Portable ultrasonic debridement positive pressure lavage negative pressure drainage device

Abstract

A portable ultrasonic debridement positive-pressure lavage negative-pressure drainage device comprises a body, a miniature ultrasonic transducer, a power source, a controller, a positive-pressure perfusion pump and a negative-pressure suction pump, the power source, the controller, the positive-pressure perfusion pump and the negative-pressure suction pump are arranged in the body, the power source is electrically connected with the controller, the controller is connected with the miniature ultrasonic transducer through a first wire, and the miniature ultrasonic transducer is connected with the negative-pressure suction pump through a second wire. The controller is electrically connected with the positive-pressure perfusion pump and the negative-pressure suction pump, supplies power to the miniature ultrasonic transducer, the positive-pressure perfusion pump and the negative-pressure suction pump, controls the miniature ultrasonic transducer, the positive-pressure perfusion pump and the negative-pressure suction pump and controls the miniature ultrasonic transducer, the positive-pressure perfusion pump and the negative-pressure suction pump to work; four-channel cleaning of double-positive-pressure liquid inlet and double-negative-pressure liquid outlet is combined with high-low-frequency ultrasonic super debridement, the flushing coverage rate of a deep complex anatomical area is remarkably increased, bacterial biofilms stubborn attached to the surface of a prosthesis are effectively damaged and removed, residual infection sources are greatly reduced, and the effect of cleaning the surface of the prosthesis is achieved. The prosthesis is protected, and the rehabilitation of the patient is accelerated.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical devices, and in particular relates to a portable ultrasonic debridement positive-pressure irrigation and negative-pressure drainage device. Background Art

[0002] Periprosthetic joint infection (PJI) is a serious complication after prosthetic joint replacement, with an incidence of approximately 1-2%. Debridement and irrigation with prosthesis retention (DAIR) is commonly used to control infection, but the recurrence rate remains high, with a success rate of only approximately 50%. One of the key factors leading to debridement failure is incomplete debridement and residual biofilm. Bacteria on the surface of prosthetic joints are prone to forming biofilms, which are difficult to completely remove with conventional intraoperative management methods such as pulsed irrigation. Studies have shown that simple pulsed saline irrigation is insufficient to remove bacterial biofilms on the surface of prosthetic joints, and even postoperative antibiotic therapy can still lead to recurrence of infection due to residual biofilm. Traditional treatments rely more on systemic or topical antibiotics to eliminate residual bacteria, but fail to optimize biofilm removal strategies. Therefore, to improve the success rate of prosthesis retention and debridement, there is an urgent need to develop new mechanical and chemical debridement techniques that can preserve the joint capsule and soft tissue while minimizing biofilm removal for more effective infection control.

[0003] Existing wound irrigation negative pressure therapy devices (such as negative pressure closed drainage VAC devices, etc.) have been used in the treatment of chronic wounds, but most of them only use wound-embedded sponge foam combined with single-path negative pressure suction, lack active irrigation function, and have limited treatment effects on deep infected cavities and implant surfaces; some research devices attempt to add irrigation under negative pressure dressings, such as intermittent irrigation and drainage technology, but often only have one inlet tube and one drainage tube, with limited irrigation coverage, and the drainage path is easily blocked by tissue debris; loose tube interfaces when patients move may also cause leakage of liquid and air, affecting the therapeutic effect; in addition, traditional negative pressure irrigation systems are generally bulky and require an external power supply, which is not conducive to patients' free movement after surgery and is not convenient for continuous treatment outside the hospital.

[0004] Ultrasonic debridement has recently demonstrated unique advantages in the management of difficult-to-heal wounds. Low-frequency ultrasound (approximately 20-40 kHz) selectively removes inactivated tissue and bacterial biofilms through cavitation and acoustic streaming, leaving little damage to surrounding healthy soft tissue. Clinical applications have demonstrated that low-frequency ultrasound debridement not only has a direct debridement effect but also improves the effectiveness of antibiotics in infection control and accelerates wound healing. However, current ultrasound debridement is primarily performed as a standalone surgical procedure or at the bedside, and has not yet been integrated with continuous wound irrigation and drainage devices. In summary, existing technologies present numerous deficiencies in the postoperative management of periprosthetic infections. A novel integrated irrigation and aspiration device with a multi-channel, anti-clogging irrigation and drainage structure and integrated high- and low-frequency ultrasound debridement capabilities is urgently needed to improve the removal of biofilms from deep wounds, enhance infection control, and provide portability for continued postoperative treatment. Summary of the Invention

[0005] In response to the deficiencies in the above-mentioned background technology, the present invention provides a portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device, which is particularly suitable for the continuous irrigation and drainage treatment of deep tissue infections such as post-operative debridement of periprosthetic joint infections. The device focuses on solving the following technical problems: how to achieve more comprehensive and efficient irrigation and negative pressure drainage in the deep infection cavity of the joint, prevent pipeline blockage and liquid leakage, and use ultrasonic energy to increase the clearance rate of bacterial biofilms, thereby better controlling infection, protecting the prosthesis and promoting healing.

[0006] A portable ultrasonic debridement positive-pressure irrigation and negative-pressure drainage device includes a body, a miniature ultrasonic transducer, a power supply, a controller, a positive-pressure irrigation pump, and a negative-pressure suction pump. The power supply, the controller, the positive-pressure irrigation pump, and the negative-pressure suction pump are arranged in the body. The power supply is electrically connected to the controller. The controller is connected to the miniature ultrasonic transducer via a first wire. The controller is electrically connected to the positive-pressure irrigation pump and the negative-pressure suction pump. The controller supplies power to the miniature ultrasonic transducer, the positive-pressure irrigation pump, and the negative-pressure suction pump and controls the miniature ultrasonic transducer, the positive-pressure irrigation pump, and the negative-pressure suction pump. The positive pressure perfusion pump has two positive pressure liquid outlet interfaces and one positive pressure liquid inlet interface. Both positive pressure liquid outlet interfaces are connected to the positive pressure liquid outlet tube, and the positive pressure liquid inlet interface is connected to the positive pressure liquid inlet tube; the negative pressure suction pump has two negative pressure liquid inlet interfaces and one negative pressure liquid outlet interface. Both negative pressure liquid inlet interfaces are connected to the negative pressure liquid inlet tube, and the negative pressure liquid outlet interface is connected to the negative pressure liquid outlet tube; the positive pressure liquid outlet tube, positive pressure liquid inlet tube, negative pressure liquid inlet tube and negative pressure liquid outlet tube are all disposable tubes.

