Modular adjustable spacer mould used for the knee

Abstract

The invention relates to a spacer mould used in the field of health, particularly in orthopaedics and traumatology, during the treatment of infections around knee prostheses. The invention particularly relates to a spacer mould for the femur and the tibia, comprising detachable and nested moulds, by means of which the length can be adjusted with the locked structure and the antibiotic cement to be seated can be shaped in the desired size.

Description

[0001] DESCRIPTION

[0002] MODULAR ADJUSTABLE SPACER MOULD USED FOR THE KNEE

[0003] Technical Field of the Invention

[0004] The invention relates to a spacer mould used in the field of health, particularly in orthopaedics and traumatology, during the treatment of infections around knee prostheses.

[0005] The invention particularly relates to a spacer mould for the femur and the tibia, comprising detachable and nested moulds, by means of which the length can be adjusted with the locked structure and the antibiotic cement to be seated can be shaped in the desired size.

[0006] State of the Art

[0007] A spacer used in the field of orthopaedics is a device temporarily used after joint prosthesis surgery in order to treat an infected joint. In particular, in cases of implant infections that may occur after hip or knee joint prosthesis surgery, doctors may remove the infected prosthesis and place a temporary spacer in its place. The spacer is used to control the infection in the joint and as a preparatory stage for the placement of a new prosthesis.

[0008] The spacer is generally made of a material coated with antibiotics. In this way, it helps to control and treat the infection within the joint. The use of a spacer allows the infected joint to rest, reduces pain, and may facilitate the treatment process. The use of a spacer aims to clean the infected joint and accelerate the healing process. Once this process is completed, the patient is generally ready for surgery for the placement of a permanent joint prosthesis. For this reason, the spacer plays an important role as a temporary solution in orthopaedic surgeries. During the treatment of infections around hip prostheses, three methods are currently used to enable removal of the original implants, to ensure that the patient’s existing joint does not remain empty during antibiotic treatment, to preserve length, and to allow the application of high-dose antibiotics. The first of these is the manual application in which the surgeon mixes antibiotics with bone cement during surgery and shapes the dough-like material by hand on a metal wire, and the second is the ready-made spacer applied as a factory-manufactured product that contains only one type of antibiotic in predetermined sizes. On the other hand, the elimination of surface roughness on the cement surface during factory production reduces antibiotic release. The third method is the mould application, which only allows a limited number of sizes and diameters. This leads to applications that are either too small or too large and may result in bone loss or dislocations.

[0009] In the abstract section of the invention disclosed in the application numbered “TR 2023 / 001403” in the state of the art, it is stated that “a modular mould for shaping an orthopaedic spacer made of medical cement defines a moulding cavity bounded by a moulding surface and configured to apply a predetermined shape onto said medical cement and to realise said orthopaedic spacer. The mould comprises a first section defining a first portion of said surface and a second section defining a second portion of the surface, and the first and second portions of the surface are variable in order to obtain separators of variable dimensions”. Here, only a few sizes and diameters can be offered.

[0010] In the invention disclosed in the application numbered “US2022346977A1” in the state of the art, hip arthroplasty trial devices and hip arthroplasty trial systems are described. The hip arthroplasty trial device comprises a head element having a central axis and defining an inner chamber, a head element opening providing access to the inner chamber, and a cavity extending inward from the outer surface of the head element. A rotatable element is positioned in the inner chamber along an axis between the central axis and one side of the head element. The cavity extends along an axis between the central axis and another opposite side of the head element. An insert is placed into the head element opening and the insert can move between a first position of the insert and a second position of the insert. In the invention disclosed in the application numbered “EP2787928B1” in the state of the art, a mould for creating a prosthesis is described. The mould comprises a body portion, a head portion, and a fastening assembly. The body portion and the head portion can be provided as a kit having various different internal dimensions. Thus, a user can select or customise a mould cavity size according to the dimensions of a particular implant region of a patient.

[0011] In the invention disclosed in the application numbered “EP3043750B1” in the state of the art, a modular adjustable spacer device for the treatment of an articulation of the human body is described. This device comprises a connection central body provided with an end having a substantially flat first surface, and a head adapted to be placed into a joint cavity. Here, the head comprises a cap and a base opposite said cap.

