An anti-infection sustained-release nursing ring device for the nail hole of an orthopedic external fixation support

Abstract

This invention discloses an anti-infection sustained-release nursing ring device for orthopedic external fixation pin sites, belonging to the field of orthopedic medical device technology. The device includes a base ring and a detachable functional replacement core ring. The base ring has an embedded through-hole, a magnetically closed lateral opening, a leak-proof sealing lip, an adhesive wing, and a core ring release assembly, allowing for quick installation without pin removal. The functional replacement core ring is available in preventative and therapeutic versions, employing a three-layer composite structure: an exudate absorption indicator layer, a drug-controlled release matrix layer, and a skin-contact healing-promoting layer. The indicator layer contains a pH-responsive color-changing indicator for visual infection warning. The preventative version uses a core-shell electrospun fiber membrane for long-acting drug release, while the therapeutic version uses a microsphere-thermosensitive hydrogel biphasic drug release system. The healing-promoting layer accelerates skin repair at the pin site. This device allows for modular assembly and disassembly, enabling self-care at home. It integrates graded anti-infection, exudate management, and healing promotion, significantly reducing the risk of pin site infection and offering convenient operation.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an anti-infection sustained-release nursing ring device for the pinway of an orthopedic external fixator. Background Technology

[0002] External fixators are an important tool for fracture reduction and fixation, widely used in clinical settings such as open fractures, limb lengthening (Ilizarov technique), joint fusion, and bone transport. External fixators use percutaneously inserted metal pins (external fixation screws) to rigidly connect the fracture ends to an external metal frame, achieving stable fracture fixation.

[0003] However, the pin site formed when external fixation pins penetrate the skin is a direct pathway for bacteria to invade deeper tissues from the body surface. Pin site infection (PSI) is the most common complication of external fixation treatment, with reported incidence rates varying, mostly between 15% and 30%, and exceeding 40% in some high-risk groups. Pin site infection can lead to serious consequences such as loosening of external fixation pins, osteomyelitis, treatment failure, and even amputation.

[0004] Currently, the main clinical methods for nursing care of nail tract openings include the following: (1) Traditional gauze / iodine solution dressing method: Cover the nail puncture site with sterile gauze and clean and change the dressing with iodine solution or chlorhexidine solution daily or every other day. This method is cumbersome and requires medical staff or trained caregivers to operate. Patient compliance is poor, and repeated exposure of the nail puncture site during dressing changes increases the risk of exogenous infection.

[0005] (2) Chlorhexidine-impregnated polyurethane foam patches (such as Biopatch): A circular polyurethane foam dressing containing chlorhexidine gluconate (CHG) with a pre-cut hole in the center to accommodate catheters or pins. This product has accumulated a large amount of evidence-based medicine in the field of central venous catheters (CVCs), and studies have shown that its application at external fixation pin sites has significantly reduced the infection rate from 25% to 0%. However, Biopatch has the following limitations: a) It is a single drug component (CHG only), and there is a lack of escalation treatment options once breakthrough infection occurs; b) It does not contain a drug-controlled release carrier, and CHG is released through simple diffusion of the foam matrix, resulting in an uncontrollable release curve, with too rapid release in the early stage and insufficient concentration in the later stage; c) It does not contain skin healing promoting ingredients, and can only be antibacterial but cannot promote the repair of the skin around the pin site; d) When changing, the old patch must be completely removed, and the new patch must be re-attached after cleaning. It lacks a modular design of "keeping the base unchanged and only changing the drug layer", which increases the risk of touching the pin site and damaging the new skin; e) It does not have a built-in infection warning indicator function, and medical staff need to make a visual judgment or culture.

[0006] (3) Silver-coated / hydroxyapatite-coated external fixators: These fixators reduce bacterial adhesion by coating the surface of the fixator with an antibacterial coating such as silver or hydroxyapatite. However, this method only protects the fixator-bone interface and cannot manage exudate and microbial colonization at the fixator opening on the skin surface; once the coating degrades and is depleted, it cannot be replenished or replaced.

[0007] (4) Antibiotic cement nail sleeve (PMMA Pin Sleeve): The subcutaneous segment of the nail rod is wrapped with antibiotic-containing polymethyl methacrylate. However, PMMA degrades very slowly, and the release of antibiotics is concentrated in the first 24-48 hours, with almost no effective concentration maintenance thereafter.

[0008] In summary, existing technologies share the following common problems: ① lack of multi-functional treatment capabilities; ② uncontrollable or insufficient duration of drug release; ③ lack of exudate management and infection warning functions; ④ complex replacement procedures requiring professional personnel; ⑤ lack of skin healing-promoting ingredients. Therefore, there is an urgent need for a nail puncture site care device that integrates multiple functions, is easy to operate, and possesses tiered treatment capabilities. Summary of the Invention

[0009] This invention provides an anti-infection sustained-release nursing ring device for the pin site of orthopedic external fixation stents, which can solve the shortcomings of existing technologies such as uncontrollable drug release, single function, complicated replacement operation, lack of graded treatment capability and infection early warning means.

