RU2730931C1 - Method of cement fixation of polyethylene insert during revision endoprosthesis replacement of hip joint and calibrating spacer for its implementation - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: group of inventions relates to medicine. Method for cement fixation of polyethylene insert during revision hip replacement involves preservation of metal acetabular component and fixation of new polyethylene insert by means of cement. In the layer of bone cement in the phase of application on the each apex of the conditional triangle one calibration spacer of the same diameter is laid so that they are located in the middle of the distance between the center and the edge of the cotyloid component, after which polyethylene insert is pressed into cement with reaching contact through spacers with cotyloid component and pressure is maintained until hardening of cement. Calibration spacer for implementation of the above method is made of solid implant material in form of a ball with diameter of 2.0 mm, 2.5 mm or 3.0 mm.

EFFECT: inventions provide uniform thickness of cement mantle and, accordingly, central position of new polyethylene insert in stable acetone component, which is the most important conditions of their reliable fixation.

2 cl, 5 dwg

Description

The invention relates to medicine, namely to traumatology and orthopedics, and can be used when performing revision arthroplasty of the hip joint while maintaining a well-fixed acetabular component.

There are known methods for installing a polyethylene liner with cement inside a well-fixed acetabular component, which is preserved during revision arthroplasty due to wear of a friction pair or recurrent dislocations, when it is necessary to change the orientation of the friction unit relative to the acetabular component, as well as in case of damage to the locking mechanism of the acetabular component and the absence of accessible polyethylene liners of the desired model of cross-linked polyethylene [Callaghan JJ, 2012, Tan TL, 2015].

However, when using such techniques, difficulties arise with ensuring the central position of the polyethylene liner relative to the acetabular component and the formation of a cement mantle of uniform thickness [Bargar W.L., 2015]. If it is necessary to change the orientation of the polyethylene liner relative to the acetabular component, even greater difficulties arise with the formation of a uniform cement mantle. This is due to the fact that with the asymmetric position of the polyethylene liner with the formation of an uneven cement mantle between the polyethylene contact zone and the surface of the preserved acetabular component, the mechanical strength of this system decreases [Meldrum R.D., 2001].

The technical result consists in ensuring a uniform thickness of the cement mantle and, accordingly, the central position of the new polyethylene liner in the stable acetabular component, which is the most important conditions for their reliable fixation.

The result of the invention is achieved due to the fact that calibration spacers in the form of balls with a diameter of 2.0 mm, 2.5 mm or 3.0 mm are used to ensure the central position and the formation of a uniform cement mantle that fixes the polyethylene liner during revision hip arthroplasty. made of solid implant material. Formation of a uniform cement mantle that anchors the polyethylene liner involves retaining the metallic acetabular component (cup) and cementing the new polyethylene liner. At the same time, one spacer of the same diameter is placed in the layer of bone cement in the phase of application, applied to the inner surface of the acetabular component, one spacer of the same diameter is placed on the vertices of the conditional triangle so that they are located in the middle of the distance between the center and the edge of the acetabular component, after which the polyethylene liner is pressed into the bone cement with the achievement of contact through the spacers with the acetabular component and hold the pressure until the cement hardens.

The illustrations show.

FIG. 1. View of a stable acetabular component after removing a worn-out polyethylene liner, where 1 is a stable acetabular component; 2 - pelvic bone; 3 - inner diameter of the acetabular component; 10 - hole for screws.

FIG. 2. View of a stable acetabular component after application of excess bone cement, where 1 is a stable acetabular component; 2 - pelvic bone; 6 - bone cement; 7 - calibration spacers; 8 - the center of the acetabular component; 9 - conditional triangle;

FIG. 3. Schematic representation of the method of cement fixation of a polyethylene liner into a stable acetabular component (in section), where 1 is a stable acetabular component; 2 - pelvic bone; 4 - polyethylene liner; 5 - outer diameter of the polyethylene liner; 6 - bone cement; 7 - calibration spacers; 11 - excess bone cement squeezed out from under the polyethylene liner; F is the vector of force application (direction) on the polyethylene liner to the acetabular component;

FIG. 4. The final view of the embedded polyethylene liner in the stable acetabular component after removal of excess bone cement (in section), where 1 is the stable acetabular component; 2 - pelvic bone; 4 - polyethylene liner; 7 - calibration spacers located in the middle of the distance between the center 8 and the edge of the acetabular component 1; 12 - uniform thickness of the cement mantle in different areas.