[0012] In the invention disclosed in the application numbered “WO2016087561A1” in the state of the art, a spacer composed of separate components is described for temporary surgical treatment of joint infections in shoulder, knee, and hip arthroplasty as a joint replacement. With at least one component of the spacer being made of a ceramic material, multiple ceramic materials, or a ceramic-coated non-ceramic material, adhesion of bone to the spacer and the release of wear products are prevented.

[0013] There are several disadvantages associated with the methods used in the state of the art.

[0014] The disadvantage of the manual application is that the shape given by hand does not conform to the original bone tissue in terms of roundness and stem length and causes great difficulty both during placement and removal. During the hand-shaping process, health personnel and the patient are exposed to the toxic vapour of the bone cement (Polymethylmethacrylate) liquid. The hand-shaping process causes a loss of time and prolongs the surgery.

[0015] The disadvantage of using a ready-made spacer is that only one type of antibiotic can be placed into the spacer in factory production. However, the bacteria present in the patient may not be sensitive to this antibiotic. As a result of the hardened surface due to factory production, antibiotic release from the surface decreases. During prosthesis procedures, the diameters and stem lengths of these implants vary. The number of combinations resulting from the different uses of implant stems and lengths approaches one hundred. In contrast, factory production offers only a few sizes and diameters.

[0016] The disadvantages of the mould application are that, during prosthesis procedures, the diameters and stem lengths of these implants vary. The number of combinations resulting from the different uses of implant stems and lengths approaches one hundred. In contrast, factory production offers only a few sizes and diameters. In the applications of existing moulds, multiple assembly increases the duration of surgery and causes loss of time. A different mould must be used for different diameters and stem lengths.

[0017] As a result, due to the drawbacks mentioned above and the inadequacy of current solutions regarding the subject matter, a development in the relevant technical field has become necessary.

[0018] The Aim of the Invention

[0019] The most important aim of the invention is to allow a large number of head and stem combinations, to permit use for both the tibia and the femur, and to prevent loss of time by enabling the length and the stem to be adjusted easily in a single operation. In this way, a spacer having any type of length and thickness, independent of patient height, can be produced with a single mould.

[0020] Another important aim of the invention is to ensure that the length of the spacer can be adjusted by means of the locked structure of the body. In this way, the desired size and stem length can be easily combined and the bone cement can be shaped without loss of time with a single material.

[0021] Another aim of the invention is to enable mixing of the desired antibiotic. Since the spacer can be produced with the mould, the doctor can integrate any antibiotic into the mixture.

[0022] Another aim of the invention is that the shape given is suitable independently of the patient by means of the nested structure of the mould. Here, since there are moulds in multiple diameters in the spacer that is the subject of the invention, the most suitable diameter for the patient is selected and the given shape conforms to this.

[0023] Another aim of the invention is to allow the desired antibiotic to be applied, differing from ready-made spacer applications, and to ensure an ideal surface roughness.

[0024] Another aim of the invention is that, by means of the nested structure of the moulds, all moulds occupy as much space as a single mould, thus providing easy application and storage.

[0025] A further aim of the invention is to offer the surgeon a very high number of head and stem lengths compared to the mould application. In this way, a single mould to be purchased can be used at once with the other nested moulds and all options can be evaluated and applied.

[0026] Another aim of the invention is that the shape of the obtained spacer is compatible with the original implant.

[0027] Description of Drawings

[0028] Figure 1 is a drawing showing the perspective view of the modular spacer mould for the tibia that is the subject of the invention.

[0029] Figure 2 is a drawing showing the perspective detailed view of the upper body of the modular spacer mould for the tibia that is the subject of the invention.

[0030] Figure 3 is a drawing showing the perspective view of the lower body of the modular spacer mould for the tibia that is the subject of the invention.

[0031] Figure 4 is a drawing showing the perspective view of the size components of the modular spacer mould for the tibia that is the subject of the invention.

[0032] Figure 5 is a drawing showing the perspective view of the closed position of the modular spacer mould for the femur that is the subject of the invention. Figure 6 is a drawing showing the view of the modular spacer mould for the femur in its closed state together with the nested position of the size components.

[0033] Figure 7 is a drawing showing the perspective view of the modular spacer mould for the femur in its open state and the external position of the size components.