[0010] To achieve the above objectives, the present invention provides the following technical solution: an anti-infection sustained-release nursing ring device for the nail track of an orthopedic external fixator, comprising a base ring, wherein an embedded through hole is provided in the middle of the base ring, and a lateral opening extending to the outside of the base ring is provided on one side of the embedded through hole. A detachable functional replacement core ring is embedded in the embedded through hole. The functional replacement core ring has a central through hole in the middle that matches the orthopedic external nail rod. The functional replacement core ring consists of, from top to bottom, an exudate absorption indicator layer, a drug controlled-release matrix layer, and a skin contact healing-promoting layer. The skin contact healing-promoting layer is used to contact the skin around the orthopedic external nail rod. The exudate absorption indicator layer contains a pH-responsive color-changing indicator. The base ring serves as a load-bearing foundation and provides an installation carrier for the functional replacement core ring. The modular quick assembly and disassembly of the functional replacement core ring and the base ring reduces the difficulty of home care operations. The functional replacement core ring adopts a three-layer structure, with a single module completing multiple care functions. The functional replacement core ring matches the external fixator rod, and the two work together to achieve quick installation without nail removal or damage.

[0011] Preferably, the functional replacement core ring is a preventative core ring or a therapeutic core ring. In the preventative core ring, the drug-controlled release matrix layer is a core-shell coaxial electrospun fiber membrane, wherein the shell material is a blend of polycaprolactone and polylactic-co-glycolic acid copolymer; the core layer encapsulates at least one antibacterial active ingredient, with the loading of the antibacterial active ingredient in the core layer being 0.5%–5.0% of the total fiber mass. The continuous release of the drug from the core layer is controlled by the shell layer degradation rate, while the shell polymer degrades slowly, precisely controlling the release rate of the antibacterial drug from the core layer. The controlled-release matrix layer in the therapeutic core ring consists of polylactic acid-glycolic acid copolymer microspheres suspended in a chitosan / β-glycerophosphate sodium thermosensitive hydrogel matrix. The microspheres have a particle size of 10–80 μm. The thermosensitive hydrogel undergoes a solution-gel transition within the temperature range of 33–37°C to achieve in-situ fixation. The microspheres encapsulate at least one sustained-release antibacterial active ingredient, and the thermosensitive hydrogel matrix loads at least one fast-release antibacterial active ingredient that is different from the component loaded in the microspheres. This achieves biphasic release kinetics, where the sustained-release antibacterial drug from the microspheres and the fast-release antibacterial drug from the hydrogel form a biphasic release kinetics of first rapid release to control infection and then sustained release to stabilize efficacy, which is suitable for the treatment needs of infected nail tract sites.

[0012] Preventive and therapeutic core rings enable tiered anti-infection care that combines prevention and treatment, eliminating the need to replace the base and allowing for flexible switching of the core ring based on infection risk, thus overcoming the shortcomings of existing products with only one function.

[0013] Preferably, in the shell material of the drug-controlled release matrix layer in the preventive core ring, the mass ratio of polycaprolactone to polylactic-co-glycolic acid is 60:40 to 80:20, and the fiber diameter is 200nm–2μm. The ratio of the two balances the degradation rate and the drug release rate, ensuring near-zero-order release in 48-72 hours. The fiber membrane has uniform pores, which not only ensures smooth drug release but also maintains the integrity of the membrane structure and avoids membrane rupture.

[0014] Preferably, the skin contact healing-promoting layer is composed of a medical-grade silicone gel mesh film or a hydrophilic polyurethane film, wherein it is loaded with at least one of human epidermal growth factor and sodium hyaluronate, which can activate skin cell proliferation, accelerate epithelialization of the nail puncture site, and shorten the healing cycle.

[0015] Preferably, the exudate absorption indicator layer is composed of sodium carboxymethyl cellulose nonwoven fabric or calcium alginate fiber, wherein bromocresol green is uniformly dispersed as a pH-responsive color-changing indicator. When in contact with exudate with a pH value ≥ 6.5, it changes from yellow-green to blue. The sodium carboxymethyl cellulose nonwoven fabric and calcium alginate fiber can have a high liquid absorption rate and quickly absorb the exudate at the nail piercing opening, avoiding the exudate from soaking the skin and causing infection.

[0016] Preferably, matching permanent magnets are embedded inside the base rings on both sides of the lateral opening. The permanent magnets can provide magnetic attraction force to automatically close the lateral opening without the need for additional clips, making operation simple.

[0017] Preferably, the bottom of the base ring is provided with a seepage-proof sealing lip around the embedded through hole. The seepage-proof sealing lip can flexibly fit the skin at the nail opening to form a ring-shaped physical sealing barrier and block the invasion path of microorganisms.

[0018] Preferably, the top side of the functional replacement core ring is equipped with multiple positioning protrusions, and the top inner side of the base ring is provided with positioning grooves corresponding to the positioning protrusions. This can achieve foolproof positioning of the core ring and the base ring, and support the functional replacement core ring to prevent the core ring from being installed backwards or rotated and shifted.

[0019] Furthermore, one of the positioning protrusions is a snap-fit ​​block. A core ring release assembly is horizontally installed on the base ring at a position corresponding to the snap-fit ​​block. The core ring release assembly includes a snap-fit ​​plate that is horizontally slidably disposed. The snap-fit ​​plate is provided with a snap-fit ​​groove that matches the snap-fit ​​block. One end of the snap-fit ​​plate is an unlocking button exposed on the outside of the base ring. A reset elastic element is installed between the outside of the snap-fit ​​plate and the base ring. The operation is convenient. The core ring can be removed without contact by pressing the unlocking button, avoiding finger contact with the core ring's medicated surface and the nail track, reducing the risk of exogenous infection, and making it suitable for home self-care.

