Invention (Patent Application Publication): Mor A.
Replacement ligamentum teres femoris. US20050131546A1 (2005).
US20050131546A1 Israel
Inventor: Amit Mor
Current Assignee: Individual
Worldwide applications 2003 US
Application US10/734,123 events:
2003-12-15 Application filed by Individual
2003-12-15 Priority to US10/734,123
2005-06-16 Publication of US20050131546A1
2024-08-07 Assigned to NEWCLEO SA
Status: Abandoned
Replacement ligamentum teres
femoris
Amit Mor
Abstract
A hip joint prosthesis including a replacement ligamentum
teres femoris. The replacement ligamentum teres femoris may be attached to a
replacement (or natural) femoral head and/or to a replacement (or natural)
acetabular structure.
Description
FIELD OF THE INVENTION
[0001]
The present invention relates generally to an enarthrodial
prosthesis, and particularly to a replacement ligamentum teres femoris for a
hip joint prosthesis.
BACKGROUND OF THE INVENTION
[0002]
The hip joint (whose scientific name is the coxal
articulation) is an enarthrosis (ball-and-socket joint). Many kinds of hip
joint prostheses are known. For a better understanding of a hip joint
prosthesis, a basic description of the human hip joint is presented here with
reference to FIGS. 1-3.
[0003]
The femoral head (head of the thigh bone) articulates with
the acetabulum of the innominate bone, known in non-technical terms as the
socket of the hipbone. The innominate bone in the area of the hip joint is made
of three portions: the upper portion is called the ilium, the middle portion is
called the pubis and the lower portion is called the ischium. The femoral head
is connected to the innominate bone by a plurality of ligaments. The ligaments
shown in FIG. 1 are the ilio-femoral ligaments and the pubo-femoral
ligament. There is also an ischio-femoral ligament on the posterior part of the
joint, not seen in the figures. The femoral head articulates with a fibrous rim
of the acetabulum called the cotyloid ligament or glenoidal labrum. A capsular
ligament (seen dissected in FIG. 2) surrounds the neck of the femur and is
attached to the margin of the acetabulum posteriorly beyond the cotyloid
ligament and anteriorly to the outer margin of the cotyloid ligament.
[0004]
The femoral head is connected to the acetabular notch by a
ligament called the ligamentum teres femoris or ligamentum teres for short.
Quoting from Gray's Anatomy: “The ligamentum teres femoris is a triangular,
somewhat flattened band implanted by its apex into the antero-superior part of
the fovea capitis femoris; its base is attached by two bands, one into either
side of the acetabular notch, and between these bony attachments it blends with
the transverse ligament. It is ensheathed by the synovial membrane, and varies
greatly in strength in different subjects; occasionally only the synovial fold
exists, and in rare cases even this is absent. The ligament is made tense when
the thigh is semiflexed and the limb then adducted or rotated outward; it is,
on the other hand, relaxed when the limb is abducted. It has, however, but
little influence as a ligament.”
[0005]
The statement that the ligamentum teres has “little
influence as a ligament” is accepted in the medical literature to the present.
Quoting from a medical dictionary website
(www.books.md/L/dic/ligamentumteresfemoris. php) that defines ligamentum teres
as follows: “A flattened ligament that passes from the fovea in the head of the
femur to the borders of the acetabular notch (transverse acetabular ligament);
developmentally, an artery passes to the head of the femur with the ligament
which may or may not persist into adulthood; the ligament does not contribute
to the integrity of the joint or control movements there.”
[0006]
Generally a hip joint replacement of the prior art involves
replacing the natural femoral head with a metallic or plastic artificial
femoral head, which is fixedly attached to a stem. The stem is generally
inserted in the femur and the femoral head articulates with the acetabulum, if
still intact, or some other depression, artificial or natural, in the
innominate bone. Some or all of the ilio-femoral, pubo-femoral and
ischio-femoral ligaments may be removed to provide access to the femoral head
and acetabulum. The ligamentum teres is generally severed and removed. No known
hip joint prostheses have or are connected to a ligamentum teres, perhaps
because of the prevalent belief that “the ligament does not contribute to the
integrity of the joint or control movements there”.
SUMMARY OF THE INVENTION
[0007]
The present invention seeks to provide a novel hip joint
prosthesis, which includes a replacement ligamentum teres femoris, as is
described more in detail hereinbelow.
[0008]
The following is provided as background information for
better appreciation of the present invention, but the invention is not limited
to the validity of this information.
[0009]
Proprioception refers to the ability to know where a body
part is located in space and to recognize movements of body parts (such as
fingers and toes, feet and hands, legs and arms). Kinesthesia is a related
term, and refers to the sensation by which position, weight, muscle tension and
movement are perceived. In some of the medical literature, proprioception
refers to the conscious and unconscious appreciation of joint position, while
kinesthesia refers to the sensation of joint velocity and acceleration.
