RU174697U1 - HIP JOINT SPACER - Google Patents

Abstract

The utility model relates to medical equipment and is intended to perform surgical interventions during the treatment of patients with infectious complications after hip replacement, including the installation of a spacer. The technical result is to reduce the risk of postoperative dislocation of the spacer, increase the accuracy of the selection of the required size of the neck length of the metal head, reduce the risk of cartilage abrasion, and thus reduce pain in the early stages after the installation of the spacer. This is achieved by the fact that the total spacer of the hip joint includes a femoral component, a metal head and a pelvic component made of bone cement with an antibiotic. A metal head is installed in the pelvic component with the possibility of its rotation, the metal head is removable, and the pelvic component is in the form of a hemisphere. The upper back part of the pelvic component extends beyond its limits by 0.4 cm, forming the so-called "visor".

Description

The utility model relates to the field of medicine, in particular to the medical equipment used in traumatology and orthopedics, and is intended to perform surgical interventions during the treatment of patients with infectious complications after hip replacement, including the installation of a “temporary” implant.

In severe forms of the pathology of the hip joint, endoprosthetics can restore movement in the joint, significantly reduce pain, which significantly improves the quality of life of the patient, but after this complex surgical operation, complications are possible. One of them - purulent lesions in the hip joint - requires removal of the components of the endoprosthesis. One of the treatment options for purulent complications of arthroplasty is a two-stage method of revision arthroplasty. At the first stage, the infected endoprosthesis is removed and temporarily replaced with a spacer made of bone cement with the addition of an antibiotic. At the second stage, after stopping the purulent process, an revision prosthesis is installed.

The bone cement spacer has a dual function: firstly, it fills the voids between the bone elements of the joint, preserving their anatomical relationship, and secondly, it is an antibiotic depot, which allows for a long time to act on the pathogenic microflora in the joint area.

There are various types of spacers: made in advance, or preformed [patent RU 110262, 2011; Patent RU 115652, 2011].

The disadvantages of preformed spacers are the limited antibacterial effect due to the use by manufacturers of a narrow circle of antibacterial substances (gentamicin, tobramycin).

Known for the use of spacers made intraoperatively:

In case of resistance of the causative agent of para-prosthetic infection with a lack of sensitivity to antibiotics, in order to enhance the antibacterial effect, bone cement containing antibiotics is introduced mechanically into the spacers with antibiotics taking into account the sensitivity of microflora (II-III generation cephalosporins, rifampicin). The manufacture and use during operation of a cast in-mold cement spacer [patent RU 110263, 2011] allows to achieve the necessary antibacterial effect, however, such spacers have lower strength and articulating characteristics.

Known spacers of the hip joint, made intraoperatively by hand by sculpting.

In order to increase the surface area of the spacer of the hip joint, without changing its volume in the spacer body, along the axis of the leg and neck, multiple longitudinal channels are formed, the channels along the axis of the leg and through, along the axis of the neck, recessed into the body of the head and limited from its side articular surface. The design of the channels in the body of the spacer made of bone cement is performed during its solidification [patent RU 135905, 2013]. The disadvantage of this spacer is a fixed head, which does not allow you to accurately select the required size of the length of the neck of the metal, which is a risk of asymmetry of the length of the limbs.

The disadvantages should also include the difficulty of installing the spacer, the high risk of its postoperative dislocation, as the spacer strength weakens when channels are formed.

Known spacers, the pelvic components of which are segments of a bone cement ball with antibiotics, for example, patent RU 138603, 2013. However, when using this design, pain may occur when the spacer is rubbed against the acetabulum while moving in the joint.

As a prototype for the closest technical essence, we have chosen a bipolar spacer of the hip joint, consisting of a metal leg fixed in the femur of the endoprosthesis. The pelvic component is made in the form of a segment of a bone cement ball with an antibiotic, in which the metal head of the endoprosthesis is blocked with rotation. A notch is made on the surface of the pelvic component.

In the wound, a sterilized metal head is put on the neck of the endoprosthesis, around which the sphere of the acetabular component of the spacer is formed from bone cement with an antibiotic, maximally adjusting its external size to the size of the acetabulum of the patient. During the hardening of bone cement by rotation of the legs relative to the head, a residual segment of the sphere of the pelvic component is formed with the possibility of rotation of the endoprosthesis head in its internal cavity [patent RU 135904, 2013].

The disadvantages of the prototype are:

- instability of the spacer during initial dysplasia or destruction of the acetabulum due to the lack of design features necessary for the formation of elements for additional fastening of the spacer inside the acetabulum. In these cases, the absence of a significant fragment of the roof area can lead to postoperative dislocation of the spacer from the acetabulum;

- blocking the head, that is, the impossibility of removing it, which does not allow you to accurately select the required size of the neck length of the metal head, which is a risk of asymmetry of the length of the limbs;

- maintaining mobility between the pelvic component and the pelvic bones leads to erasure of the cartilage of the EP and the appearance of pain in the early stages after installing the spacer.