[0020] Preferably, the base ring has at least one adhesive wing on its outer bottom. The bottom surface of the adhesive wing is coated with a medical hypoallergenic silicone gel pressure-sensitive adhesive layer or an acrylic hydrogel pressure-sensitive adhesive layer, which is used to reversibly fix the base ring to the intact skin surface around the nail track. The adhesive wing can increase the contact area between the base ring and the skin and improve the fixation stability.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1. The modular base ring and replaceable functional core ring are adopted. After the base ring is installed, subsequent replacements only involve the core ring. The base ring always stays in contact with the skin, avoiding mechanical damage to the new skin around the nail track caused by repeated removal and removal of adhesive during traditional dressing changes, and reducing the time and area of ​​nail track exposure during dressing changes.

[0022] 2. The preventive and therapeutic core rings can be interchangeably installed on the same base ring, enabling tiered treatment that includes routine postoperative prevention and, when necessary, upgraded treatment, filling the gap in existing products that only have a single preventive function.

[0023] 3. The use of a core-shell electrospun fiber membrane and a PLGA microsphere / thermosensitive gel biphase release system can achieve a sustained antibacterial concentration of 48-72 hours with a controllable release curve, overcoming the shortcomings of traditional CHG foam dressings, which have excessively rapid release in the early stage and insufficient concentration in the later stage.

[0024] 4. The bromocresol green color-changing indicator embedded in the exudate absorption layer can provide a real-time, visually identifiable color warning by changing the pH value of the exudate. This helps patients assess their infection risk level at home and seek medical attention promptly.

[0025] 5. Synergistic Three-Layer Function: The exudate absorption indicator layer, the drug controlled-release matrix layer, and the skin contact healing-promoting layer work together in a single replaceable module to produce a synergistic overall effect.

[0026] 6. The positioning protrusion enables quick and accurate positioning of the functional replacement core ring, and the core ring release component enables contactless removal without touching the drug surface or the nail track. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of the invention in its explosive state; Figure 2 This is a front sectional view of the present invention; Figure 3 for Figure 2 Enlarged structural diagram at point A; Figure 4 This is a schematic diagram of the preventive and therapeutic core rings of the present invention; Figure 5 This is a schematic diagram of the patient home replacement procedure and supporting components of the present invention.

[0028] Figure label: 1. Base ring; 3. Orthopedic external nail rod; 11. Adhesion wing; 12. Embedded through hole; 13. Permanent magnet; 14. Core ring release assembly; 15. Lateral opening; 16. Positioning groove; 17. Leak-proof sealing lip; 20. Functional replacement core ring; 20A. Preventive core ring; 20B. Therapeutic core ring; 21. Central through hole; 22. Positioning protrusion; 23. Exudate absorption indicator layer; 24. Drug controlled release matrix layer; 25. Skin contact healing-promoting layer; 26. Clip block; 141. Unlock button; 142. Reset elastic element; 143. Clip plate; 144. Clip groove; C4. Non-woven skin cleaning wipes. Detailed Implementation The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0029] like Figure 1-5As shown, this invention provides a solution to address the shortcomings of existing technologies, such as uncontrollable drug release, limited functionality, complex replacement procedures, lack of tiered treatment capabilities, and infection early warning mechanisms. The invention offers the following technical solution: an anti-infection sustained-release nursing ring device for the nail tract of an orthopedic external fixator, comprising a base ring 1. The base ring 1 has an embedded through-hole 12 in its center. One side of the embedded through-hole 12 has a lateral opening 15 extending to the outside of the base ring 1. A detachable functional replacement core ring 20 is embedded within the embedded through-hole 12. The functional replacement core ring 20 has a central through-hole 21 in its center that matches the orthopedic external nail rod 3. The replacement core ring 20 consists of, from top to bottom, an exudate absorption indicator layer 23, a drug controlled-release matrix layer 24, and a skin contact healing-promoting layer 25. The skin contact healing-promoting layer 25 is used to contact the skin around the orthopedic external nail rod 3. The exudate absorption indicator layer 23 contains a pH-responsive color-changing indicator. The base ring 1 serves as a load-bearing foundation and provides an installation carrier for the functional replacement core ring. The modular quick assembly and disassembly of the functional replacement core ring 20 and the base ring 1 reduces the difficulty of home care operations. The functional replacement core ring 20 adopts a three-layer structure, with a single module completing multiple care functions. The functional replacement core ring 20 matches the external fixation nail rod, and the two work together to achieve quick installation without nail removal or damage.

[0030] The base ring 1 is integrally formed from medical-grade thermoplastic polyurethane through injection molding. The central through hole 21 is a circular through hole. This embodiment provides three inner diameter specifications: 4.5±0.2mm (suitable for 3.0-4.0mm small diameter half-needles), 5.0±0.2mm (suitable for 4.0-4.5mm standard diameter Schanz nails), and 6.0±0.2mm (suitable for 5.0-5.5mm large diameter nails). In clinical use, the corresponding specification is selected according to the actual outer diameter of the external fixation rod 3 used by the patient. The width of the lateral opening 15 is not less than the outer diameter of the adapted rod, so that the base ring 1 can slide laterally into and fit the rod 3 without removing it.

