside rear heel location (shown at
52
in
FIG. 5
) towards the location indicated at
54
in FIG.
5
. This pronating of the subtalar joint
36
produces a degree of relaxation of the midtarsal joint
38
and subsequent relaxation of the other stabilization mechanisms within the arch of the foot, which reduces the potential shock that would otherwise be imparted to the foot by the forward part of the foot making ground contact.
With further movement from the 25% to the 75% position, the leg rotates in an opposite direction (i.e., to the outside so that the midtarsal joint
38
becomes supinated at the 75% location of FIG.
4
. This locks the midtarsal joint
38
so that the person is then able to operate his foot as a rigid lever so as to rise up onto the ball of the foot and push off as the other leg moves into ground contact at a more forward location.
With reference again to
FIG. 5
, it will be seen that the initial pressure at ground contact is at
52
and moves laterally across the heel to the location at
54
. Thereafter, the pressure center moves rather quickly along the broken line indicated at
56
toward the ball of the foot. As the person pushes off from the ball of the foot and then to some extent from the toes of the foot, the center of pressure moves to the location at
58
.
c) Abnormal Gait Cycle of the Foot of a Person Suffering From Diabetes or Rheumatoid Arthritis
FIG. 6
shows a side view of the foot
60
of a person suffering from diabetes or rheumatoid arthritis, this view being essentially identical to the corresponding view of the normal foot that is shown in FIG.
2
.
A common problem is that people suffering from these conditions tend to avoid using their toes when they walk. Typically, this is because of the pain that exists in the areas of the ball of the foot
62
(under the metatarsal heads) and the toes
64
. Furthermore, in the case of a diabetic condition, the poor circulation caused by this disease frequently leads to the development of painful sores in those areas which are subjected to repeated pressure or friction, again especially under the ball of the foot and toes.
Because of the discomfort, a person suffering from rheumatoid arthritis or diabetes learns more or less unconsciously to minimize the pressure on the forward portion of the foot when walking, resulting in the abnormal gait cycle that is illustrated in FIG.
7
. These views show the person's right foot and lower leg, and correspond to the views shown in FIG.
4
. As can be seen, during the initial phases the action of the person's foot is essentially the same as in a normal gait cycle. However, when the person's foot moves from the 50% point towards the 75% point in the cycle, as is shown in the fourth view, the weight begins to be transferred forwardly and generally towards the area of the first metatarsal head, as indicated above with reference to FIG.
5
. If rheumatoid arthritis is present in the forefoot area, this causes the person significant pain or discomfort, which tends to increase in intensity as the weight moves forwardly towards the toes. Consequently, the person seeks to reduce the pain by avoiding transfer of weight forwardly beyond the ball of the foot, with the result that the normal “toe-off” action does not occur; instead, the foot is lifted away from the ground more or less horizontally at the end of the gait cycle, as is shown in the right-hand view of FIG.
7
.
Over time, this action becomes automatic, so that the person develops a shuffling gait in which the feet simply flatten out after heel strike and then lift off again in a horizontal orientation. This abnormal gait cycle is extremely inefficient, and frequently leads to development of other problems in the person's feet and legs. Moreover, the constant pressure on the ball of the foot at the end of the abor
DeMille Danton D.
Hathaway Todd N.
Northwest Podiatric Laboratory, Inc.
Thanh Quang D
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