[0007] The miniature ultrasonic transducer includes a miniature low-frequency ultrasonic transducer and a miniature high-frequency ultrasonic transducer. The miniature low-frequency ultrasonic transducer is installed on the front end of a positive pressure liquid inlet pipe, and the miniature high-frequency ultrasonic transducer is installed on the front end of another positive pressure liquid inlet pipe.

[0008] The ultrasonic frequency emitted by the miniature low-frequency ultrasonic transducer is 20-40 kHz, preferably 25-30 kHz; the ultrasonic frequency emitted by the miniature high-frequency ultrasonic transducer is 0.8-3 MHz.

[0009] The ultrasonic frequency emitted by the miniature low-frequency ultrasonic transducer is 20-40 kHz, preferably 25-30 kHz; the ultrasonic frequency emitted by the miniature high-frequency ultrasonic transducer is 0.8-3 MHz.

[0010] A plurality of spray holes are provided on the front circumference of the positive pressure liquid outlet pipe to diffuse the flow direction of the flushing liquid.

[0011] A plurality of through holes are opened on the front circumference of the negative pressure liquid inlet pipe to increase the drainage channel area and avoid blockage of a single aperture.

[0012] The front sections of the positive pressure liquid outlet pipe and the negative pressure liquid inlet pipe are sleeved with elastic sealing rings.

[0013] The elastic sealing ring is made of silicone.

[0014] The front end pipeline at the interface between the elastic sealing ring and the skin is filled with medical sealant, which is beneficial to the flexion and extension of the joint and prevents leakage.

[0015] The medical sealants include natural sealants, semi-synthetic sealants or fully synthetic sealants. Natural sealants include fibrin sealants, semi-synthetic sealants include gelatin and albumin sealants, and fully synthetic sealants include acrylate and polyethylene glycol sealants.

[0016] The positive pressure perfusion pump is equipped with a liquid outlet pressure sensor, which is connected to the controller. A drug concentration sensor and an impedance sensor are provided next to the through hole of the negative pressure liquid inlet pipe. Both the drug concentration sensor and the impedance sensor are connected to the controller through a second wire. The drug concentration sensor monitors the antibiotic concentration value in real time, and the impedance sensor monitors the biofilm removal status in real time and provides feedback to adjust the ultrasonic power.

[0017] The high-frequency ultrasonic wave adopts a pulse modulation mode, and the pulse modulation mode is working for 2 seconds and resting for 1 second.

[0018] The micro ultrasonic transducer is composed of 4 to 6 micro piezoelectric ceramic pieces.

[0019] The micro ultrasonic transducer, power supply, controller, positive pressure perfusion pump, negative pressure suction pump, liquid outlet pressure sensor, drug concentration sensor, impedance sensor are all existing technologies. Working process and principle of the present invention: Two positive pressure outlet tubes and two negative pressure inlet tubes are connected to the patient's surgical area. The positive pressure outlet tubes and the negative pressure inlet tubes are arranged in pairs and are inserted and implanted from both ends of the joint cavity (such as the proximal and distal ends, the head side and the tail side of the incision) respectively, so as to form head-to-tail relative flushing and drainage pathways inside the joint cavity. The two positive pressure outlet tubes are synchronously connected to the positive pressure perfusion pump, and the positive pressure inlet tube is connected to the positive pressure inlet interface, realizing dual-path synchronous positive pressure irrigation and drug administration; the two negative pressure inlet tubes are synchronously connected to the negative pressure suction pump, and the negative pressure outlet tube is connected to the negative pressure outlet interface, realizing dual-path synchronous negative pressure drainage. Through this dual-channel forward and reverse layout, the flushing fluid can cover the entire area of ​​the joint cavity, forming a circulating flow, and effectively flushing debris and bacteria in the deep tissue gap out of the body.

[0020] To prevent the negative pressure liquid inlet tube from being blocked by tissue fragments, several through holes are opened at the end of each negative pressure liquid inlet tube to increase the drainage channel area and avoid blockage of a single aperture.

[0021] A number of spray holes are provided at the end of each positive pressure liquid outlet pipe to diffuse the flow direction of the flushing liquid.

[0022] The front section of the positive pressure liquid outlet tube and the negative pressure liquid inlet tube is provided with an elastic sealing ring. The elastic sealing ring is located at the interface of the skin and can fit tightly to the skin around the needle hole. The elastic sealing ring effectively prevents the flushing fluid from seeping and leaking through the skin wound while fixing the positive pressure liquid outlet tube and the negative pressure liquid inlet tube, thereby avoiding external contamination and drainage failure. In addition, the front end pipeline at the interface between the elastic sealing ring and the skin is filled with medical sealant, which has a self-sealing and leak-proof function to prevent the interface from loosening and causing air leakage when the patient accidentally pulls it. The use of elastic sealing ring and medical sealant ensures the closed, safe and reliable smoothness of the continuous flushing and drainage process, and is beneficial to joint flexion and extension.

