Knee joint soft tissue tension gap measuring device
By designing a knee joint soft tissue tension gap measuring device, using a pressure sensor and a stepper motor, accurate measurement of the medial and lateral knee joint gap and soft tissue tension is achieved. This solves the problems of inaccurate measurement and high cost in existing technologies, improves surgical outcomes, and reduces the burden on patients.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JILIN UNIV FIRST HOSPITAL
- Filing Date
- 2025-03-31
- Publication Date
- 2026-06-30
AI Technical Summary
Current knee replacement surgeries lack instruments that can simultaneously and separately measure the distance and tension of the soft tissue gaps on the inner and outer sides of the knee joint. Furthermore, existing devices are not accurate enough and are costly, affecting surgical outcomes and patient treatment expenses.
A knee joint soft tissue tension and gap measuring device was designed, comprising a handheld end body, a fixed detection plate, a tension and gap measuring device, and a movable detection plate. It uses a pressure sensor and a stepper motor to achieve accurate measurement of the gap between the inner and outer sides of the knee joint and the soft tissue tension. It measures the inner and outer sides separately, reducing costs.
It achieves precise adjustment and balance of the soft tissue space of the knee joint, improves the success rate of surgery, extends the life of the prosthesis, reduces production costs, and reduces treatment expenses for patients.
Smart Images
Figure CN224421014U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the technical field of total knee arthroplasty instruments, and in particular relates to a knee joint soft tissue tension gap measuring device. Background Technology
[0002] With the increasing aging of the population, the number of patients suffering from knee osteoarthritis is constantly rising. In terms of knee joint treatment, total knee replacement surgery is currently one of the most successful surgical methods for treating knee joint diseases. Total knee replacement surgery can alleviate knee pain and greatly improve patients' quality of life.
[0003] As a complex joint in the human body, the difficulty of total knee replacement surgery is self-evident. In addition to accurate osteotomy, proper ligament release and soft tissue balance are key to the surgery. Therefore, special attention must be paid to the release of soft tissues around the tibial plateau during the operation to ensure that the knee joint has appropriate tightness and that the pressure on the inner and outer sides is as equal as possible.
[0004] Restoring the balance between the extension and flexion gaps of the knee joint, the balance between the medial and lateral gaps, and the tension balance of the corresponding soft tissues are crucial steps affecting the surgical outcome. However, in current knee replacement surgery, surgeons largely rely on experience and touch to determine whether the implanted prosthesis meets the soft tissue balance requirements. Some surgeons typically rely on manual assessment of the tension of the medial and lateral soft tissues of the knee joint with both knees extended and flexed at 90 degrees. This results in excessively long training periods for total knee replacement surgeons and introduces instability and certain risks to the soft tissue balance during surgery. While gap measuring blocks or gauges are commonly used to measure the knee joint gap, these instruments only measure the gap distance and cannot measure the tension of the knee joint soft tissues.
[0005] Currently, there are devices on the market that assist in soft tissue balancing. However, when using these devices, the area covered by their internal sensors is often small, resulting in inaccurate measurements of knee joint pressure. Furthermore, the housings of these devices are made of rigid materials and are molded in one piece, making it difficult to fit well with the femoral condyle and preventing the simultaneous measurement of pressure and inter-articular distance. Moreover, deformation under stress on either side causes pressure loss, further hindering accurate pressure measurements. Additionally, these one-piece molded devices cannot independently measure the inter-articular soft tissue gaps and tension on the medial and lateral sides.
[0006] In related technologies, the adjustable spacer and the system 1300 used together with the robotic surgical device mentioned in the soft tissue balance of the robotic knee surgery disclosed in patent application CN111615359A can measure the knee joint gap and soft tissue tension. However, such a device includes a robotic surgical system or device structure that is complex and expensive, which increases the cost of surgery and increases the treatment expenses for patients. Summary of the Invention
[0007] This invention provides a knee joint soft tissue tension gap measuring device to solve the current problem of lacking a device that can simultaneously and separately measure the distance between the inner and outer soft tissues of the knee joint and the soft tissue tension of the knee joint.
[0008] The technical solution adopted by this utility model is as follows: it includes a handheld end body, a fixed detection plate, a tension and gap measuring device 1, a tension and gap measuring device 2, a movable detection plate 1, and a movable detection plate 2. The lower part of the fixed detection plate is fixedly connected to the inside of the handheld end body. The lower parts of the tension and gap measuring device 1 and the tension and gap measuring device 2 are respectively located in the handheld end body and their bottoms are fixedly connected to the bottom of the fixed detection plate. The movable detection plate 1 and the movable detection plate 2 are respectively connected to the middle parts of the tension and gap measuring device 1 and the tension and gap measuring device 2.