[0034] Figure 8 is a drawing showing the upper perspective view of the modular spacer mould for the femur that is the subject of the invention.

[0035] Figure 9 is a drawing showing the isometric view of the cutting-channel tab of the modular spacer mould for the femur that is the subject of the invention.

[0036] Figure 10 is a drawing showing the perspective view of the spacer obtained using the modular spacer mould for the femur that is the subject of the invention.

[0037] Reference Numbers

[0038] 100. Spacer Mould

[0039] 110. Lower body

[0040] 111. Body Lock

[0041] 120. Upper body

[0042] 121. Body Chamber

[0043] 122. Body Cap

[0044] 123. Stem Recess

[0045] 124. Body Channel

[0046] 125. Body Cap Lock

[0047] 126. Body Chamber Lock 127. Cutting-Channel Tab

[0048] 128. Body Cutting Channel

[0049] 129. Plaster Filling Recess

[0050] 130. Tibial Block Components

[0051] 140. Tibial Plug

[0052] 150. Tibial Size Component

[0053] 160. Femoral Size Components

[0054] 200. Resulting Spacer Component

[0055] Description of the Invention

[0056] The modular adjustable spacer mould (100) comprises the lower body (110), the upper body (120), the tibial plug (140), and the block components (130), the tibial size components (150) and the femoral size components (160) which are positioned inside the upper body (120). The lower body (110) comprises the body lock (111 ), while the upper body (120) comprises the body chamber (121 ), the body cap (122), the stem recess (123), the body channel (124), the body cap lock (125) and the body chamber lock (126).

[0057] The modular adjustable spacer mould (100) that is the subject of the invention enables the production of a spacer suitable for both the tibial bone and the femoral bone of the knee. Here, producing a compatible and scaled spacer for both bones is of great importance. The modular adjustable spacer mould (100) that is the subject of the invention ensures that a spacer mould can be produced for both the tibia and the femur in order to meet this requirement.

[0058] In the modular adjustable spacer mould (100) that is the subject of the invention, the length is adjusted by means of the lower body (110) and the upper body (120). Here, the body lock (111 ) located on the lower body (110) enters the upper body (120), which comprises the body channel (124) that forms the space into which the body lock (111 ) enters, and the length can be adjusted step by step at 5-millimetre intervals I with a 5-mm precision. Adjusting the antibiotic cement to be seated to the desired size for the tibia is achieved by means of the tibial block components (130) and the tibial size component (150). Adjusting it to the desired size for the femur is achieved by means of the femoral size components (160). Here, a detachable model is used for the tibial block components (130) and the tibial size components (150). The tibial block components (130), the tibial size component (150) and the femoral size components (160) of the desired size must be placed into the tibial body chamber (121 ).

[0059] The modular adjustable spacer mould (100) comprises two parts, namely the lower body (110) and the upper body (120). The lock mechanism on the lower body (110) enables forward and backward movement of the stem portion. This locked mechanism also prevents the cement from leaking back during the cement application and ensures that the ideal length can be adjusted with a single spacer according to the patient’s leg length. The lower body (110), by means of the body lock (111 ), provides applicability for patients of all sizes without the need for an additional intermediate body component. The lower body (110) comprises the body lock (111 ). The lower body (110) forms a channel in which the cylindrical extension part is positioned. Its main function is to ensure that the stem portion remains fixed at the length desired by the practitioner. The body lock (111 ) located on the lower body (110) allows the stem portion to move forwards and backwards, and this locked structure also prevents the cement from leaking back during the cement application. The lower body (110), by means of the teeth of the body lock (111 ) located thereon, moves upwards and downwards within the upper body channel (124) and allows the desired stem length to be used. In addition, on the body lock (111 ), the millimetre measurements for adjusting the stem length are provided. Thus, the practitioner can see the length of the stem that will be obtained when each tooth is shifted and can perform the adjustment accordingly.