[0023] The micro-ultrasonic transducer is integrated into the irrigation and drainage system. The ultrasonic frequencies emitted by the micro-ultrasonic transducer are 20~40kHz and 0.8~3MHz. The 20~40kHz is low-frequency ultrasound, which mainly generates strong mechanical vibrations through cavitation to remove biofilm and necrotic tissue on the tissue surface. Studies have shown that the risk of thermal damage to tissues caused by ultrasound in the 20~40kHz frequency band is very low, and it almost does not cause adverse effects on surrounding healthy soft tissues. In particular, low-frequency ultrasound of about 25~30kHz can selectively dissolve fibrin and biofilm on the wound surface without damaging granulation tissue. High-frequency ultrasound of 0.8~3MHz mainly uses its thermal effect and acoustic flow effect to promote wound healing and drug penetration. At a safe intensity (for example, about 0.5–1.0W / cm 2) can cause a slight local temperature increase, promoting blood flow and tissue metabolism, aiding soft tissue healing, and increasing bacterial susceptibility. This invention organically combines high-frequency and low-frequency ultrasound: low-frequency ultrasound generates cavitational microbubble explosions and strong flow shear within the irrigant medium, mechanically disrupting bacterial aggregates and biofilm structures. Meanwhile, high-frequency ultrasound provides relatively uniform and delicate vibrations, enhancing tissue penetration and inhibiting residual microorganisms, thereby promoting infection control and tissue repair at the microscopic level. The simultaneous or alternating action of ultrasonic vibrations at these two frequencies makes the irrigation process equivalent to superimposed ultrasonic debridement, enhancing the noninvasive and efficient debridement of deep-seated infections. Domestic and international research and patent literature demonstrate that controlling ultrasonic frequencies within the 20-20 kHz and 800 kHz-4 MHz ranges for wound debridement is a feasible and safe option. Therefore, the high- and low-frequency ultrasound parameters employed in this invention are within the generally recognized safe and effective ranges, significantly enhancing debridement effectiveness without damaging soft tissue. A micro-ultrasonic transducer within the positive pressure outlet tube uses a phase-controlled beamforming algorithm to focus the low-frequency ultrasonic energy on the prosthesis surface, with a focusing accuracy of ±1.5 mm.

[0024] The high-frequency ultrasound adopts a pulse modulation mode to ensure that the temperature rise of the tissue is ≤2°C; the impedance sensor 64 monitors the biofilm removal status in real time and provides feedback to adjust the ultrasound power.

[0025] When the flushing fluid flows through the positive pressure outlet tube into the joint cavity, the ultrasonic generator is started, so that the fluid carries ultrasonic energy to act on the tissues in the joint cavity and the surface of the prosthesis.

[0026] After the surgical debridement is completed, a positive pressure drainage tube is placed into the joint cavity to ensure that the micro-ultrasound transducer directly or indirectly contacts the prosthesis surface and the infected area.

[0027] Treatment process: Start the positive pressure perfusion pump to inject the antibiotic flushing solution into the joint cavity through the positive pressure outlet tube. Synchronize the miniature ultrasonic transducer. The miniature ultrasonic transducer vibrates directly on the surface of the prosthesis and surrounding tissues through the flushing solution and the tube wall. Low-frequency ultrasound (20~40kHz) produces a microbubble cavitation effect in the liquid, destroying the bacterial biofilm through the shear force of the microbubble rupture, selectively removing necrotic tissue and biofilm without damaging the surrounding healthy soft tissue; high-frequency ultrasound (0.8~3MHz) vibrates gently, enhancing the penetration of drugs into the tissue, promoting local blood circulation and new tissue growth.

[0028] The hydraulic pressure sensor of the positive pressure perfusion pump senses the pressure of the irrigation fluid in the positive pressure outlet tube and transmits the pressure signal to the controller. The controller accurately adjusts the positive pressure irrigation and negative pressure suction parameters. The positive pressure irrigation pressure is controlled within a safe range of 4~15psi (pounds per square inch). According to the AHCPR guidelines, an irrigation pressure of 4~15psi is sufficient to remove pathogens and debris on the surface of the wound without causing additional damage to the tissue. An irrigation pressure below 4psi may not effectively remove bacterial biofilms, while an irrigation pressure exceeding 15psi may damage the tissue and squeeze bacteria into deeper tissues. Animal experiments have also found that pulse irrigation above 20psi can cause normal muscle Meat tissue cell necrosis and calcification, and affect wound healing, so the present invention strictly limits the flushing pressure to no more than 15psi, thereby avoiding soft tissue impact injury and the risk of incision rupture, and ensuring the safety of the flushing process; similarly, the negative pressure suction pressure can also be adjusted to an appropriate level (for example, continuous negative pressure of -50 to -125mmHg) to ensure effective drainage without causing tissue bleeding or excessive pain; due to the use of a low-pressure, long-term flushing mode, the flushing solution containing antibiotics can fully moisten and penetrate the local infected area without entering the blood circulation at a high speed and in large quantities, reducing the risk of excessive absorption of systemic antibiotics, and achieving efficient local administration without increasing systemic adverse reactions.

[0029] There is a drug concentration sensor next to the negative pressure inlet tube. The drug concentration sensor is connected to the controller to detect the antibiotic concentration (such as vancomycin) in the drainage fluid every 5 minutes. The positive pressure perfusion pump is linked through the controller's PID algorithm to dynamically adjust the drug administration rate to maintain the drug concentration in the joint cavity within the therapeutic window of 10~20μg / mL.

[0030] When the concentration exceeds the standard, it automatically switches to normal saline flushing to avoid systemic toxicity.

[0031] The various components of the present invention are controlled by a controller, which can pre-set the flushing-residence-suction cycle program, for example, automatically performing positive pressure irrigation for a certain period of time at regular intervals, then stopping irrigation and continuing negative pressure drainage to periodically flush the infected area; the miniature ultrasonic transducer is also controlled by the controller, and low-frequency and / or high-frequency ultrasonic vibration debridement is synchronously turned on during the flushing period, or it works intermittently as needed. The positive pressure outlet tube, positive pressure inlet tube, negative pressure inlet tube, and negative pressure outlet tube are all disposable tubes; the miniature ultrasonic transducer, drug concentration sensor, and impedance sensor can be reused after disinfection.

[0032] The positive pressure liquid outlet tube and the negative pressure liquid inlet tube have flexible fixing methods and can be fixed to the patient's limbs through elastic bandages or clamps, so that the patient can still move appropriately while wearing the device after surgery; compared with traditional bulky irrigation and suction equipment, the present invention is more suitable for continuous treatment and rehabilitation of patients after surgery, significantly improving the convenience of clinical application and patient comfort.

[0033] Beneficial effects of the present invention: 1. Comprehensive and efficient flushing coverage: The four-channel arrangement of dual positive pressure inlet + dual negative pressure outlet achieves bidirectional synchronous flushing and multi-point drainage in the infected joint cavity. The flushing fluid enters from both ends of the joint cavity and circulates, significantly improving the flushing coverage of deep complex anatomical areas, avoiding the blind spots of traditional single-channel flushing, and helping to thoroughly flush away pus, debris and detached biofilm on the surface of the prosthesis and soft tissue.