[0031] The lateral opening 15 has matching permanent magnets 13 embedded inside the base rings 1 on both sides. These permanent magnets 13 provide magnetic attraction, automatically closing the lateral opening without the need for additional clips, simplifying operation. Each permanent magnet 13 is nickel-plated and then coated with a medical-grade silicone rubber coating approximately 0.3 mm thick, ensuring no direct contact between the magnet and human tissue. Alternatively, a vapor-deposited parylene coating can be used. The permanent magnets 13 are arranged with opposite polarities. When the lateral opening 15 is closed, the two magnets attract each other magnetically (with a single-sided attraction force of not less than 0.3 N), restoring the base ring 1 to its continuous, closed annular structure. This magnetic force is sufficient to maintain closure during the patient's daily activities (walking, turning over), while allowing the operator to easily pry it open with their fingers for installation and removal.

[0032] The base ring 1 has a leak-proof sealing lip 17 surrounding the embedded through hole 12 at its bottom. This lip 17 flexibly conforms to the skin around the nail entry point, forming a ring-shaped physical barrier to block microbial invasion. Made of medical-grade silicone rubber with a hardness of Shore A20-40 (lower than the base ring body), the lip 17 can be integrally molded using two-color injection molding, with a lip-shaped cross-section folded inwards at approximately 45°. In the installed state, the sealing lip 13 forms a flexible ring-shaped seal with the skin within a 3-8mm radius around the nail entry point. This prevents seepage from the nail entry point from overflowing and contaminating surrounding skin and clothing, while also forming a physical barrier to prevent external environmental microorganisms from migrating along the skin surface towards the nail entry point.

[0033] In this embodiment, at least one adhesive wing 11 is provided on the outer bottom of the base ring 1. The bottom surface of the adhesive wing 11 is coated with a medical hypoallergenic silicone gel pressure-sensitive adhesive layer or an acrylic hydrogel pressure-sensitive adhesive layer, which is used to reversibly fix the base ring 1 to the intact skin surface around the pin opening. The adhesive wing 11 can increase the contact area between the base ring and the skin and improve the fixation stability. The adhesive wing 11 has a thin wing structure, and its bottom surface is coated with a layer of medical hypoallergenic silicone gel pressure-sensitive adhesive PSA. Alternatively, an acrylic hydrogel pressure-sensitive adhesive can also be used. During installation, the adhesive wing 11 adheres to the intact skin surface around the pin opening, providing a reversible adhesive force to fix the base ring 1 to the skin. This adhesive force is designed to be sufficient to keep the base ring in a stable position during daily activities, while allowing for painless removal of the base ring without damaging the skin when removal is required.

[0034] In this embodiment, the functional replacement core ring 20 is either a preventative core ring 20A or a therapeutic core ring 20B. The preventative core ring 20A contains a drug-controlled release matrix layer 24 that is a core-shell coaxial electrospun fiber membrane. The shell material is a blend of polycaprolactone and polylactic acid-glycolic acid copolymer. The core layer encapsulates at least one antibacterial active ingredient, with the loading of the antibacterial active ingredient in the core layer being 0.5%–5.0% of the total fiber mass. The continuous release of the drug from the core layer is controlled by the shell degradation rate, while the shell polymer degrades slowly, precisely controlling the release rate of the antibacterial drug from the core layer. The drug-controlled release matrix layer 24 in the therapeutic core ring 20B consists of polylactic acid-glycolic acid copolymer microspheres suspended in a chitosan / β-glycerophosphate sodium thermosensitive hydrogel matrix. The microspheres have a particle size of 10–80 μm. The thermosensitive hydrogel undergoes a solution-gel transition within the temperature range of 33–37°C to achieve in-situ fixation. The microspheres encapsulate at least one sustained-release antibacterial active ingredient, and the thermosensitive hydrogel matrix loads at least one fast-release antibacterial active ingredient that is different from the component loaded in the microspheres. This achieves biphasic release kinetics, where the sustained-release antibacterial drug from the microspheres and the fast-release antibacterial drug from the hydrogel form a biphasic release kinetics of first rapid release to control infection and then sustained release to stabilize efficacy, which is suitable for the treatment needs of infected nail tract sites.

[0035] The preventive core ring 20A and the therapeutic core ring 20B can achieve graded anti-infection care for prevention and treatment without the need to replace the base. The core ring can be flexibly switched according to the infection risk, thus filling the gap of the single function of existing products.

[0036] In the preventive core ring 20A, the shell material of the drug controlled-release matrix layer 24 has a mass ratio of polycaprolactone to polylactic-co-glycolic acid of 60:40 to 80:20, and the fiber diameter is 200nm–2μm. The ratio of the two balances the degradation rate and the drug release rate, ensuring quasi-zero-order release in 48-72 hours. The fiber membrane has uniform pores, which not only ensures smooth drug release but also maintains the integrity of the membrane structure and avoids membrane rupture.