[0060] The upper body (120) comprises the body chamber (121 ), the body cap (122), the stem recess (123) and the upper body channel (124). If cement is to be prepared for the tibia, the tibial block components (130) and the tibial size components (150) are positioned inside the body chamber (121), and if cement is to be prepared for the femur, the femoral size components (160) are positioned therein. The tibial block components (130) and the tibial size components (150) are used in a nested structure, and all dimensions can be positioned inside the body chamber (121) simultaneously. Thus, all tibial block components (130) and tibial size components (150) are stored inside the tibial body chamber (121 ) both before and after use. By means of six nested size-adjusting components positioned inside the body chamber (121 ), it becomes possible to produce four different tibial sizes. The femoral size components (160), on the other hand, are used in a detachable manner, and a single size component can be positioned inside the body chamber (121) during use. By means of the femoral size components (160), which are available in four different sizes, four different femoral plaster structures can also be produced. If cement is to be produced for the tibia, the modular adjustable spacer mould (100) comprises the lower body (110), the upper body (120), the tibial plug (140), and the tibial block components (130) and tibial size components (150) positioned inside the upper body (120). If cement is to be produced for the femur, it comprises the lower body (110), the upper body (120) which includes the body cap lock (125) and the body chamber lock (126), and the femoral size components (160) positioned on the upper body (120).

[0061] The body cap (122) is produced integrally with the body chamber (121 ) and, after being closed and seated onto the lower body (110), has an upper body channel (124) that allows the bone cement to be injected inside by means of a cement gun. The stem recess (123) located on the body chamber (121 ) enables a stem of the desired length to be produced after the lower body (110) has been adjusted. The plaster filling recess (129) allows the plaster to fill the upper body channel (124). The upper body channel (124) contains the cavity into which the lower body (110) can enter, and after the lower body has been adjusted, it enables the stem to be produced with the plaster that fills the channel and ensures the production of the resulting spacer component obtained by injecting the bone cement inside by means of a cement gun. The upper cap (122) has a clasped structure, locks when closed, and does not open due to pressure. When it is intended to be opened, it opens easily when pushed by hand. The upper body (120) comprises the body cutting channel (128) and the cutting-channel tab (127). This body cutting channel (128) is a surface that can be torn manually or with the aid of forceps. Here, when the cutting-channel tab (127) is grasped with forceps and rotated, or grasped by hand and pulled, the body cutting channel (128) tears and separates the stem portion of the lower body (110). By means of this feature, removal of the spacer from inside the mould after cement injection is facilitated.

[0062] The tibial block components (130) sit inside the body chamber (121) and, depending on the practitioner’s preference, can be removed to produce a mould of the desired width. The tibial plug (140) is used to plug the upper body channel by being positioned in the stem recess (123) in cases where a stem length of zero is desired, that is, where a stem is not required in the spacer. The tibial size components (150) sit inside the body chamber (121 ) and, depending on the practitioner’s preference, can be removed to produce a mould of the desired height.

[0063] For tibial cement production, the practitioner first decides on a size and stem height depending on the size of the extracted prosthesis and any new bone effects that may occur during extraction. During this stage, the practitioner may measure the size of the existing prosthesis with a ruler or decide on a larger or smaller size. After deciding on the size, the practitioner removes the appropriate tibial block component (130) and tibial size component (150) from inside the body chamber (121 ). For example, if the smallest size is chosen, all components remain in place. If a blocked smallest size is chosen, only the tibial block component (130) shown at the top in Figure 4 is removed. If the largest size is chosen, the tibial size components (150) are removed. If a blocked largest size is chosen, all tibial size components (150) and all tibial block components (130) are removed. In this way, the largest mould is obtained. After this, a decision is made regarding whether a stem will be used. If a stem is not desired, the tibial plug (140) remains in place, that is, positioned on the stem recess (123). Thus, the mould is produced without a stem. If a stem is desired, the lower body (110) is moved upwards or downwards to the desired height, adjusted with the body lock (111 ), and left in that position. If reinforcement is desired by placing a metal part inside, a metal wire is cut to the appropriate length and positioned inside. Finally, the body cap (122) is closed. The spacer mould (100) is now ready for cement injection. After this, the bone cement into which the desired amount and type of antibiotic has been mixed is prepared and made ready inside a bone-cement injector. Lastly, for the tibia, injection is performed into the tibial spacer mould (100) by means of the cement filling recess (129) located on the body cap (122). After the cement has set, the tibial block components (130) and tibial size components (150), if present around it, are removed and the spacer to be applied is made ready. Additionally, in order to facilitate removal of the resulting spacer component (200), a body cutting channel (128) designed to facilitate cutting using the cutting-channel tab (127) has been formed on the upper body channel (124).

