Static spacer for treating infection around knee joint prosthesis

Abstract

The invention relates to the technical field of medical equipment, and discloses a static position occupying device for knee joint periprosthetic infection treatment, which comprises a thighbone position occupying component, a tibia position occupying component and a connecting component, a first articular surface is arranged on one side of the femur occupying component away from the femur; a second articular surface is arranged on the side, close to the proximal tibia end, of the tibia occupying assembly, and the second articular surface is movably connected with the first articular surface through a clamping part; the connecting assembly is arranged between the thighbone occupying assembly and the tibia occupying assembly, and the two ends of the connecting assembly are detachably connected with the thighbone occupying assembly and the tibia occupying assembly correspondingly, so that relative fixation and position adjustment between the thighbone occupying assembly and the tibia occupying assembly are achieved; medicine storage cavities are formed in the femur occupying assembly and the tibia occupying assembly. The spacer can be accurately matched with individual anatomy, and joint stability and tissue safety are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and more specifically to a static spacer for the treatment of periprosthetic knee infection. Background Technology

[0002] Knee replacement surgery, as an effective treatment for end-stage knee joint diseases (such as severe osteoarthritis, rheumatoid arthritis, and traumatic arthritis), has been widely used in clinical practice and can significantly improve patients' joint function and quality of life. However, periprosthetic infection of the knee joint, as one of the serious postoperative complications, although its incidence is low, once it occurs, it can not only lead to surgical failure, but also cause severe pain, joint deformity, limb dysfunction, and even induce systemic infection (such as sepsis), bringing heavy physical suffering and economic burden to patients, while significantly increasing the difficulty of clinical treatment.

[0003] Currently, the mainstream clinical treatment for periprosthetic knee infections is "two-stage revision surgery." A core step in this approach is the removal of the infected prosthesis and bone cement during the initial surgery, followed by the implantation of a "space-occupying device" to maintain the knee joint space, restore limb alignment, temporarily replace joint function, and create favorable local tissue conditions for subsequent two-stage revision surgery. Based on functional differences, space-occupying devices are mainly divided into dynamic and static types. While dynamic space-occupying devices can simulate knee joint movement and reduce the risk of postoperative joint stiffness, they are structurally complex, surgically difficult, and the gaps in the moving parts can easily lead to local bacterial colonization, increasing the probability of infection recurrence. Static space-occupying devices are more widely used clinically due to their simple structure, strong stability, and more definitive infection control. Dynamic space-occupying devices are mainly needed for cases with recurrent infections that are difficult to control or severe bone defects.

[0004] Existing static spacers are insufficient to meet the dual needs of infection control and tissue protection in clinical applications. Significant individual differences exist in the knee joint anatomy of different patients (such as femoral condyle size, tibial plateau thickness, and joint space width), while existing static spacers are mostly designed with fixed specifications, making it difficult to accurately match individualized anatomical parameters. Post-implantation, problems such as excessively narrow or wide knee joint spaces and limb misalignment are common. This not only fails to effectively maintain joint stability but may also compress surrounding soft tissues (such as ligaments, tendons, and nerves), leading to increased postoperative pain, limited joint movement, and even secondary injuries such as bone loss and cartilage degeneration, affecting the outcome of revision surgery.

[0005] Existing static placebos are mostly solid structures or only have an antibacterial coating on the surface, which cannot achieve long-term storage and precise release of antibacterial drugs. As a result, it is difficult to maintain the local drug concentration at an effective therapeutic level, and systemic intravenous infusion of antibiotics is required as an adjunct therapy. However, systemic medication is not only prone to causing side effects such as liver and kidney damage and gastrointestinal reactions, but may also lead to bacterial resistance and reduce the therapeutic effect. Summary of the Invention

[0006] In view of the above-mentioned shortcomings in the prior art, the present invention provides a static spacer for the treatment of periprosthetic infection of the knee joint, which solves the problem of poor fit between the existing spacer and the force line.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows: a static spacer for the treatment of periprosthetic infection of the knee joint, comprising a femoral spacer component, a tibial spacer component, and a connecting component;

[0008] The femoral spacer component has a first articular surface on the side away from the femur; the tibial spacer component has a second articular surface on the side away from the tibia, and the second articular surface and the first articular surface are movably connected by a snap-fit ​​part; a connecting component is disposed between the femoral spacer component and the tibial spacer component, and the two ends of the connecting component are detachably connected to the femoral spacer component and the tibial spacer component respectively, so as to realize the relative fixation and position adjustment between the femoral spacer component and the tibial spacer component; both the femoral spacer component and the tibial spacer component have a drug storage cavity inside.