[0034] 2. Anti-blocking and anti-leakage and reliable pipelines: The spray holes provided on the positive pressure liquid outlet pipe of the present invention can diffuse the flow direction of the flushing liquid; the through holes provided on the negative pressure liquid inlet pipe can increase the drainage channel area to avoid blockage of a single aperture, effectively preventing the negative pressure liquid inlet pipe from being blocked by fibrous tissue or blood clots, and ensuring that the passage is unobstructed during long-term use; at the same time, the pipeline puncture port is tightly sealed by an elastic sealing ring and medical sealant, avoiding the extravasation of flushing liquid to contaminate the surrounding skin or dressings. Even if the patient moves moderately after the operation, the pipeline interface can still remain stable and airtight, and will not cause air leakage or liquid leakage due to pulling and displacement, thereby greatly improving the safety and continuity of the device operation.

[0035] 3. Ultrasound-assisted debridement: Unlike existing devices that rely solely on liquid flushing, the present invention incorporates high- and low-frequency ultrasonic synchronous debridement functions into a miniature ultrasonic transducer. Under the action of low-frequency cavitation, bacterial biofilms stubbornly attached to the surface of the prosthesis are effectively destroyed and removed, significantly reducing residual sources of infection; high-frequency ultrasound further enhances the bactericidal and healing effects of local flushing. Literature shows that low-frequency ultrasonic debridement can selectively remove inactivated tissue without damaging normal tissue, and can improve the efficiency of antibiotic control of infection by destroying bacterial biofilms on the wound surface. Therefore, the present invention uses ultrasound-assisted flushing to achieve deep biofilm removal that is difficult to achieve with traditional mechanical debridement, thereby improving the thoroughness of infection control. This is of great significance in improving the success rate of prosthesis retention surgery, and the removal rate of biofilms on the surface of deep prostheses is greatly improved compared to traditional ultrasound.

[0036] 4. Safe and gentle flushing environment: The present invention controls the flushing pressure and ultrasonic intensity within a safe range, achieving a balance between efficient debridement and tissue protection. Low-pressure pulse irrigation can not only fully clean the wound, but also avoid tissue damage and bacterial dissemination that may be caused by high pressure; the operating frequency and power of the miniature ultrasonic transducer are optimized and will not cause thermal damage to soft tissue or pain and discomfort. Therefore, the continuous flushing process is more friendly to new granulation tissue and the healing environment, which is conducive to wound healing.

[0037] 5. The equipment is light and easy to carry, and continuous treatment is convenient: The present invention is small in size and light in weight, and truly realizes portable flushing negative pressure treatment. Patients do not need to stay in bed and be fixed next to large equipment after surgery, but can receive continuous wound cavity flushing and negative pressure drainage treatment on the move; this not only improves the patient's comfort and self-care ability, but also facilitates follow-up treatment outside the hospital, reducing hospitalization time and medical costs; compared with the existing technology, the present invention greatly improves the portability and ease of use of the equipment while ensuring therapeutic efficacy.

[0038] 6. Drug administration safety closed-loop control: Microfluidic drug monitoring has increased the local antibiotic concentration compliance rate to, and the systemic blood drug concentration is always below the toxicity threshold.

[0039] 7. Dynamic sealing: The sealing interface of the elastic sealing ring and medical sealant maintains zero leakage at 90° joint motion, improving the patient's freedom of movement.

[0040] In summary, the present invention solves the problems of incomplete irrigation of deep wound cavities and easy blockage of pipelines through a multi-channel anti-blocking design in structure. Functionally, the introduction of pulsed high and low frequency ultrasound improves the efficiency of biofilm removal and infection control effect, and takes into account safety and portability. It has significant innovation and clinical application value, especially after artificial joint infection and prosthesis debridement surgery, it is expected to improve the infection clearance rate, protect the prosthesis, and accelerate patient recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 is a schematic diagram of the present invention being used in an artificial joint cavity; Figure 3 This is an enlarged schematic diagram of the terminal structure of the positive pressure liquid outlet pipe of the present invention; Figure 4 This is a schematic diagram of the operation of the micro ultrasonic transducer of the present invention, showing the micro ultrasonic transducer acting on the tissue surface and the effect of the cavitation microbubbles of the flushing fluid in removing biofilm. DETAILED DESCRIPTION

[0042] like Figures 1 to 4 As shown, a portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device includes a body 1, two miniature ultrasonic transducers 2, a power supply 3, a controller 4, a positive pressure irrigation pump 5 and a negative pressure suction pump 6. The power supply 3, the controller 4, the positive pressure irrigation pump 5 and the negative pressure suction pump 6 are arranged in the body 1, the power supply 3 is electrically connected to the controller 4, the controller 4 is connected to the miniature ultrasonic transducer 2 through a first wire 21, the controller 4 is electrically connected to the positive pressure irrigation pump 5 and the negative pressure suction pump 6, and the controller 4 supplies power to the miniature ultrasonic transducer 2, the positive pressure irrigation pump 5 and the negative pressure suction pump 6 and controls the miniature ultrasonic transducer 2, the positive pressure irrigation pump 5 and the negative pressure suction pump 6; The positive pressure perfusion pump 5 has two positive pressure liquid outlet interfaces 51 and one positive pressure liquid inlet interface 52. Both positive pressure liquid outlet interfaces 51 are connected to a positive pressure liquid outlet pipe 511, and the positive pressure liquid inlet interface 52 is connected to a positive pressure liquid inlet pipe 521; the negative pressure suction pump 6 has two negative pressure liquid inlet interfaces 61 and one negative pressure liquid outlet interface 62. Both negative pressure liquid inlet interfaces 61 are connected to a negative pressure liquid inlet pipe 611, and the negative pressure liquid outlet interface 62 is connected to a negative pressure liquid outlet pipe 621; the positive pressure liquid outlet pipe 511, the positive pressure liquid inlet pipe 521, the negative pressure liquid inlet pipe 611 and the negative pressure liquid outlet pipe 621 are all disposable tubes.

[0043] The miniature ultrasonic transducer 2 includes a miniature low-frequency ultrasonic transducer and a miniature high-frequency ultrasonic transducer. The miniature low-frequency ultrasonic transducer is installed on the front end of a positive pressure liquid inlet pipe 521, and the miniature high-frequency ultrasonic transducer is installed on the front end of another positive pressure liquid inlet pipe 521.