[0037] Specifically, the core-shell coaxial electrospun fiber membrane of the drug-controlled release matrix layer 24 of the preventive core ring 20A is prepared using a coaxial electrospinning process. The core layer solution consists of silver sulfadiazine (SSD) and polyhexamethylene biguanide (PHMB) dissolved in a dimethyl sulfoxide / N,N-dimethylformamide mixed solvent; the shell layer solution consists of polycaprolactone (PCL) and polylactic-co-glycolic acid copolymer (PLGA) mixed in a mass ratio of 70:30 in hexafluoroisopropanol. The electrospinning parameters are as follows: inner needle flow rate 0.3-0.8 mL / h, outer needle flow rate 1.0-2.0 mL / h, voltage 15-22 kV, and receiving distance 12-18 cm. The resulting fiber diameter is 500 nm-1.5 μm, the SSD content in the core layer is 2.0% (w / w) of the total fiber mass, and the PHMB content is 0.8% (w / w) of the total fiber mass. Silver sulfadiazine (SSD) exhibits broad-spectrum antibacterial activity against both Gram-positive bacteria (such as Staphylococcus aureus) and Gram-negative bacteria (such as Pseudomonas aeruginosa), and its silver ion release provides long-lasting antibacterial effects. Polyhexamethylene biguanide (PHMB) is a cationic polymer disinfectant that can disrupt bacterial cell membranes, forming a synergistic antibacterial effect with SSD. Both are non-antibiotic antibacterial agents, and long-term use is unlikely to induce drug resistance, making them suitable for routine postoperative prophylaxis.

[0038] The degradation rate of the shell polymer determines the release kinetics of the core drug. PCL degrades slowly, providing skeletal support and basic sustained release, while PLGA degrades more rapidly, providing an early release pathway. By adjusting the PCL:PLGA ratio to 70:30, a near-zero-order release profile can be achieved over 48-72 hours: approximately 15%-20% cumulative release in the first 8 hours, sustained release at a near-constant rate from 8 to 72 hours, and 80%-90% cumulative release at 72 hours.

[0039] Additionally, the therapeutic core ring 20B is used for escalation treatment after signs of infection appear (the exudate absorption indicator layer turns blue), and is visually indicated in red. Its drug-controlled release matrix layer 24 consists of PLGA microspheres suspended in a chitosan / β-glycerophosphate (CS / β-GP) thermosensitive hydrogel matrix.

[0040] The preparation of PLGA microspheres involved using PLGA as the wall material and a dual emulsification-solvent evaporation method. The inner aqueous phase encapsulated a combination of silver sulfadiazine (SSD) and rifampicin, with a SSD:rifampicin mass ratio of 70:30. Polyvinyl alcohol (PVA) was used as the emulsifier. The resulting microspheres had a particle size of 30-60 μm, a drug encapsulation efficiency ≥70%, and a drug loading of approximately 15% (w / w). Rifampicin exhibits excellent penetration and bactericidal ability against Staphylococcus aureus biofilms, forming a synergistic combination with silver sulfadiazine to combat both planktonic bacteria and biofilm formation.

[0041] Preparation of the thermosensitive hydrogel matrix: Chitosan (degree of deacetylation ≥85%, molecular weight 100-300kDa) was dissolved in 0.1M hydrochloric acid to prepare a 2% (w / v) solution. β-glycerophosphate sodium was added to adjust the pH to 7.0-7.2, and the solution was stored at 4℃. This system is a flowable solution at room temperature (20-25℃), and undergoes a solution-to-gel transition within the range of 33-37℃ (skin contact temperature), forming a semi-solid gel within minutes, thus immobilizing PLGA microspheres in situ within the matrix.

[0042] Mupirocin was directly loaded into a thermosensitive hydrogel matrix as a rapid-release component at a concentration of 2.0% (w / w) of the total mass of the gel matrix. Mupirocin is a topical antibiotic effective against methicillin-resistant Staphylococcus aureus (MRSA). After loading, it rapidly diffuses and releases through the gel matrix, releasing ≥50% of the total load within 0-8 hours, quickly establishing a high-concentration antibacterial environment to control acute infections.

[0043] SSD and rifampin in the microspheres are slowly released through the degradation of the PLGA wall material, providing sustained release for 8-72 hours after installation, offering maintenance therapy after infection control. This achieves a biphasic release kinetics of "fast at first, then slow." The skin-contact healing-promoting layer 23 of the therapeutic core ring 20B, in addition to rhEGF and HA-Na, is further loaded with dexamethasone sodium phosphate as a local anti-inflammatory component, with the total loading of dexamethasone sodium phosphate in a single core ring not exceeding 0.5 mg. Low-dose local corticosteroids can suppress excessive inflammation around the pin puncture site, reducing redness, swelling, and pain, without affecting systemic immune function.

[0044] The recommended replacement cycle for the therapeutic core ring 20B is every 24-48 hours, and users are advised to consult a doctor for a prescription for oral antibiotics to complement systemic treatment.

[0045] The skin-contact healing-promoting layer 23, located at the bottom of the core ring, is 0.3 mm thick and is made of a medical-grade silicone gel mesh membrane. Alternatively, a hydrophilic polyurethane film can be used. This layer is loaded with recombinant human epidermal growth factor (rhEGF) and sodium hyaluronate (HA-Na), continuously releasing healing-promoting factors into the skin around the nail track after installation, maintaining a moist healing microenvironment. Simultaneously, the healing-promoting layer 23 acts as a permeation rate regulating membrane for drug release from the middle layer 22 to the skin side. Its pore size and hydrophilicity / hydrophobicity control the final drug permeation rate, preventing excessively high local drug concentrations that could cause skin irritation.