[0009] The handheld device includes an outer shell, an outer shell cover, a bottom fixing block, a plug fixing plate, an outer shell cover support plate, and an upper sealing ring. The bottom of the bottom fixing block is fixedly connected to the bottom of the outer shell, the top of the bottom fixing block is fixedly connected to the bottom of the fixed detection plate, the plug fixing plate is fixedly connected to the bottom fixing block, the outer shell cover support plate is fixedly connected to the lower part of the outer shell cover, the outer shell cover is inserted into the upper part of the outer shell, and there is an upper sealing ring between the outer shell cover and the outer shell.
[0010] There is a sealing ring at the lower end of the outer shell between the outer shell and the bottom fixing block.
[0011] The tension and gap measuring device one and the tension and gap measuring device two have the same structure.
[0012] The tension and gap measuring device two includes a pressure sensor, a stepper motor, a bottom guide housing of the moving end, a sealing ring for the bottom guide housing of the moving end, a lower slider of the moving end, a nut, an upper slider of the moving end, a connecting rod, a top cover assembly, and a stepper motor screw. The pressure sensor is mounted on top of a fixed detection plate at its bottom, and its top is fixedly connected to the stepper motor. The stepper motor has a stepper motor screw. The bottom guide housing of the moving end is fixedly connected to the top of the stepper motor at its bottom. One end of the sealing ring for the bottom guide housing of the moving end is connected to the upper part of the bottom guide housing of the moving end, and the other end is connected to the upper part of the housing cover. The center of the lower slider of the moving end is threadedly connected to the stepper motor screw, and its exterior is slidably connected to the bottom guide housing of the moving end. The second movable detection plate is located above the lower slider of the moving end and is threadedly connected to the stepper motor screw. The nut is located above the second movable detection plate, and the upper slider of the moving end is located above the nut. The connecting rod connects the upper slider of the moving end, the nut, the second movable detection plate, and the lower slider of the moving end together. The upper part of the top cover assembly is connected to the stepper motor screw, and the lower part is connected to the upper slider of the moving end.
[0013] The sliding block of the moving end is sealed to the bottom guide shell of the moving end by a bottom sealing ring.
[0014] The top cover assembly includes a rubber cover, a top limiting spring, a bottom sealing ring, and a cover body. The upper part of the cover body is threaded to the rubber cover, the top limiting spring is engaged with the stepper motor screw, and the lower part of the cover body is sleeved with the upper slider of the moving end and sealed by the bottom sealing ring.
[0015] The advantages of this invention are its novel structure. A pressure sensor and a stepper motor are integrated into the handheld end of the measuring device, enabling simultaneous and precise adjustment of the knee joint gap and soft tissue tension. Real-time, accurate measurement yields a more precise rectangular bend-straight gap, achieving good soft tissue gap balance in the knee joint, improving the success rate of total knee arthroplasty, and extending the lifespan of the prosthesis. The stepper motor drives the rotating in and out movement, precisely controlling the movement distance of the movable detection plate. The movable detection plate is divided into inner and outer parts, corresponding to the pressure sensor and stepper motor, allowing for simultaneous measurement of the gap and soft tissue tension on both sides of the knee joint. This simplifies intraoperative operation and facilitates comparison of the inner and outer gap differences. Furthermore, it is less susceptible to external influences that could lead to detection errors or surgical accidents. It can be sterilized and reused, achieving excellent detection results while reducing production costs, thus effectively reducing testing expenses and alleviating the burden of treatment for patients. The use of a pressure sensor, coupled with algorithm optimization, improves reading accuracy and reduces measurement errors. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the structure of this utility model;
[0017] Figure 2 This is the front view of this utility model;
[0018] Figure 3 yes Figure 2 The right view;
[0019] Figure 4 yes Figure 2 AA section view;
[0020] Figure 5 yes Figure 3 BB cross-sectional view. Detailed Implementation
[0021] See Figure 1 , 2 3, including a handheld end body 1, a fixed detection plate 2, a tension and gap measuring device 1 3, a tension and gap measuring device 2 4, a movable detection plate 1 5, and a movable detection plate 2 6, wherein the lower part of the fixed detection plate 2 is fixedly connected to the inside of the handheld end body 1, the lower parts of the tension and gap measuring device 1 3 and the tension and gap measuring device 2 4 are respectively located in the handheld end body 1 and their bottoms are fixedly connected to the bottom of the fixed detection plate 2, and the movable detection plate 1 5 and the movable detection plate 2 6 are respectively connected to the middle parts of the tension and gap measuring device 1 3 and the tension and gap measuring device 2 4.