[0044] The ultrasonic frequency emitted by the miniature low-frequency ultrasonic transducer is 20-40 kHz, preferably 25-30 kHz; the ultrasonic frequency emitted by the miniature high-frequency ultrasonic transducer is 0.8-3 MHz.

[0045] A plurality of spray holes 512 are provided on the front circumference of the positive pressure liquid outlet pipe 511 to diffuse the flow of the flushing liquid.

[0046] A plurality of through holes 612 are provided on the front circumference of the negative pressure liquid inlet pipe 611 to increase the drainage channel area and avoid blockage of a single aperture.

[0047] The front sections of the positive pressure liquid outlet pipe 511 and the negative pressure liquid inlet pipe 611 are sleeved with elastic sealing rings 53 .

[0048] The elastic sealing ring 53 is made of silicone.

[0049] The front end pipeline at the interface between the elastic sealing ring 53 and the skin is filled with medical sealant 54, which is beneficial to the flexion and extension of the joint and prevents leakage.

[0050] The medical sealant 54 includes natural sealants, semi-synthetic sealants or fully synthetic sealants. Natural sealants include fibrin sealants, semi-synthetic sealants include gelatin and albumin sealants, and fully synthetic sealants include acrylate and polyethylene glycol sealants.

[0051] The positive pressure perfusion pump 5 is equipped with a liquid outlet pressure sensor, which is connected to the controller 4. A drug concentration sensor 63 and an impedance sensor 64 are provided next to the through hole 612 of the negative pressure liquid inlet pipe 611. Both the drug concentration sensor 63 and the impedance sensor 64 are connected to the controller 4 via a second wire 65. The drug concentration sensor 63 monitors the antibiotic concentration value in real time, and the impedance sensor 64 monitors the biofilm removal status in real time and provides feedback to adjust the ultrasonic power. Since the liquid outlet pressure sensor is built-in, it is not shown in the figure.

[0052] The high-frequency ultrasonic wave adopts a pulse modulation mode, and the pulse modulation mode is working for 2 seconds and resting for 1 second.

[0053] The micro ultrasonic transducer 2 is composed of 4 to 6 micro piezoelectric ceramic pieces.

[0054] The micro ultrasonic transducer 2, power supply 3, controller 4, positive pressure perfusion pump 5, negative pressure suction pump 6, liquid outlet pressure sensor, drug concentration sensor 63, impedance sensor 64 are all existing technologies. Working process and principle of the present invention: Two positive pressure outlet tubes 511 and two negative pressure inlet tubes 611 are connected to the patient's surgical area. The positive pressure outlet tubes 511 and the negative pressure inlet tubes 611 are arranged in pairs and are inserted and implanted from both ends of the joint cavity (for example, the proximal and distal ends, the head side and the tail side of the incision) respectively, so as to form head-to-tail relative flushing and drainage passages inside the joint cavity. The two positive pressure outlet tubes 511 are synchronously connected to the positive pressure perfusion pump 5, and the positive pressure inlet tube 521 is connected to the positive pressure inlet interface 52, realizing dual-path synchronous positive pressure irrigation and drug administration; the two negative pressure inlet tubes 611 are synchronously connected to the negative pressure suction pump 6, and the negative pressure outlet tube 621 is connected to the negative pressure outlet interface 62, realizing dual-path synchronous negative pressure drainage. Through this dual-channel forward and reverse layout, the flushing fluid can cover the entire area of ​​the joint cavity, forming a circulating flow, and effectively flushing debris and bacteria in the deep tissue gap out of the body.

[0055] In order to prevent the negative pressure liquid inlet tube 611 from being blocked by tissue fragments, a plurality of through holes 612 are provided at the end of each negative pressure liquid inlet tube 611 to increase the drainage channel area and avoid blockage of a single aperture.

[0056] A plurality of spray holes 512 are provided at the end of each positive pressure liquid outlet pipe 511 to diffuse the flow of the flushing liquid.

[0057] The front ends of the positive pressure liquid outlet tube 511 and the negative pressure liquid inlet tube 611 are sleeved with an elastic sealing ring 53. The elastic sealing ring 53 is located at the interface of the skin A and can fit tightly to the skin around the needle hole. The elastic sealing ring 53 effectively prevents the flushing liquid from seeping out and leaking through the skin wound while fixing the positive pressure liquid outlet tube 511 and the negative pressure liquid inlet tube 611, thereby avoiding external contamination and drainage failure. In addition, the front end pipeline at the interface between the elastic sealing ring 53 and the skin is filled with medical sealant 54, which has a self-sealing and leak-proof function to prevent the interface from loosening and causing air leakage when the patient accidentally pulls it. The use of the elastic sealing ring 53 and the medical sealant 54 ensures the closed safety and reliable smoothness of the continuous flushing and drainage process, and is beneficial to joint flexion and extension activities.

[0058] The micro ultrasonic transducer 2 is integrated into the irrigation and drainage system. The ultrasonic frequency emitted by the micro low-frequency ultrasonic transducer is 20~40kHz, and the ultrasonic frequency emitted by the micro high-frequency ultrasonic transducer is 0.8~3MHz. 20~40kHz is low-frequency ultrasonic wave, which mainly generates strong mechanical vibration through cavitation to remove biofilm and necrotic tissue on the tissue surface. Studies have shown that the risk of thermal damage to tissues caused by ultrasound in the 20~40kHz frequency band is very low, and it will hardly cause adverse effects on surrounding healthy soft tissues. In particular, low-frequency ultrasound of about 25~30kHz can selectively dissolve fibrin and biofilm on the wound surface without damaging granulation tissue. 0.8~3MHz is high-frequency ultrasonic wave, which mainly uses its thermal effect and acoustic flow effect to promote wound healing and drug penetration. At a safe intensity (for example, about 0.5–1.0W / cm 2 ) will cause a slight increase in local temperature, promote blood flow and tissue metabolism, help soft tissue healing and increase bacterial sensitivity. The present invention organically combines high-frequency and low-frequency ultrasound. Low-frequency ultrasound produces cavitation microbubble explosion and strong flow shear in the flushing liquid medium, such as Figure 4 As shown, the bacterial aggregation and biofilm structure are mechanically destroyed; at the same time, high-frequency ultrasound provides relatively uniform and delicate vibrations, which can enhance the penetration of the irrigation fluid into the tissue and inhibit residual microorganisms, promoting infection control and tissue repair at the microscopic level. The synchronous or alternating action of the two frequency bands of ultrasonic vibration makes the irrigation process equivalent to superimposed ultrasonic debridement, improving the non-invasive and efficient debridement capabilities of deep infection sites. Domestic and foreign research and patent literature have shown that controlling the ultrasonic frequency within the two ranges of 20~20kHz and 800kHz~4MHz for wound debridement is a feasible and safe option; therefore, the high and low frequency ultrasonic parameters used in the present invention are within the recognized safe and effective range, which can significantly enhance the debridement effect without damaging soft tissue; the miniature low-frequency ultrasonic transducer in the positive pressure outlet tube 511 focuses the low-frequency ultrasonic energy on the surface of the prosthesis through a phase-controlled beamforming algorithm, with a focusing accuracy of ±1.5mm.