Proprioception is often used interchangeably with kinesthesia, and herein as
well, the terms will be used interchangeably.
[0010]
The neuromuscular control system of the body integrates
peripheral sensations relative to joint loads and processes these signals into
coordinated motor responses. This muscle activity serves to protect joint
structures from excessive strain.
[0011]
Certain mechanoreceptors are present throughout the soft
tissues of the musculoskeletal system, which interact with the central nervous
system and coordinate body movements, postural alignment, and balance.
Mechanoreceptors are located in the muscles, tendons, ligaments, joint capsules
and the skin. These nerve fibers provide information to the brain regarding the
status and function of the musculoskeletal system. The mechanoreceptors send
electrical signals along peripheral nerves to the spinal cord. The electrical
signals travel via the spinal cord to the brain where the signals are
interpreted to recognize movements of body parts, muscle tension, movement and
the like.
[0012]
Some examples of mechanoreceptors for controlling the
muscular system include muscle spindles. Muscle spindles are found interspersed
within the contractile fibers of skeletal muscles, with the highest
concentration in the central portion of each muscle. Muscle spindle fibers
respond to changes in the length of muscles. These nerve endings provide the
central nervous system information used to maintain muscle tone and the correct
muscle tension on opposite sides of each joint.
[0013]
Fibrous tissues that surround and protect most joints
generally contain a variety of sensory nerve endings for proprioception and
kinesthesia. The input from these sensory nerve endings provides the central
nervous system information regarding the location, stretch, compression,
tension, acceleration, and rotation of the joint.
[0014]
The present inventors postulate that contrary to the
abovementioned statements of the medical literature, the ligamentum teres does
indeed play a role, perhaps an important role, in the function of the hip
joint, particularly biomechanical and in proprioception and/or kinesthesia.
However, it is emphasized that the invention is not limited in any way to the
correctness or incorrectness of this postulation.
[0015]
There is thus provided in accordance with an embodiment of
the present invention a hip joint prosthesis including a replacement ligamentum
teres femoris. The replacement ligamentum teres femoris may be attached to a
replacement (or natural) femoral head and/or to a replacement (or natural)
acetabular notch. The replacement ligamentum teres femoris may be attached to
any part of the femur (e.g., head, neck, stem, body) and to any part of the
acetabulum (not just the notch) and/or pelvis, including natural and artificial
femurs, acetabula and pelvises.
[0016]
In accordance with an embodiment of the present invention
the replacement ligamentum teres femoris may include one attachment zone for
attachment to a femoral head and at least one attachment zone to acetabular
structure.
[0017]
Further in accordance with an embodiment of the present
invention the replacement ligamentum teres femoris may extend outwards from a
portion of the replacement femoral head corresponding to a fovea (or other
portion) of a natural femoral head.
[0018]
Still further in accordance with an embodiment of the
present invention the replacement femoral head extends from a stem insertable
into a femur. The stem may include an alignment device adapted to orient the
replacement femoral head in a predefined orientation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
The present invention will be understood and appreciated
more fully from the following detailed description taken in conjunction with
the drawing in which:
[0020]
FIG. 1 is a simplified illustration of a right-side hip
joint, showing the outer ligaments;
[0021]
FIG. 2 is a simplified illustration of the right-side
hip joint, showing the ligamentum teres and the acetabulum;
[0022]
FIG. 3 is a simplified illustration of the left-side
hip joint, showing the ligamentum teres by cutting away from the floor of the
acetabulum;
[0023]
FIG. 4 is a simplified illustration of a hip joint
prosthesis, constructed and operative in accordance with an embodiment of the
present invention; and
[0024]
FIG. 5 is a simplified illustration of a hip joint
prosthesis, constructed and operative in accordance with another embodiment of
the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0025]
Reference is now made to FIG. 4, which illustrates a
hip joint prosthesis 10, constructed and operative in accordance with
an embodiment of the present invention.
[0026]
The prosthesis 10 may comprise a
replacement ligamentum teres femoris 12, which may be attached to a
replacement femoral head 14. Alternatively, replacement ligamentum
teres femoris 12 may be attached to a natural femoral head. The
replacement ligamentum teres femoris 12 may be stretchable and
may be constructed of any suitable medically-safe elastomer, such as but not
limited to, polyurethane, polyurethane bionate, silicone and the like, or may
be obtained or made from a natural ligament or other natural tissue or
substance (e.g., some other ligamentum teres femoris and the like). The
properties of the elastomer may be selected or engineered to mimic the properties
of a natural ligamentum teres femoris.
