RU2732960C1 - Method for augmentation of unbounded bone defect of hip bone in cotyloid cavity area - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to traumatology and orthopaedics, and can be used in revision hip replacement in the presence of massive unlimited bone defects in the cotyloid cavity as a result of osteolytic process or mechanical bone wear during loosening of the acetabular or infectious endoprosthesis cotyloid component. Method involves computer tomography, determining the shape and size of a bone defect of the cotyloid cavity, designing and manufacturing of titanium powder by 3D printing of an individual design in the form of a mesh anatomical pre-bent plate for bone defect augmentation, as well as a plastic fitting pattern. Surgical approach to the endoprosthesis is performed, a bone defect of the hip bone is isolated in the cotyloid cavity. Cotyloid cavity is de-folded with fibrous membrane removed to bleeding bone, bone surface is prepared for individual mesh by fitting the plastic template, implantation of the manufactured individual net with fixation by screws along the edge of the structure adjacent to the bone at distance of 1 cm, impaction of the crushed bone allograft and cement-based installation of the polyethylene cavity of the endoprosthesis. Design is designed individually for a specific defect. Screws are directed towards the most pronounced bone mass specified during design. First screw is drawn along the top of the defect, two further along the edges. Rest screws are made by means of guide sleeves on the plate surface around each hole along the edge adjoining the bone.

EFFECT: method provides optimization of operative intervention and reduction of total length of operation due to individual designing of the shape and planning of direction and size of fixing screws.

1 cl, 7 dwg

Description

The invention relates to medicine and can be used in traumatology and orthopedics in revision endoprosthetics of the hip joint in the presence of massive unlimited bone defects in the acetabulum region as a result of the osteolytic process or mechanical wear of the bone during loosening of the acetabular component of the endoprosthesis of aseptic or infectious origin.

The relevance of this issue is that without full replacement of the bone defect in the acetabulum during revision arthroplasty, the installation of a new pelvic component of the endoprosthesis in the correct position is practically impossible.

A known method (analogue) of augmentation of bone defects in the acetabulum region using metal semicircular implants made of porous tantalum, first described by W. Paprosky [https://www.zimmerbiomet.com/content/dam/zimmer-biomet/medical-professionals/hip/trabecular -metal-acetabular-revision-system / zimmer-trabecular-metal-acetabular-revision-system-tmars-brochure.pdf]. With the help of a spherical cutter, the defect zone is processed, a concave bone bed is formed, into which a congruent metal augment of the appropriate size is installed, which completely fills the bone defect, restores the sphericity of the acetabulum, creates support for the acetabular component of the endoprosthesis, and is fixed to the bone with screws. Next, the acetabulum is installed with a layer of bone cement between the augment and is also fixed to the bone with screws.

The disadvantages of this method are:

• The bone defect is replaced by a metal implant, which is unable to rebuild into bone in the future;

• Requires specialized tools to install this augment;

• When modeling the bone bed under the augment, a part of the bone tissue is lost, which in fact increases the bone defect;

• There is a risk of non-adhesion of the established augment to the bone in the area of the prepared bed.

A known method of augmentation of an unlimited bone defect in the acetabulum region using a Stryker reconstructive mesh [http://www.rpa.spot.pt/getdoc/a0f81753-772d-45e0-af99-887cc5b7841c/X-Change-Revision-Instruments-(Stryker) .aspx] [The Exeter Hip, Published by Exeter Hip Publishing, 2010 Copyright © Exeter Hip Unit ISBN: 978-0-9564521-0-8 The Exeter Hip Hardback, 978-0-9564521-1-5 The Exeter Hip Paperback] , which consists in limiting the bone defect by modeling a standard metal mesh in the wound along the outer surface of the pelvic bone with the overlap of the bone defect approximately 1 cm from the edge and fixing the mesh along the perimeter to the bone using screws at a distance of 1 cm from each other. Further, the limited defect is filled with an impactional bone allograft using the X-Change method using specialized instrumentation. After tight filling of the cement-based bone defect, a standard polyethylene pelvic component is implanted.

The disadvantages of this method are:

• It is necessary to measure the size of the defect in the wound and select a mesh of a suitable size;

• The size of the standard serial mesh does not always absolutely coincide with the size of the defect; therefore, it is necessary to adjust the mesh to size using scissors;

• The shape of a standard serial mesh does not correspond absolutely to the surface, but is only a blank and further modeling of the mesh is required along the bone relief along the periphery of the bone defect;

• The mesh is fixed to the bone along the perimeter of the defect, while the direction of the screws is determined visually, based on visible bony landmarks, and the length of the screws is determined using a canal gauge.

• Taken together, the above manipulations require significant additional time, which increases the overall duration of the surgical intervention.

The technical result of the proposed invention is the optimization of surgical intervention due to individual design of the shape and planning of the direction and size of the fixing screws, as well as reducing the total duration of the operation.

The term "optimization" means improving a process to increase efficiency, achieve better results.

A method for augmentation of an unlimited bone defect of the pelvic bone in the acetabulum region, including computed tomography and determination of the shape and size of the bone defect in the acetabulum, design and manufacture of an individual design from titanium powder by 3D printing in the form of a mesh anatomical pre-curved plate for augmentation of the bone defect, and also a plastic trial template, surgical access to the hip joint, removal of the unstable pelvic component of the endoprosthesis, isolation of the defect and debridement of the acetabulum with removal of the fibrous membrane to the bleeding bone, preparation of the bone surface for an individual mesh using a plastic template, implantation of a custom mesh with fixation screws along the edge of the structure adjacent to the bone at a distance of 1 cm, impaction of the crushed bone allograft using a specialized profiling instrument aria and the installation of a cement-based polyethylene cavity of the endoprosthesis.