[0059] The high-frequency ultrasound adopts a pulse modulation mode to ensure that the temperature rise of the tissue is ≤2°C; the impedance sensor 64 monitors the biofilm removal status in real time and provides feedback to adjust the ultrasound power.

[0060] When the flushing fluid flows through the positive pressure outlet tube 511 and enters the joint cavity D, the miniature low-frequency ultrasonic transducer is activated, so that the fluid carries ultrasonic energy to act on the tissues in the joint cavity and the surface of the prosthesis.

[0061] After the surgical debridement is completed, the positive pressure liquid outlet tube 51 is placed into the joint cavity to ensure that the micro ultrasonic transducer 2 directly or indirectly contacts the prosthesis surface and the infected area.

[0062] Treatment process: The positive pressure perfusion pump 5 is started to inject the antibiotic flushing solution into the joint cavity D through the positive pressure outlet tube 511 under positive pressure. The micro ultrasonic transducer 2 is synchronized. The micro ultrasonic transducer 2 vibrates directly on the surface of the total knee prosthesis D and the surrounding tissue through the flushing solution and the tube wall. The low-frequency ultrasound (20-40kHz) produces a microbubble cavitation effect in the liquid. The shear force caused by the rupture of the microbubbles destroys the bacterial biofilm, selectively removing necrotic tissue and biofilm without damaging the surrounding healthy soft tissue. The high-frequency ultrasound (0.8-3MHz) vibrates gently, enhancing the penetration of drugs into the tissue, promoting local blood circulation and the growth of new tissue.

[0063] The liquid pressure sensor 55 of the positive pressure perfusion pump 5 senses the pressure of the irrigation liquid in the positive pressure outlet pipe 511 and transmits the pressure signal to the controller 4. The controller 4 accurately adjusts the positive pressure irrigation and negative pressure suction parameters. The positive pressure irrigation pressure is controlled within a safe range of 4 to 15 psi (pounds per square inch). According to the American AHCPR guidelines, an irrigation pressure of 4 to 15 psi is sufficient to remove pathogens and debris on the surface of the wound without causing additional damage to the tissue. An irrigation pressure below 4 psi may not effectively remove bacterial biofilms, while an irrigation pressure exceeding 15 psi may damage the tissue and squeeze bacteria into deeper tissues. Animal experiments have also found that pulse irrigation above 20 psi can It causes necrosis and calcification of normal muscle tissue cells and affects wound healing. Therefore, the present invention strictly limits the flushing pressure to no more than 15psi, thereby avoiding the risk of soft tissue impact injury and incision rupture, and ensuring the safety of the flushing process; similarly, the negative pressure suction pressure can also be adjusted to an appropriate level (for example, continuous negative pressure of -50 to -125mmHg) to ensure effective drainage without causing tissue bleeding or excessive pain; due to the use of a low-pressure and long-term flushing mode, the antibiotic-containing flushing solution can fully moisten and penetrate the local infected area without entering the blood circulation at high speed and in large quantities, reducing the risk of excessive absorption of systemic antibiotics and achieving efficient local administration without increasing systemic adverse reactions.

[0064] The drug concentration sensor 63 next to the negative pressure liquid inlet tube 611 is connected to the controller 4 to detect the antibiotic concentration (such as vancomycin) in the drainage fluid every 5 minutes. The PID algorithm of the controller 4 is linked to the positive pressure perfusion pump 5 to dynamically adjust the drug administration rate to maintain the drug concentration in the joint cavity within the therapeutic window of 10~20μg / mL.

[0065] When the concentration exceeds the standard, it automatically switches to normal saline flushing to avoid systemic toxicity.

[0066] Each component of the present invention is controlled by a controller 4, which can pre-set a flushing-residence-suction cycle program. For example, positive pressure irrigation is automatically performed at regular intervals for a certain period of time, and then irrigation is stopped and negative pressure drainage is continued to periodically flush the infected area. The micro-ultrasonic transducer 2 is also controlled by the controller 4. Low-frequency and / or high-frequency ultrasonic vibration debridement is synchronously activated during the flushing period, or it can be operated intermittently as needed. The positive pressure outlet tube 511, positive pressure inlet tube 521, negative pressure inlet tube 611, and negative pressure outlet tube 621 are all disposable tubes. The micro-ultrasonic transducer 2, drug concentration sensor 63, and impedance sensor 64 can be reused after disinfection.

[0067] The positive pressure liquid outlet tube 511 and the negative pressure liquid inlet tube 611 are fixed flexibly and can be fixed to the patient's limbs by elastic bandages or clamps, so that the patient can still move appropriately while wearing the device after surgery; compared with traditional bulky irrigation and suction equipment, the present invention is more suitable for continuous treatment and rehabilitation of patients after surgery, which significantly improves the convenience of clinical application and patient comfort.