[0009] Furthermore, the aforementioned static spacer for treating periprosthetic knee infection includes a connecting component comprising a groove and a pin matching the groove, with bolt holes at both ends of the groove and the pin, and bolts movably disposed within the bolt holes.

[0010] Furthermore, the outer surfaces of the static spacer, femoral spacer component, and tibial spacer component used for the treatment of periprosthetic knee infections described above are all roughened.

[0011] Furthermore, the aforementioned static spacer for treating periprosthetic knee infection includes at least two specifications for the femoral spacer component and the tibial spacer component, with the length and diameter of the femoral spacer component and the tibial spacer component of different specifications gradually increasing by 1 mm.

[0012] Furthermore, in the aforementioned static spacer for treating periprosthetic infection of the knee joint, the first articular surface is an arc-shaped concave structure, and the second articular surface is an arc-shaped convex structure adapted to the first articular surface.

[0013] The beneficial effects of this invention are as follows: the femoral space-occupying component and the tibial space-occupying component are provided with at least two specifications, and the length and diameter of different specifications gradually increase in a 1mm gradient. The matching component can be accurately selected according to the actual anatomical parameters of the patient's knee joint (such as the size of the femoral condyle and the thickness of the tibial plateau), avoiding the size deviation problem caused by fixed specifications.

[0014] The connecting component enables a detachable connection between the femoral and tibial spacer components. Surgeons can precisely control the knee joint space width by adjusting their relative positions, avoiding excessive narrowing that compresses soft tissues or excessive width that affects stability, while also correcting limb alignment deviations. This effectively reduces postoperative joint stiffness, soft tissue compression (such as ligament and nerve damage), and bone loss, laying a good local tissue foundation for secondary prosthesis revision.

[0015] The femoral and tibial spacer components have internal drug storage cavities, which are wrapped with antibiotic bone cement. The surface of the spacer components is roughened to increase the holding force between the spacer components and the bone cement. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the side structure of the placeholder;

[0017] Figure 2 This is a schematic diagram of the front structure of this placeholder;

[0018] Figure 3 This is a schematic diagram of the measuring instrument.

[0019] The components are: 1. Femoral occlusion component, 2. Tibial occlusion component, 3. Connecting component, 4. First articular surface, 5. Second articular surface, 6. Drug storage cavity, 7. Groove, 8. Pin, 9. Bolt hole, 10. Bolt. Detailed Implementation

[0020] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0021] like Figure 1 As shown, this embodiment provides a static spacer for the treatment of periprosthetic knee infection, including a femoral spacer component 1, a tibial spacer component 2, and a connecting component 3.

[0022] The femoral spacer assembly 1 is made of medical-grade polymethyl methacrylate (PMMA), and has a first articular surface 4 on the side away from the femur. This first articular surface 4 has an arc-shaped concave structure for mating with the articular surface of the tibial spacer assembly 2. The femoral spacer assembly 1 has a cylindrical drug storage cavity 6 inside.

[0023] The tibial spacer component 2 is also made of PMMA material, and a second articular surface 5 is provided on the side away from the tibia. The second articular surface 5 is an arc-shaped convex structure that is adapted to the first articular surface 4.

[0024] The connecting component 3 includes a groove 7 located at the bottom of the femoral locator component 1 and a pin 8 located at the top of the tibial locator component 2. Both the groove 7 and the pin 8 have rectangular cross-sections and are fixedly connected by bolts 10. Each end of the groove 7 and the pin 8 has an M3 threaded hole for fastening with stainless steel bolts 10, enabling a detachable connection and height adjustment between the femoral and tibial locator components 2.

[0025] Both the femoral spacer component 1 and the tibial spacer component 2 have a drug storage cavity inside. The drug storage cavity is wrapped with antibiotic bone cement. The surface of the spacer component is rough to increase the holding force of the spacer component and the bone cement.

[0026] In this embodiment, the femoral spacer component 1 and the tibial spacer component 2 are provided in 21 different sizes ranging from 30mm to 50mm, with the length and diameter increasing in increments of 1mm. Figure 3 This is a schematic diagram of the measuring device. The length and diameter both increase in increments of 1 mm. Doctors can use the measuring device to select appropriate components based on the femoral condyle size and tibial plateau thickness measured during surgery.

[0027] Preoperative knee anatomical data were obtained using knee CT and MRI scans. Specific measurement indicators included:

[0028] Femoral condyle: anteroposterior diameter (distance from the anterior end of the anterior cortex to the posterior end of the posterior cortex), medial and lateral diameter (distance from the medial end of the medial condyle to the lateral end of the lateral condyle), and distance from the distal articular surface of the femur to the opening of the femoral medullary cavity.