[0064] For femoral cement production, the practitioner, who is the surgeon, first decides on a size and a stem height depending on the size of the extracted prosthesis and any new bone effects that may occur during removal. During this stage, the practitioner may measure the size of the existing prosthesis with a ruler or decide on a larger or smaller size. After deciding on the size, the appropriate femoral size component (160) is placed inside the body chamber (121 ). If a stem is desired, the lower body

[0065] (110) is moved upwards or downwards to the desired height, adjusted by means of the body lock (111 ), and left in that position. If reinforcement is desired by placing a metal part inside, a metal wire is cut to the appropriate length and positioned inside. Finally, the body cap (122) is closed. Here, the body cap lock (125) and the body chamber lock (126) engage with each other, ensuring that the body cap (122) and the body chamber (121 ) are interlocked. The spacer mould (100) is now ready for cement injection. After this, the bone cement containing the desired amount and type of antibiotic is mixed and prepared inside a bone cement injector. Finally, injection is performed into the spacer mould (100) by means of the upper body channel (124). After the cement has hardened, the body cap (122) is opened, and the obtained spacer part (200) inside the body chamber (121 ) is removed, making the spacer ready for application. The femoral mould comprises four femoral size components (160). After the body cap (122) is opened, the size suitable for the patient is selected and seated onto the mould surface, and the body cap (122) is closed. The body lock

[0066] (111 ) can be adjusted according to the measurement guide located on it. After the stem length is adjusted by means of the body lock (111), cement is added into the upper body channel (124) at the top point using the plaster filling recess (129), and it is allowed to set. Once the spacer has dried inside the mould, the body cap (122) is opened and removed. Thus, the resulting spacer component (200) is produced. The upper body (120) comprises the body cutting channel (128) and the cuttingchannel tab (127). This body cutting channel (128) is a surface that can be tom manually or with the aid of forceps. Here, when the cutting-channel tab (127) is grasped with forceps and rotated, or grasped by hand and pulled, the body cutting channel (128) tears and separates the stem portion of the lower body (110). By means of this feature, removal of the spacer from inside the mould after cement injection is facilitated.

[0067] To counter the possibility of the produced spacer not releasing from inside the mould, two cutting channels are positioned on the spacer mould (100). In order to facilitate removal of the resulting spacer component (200), a body cutting channel (128) designed to facilitate cutting using the cutting-channel tab (127) has been formed on the upper body channel (124). By grasping the cutting-channel tab (127), the upper body (120) can be tom along the body cutting channels (128), allowing the spacer mould (100) to be cut and the resulting spacer component (200) to be removed.

Claims

CLAIMS1. A modular spacer mould (100) for producing tibial cement and obtaining spacers that eliminate infections around knee prostheses, comprising:• the lower body (110), which ensures that the stem portion remains fixed at the adjusted length, allows the stem portion to move forwards and backwards by means of the body lock (111 ) located thereon with a locked structure, and also prevents the cement from leaking back during the cement application;• the upper body (120), which comprises the body chamber (121), in which all tibial block components (130) and tibial size components (150) are stored before and after use; the body cap (122) that is produced integrally with the body chamber (121 ) and, after being closed and seated onto the lower body (110), allows the bone cement to be injected inside by means of the cement filling recess (129); the stem recess (123) that allows a stem of the desired length to be produced by enabling the plaster to fill the upper body channel (124) after the lower body (110) has been adjusted; the upper body channel (124) that ensures that the plaster enters the body chamber (121 ), comprises the cavity into which the lower body (110) can enter, and enables the stem to be produced with the plaster that fills the channel after the lower body (110) has been adjusted; the body cutting channel (128) and the cutting-channel tab (127);• the tibial block components (130), which sit inside the body chamber (121 ) and, depending on the practitioner’s preference, can be removed to produce a mould of the desired width;• the tibial plug (140), which is used to plug the upper body channel by being positioned in the stem recess (123) in conditions where a stem length of zero is desired, that is, where a stem is not required in the mould; and• the tibial size components (150), which sit inside the body chamber (121 ) and which, depending on the practitioner’s preference, can be removed to produce a mould of the desired height.