The difference is that the structure is designed individually for a specific defect of the patient, the screws are guided in the direction of the most pronounced bone mass specified during the design, using guide sleeves on the plate surface around each hole along the edge adjacent to the bone, the length of the screws is planned from the thickness of the bone mass in the direction of the screw.

The technical result is achieved due to the fact that in the preoperative period the patient undergoes computed tomography of the hip joint, additional software processing of the obtained scans is performed, the shape and size of the bone defect of the acetabulum is determined. Along the edge of the bone defect, an individual design is designed, overlapping the defect and absolutely repeating the anatomy along the edge of the defect, as well as the direction and length of the screws in the direction of the maximally preserved bone mass with planning of guide sleeves along the edge of the individual design adjacent to the bone. The directions of installation of the screws and their proposed size depending on their location are shown in Fig. 1.

After planning, an individual construction for augmentation of a bone defect is made of titanium powder by 3D printing and is a pre-curved mesh plate that repeats the surface of the defect and has an edge directly adjacent to the surface of the hole with guide sleeves for screws. The edge of the structure, which forms the contour of the cavity, is bent towards the cavity of the acetabulum to further restrict the bone graft. Shown in Fig. 2.

During revision arthroplasty surgery, surgical access to the hip joint is performed. The endoprosthesis bed is separated and unstable components of the endoprosthesis are removed. Debridement of the acetabulum is performed with the removal of the fibrous membrane to the bleeding surface of the bone and the isolation of the defect from the scar tissue and muscle mass, skeletonizing the outer surface at a distance of at least 1 cm from the edge. Then, using a plastic template that completely repeats the true design, fitting is performed and, if necessary, the surface is additionally processed. Shown in Fig. 3

Due to its individuality, the template fits completely congruently to the surface of the pelvic bone, ensuring full contact. After reaching the planned position, the true structure is installed on the prepared bed. Through the holes of the guide bushings, using a drill, holes for screws are formed in the bone and the structure is fixed with screws of a predetermined length during design. The first screw is carried out at the apex of the defect, the next two along the edges, the rest in an arbitrary sequence. Shown in Fig. 4. After completion of the fixation with the help of a clinical trial by traction on the structure, we are convinced of an absolutely stable fixation.

Impact bone grafting is performed using the standard technique using the X-Change instrumentation. After tight filling of the defect and profiling of the bed under the cup in a cement-based bone graft, a standard polyethylene pelvic endorothesis component is implanted. Shown in Fig. 5.

The claimed technical result, expressed in the optimization and reduction of the duration of surgery due to the design of an individual form of the structure in the form of an anatomical mesh pre-curved plate and planning the direction and size of fixing screws in the preoperative period.

The production of a plastic template and its use in the preparation of the bone surface for the implantation of an individual mesh can reduce infectious risks by reducing manipulations with the true structure, which increases the efficiency of the surgical intervention and promotes the fastest recovery, which increases the efficiency.

An individual design limiting the bone defect before impacted bone grafting is made absolutely congruent in shape to the bone surface along the periphery of the defect, which ensures maximum adhesion of the design to the surface (and its stability). There is no need to model it and adjust it to the defect during surgery; it is enough to skeletonize the bone along the edge of the bone defect. Thus, the operation time is reduced.

Due to the absence of the need to form a bone bed for the implant, there is no additional bone loss in the defect area .

As a result of individual design, the screws are passed safely and as accurately as possible into the most pronounced bone mass when fixing the individual mesh. Also at the design stage, depending on the direction of the screws in the bone, their size is set.

In general, the installation time of the implant limiting the acetabular defect is reduced due to the transfer of the main stages of construction modeling to the preoperative period.

As an example, we present a clinical case of using an individual mesh for augmentation of an unrestricted acetabular defect. H Fig. 6 shows the right hip joint replaced with a temporary spacer for periprosthetic infection based on the components of the endoprosthesis, and Fig. 7 shows the result of using an individual mesh for augmentation of a bone defect with impacted bone grafting at the second stage of treatment of a periprosthetic infection with the installation of a final endoprosthesis.

The features of the claims are essential and are in causal relationship with the claimed technical result.

Claims (1)

A method of revision hip arthroplasty in the presence of massive unrestricted bone defects in the acetabulum region, including computed tomography and determination of the shape and size of the bone defect in the acetabulum, design and manufacture of an individual design from titanium powder by 3D printing in the form of a mesh anatomical pre-curved plate for bone augmentation defect, as well as a plastic trial template, including performing a surgical access to the endoprosthesis, isolating a bone defect of the pelvic bone in the acetabulum, debridement of the acetabulum with removal of the fibrous membrane to the bleeding bone, preparing the bone surface for an individual mesh using a plastic template, implantation made individual mesh with fixation with screws along the edge of the structure adjacent to the bone at a distance of 1 cm, impaction of crushed bone allot transplant and installation on a cement basis of a polyethylene cavity of the endoprosthesis, characterized in that the design is designed individually for a specific defect of the patient, the screws are carried out in the direction of the most pronounced bone mass specified during the design, the first screw is carried out along the apex of the defect, two subsequent ones along the edges, the remaining screws are carried out by means of guide sleeves on the surface of the plate around each hole along the edge adjacent to the bone.

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