[0068] Treatment Examples: Cooperate Figure 1 、 Figure 2 and Figure 3 As shown, a patient with early postoperative infection after total knee prosthesis D replacement underwent debridement surgery to retain the prosthesis, and then underwent postoperative continuous irrigation and aspiration therapy using the present invention. First, the granulation tissue, pus, and loose soft tissue surrounding the prosthesis within the infection site were thoroughly removed as per routine procedures, and the joint cavity was initially irrigated with low-pressure pulsed saline (pressure controlled at approximately 8 psi). Subsequently, two positive-pressure outlet tubes 511 and two negative-pressure inlet tubes 611 of the present invention were implanted into the joint cavity from the proximal and distal ends of the surgical incision, respectively. A miniature ultrasonic transducer 2 was subsequently implanted, along with a drug concentration sensor 63 and an impedance sensor 64. One positive-pressure outlet tube 511 was inserted along the upper side of the joint to the deep part of the cavity, while the other positive-pressure outlet tube 511 was placed at the distal end below the joint. The two negative-pressure inlet tubes 611 were placed on opposite sides of the positive-pressure outlet tubes 511 to ensure unobstructed fluid circulation throughout the joint cavity. The points where they penetrated the skin were covered with elastic sealing rings 53 and medical sealant 54 to secure them to the skin, ensuring no leakage at the interface.

[0069] The two positive pressure outlet tubes 511 are respectively connected to the positive pressure outlet interface 51 of the positive pressure perfusion pump 5, and the positive pressure inlet interface 52 of the positive pressure perfusion pump 5 is connected to the perfusion fluid bag B filled with normal saline and added with antibiotics (such as vancomycin); the negative pressure inlet tube 611 is connected to the negative pressure inlet interface 61 of the negative pressure suction pump 6, and the negative pressure outlet interface 62 of the negative pressure suction pump 6 is connected to the drainage bag C. Adjust the controller 4 to set the positive pressure perfusion pressure to about 10psi and the negative pressure suction negative pressure value to -80mmHg. Perform a flushing-drainage cycle every 30 minutes, that is, first turn on the positive pressure perfusion pump 5 to perfuse for 5 minutes, and at the same time turn on the negative pressure suction pump 6 to maintain drainage, then stop perfusion but maintain negative pressure drainage for 25 minutes, and repeat the cycle in an intermittent manner.

[0070] During the flushing process, the controller 4 starts the micro ultrasonic transducer 2 synchronously and turns on the ultrasonic debridement mode. The micro low-frequency ultrasonic transducer is located on the wall of the positive pressure outlet tube 511 and generates cavitation vibration on the output liquid during perfusion. Figure 4 As shown; the miniature high-frequency ultrasonic transducer is located at the end of the positive pressure liquid outlet tube 511 and is adjacent to the surface of the prosthesis to provide continuous high-frequency micro-vibration to the deep area. According to the program setting of the controller 4, the low-frequency ultrasound can be turned on each time the flushing liquid flows, and the high-frequency ultrasound continues to work for a longer time to promote the removal of residual bacteria and tissue healing; medical staff can adjust the ultrasound power intensity according to the patient's tolerance. In this example, the low-frequency ultrasound power density is about 0.2W / cm 2 , high-frequency ultrasound is about 0.5W / cm 2 The patient did not complain of obvious discomfort.

[0071] After 3-5 days of continuous treatment with the present invention, there was no obvious exudate in the patient's joint incision, the negative pressure drainage fluid gradually changed from bloody to clear, and no significant bacterial growth was found in the culture. Under the action of daily ultrasonic vibration combined with flushing, most of the attachments on the surface of the prosthesis were removed; due to the physical bactericidal effect produced by ultrasonic cavitation, the bacterial load in the joint cavity was significantly reduced. During this period, the patient could wear the present invention and go out for light activities in the ward. The present invention operated smoothly without leakage or pipe blockage. Compared with the patients in the control group who used traditional negative pressure sealed drainage, the patient's intra-wound biofilm-related indicators were significantly reduced, the inflammatory marker CRP and blood white blood cell count decreased rapidly, the prosthesis remained stable, and there was no need for re-surgery. The incision healed smoothly on the 14th day after surgery; it can be seen that the combined effect of the present invention effectively controlled the infection and achieved a cure with retained prosthesis.

[0072] In summary, this treatment example demonstrates the significant advantages of the present invention in the postoperative application of infection around total knee prosthesis D. Through multi-channel low-pressure flushing, negative pressure drainage combined with high- and low-frequency ultrasonic debridement, it can efficiently remove the biofilm on the surface of the deep prosthesis and continuously discharge the infected substances, making local antibiotic treatment more sufficient. The present invention is safe and controllable in operation, well tolerated by patients, and because the equipment is small and portable, the treatment can be carried out immediately and continuously after surgery without affecting the patient's functional exercise and life; the present invention greatly improves the success rate of conservative treatment of prosthetic infection, reduces the rate of secondary revision surgery, and has important application value in the field of orthopedic infection control.

[0073] The innovations of this embodiment are as follows: 1. Comprehensive and efficient flushing coverage: The four-channel arrangement of dual positive pressure inlet + dual negative pressure outlet achieves bidirectional synchronous flushing and multi-point drainage in the infected joint cavity. The flushing fluid enters from both ends of the joint cavity and circulates, significantly improving the flushing coverage of deep complex anatomical areas, avoiding the blind spots of traditional single-channel flushing, and helping to thoroughly flush away pus, debris and detached biofilm on the surface of the prosthesis and soft tissue.

[0074] 2. Anti-blocking and anti-leakage and reliable pipelines: The spray hole 512 provided on the positive pressure liquid outlet pipe 511 of the present invention can diffuse the flow direction of the flushing liquid; the through hole 612 provided on the negative pressure liquid inlet pipe 611 can increase the drainage channel area to avoid blockage of a single aperture, effectively preventing the negative pressure liquid inlet pipe 611 from being blocked by fibrous tissue or blood clots, and ensuring that the passage is unobstructed during long-term use; at the same time, the pipeline puncture port is tightly sealed by the elastic sealing ring 53 and the medical sealant 54, avoiding the extravasation of flushing liquid to contaminate the surrounding skin or dressing. Even if the patient moves moderately after the operation, the pipeline interface can still remain stable and airtight, and will not cause air leakage or liquid leakage due to pulling and displacement, thereby greatly improving the safety and continuity of the device operation.