FIG. 5. An example of selection of a calibration spacer depending on the diameter of the polyethylene liner, where: a - the difference between the inner diameter of the acetabular component and the outer diameter of the polyethylene liner: 2.0 mm + 2.0 mm = 4.0 mm; b - the difference between the inner diameter of the acetabular component and the outer diameter of the polyethylene liner: 2.5 mm + 2.5 mm = 5.0 mm; c - the difference between the inner diameter of the acetabular component and the outer diameter of the polyethylene liner: 3.0 mm + 3.0 mm = 6.0 mm

The method is carried out as follows: during the operation of revision hip arthroplasty, after obtaining convincing data on the stability of fixation of the acetabular component 1 to the pelvic bone 2, the inner diameter 3 of the acetabular component 1 is determined (Figure 1). Based on the data obtained, a new polyethylene liner 4 is selected so that its outer diameter 5 is less than the inner diameter 3 of the retained acetabular component 1 by at least 4.0 mm. Next, the inner surface of the acetabular component 1 is thoroughly washed and the bone cement 6 of medium viscosity is kneaded. When the bone cement 6 reaches the optimal consistency, it is applied in excess to the inner surface of the acetabular component 1 and three calibration spacers 7 are introduced into the cement layer 6 so that they are located in the middle of the distance between the center 8 and the edge of the acetabular component 1 at the vertices of the conditional triangle 9 (Figure 2). Make sure that the calibration spacer 7 does not fall into the hole for the screws 10 if they are present at the acetabular component 1. After the introduction of the calibration spacers 7 into the layer of bone cement 6, the polyethylene liner 4 is inserted into the acetabular component 1 and pressed (F), noting squeezing out excess bone cement 11 along the edges of the acetabular component 1 (Figure 3). Then, the excess bone cement 11 is removed and the polyethylene liner 4 is held until the bone cement hardens 6. In this case, the calibration spacers 7 act as restraints and ensure the formation of a uniform thickness of the cement mantle 12, equal to one of the options for the size of the spacer 7, which excludes the formation of fragile thinned sections (Figure 4).

The size of the calibration spacer 7 is selected based on the fact that the optimal thickness of the cement mantle 12 should be 2.0-3.0 mm [Tikhilov RM, 2014]. To do this, first determine the inner diameter 3 of the acetabular component 1. Based on the data obtained, select the polyethylene liner 4 so that its outer diameter 5 is less than the inner diameter 3 of the preserved acetabular component 1 by 4.0 mm, 5.0 mm or 6.0 mm. To improve the accuracy of hitting a given interval, the calibration spacers 7 of the appropriate size are selected from the available polyethylene liners 4 (Figure 5).

The method and device allow: - to create a cement mantle of uniform thickness, ensuring the reliability of fixation of the polyethylene liner in the acetabular component preserved during revision hip arthroplasty;

- to ensure the central position of the new polyethylene liner in the stable acetabular component;

- to do without special devices and to exclude an electrochemical conflict of alloys, since the calibration spacers are made of solid implant material.

List of references

1. Tan T.L., Le Duff M.J., Ebramzadeh E., Bhaurla S.K., Amstutz H.C. Long-Term Outcomes of Liner Cementation into a Stable Retained Shell: A Concise Follow-up of a Previous Report // J. Bone Joint Surg. Am. 2015; 97 (11): 920-924.

2. Callaghan J.J., Hennessy D.W., Liu S.S., Goetz K.E., Heiner A.D. Cementing acetabular liners into secure cementless shells for polyethylene wear provides durable mid-term fixation // Clin. Orthop. Relat. Res. 2012; 470 (11): 3142-3147.

3. Bargar W.L. The Surgeon's Dilemma: Cement or Revise? Commentary on an article by Timothy L. Tan, MD, et al .: "Long-Term Outcomes of Liner Cementation into a Stable Retained Shell. A Concise Follow-up of a Previous Report" // J. Bone Joint Surg. Am. 2015; 97 (11): e49.

4. Meldrum R.D., Hollis J.M. The strength of a cement acetabular locking mechanism // J. Arthropasty. 2001; 16 (6): 748-752.

5. Guide to surgery of the hip joint / ed. R.M. Tikhilova, I.I. Shubnyakov. - SPb: RNIITO im. R.R. Vredena, 2014 - T. I. - 257-261 p.

Claims (2)

1. A method of cement fixation of a polyethylene liner during revision hip arthroplasty, including preserving the metal acetabular component and fixing a new polyethylene liner with cement, characterized in that one calibration spacer of the same diameter is placed in the bone cement layer in the application phase at the vertices of the conditional triangle so that they are located in the middle of the distance between the center and the edge of the acetabular component, after which the polyethylene liner is pressed into the cement with reaching contact through the spacers with the acetabular component and holding the pressure until the cement hardens. 2. A calibration spacer for performing the method according to claim 1, characterized in that it is made of solid implant material in the form of a ball with a diameter of 2.0 mm, 2.5 mm, or 3.0 mm.

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