[0046] In this embodiment, the exudate absorption indicator layer 23 is located on the top layer of the core ring, facing outwards after installation, and is made of sodium carboxymethyl cellulose (CMC-Na) nonwoven fabric. Alternatively, calcium alginate fiber can also be used. This layer has excellent liquid absorption performance and can absorb 10-15 times its own weight in exudate. Bromocresol green is uniformly dispersed in the CMC-Na fiber matrix as a pH-responsive color-changing indicator by impregnation. The color-changing range of bromocresol green is pH 3.8-5.4 (yellow → blue), but in the fiber matrix environment of this embodiment, after being adjusted by a buffer system, its effective visual color-changing threshold is set to show a clear color change from yellow-green to blue when pH ≥ 6.5. The pH of normal nail track exudate is about 5.5-6.0 (slightly acidic). When bacterial infection occurs, bacterial metabolites (such as amines produced by amino acid decarboxylases) cause the local pH to rise to above 6.5 or even reach 7.0-8.0. Therefore, the color change of the exudate absorption indicator layer 23 can serve as a visual signal for infection early warning. This color change response is completed within 15 minutes of exudate contact and is visible to the naked eye.

[0047] In this embodiment, the top side of the functional replacement core ring 20 is equipped with multiple positioning protrusions 22, and the top inner side of the base ring 1 is provided with positioning grooves 16 corresponding to the positioning protrusions 22. This enables foolproof positioning of the core ring and the base ring, and supports the functional replacement core ring 20, preventing the core ring from being installed backwards or rotated out of place. The multiple positioning protrusions 22 can be set in different shapes, such as one of the four positioning protrusions 22 being triangular and the other three being rectangular structures. Therefore, only when the triangular positioning protrusion 22 is embedded in the corresponding positioning groove 16 can the correct installation angle of the functional replacement core ring 20 be guaranteed.

[0048] Furthermore, one of the positioning protrusions 22 is a latching block 26. A core ring release assembly 14 is horizontally installed on the base ring 1 at a position corresponding to the latching block 26. The core ring release assembly 14 includes a latching plate 143 that is horizontally slidably disposed. The latching plate 143 is provided with a latching groove 144 that matches the latching block 26. One end of the latching plate 143 is an unlocking button 141 that protrudes from the outside of the base ring 1. A reset elastic element 142 is installed between the outside of the latching plate 143 and the base ring 1. The operation is convenient. The core ring can be removed without contact by pressing the unlocking button 141, avoiding finger contact with the core ring's medicated surface and the nail track, reducing the risk of exogenous infection, and making it suitable for home self-care. When using the replacement core ring 20, insert it into the embedded through hole 12. When inserting it into the through hole 12, insert the latching block 26 downward into the latching through slot 144 on the latching plate 143. When inserting, the latching plate 143 can be pushed outward. After latching, the latching plate 143 is reset under the action of the reset elastic element 142, so that the latching plate 143 latches the latching block 26. In this way, the replacement core ring 20 will not come off from the embedded through hole 12.

[0049] When the function replacement core ring 20 needs to be replaced, simply press the unlock button 141 to disengage the card slot 144 from the card plate 143, and the function replacement core ring 20 can be removed from the top.

[0050] As a usage method in this embodiment, such as Figure 5 As shown, it includes the following steps: Step S1: The user removes and puts on disposable sterile polyethylene gloves from the sterile packaging unit.

[0051] Step S2: The user takes out a non-woven skin cleaning wipe C4 containing 0.5% chlorhexidine gluconate and wipes the exposed surface of the base ring 1 and the skin around the nail track to remove surface stains and airborne bacteria.

[0052] Step S3: The user presses the exposed end of the core ring release assembly 14 from the outside of the base ring 1 with his / her finger. The buckle block 26 of the old function replacement core ring 20 disengages from the positioning groove 16. The user pinches the outer edge of the core ring with his / her finger to remove it. Throughout the process, the user's finger does not touch the bottom surface (medication surface) or the nail hole area of ​​the core ring.

[0053] Step S4: The user observes the color of the exudate absorption indicator layer 23 on the removed old core ring. If the exudate absorption indicator layer 23 remains yellow-green or the color change has not reached blue, it is considered a low risk of infection, and a new prophylactic core ring 20A is selected. If the exudate absorption indicator layer 23 has turned completely or mostly blue (indicating exudate pH ≥ 6.5), it is considered a high risk of infection, and a therapeutic core ring 20B is selected, and the user is advised to seek medical attention as soon as possible.

[0054] Step S5: The user removes the new functional replacement core ring 20 from the sterile packaging unit, peels off the peelable polyethylene protective film on its bottom surface, and exposes the skin to the healing-promoting layer 25.

[0055] Step S6: The user aligns the new core ring 20 with the irregular positioning protrusion on the base ring 1, so that the positioning protrusion 22 of the core ring is aligned with the corresponding positioning groove 16, and then presses down until all the snap-fit ​​blocks 26 are fully engaged and locked with the snap-fit ​​plate 143. At this time, a "click" sound can be heard or felt to indicate that the installation is in place.