[0027]
The replacement ligamentum teres femoris 12 may
be of any shape or size, such as but not limited to, a wire, cord, string,
ligament, band, ribbon, and the like.
[0028]
The replacement ligamentum teres femoris 12 may
be attached to acetabular structure, such as but not limited to,
a replacement acetabular notch 16. Notch 16 may be
associated with an artificial or replacement acetabulum 18.
Alternatively, the replacement ligamentum teres femoris 12 may be
attached to a natural acetabular notch. Alternatively, the
replacement ligamentum teres femoris 12 may be attached to
the replacement acetabulum 18 or some structure of the
innominate bone or neighboring tissue or bones (e.g., attached to any portion
of the pelvis, directly or through an orifice). It is noted that the
replacement ligamentum teres femoris 12 of the present invention does
not have to be attached to the same place on the femoral head and acetabular
structure as the natural ligamentum teres femoris. Any attachment zone is
within the scope of the invention.
[0029]
Attachment of the replacement ligamentum teres femoris 12 to
either or both of the femoral head 14 and the acetabular
structure may be effected by any convenient method, such as but not limited to,
mechanical fasteners, bonding with adhesive, or suturing with stitches, or an
EndoButton CL Fixation Device (commercially available from Smith & Nephew,
Inc. Andover, Mass.) for example.
[0030]
The replacement ligamentum teres femoris 12 may
comprise one attachment zone 20 for attachment to
the femoral head 14 and one or more attachment zones 22 (two such
attachments zones 22 are illustrated in FIG. 4; one is
illustrated in FIG. 5) to the acetabular structure. The
replacement ligamentum teres femoris 12 may extend outwards from
a portion 24 of the replacement femoral head 14 corresponding
to a fovea of a natural femoral head.
[0031]
It is noted that FIG. 4 illustrates a femoral head
prosthesis with the replacement ligamentum teres femoris 12 attached
to the femoral head 14 and ready for attachment to
the replacement acetabulum 18. In contrast, FIG.
5 illustrates an acetabular prosthesis with the replacement ligamentum
teres femoris 12 attached to the replacement acetabular
notch 16 and ready for attachment to the replacement femoral
head 14.
[0032]
The replacement femoral head 14 may extend
from a stem 26 insertable into a femur (not
shown). Stem 26 may include an alignment device 28 that
can orient the replacement femoral head 14 in a predefined
orientation. For example, alignment device 28 may comprise a key
or lug that protrudes outwards from stem 26 which may fit in a
corresponding notch formed in the femur (not shown). One purpose
of alignment device 28 would be to align the replacement
ligamentum teres femoris 12 jutting from the replacement femoral
head 14 to point in the correct direction of its attachment to
the acetabular notch 16.
[0033]
It will be appreciated by persons skilled in the art that
the present invention is not limited by what has been particularly shown and
described hereinabove. Rather the scope of the present invention includes both
combinations and subcombinations of the features described hereinabove as well as
modifications and variations thereof which would occur to a person of skill in
the art upon reading the foregoing description and which are not in the prior
art.
Claims:
1. A hip joint prosthesis comprising:
a replacement ligamentum teres femoris non-slidingly
attached to a replacement femoral head.
2. (canceled)
3. The prosthesis according to claim 1, further
comprising a replacement acetabular structure to which said replacement
ligamentum teres femoris is attached.
4. The prosthesis according to claim 1, wherein said
replacement ligamentum teres femoris comprises one attachment zone for
attachment to a femoral head and at least one attachment zone to acetabular
structure.
5. The prosthesis according to claim 1, wherein said
replacement ligamentum teres femoris extends outwards from a portion of said
replacement femoral head corresponding to a fovea of a natural femoral head.
6. The prosthesis according to claim 1, wherein said
replacement femoral head extends from a stem insertable into a femur.
7. The prosthesis according to claim 6, wherein said
stem comprises an alignment device adapted to orient said replacement femoral
head in a predefined orientation.
8. The prosthesis according to claim 1, wherein said replacement
ligamentum teres femoris is stretchable.
9. The prosthesis according to claim 1, wherein said
replacement ligamentum teres femoris does not pass through said replacement
femoral head.
External links
Authors & Affiliations
Amit Mor – Rehovot (IL)
Keywords:
ligamentum capitis femoris, ligamentum teres, ligament of head of femur, endoprosthesis, prosthesis, invention, unipolar, subtotal
NB! Fair practice / use: copied for the purposes of criticism, review, comment, research and private study in accordance with Copyright Laws of the US: 17 U.S.C. §107; Copyright Law of the EU: Dir. 2001/29/EC, art.5/3a,d; Copyright Law of the RU: ГК РФ ст.1274/1.1-2,7
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