RU2004217C1 - Femoral component of endoprosthesis of hip joint - Google Patents

Description

The invention relates to medicine, in particular to orthopedics and traumatology, and is intended for hip arthroplasty.

Walking is one of the most important biomechanical functions of a person, which requires a certain mobility in the hip joint in three mutually perpendicular planes - frontal, sagittal and horizontal.

Walking can conditionally be divided into several functionally different phases, which are characterized by different mutual positions of the pelvis (acetabulum) and the femoral head.

In the phase of the anterior push in the plane of the horizontal section of the joint, the rotation of the pelvis to the side of the forward leg is noted by about 15 ° relative to the frontal plane. The indicated rotations of the pelvis are equivalent to the external rotational movements of the femur and, therefore, are possible only under conditions of the preserved external rotational mobility of the femur in this walking phase.

In a prosthetic hip joint, mobility when walking is not always adequate. For example, the external rotational mobility in the phase of the anterior propulsion is insufficient.

One of the tasks in hip joint prosthetics is to increase the range of motion in the prosthetic joint. To do this, use the way to change the geometry of the articulation in the prosthesis.

A total hip arthroplasty is known, comprising endoprostheses of the proximal end of the femur and acetabulum. To increase the volume of certain movements, a notch has been made at the edge of the acetabular endoprosthesis.

The disadvantage of this design is the reduction in the area of mutual contact between the prosthesis and the bone bed, and the fact that the operations of the acetabular endoprosthesis must be specially oriented relative to the pelvic bone at the location of the notch. This complicates the operation, increases its trauma, in addition, a special measuring tool is required to control the position of the acetabular incision.

The femoral component of the hip joint endoprosthesis is known, including the head, neck and intraosseous shaft, the axis of the neck being bent in an arcuate manner as an antversion to the longitudinal plane of the shaft and forms

with it an angle of 5-15 °. Such a design makes it possible to develop external rotational mobility in the prosthetic joint.

A disadvantage of the known design

it is that the volume of external rotational movements in the prosthetic joint in the supporting phase of walking remains small. Anterversion cervical curvature reduces

bending volume, which in turn leads to collision of the neck against the edge of the acetabular endoprosthesis cup and, as a result, to loss of stability of the prosthesis and a decrease in its service life.

5 The reason for such events is

a significant discrepancy between the linear and angular parameters of the endoprosthesis to the anatomical parameters of the proximal end of the femur and acetabulum.

0 The femoral component of the hip joint prosthesis is also known, containing a head, a neck of non-circular section, displaced downward from the center of the head, and an intraosseous shaft.

5 The cross-sectional height of the neck exceeds its width. This design simulates the normally well-known non-circular section of the femoral neck and allows some

0 part of the necessary external rotational movements. Moving the neck downward relative to the center of the head allows you to increase the amount of necessary flexion-abduction movements in the joint.

5 Disadvantages of a known endoprosthesis

are:

insufficient volume of external rotational movements in the supporting phase of walking, which requires that external rotation

0 was at least 15 °;

instability of the joint during its operation is due to the fact that, with insufficient external rotational movements, the neck of the prosthetic joint hits the edge of the acetabular endoprosthesis and loosens it, which leads to a reduction in the endoprosthesis service and the need to replace it.

The aim of the invention is to increase the amplitude of the external rotational movements in the joint in the supporting phase of walking and to increase the stability of the endoprosthesis.

The specified goal is achieved by the fact that in

5, the femoral component of the hip joint prosthesis, comprising a head displaced from the center of the head down the neck with a non-circular cross section, the height of which exceeds the width, and an intraosseous shaft, the axis of the neck

additionally offset from the center of the head anteriorly.

An additional displacement of the neck relative to the center of the head anterior allows increasing the amplitude of external rotational movements in the prosthetic joint in the supporting phase of walking, eliminating collisions of the neck against the edge of the acetabular endoprosthesis, and creates conditions for increasing the stability and durability of the hip joint prosthesis.

Comparative analysis with the prototype shows that the claimed femoral component of the hip joint prosthesis is characterized in that the axis of the neck is further shifted anteriorly. Thus, the claimed femoral component of the hip joint meets the criteria of the invention of novelty.

Comparison of the claimed solution not only with the prototype, but also with other technical solutions in the art did not allow them to identify a feature that distinguishes the claimed solution from the prototype, which allows us to conclude that the criterion meets significant differences.

On Fig, 1 shows the femoral component of the hip joint endoprosthesis, General view; in FIG. 2 is a section along AA in FIG. 1; in FIG. 3 - in the horizontal plane, a schematic representation of the rotation of the pelvis relative to the frontal plane in the phase of the front push.

The femoral component of the hip joint implant contains a head 1 with a center Cm, a neck 2 and an intraosseous shaft 3. A neck 2 (see Fig. 2) has a non-circular cross-section with dimensions D and B, moreover. The axis of the neck 02-02 is shifted relative to the center Oi of the head 1 downward by an amount E and anteriorly by an amount C.

When walking (see Fig. 3), the pelvis is rotated by an angle a, which is formed between the bi-spinal line of the pelvis KK in the phase of the anterior push of the left lower limb and the frontal plane NN (in the phase of the bicompore symmetrical state, the frontal plane and the bispinal line match up).

In this way, the femoral component of the endoprosthetase hip femur becomes not universal, but left-sided and right-sided.

Studies conducted on macroscopic samples of the human femur revealed the following average ratios of the size of the femoral neck:

f-1.3.

In a specific embodiment of the femoral component of the endolrothesis with a head diameter of 33 mm; D - 16 mm; B - 12 mm, with a shift of the neck axis anteriorly equal to 2 mm and down-2 mm, the amplitude of the external rotation increases by 10 °, without prejudice to the required volume of flexion and deflection movements.

Normalization of the external rotational range of motion in the prosthetic hip joint eliminates compensatory overstresses and overloads in adjacent joints - the knee, ankle, and lumbosacral joints, to normalize the gait while maintaining important functionally necessary positions.

The medical and clinical efficacy of the invention consists in increasing the functional outcome of hip replacement surgery, in reducing pain during walking, in increasing working capacity, in reducing the number of complications associated with instability of the endoprosthesis, in prolonging the life of the endoprosthesis and delaying the duration of the reoperation.

(56) M, A. Metayer-Mesure ctlnlqne de la mobillte de la hanche Introduction du Systeme a coordonnees spheriques // Ann Kinesither, 1978.5, 199-208 //.

Swiss Patent 555672, CL A 61 F 1/04, 1972.

EPO application No. 0222236. cl. A 61 F 2/36, 1987.

UK patent N 1409054, CL A 61 F 1/00, 1972.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A FEMORAL HIP Joint Endoprosthesis Component, comprising a head displaced from the center of the head down a neck with a cross section whose height is greater than the width, and a snyipiu-wall rod, wherein the neck axis is further biased, relates “only about the center of the head to the front Fig 2 Fig.Z