[0056] Steps S3 to S5 above constitute a nursing cycle that can be repeatedly performed by the patient or their caregiver in a home environment, with each operation taking no more than 2 minutes. The preventive core ring 20A should be changed every 48 hours, and the therapeutic core ring 20B should be changed every 24-48 hours.

[0057] The initial installation procedure for base ring 1 is as follows: Performed by medical staff in the hospital post-surgery. Open the lateral opening 15 of base ring 1, slide it laterally into the ring from the side, and enclose the nail rod 3. After release, the permanent magnet 13 automatically attracts and closes the lateral opening 15. Adjust the position of the base ring so that the leak-proof sealing lip 17 evenly conforms to the skin around the nail entry point, and smoothly adhere the adhesive wing 11 to the surrounding intact skin. Then, install the first preventative core ring 20A according to steps S5-S6.

[0058] like Figure 5 As shown, this embodiment also provides an orthopedic external fixation device nail tract wound care kit, including: At least two base rings 1 with the same inner diameter specification that match the outer diameter of the patient's nail rod, one of which is installed and used, and one is a spare; at least fourteen preventive core rings 20A, calculated based on replacement every 48 hours and coverage for 4 weeks; and at least four therapeutic core rings 20B.

[0059] Each replacement core ring is individually sealed in an ethylene oxide sterilized aseptic packaging unit. The aseptic packaging unit is an aluminum foil / Tyvek composite heat-sealed bag containing: one replacement core ring, one pair of disposable sterile polyethylene gloves, and one C4 non-woven skin cleaning wipe containing 0.5% chlorhexidine gluconate.

[0060] The kit also includes an instruction manual, which contains illustrations of the replacement procedure and an infection warning checklist based on the color change of bromocresol green. The checklist is marked with standard color blocks corresponding to yellow-green (normal, pH < 6.5) and blue (indicating infection, pH ≥ 6.5) for users to compare and judge.

[0061] To verify the in vivo anti-infection effect of the device in this embodiment, an SD rat tibial external fixation nail orifice infection model was established for animal experiments.

[0062] Experimental animals: 15 adult male SD rats, weighing 250-280g, SPF grade; Experimental grouping: The animals were randomly divided into 3 groups of 5 each (n=5): (1) Blank control group: A stainless steel external fixation nail with a diameter of 1.5 mm was implanted in the proximal tibia of rats. The nail opening was covered with conventional sterile gauze and the device of the present invention was not used. (2) Preventive core ring group: After implanting external fixation nails into the proximal tibia of rats, the base ring 1 and the preventive core ring 20A of the present invention were installed, and the core ring was replaced every 48 hours; (3) Therapeutic core ring group: After implanting an external fixation nail into the proximal tibia of rats, 20 μL of Staphylococcus aureus (ATCC25923) suspension (concentration 1×10⁻⁶) was locally inoculated at the nail tract opening. 6 An infection model was established using CFU / mL, and then the base ring 1 and therapeutic core ring 20B of the present invention were installed. The core ring was replaced every 24 hours.

[0063] The observation period was 7 days. Tissue swabs were taken from around the nail tract opening on days 3 and 7 for bacterial culture and counting, and the inflammation score of the nail tract opening was determined according to the Checketts-Otterburns grading system. The results are shown in Table 1.

[0064] Table 1. Bacterial count and inflammation score at the nail puncture site in SD rats of each group (mean ± standard deviation, n=5) All experimental animals were sacrificed on day 7, and tissue around the nail puncture site was collected for HE staining and Masson's trichrome staining for histopathological evaluation. The results are shown in Table 2.

[0065] Table 2. Pathological assessment of tissues around the nail incision site in each group (mean ± standard deviation, n=5) As shown in Tables 1 and 2, the bacterial counts in the prophylactic core ring group were significantly lower than those in the blank control group on both days 3 and 7. The inflammation score decreased to 0.8 ± 0.4 on day 7, and the epithelialization rate reached 82.4%, indicating that the prophylactic core ring 20A can effectively prevent infection at the nail puncture site and promote healing. Although the therapeutic core ring group was initially inoculated with a large amount of Staphylococcus aureus, after intervention with the therapeutic core ring 20B, the bacterial count on day 3 decreased from 12.36 × 10⁻⁶. 3 Reduced to 3.28×10 3 CFU / mL, further decreased to 1.47×10 on day 7. 3 The CFU / mL level decreased, and the inflammation score dropped from 3.6 to 1.2, confirming that the biphasic release strategy of the therapeutic core ring can effectively control established pinway infection.

[0066] The in vitro cumulative drug release curve of the prophylactic core ring 20A was determined using the dialysis bag method. The drug-controlled release matrix layer 24 of the prophylactic core ring 20A was placed in a dialysis bag and immersed in PBS buffer containing 0.5% Tween 80. Samples were taken at each time point, and the cumulative release rates of silver sulfadiazine (SSD) and polyhexamethylene biguanide (PHMB) were determined by ultraviolet spectrophotometry. Five parallel samples were used in each group, and the results are shown in Table 3.