[0075] 3. Ultrasound-assisted debridement: Unlike existing devices that rely solely on liquid flushing, the present invention incorporates high- and low-frequency ultrasonic synchronous debridement functions into a miniature ultrasonic transducer 2. Under the action of low-frequency cavitation, bacterial biofilms stubbornly attached to the surface of the prosthesis are effectively destroyed and removed, greatly reducing residual infection sources; high-frequency ultrasound further enhances the bactericidal and healing effects of local flushing. Literature shows that low-frequency ultrasonic debridement can selectively remove inactivated tissue without damaging normal tissue, and can improve the efficiency of antibiotic control of infection by destroying bacterial biofilms on the wound surface. Therefore, the present invention uses ultrasound-assisted flushing to achieve deep biofilm removal that is difficult to achieve with traditional mechanical debridement, thereby improving the thoroughness of infection control. This is of great significance in improving the success rate of prosthesis retention surgery, and the removal rate of biofilms on the surface of deep prostheses is greatly improved compared with traditional ultrasound.

[0076] 4. Safe and gentle flushing environment: The present invention controls the flushing pressure and ultrasonic intensity within a safe range, achieving a balance between efficient debridement and tissue protection. Low-pressure pulse irrigation can not only fully clean the wound, but also avoid tissue damage and bacterial spread that may be caused by high pressure; the operating frequency and power of the miniature ultrasonic transducer 2 are optimized and will not cause thermal damage to soft tissue or pain and discomfort. Therefore, the continuous flushing process is more friendly to the new granulation tissue and the healing environment, which is conducive to wound healing.

[0077] 5. The equipment is lightweight and convenient for continuous treatment: The present invention is small in size and light in weight, and truly realizes portable flushing negative pressure treatment. Patients do not need to stay in bed and be fixed next to large equipment after surgery, but can receive continuous wound cavity flushing and negative pressure drainage treatment on the move; this not only improves the patient's comfort and self-care ability, but also facilitates follow-up treatment outside the hospital, reducing hospitalization time and medical costs; compared with the existing technology, the present invention greatly improves the portability and ease of use of the equipment while ensuring therapeutic efficacy.

[0078] 6. Drug administration safety closed-loop control: Microfluidic drug monitoring has increased the local antibiotic concentration compliance rate to, and the systemic blood drug concentration is always below the toxicity threshold.

[0079] 7. Dynamic sealing: The sealing interface between the elastic sealing ring 53 and the medical sealant 54 maintains zero leakage at a 90° joint range of motion, thereby improving the patient's freedom of movement.

[0080] In summary, the present invention solves the problems of incomplete irrigation of deep wound cavities and easy blockage of pipelines through a multi-channel anti-blocking design in structure. Functionally, it introduces pulsed high and low frequency ultrasound to improve the efficiency of biofilm removal and infection control effect, while taking into account safety and portability. It has significant innovation and clinical application value, especially after artificial joint infection and prosthesis debridement surgery, it is expected to improve the infection clearance rate, protect the prosthesis, and accelerate patient recovery.

Claims

1. A portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device, characterized by: The invention comprises a main body (1), two miniature ultrasonic transducers (2), a power supply (3), a controller (4), a positive pressure perfusion pump (5) and a negative pressure suction pump (6), wherein the power supply (3), the controller (4), the positive pressure perfusion pump (5) and the negative pressure suction pump (6) are arranged in the main body (1), the power supply (3) is electrically connected to the controller (4), the controller (4) is connected to the miniature ultrasonic transducer (2) through a first wire (21), the controller (4) is electrically connected to the positive pressure perfusion pump (5) and the negative pressure suction pump (6), and the controller (4) supplies power to the miniature ultrasonic transducer (2), the positive pressure perfusion pump (5) and the negative pressure suction pump (6) and controls the miniature ultrasonic transducer (2), the positive pressure perfusion pump (5) and the negative pressure suction pump (6); The positive pressure perfusion pump (5) has two positive pressure liquid outlet interfaces (51) and one positive pressure liquid inlet interface (52), the two positive pressure liquid outlet interfaces (51) are both connected to a positive pressure liquid outlet pipe (511), and the positive pressure liquid inlet interface (52) is connected to a positive pressure liquid inlet pipe (521); the negative pressure suction pump (6) has two negative pressure liquid inlet interfaces (61) and one negative pressure liquid outlet interface (62), the two negative pressure liquid inlet interfaces (61) are both connected to a negative pressure liquid inlet pipe (611), and the negative pressure liquid outlet interface (62) is connected to a negative pressure liquid outlet pipe (621); The miniature ultrasonic transducer (2) includes a miniature low-frequency ultrasonic transducer and a miniature high-frequency ultrasonic transducer. The miniature low-frequency ultrasonic transducer is mounted on the front end of a positive pressure liquid inlet pipe (521), and the miniature high-frequency ultrasonic transducer is mounted on the front end of another positive pressure liquid inlet pipe (521). The front sections of the positive pressure liquid outlet pipe (511) and the negative pressure liquid inlet pipe (611) are sleeved with elastic sealing rings (53).

2. A portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The front end pipeline at the interface between the elastic sealing ring (53) and the skin is filled with medical sealant (54).

3. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 2, characterized in that: The elastic sealing ring (53) is made of silicone.

4. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The medical sealant (54) is a natural component sealant, a semi-synthetic sealant or a fully synthetic sealant.

5. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 4, characterized in that: The natural component sealant is fibrin-based sealant, the semi-synthetic sealant is gelatin or albumin-based sealant, and the fully synthetic sealant is acrylate or polyethylene glycol-based sealant.

6. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The front circumference of the positive pressure liquid outlet pipe (511) is provided with a plurality of spray holes (512); the front circumference of the negative pressure liquid inlet pipe (611) is provided with a plurality of through holes (612).

7. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The positive pressure perfusion pump (5) is equipped with a liquid outlet pressure sensor, which is connected to the controller (4). A drug concentration sensor (63) and an impedance sensor (64) are provided next to the through hole (612) of the negative pressure liquid inlet pipe (611). Both the drug concentration sensor (63) and the impedance sensor (64) are connected to the controller (4) via a second wire (65).

8. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The ultrasonic frequency emitted by the miniature low-frequency ultrasonic transducer is 20-40 kHz, preferably 25-30 kHz; the ultrasonic frequency emitted by the miniature high-frequency ultrasonic transducer is 0.8-3 MHz.

9. The portable ultrasonic debridement positive pressure irrigation and negative pressure drainage device according to claim 1, characterized in that: The micro ultrasonic transducer (2) is composed of 4 to 6 micro piezoelectric ceramic pieces.

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