2. A modular spacer mould (100) for producing femoral cement and obtaining spacers that eliminate infections around knee prostheses, comprising:• the lower body (110), which ensures that the stem portion remains fixed at the adjusted length, allows the stem portion to move forwards and backwards by means of the body lock (111 ) located thereon with a locked structure, and also prevents the cement from leaking back during the cement application;• the upper body (120), which comprises the upper body channel (124) that allows the plaster to enter the body chamber (121 ), comprises the cavity into which the lower body (110) can enter and enables the stem to be produced with the plaster that fills it after the lower body (110) has been adjusted; the body chamber (121 ), in which the femoral size components (160) are positioned during use; the stem recess (123) that enables a stem of the desired length to be produced after the lower body (110) has been adjusted; the cement filling recess (129) that allows the plaster to fill the upper body channel (124); the body cap (122) that is produced integrally with the body chamber (121) and, after being closed and seated onto the lower body (110), allows the bone cement to be injected inside by means of a cement gun; the upper body channel (124); the body cap lock (125) and the body chamber lock(126); and the body cutting channel (128) and the cutting-channel tab(127); and• the femoral size components (160), which sit inside the body chamber (121 ) and, depending on the practitioner’s preference, can be removed to produce a mould of the desired size.

3. A modular spacer mould (100) according to claim 1 or claim 2, comprising the lower body (110), which, by means of the teeth of the body lock (111 ) located on its exterior, moves upwards and downwards within the upper body channel (124) and allows the desired stem length to be used.

4. A modular spacer mould (100) according to claim 1 or claim 2, comprising the body lock (111 ), on which the measurements at which the stem length is intended to be adjusted are provided in millimetres, and which allows thepractitioner to see the resulting stem length when each tooth step is shifted and to perform adjustment accordingly.

5. A modular spacer mould (100) according to claim 1 , comprising the body chamber (121 ), which is dimensioned to accommodate all of the tibial block components (130) and tibial size components (150).

6. A modular spacer mould (100) according to claim 2, comprising the body chamber (121 ), which is dimensioned to accommodate the femoral size component (160).

7. A modular spacer mould (100) according to claim 1 , comprising the tibial block components (130) and tibial size components (150), which are positioned within the body chamber (121), are configured in a nested structure, and which, being six in number, allow four different tibial spacers to be produced.

8. A modular spacer mould (100) according to claim 2, comprising the femoral size components (160), which are positioned within the body chamber (121 ), are configured in a removable structure, and which, being four in number, allow four different femoral spacers to be produced.

9. A modular spacer mould (100) according to claim 1 or Claim 2, comprising a body cap (122) that has a clasped structure that locks when closed, does not open due to pressure, and can be opened when pushed by hand.

10. A modular spacer mould (100) according to claim 2, comprising the body cap lock (125) and the body chamber lock (126), which engage with one another and allow the body cap (122) and the body chamber (121 ) to be interlocked.

11. A modular spacer mould (100) according to claim 1 , comprising the upper body channel (124), on which a body cutting channel (128) is formed to facilitate cutting or tearing, thereby enabling easier removal of the obtained spacer piece (200).

12. A modular spacer mould (100) according to claim 1 , comprising an opening on the body cap (122), through which injection is performed into the upper body (120) in order to obtain a tibial spacer.

13. A modular spacer mould (100) according to claim 2, comprising the cuttingchannel tab (127), which enables the body cutting channel (128) to be tom manually or with forceps, thereby allowing the spacer to be removed from the mould after the cement injection.

14. A modular spacer mould (100) according to claim 2 or claim 13, comprising the body cutting channel (128) which is located on the upper body (120), is a surface that can be tom manually or with the aid of forceps and, when the cutting-channel tab (127) is grasped with forceps and rotated or grasped by hand and pulled, enables the stem portion of the lower body (110) to be tom.

15. A modular spacer mould (100) according to claim 1 , comprising the cuttingchannel tab (127), which enables the body cutting channel (128) to be tom manually or with forceps, thereby allowing the spacer to be removed from the mould after the cement injection.

16. A modular spacer mould (100) according to claim 1 or claim 15, comprising a body cutting channel (128) that is located on the upper body (120), is a surface that can be tom manually or with the aid of forceps and, when the cutting-channel tab (127) is grasped with forceps and rotated or grasped by hand and pulled, enables the stem portion of the lower body (110) part to be tom.

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