[0067] Table 3. Cumulative in vitro drug release rate of the prophylactic core ring (20A) (mean ± standard deviation, n=5) As shown in Table 3, the release curves of SSD and PHMB in the prophylactic core ring 20A exhibit near-zero-order characteristics: approximately 16%-20% cumulative release in the first 8 hours (the initial release phase of drug adsorbed on the shell surface), followed by continuous release at an almost constant rate, reaching cumulative releases of 83.6% and 88.2% respectively by 72 hours. This release kinetic characteristic is consistent with the design expectation of the core-shell coaxial electrospun fiber, confirming that the shell PCL / PLGA blend (70:30) can effectively regulate the continuous release of the core layer drug, meeting the clinical use cycle requirement of replacement every 48 hours.

[0068] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0069] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly and specifically defined.

[0070] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. An anti-infection sustained-release nursing ring device for the nail tract of an orthopedic external fixator, comprising a base ring (1), wherein the base ring (1) has an embedded through hole (12) in the middle, and a lateral opening (15) extending to the outside of the base ring (1) is provided on one side of the embedded through hole (12), wherein a removable functional replacement core ring (20) is embedded in the embedded through hole (12), wherein the functional replacement core ring (20) has a central through hole (21) matching the orthopedic external nail rod (3) in the middle, wherein the functional replacement core ring (20) comprises, from top to bottom, an exudate absorption indicator layer (23), a drug controlled-release matrix layer (24), and a skin contact healing-promoting layer (25), wherein the skin contact healing-promoting layer (25) is used to contact the skin around the orthopedic external nail rod (3), and wherein a pH-responsive color-changing indicator is dispersed in the exudate absorption indicator layer (23).

2. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The functional replacement core ring (20) is either a preventive core ring (20A) or a therapeutic core ring (20B). In the preventive core ring (20A), the drug-controlled release matrix layer (24) is a core-shell coaxial electrospun fiber membrane. The shell material is a blend of polycaprolactone and polylactic acid-glycolic acid copolymer. The core layer encapsulates at least one antibacterial active ingredient. The loading of the antibacterial active ingredient in the core layer is 0.5%–5.0% of the total fiber mass. The continuous release of the drug in the core layer is controlled by the shell degradation rate. The drug-controlled release matrix layer (24) in the therapeutic core ring (20B) consists of polylactic acid-glycolic acid copolymer microspheres suspended in a chitosan / β-glycerophosphate sodium thermosensitive hydrogel matrix. The microspheres have a particle size of 10–80 μm. The thermosensitive hydrogel undergoes a solution-gel transition within the range of 33–37°C to achieve in-situ fixation. The microspheres encapsulate at least one sustained-release antibacterial active ingredient, and the thermosensitive hydrogel matrix loads at least one fast-release antibacterial active ingredient that is different from the component loaded in the microspheres, thereby achieving biphasic release kinetics.

3. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 2, characterized in that: The shell material of the drug controlled-release matrix layer (24) in the preventive core ring (20A) has a mass ratio of polycaprolactone to polylactic acid-glycolic acid of 60:40 to 80:20 and a fiber diameter of 200 nm–2 μm.

4. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The skin contact healing layer (23) is composed of a medical-grade silicone gel mesh film or a hydrophilic polyurethane film, wherein at least one of human epidermal growth factor and sodium hyaluronate is loaded.

5. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The permeation absorption indicator layer (21) is composed of sodium carboxymethyl cellulose nonwoven fabric or calcium alginate fiber, wherein bromocresol green is uniformly dispersed as a pH-responsive color-changing indicator. When the pH value is ≥ When the seepage reaches 6.5, it changes from yellowish-green to blue.

6. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The base rings (1) on both sides of the lateral opening (15) are fitted with matching permanent magnets (13).

7. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The bottom of the base ring (1) is provided with a leak-proof sealing lip (17) around the embedded through hole (12).

8. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 1, characterized in that: The top side of the functional replacement core ring (20) is equipped with multiple positioning protrusions (22), and the top inner side of the base ring (1) is provided with positioning grooves (16) corresponding to the positioning protrusions (22).

9. The anti-infection sustained-release nursing ring device for the pinway of orthopedic external fixation brace according to claim 8, characterized in that: One of the positioning protrusions (22) is a snap-fit ​​block (26). A core ring release assembly (14) is horizontally installed on the base ring (1) at a position corresponding to the snap-fit ​​block (26). The core ring release assembly (14) includes a snap-fit ​​plate (143) that is horizontally slidably arranged. The snap-fit ​​plate (143) is provided with a snap-fit ​​through groove (144) that matches the snap-fit ​​block (26). One end of the snap-fit ​​plate (143) is an unlocking button (141) exposed on the outside of the base ring (1). A reset elastic element (142) is installed between the outside of the snap-fit ​​plate (143) and the base ring (1).

10. The anti-infection sustained-release nursing ring device for the pinway of an orthopedic external fixator according to claim 1, characterized in that: The base ring (1) is provided with at least one adhesive wing (11) on its outer bottom. The bottom surface of the adhesive wing (11) is coated with a medical low-allergenic silicone gel pressure-sensitive adhesive layer or an acrylic hydrogel pressure-sensitive adhesive layer, which is used to reversibly fix the base ring (1) to the intact skin surface around the nail entrance.

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