The technical result achieved using the claimed utility model:

- reducing the risk of postoperative dislocation of the spacer from the acetabulum;

- improving the accuracy of the selection of the required size of the neck length of the metal head, which will reduce the risk of asymmetry of the length of the limbs;

reducing the risk of cartilage abrasion and, thus, reducing pain in the early stages after installing the spacer.

The technical result is achieved by the fact that the total spacer of the hip joint includes a femoral component, a metal head and a pelvic component made of bone cement with an antibiotic. A metal head is installed in the pelvic component with the possibility of its rotation, the metal head is removable, and the pelvic component is in the form of a hemisphere. The upper back part of the pelvic component extends beyond its limits by 0.4 cm, forming the so-called "visor".

Distinctive essential features and a causal relationship between them and the achieved result:

- The metal head is installed removable, that is, with the possibility of its extraction, which increases the accuracy of selecting the size of the length of the neck of the head to maintain the same limb lengths.

- The upper-rear part of the hemisphere extends beyond its limits by 0.4 cm, forming the so-called “visor”, thereby increasing the area of the upper-posterior part of the acetabulum, which prevents the spacer from dislocating from the acetabulum.

- The implementation of the spacer is not bipolar, but total, in contrast to the prototype, provides a lack of mobility between the pelvic component and the bones of the pelvis, which prevents the erasure of the cartilage of the EP and the appearance of pain in the early stages after the installation of the spacer.

The essence of the utility model is illustrated in FIG. 1, which shows a General view of the claimed utility model, where:

1 - pelvic component in the form of a hemisphere;

2 - femoral component;

3 - metal head;

4 - upper back part of the pelvic component.

The proposed utility model can be used as follows:

The posterior-external access exposes the trochanteric region of the femur and the posterior wall of the capsule of the hip joint. Secondary surgical treatment of the purulent focus is carried out. Hip joint prosthesis is removed. Produce mechanical and drug treatment of the cavity of the hip joint. Remove non-viable tissue and purulent discharge. The cavity of the acetabulum is densely filled with bone cement with antibiotics and the pelvic component is formed in the form of a hemisphere (1). At the time of cement hardening (when it ceases to adhere to the gloves), a sterile femoral component (2) is taken with a metal head (3) worn on its neck (3) with a diameter of 26 or 28 mm, it is inserted into the cement until it covers half of the metal head and slowly rotate it around its own axis until the bone cement has completely hardened (polymerized). At the same time, the so-called “visor” is formed from the non-hardened bone cement by displacing the upper back part (4) of the pelvic component (1) by 0.4 cm beyond its limits.

After the cement has solidified and is firmly bonded to the acetabulum, the metal head (3) is removed.

Then a second portion of bone cement with an antibiotic is stirred, when it ceases to adhere to the gloves, it is introduced into the bone marrow of the femur. In the functionally advantageous position of the lower extremity (15 ° abduction, 170 ° flexion in the hip joint), the femoral component (2) of the endoprosthesis selected in size is inserted into the marrow space and held until it solidifies completely. Pick up the head with the neck length necessary to align the length of the legs. A metal head (3) is put on the neck of the femoral component of the endoprosthesis with a diameter equal to the diameter of the cavity previously formed in the bone cement. Drive the head into the formed cavity in the cement of the pelvic component. Check the range of motion in the hip joint. A postoperative wound is drained and sutured.

We give a clinical example:

Patient K., 56 years old, was undergoing treatment at the clinic of SZMU named after II Mechnikov with a diagnosis of Left-sided coxarthrosis 3-4 tbsp. In January 2006, an operation was performed - total endoprosthetics of the left hip joint. The long-term result after three years is rated as good. In December 2011, after an acute respiratory illness and an injury to the left thigh (fell), there was hyperemia of the skin and a fistula appeared in the area of the left hip joint, the fistulous course communicates with the joint cavity. On March 18, 2012, a radical treatment of the purulent focus was performed, removal of both components of the endoprosthesis and a spacer was installed according to the method described above. In the postoperative period, she received antibiotic therapy taking into account the antibioticogram. The surgical wound healed by first intention. The patient began to walk with a metered load on the operated leg. Five months later, revision arthroplasty of the left hip joint was performed. After 4 years, the long-term result was rated as good.

The inventive utility model, in contrast to the prototype:

- reduces the risk of postoperative dislocation of the spacer from the acetabulum;

- improves the accuracy of the selection of the required size of the neck length of the metal head, which allows to maintain the same limb length;

- reduces the risk of cartilage abrasion and, thus, reduces pain in the early stages after installing the spacer.

Claims (1)

The spacer of the hip joint, including the femoral component, the metal head and the pelvic component made of bone cement with an antibiotic, while the metal head is rotatable in the pelvic component, characterized in that the spacer is total, the metal head is removable, and the pelvic component - in the form of a hemisphere, the upper back part of which is shifted beyond its limits by 0.4 cm, forming the so-called "peak".

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