[0029] Tibial plateau: medial and lateral diameters (distance from the medial condyle of the tibia to the lateral condyle of the tibia), anteroposterior diameters (distance from the anterior edge to the posterior edge of the tibial plateau), and distance from the proximal articular surface of the tibia to the tibial tuberosity;

[0030] Joint space width: The joint space widths on the medial and lateral sides were measured with the knee in extension and 30° flexion, and the average value was taken as the target joint space width.

[0031] Surface marking and actual verification: During the operation, the above anatomical parameters were measured again with calipers under arthroscopy or open surgery, and compared with the imaging measurement results. The error was controlled within ±0.5mm to ensure the accuracy of the specification selection.

[0032] Select the corresponding component size based on the anteroposterior diameter of the femoral condyle and the medial and lateral diameters of the tibial plateau, ensuring that the contact area between the component and the bone bed is ≥90% to avoid local stress concentration; if there is a difference between the target joint space width and the initial gap of the selected component size, the sliding adjustment function of the connecting component 3 can be used to compensate for it, and the adjustment range should be controlled within 0-3mm (if it exceeds 3mm, the adjacent component size needs to be replaced to avoid excessive force on the connecting component 3 and breakage).

[0033] During the surgery, a specialized prosthesis removal tool was used to sequentially remove the femoral condyle component, tibial plateau component, and bone cement of the original knee joint prosthesis, avoiding damage to the distal femur and proximal tibia bone beds. The joint cavity was irrigated with a pulse irrigator to remove necrotic tissue, pus, and bacterial biofilm. The joint cavity was then soaked in povidone-iodine solution for 10 minutes and rinsed clean with sterile saline. The distal femur and proximal tibia bone beds were ground down to remove surface sclerotic bone and expose fresh trabeculae. Simultaneously, a positioning pin was inserted into the positioning hole at the location of the tibial bone bed.

[0034] The selected femoral spacer component 1 is attached to the distal femoral bone bed, ensuring that the porous coating surface is in close contact with the bone bed, and then fixed with medical titanium alloy screws.

[0035] Tibial spacer component 2 implantation: Tibial spacer component 2 is attached to the proximal tibial bone bed, with the positioning hole aligned with the bone bed positioning pin, and is also fixed by medical titanium alloy screws. The screws are implanted at the medial and lateral cortical regions of the tibial plateau.

[0036] Installation of connecting component 3: Insert the pin 8 component into the "U" groove of the groove 7 component, adjust the position of the pin 8 according to the target joint gap width, and after confirming that the gap width is correct with a vernier caliper, tighten the bolts 10 at both ends. Then wipe the surface of the component with sterile gauze to check for any looseness.

Claims

1. A static spacer for treating periprosthetic knee infection, characterized in that, It includes a femoral locator component (1), a tibial locator component (2), and a connecting component (3); The femoral locating component (1) has a first articular surface (4) on the side away from the femur; the tibial locating component (2) has a second articular surface (5) on the side away from the tibia, and the second articular surface (5) and the first articular surface (4) are movably connected by a snap-fit ​​part; the connecting component (3) is disposed between the femoral locating component (1) and the tibial locating component (2), and the two ends of the connecting component (3) are detachably connected to the femoral locating component (1) and the tibial locating component (2) respectively, so as to realize the relative fixation and position adjustment between the femoral locating component (1) and the tibial locating component (2); both the femoral locating component (1) and the tibial locating component (2) are provided with a drug storage cavity (6).

2. The static spacer for treating periprosthetic knee infection according to claim 1, characterized in that, The connecting component (3) includes a groove (7) and a pin (8) that matches the groove (7). Both ends of the groove (7) and the pin (8) are provided with bolt holes (9), and bolts (10) are movably installed in the bolt holes (9).

3. The static spacer for treating periprosthetic knee infection according to claim 1, characterized in that, The outer surfaces of the femoral occupant component (1) and the tibial occupant component (2) are both rough surfaces.

4. The static spacer for treating periprosthetic knee infection according to claim 1, characterized in that, The femoral spacer component (1) and tibial spacer component (2) are provided in at least two specifications, and the length and diameter of the femoral spacer component (1) and tibial spacer component (2) of different specifications gradually increase by 1 mm.

5. The static spacer for treating periprosthetic knee infection according to claim 1, characterized in that, The first joint surface (4) is an arc-shaped concave structure, and the second joint surface (5) is an arc-shaped convex structure adapted to the first joint surface (4).

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