[0022] See Figure 4 , 5 The handheld end body 1 includes an outer shell 101, an outer shell cover 102, a bottom fixing block 103, a plug fixing plate 104, an outer shell cover support plate 105, and an upper sealing ring 106. The bottom of the bottom fixing block 103 is fixedly connected to the bottom of the outer shell 101, the top of the bottom fixing block 103 is fixedly connected to the bottom of the fixed detection plate 2, the plug fixing plate 104 is fixedly connected to the bottom fixing block 103, the outer shell cover support plate 105 is fixedly connected to the lower part of the outer shell cover 102, the outer shell cover 102 is inserted into the upper end of the outer shell 101, and there is an upper sealing ring 106 between the outer shell cover 102 and the outer shell 101.
[0023] A sealing ring 107 at the lower end of the outer shell is provided between the outer shell 101 and the bottom fixing block 103.
[0024] The tension and gap measuring device 3 and the tension and gap measuring device 4 have the same structure.
[0025] See Figure 4 , 5The tension and gap measuring device 4 includes a pressure sensor 401, a stepper motor 402, a bottom guide housing 403 of the moving end, a sealing ring 404 of the bottom housing of the moving end, a lower slider 405 of the moving end, a nut 406, an upper slider 407 of the moving end, a connecting rod 408, a top cover assembly 409, and a stepper motor screw 410. The pressure sensor 401 is mounted on the top of the fixed detection plate 2, and its top is fixedly connected to the stepper motor 402. The stepper motor 402 has a stepper motor screw 410. The bottom of the bottom guide housing 403 of the moving end is fixedly connected to the top of the stepper motor 402. One end of the sealing ring 404 of the bottom housing of the moving end is connected to the bottom of the moving end. The upper part of the guide housing 403 is connected to the upper part of the housing cover 102, and the center of the moving end lower slider 405 is threadedly connected to the stepper motor screw 410, and the outside is slidably connected to the bottom guide housing 403 of the moving end. The movable detection plate 2 6 is located above the moving end lower slider 405 and is threadedly connected to the stepper motor screw 410. The nut 406 is located above the movable detection plate 2 6, and the moving end upper slider 407 is located above the nut 406. The connecting rod 408 connects the moving end upper slider 407, the nut 406, the movable detection plate 2 6 and the moving end lower slider 405 together. The upper part of the top cover assembly 409 is connected to the stepper motor screw 410, and the lower part is connected to the moving end upper slider 407.
[0026] The sliding block 405 of the moving end is sealed to the bottom guide shell 403 of the moving end by the bottom sealing ring 40501.
[0027] The top cover assembly 409 includes a rubber cover 40901, a top limiting spring 40902, a bottom sealing ring 40903, and a cover body 40904. The upper part of the cover body 40904 is threadedly connected to the rubber cover 40901, the top limiting spring 40902 is engaged with the stepper motor screw 410, and the lower part of the cover body 40904 is sleeved with the upper slider 407 of the moving end and sealed by the bottom sealing ring 40903.
[0028] Working principle:
[0029] (1) In tension mode, the position of the measuring device is determined based on the tension measurement of the target ligament within the knee joint. That is, the gap displacement change of the measuring device is used to maintain consistent ligament tension, thereby generating a quantified displacement vector gap. Specifically: First, the surgeon performs a femoral-tibial osteotomy. According to the size of the patient's tibia and femur, the appropriate size of the fixed detection plate 2 and two movable detection plates 5 and 6 are selected. The movable detection plates and the fixed detection plates are inserted into the joint gap, so that the fixed detection plate fully contacts the proximal surface of the tibia after osteotomy. The movable detection plates on the medial and lateral sides are adjusted by rotating in and out using two stepper motors, so that they fully contact the surface of the femur after osteotomy. Then, the patient's knee joint is moved to perform flexion and extension movements. At this time, the pressure sensor detects the pressure in the medial and lateral compartments of the knee joint respectively, and the stepper motor provides the gap distance between the medial and lateral compartments. At this time, the medial and lateral pressures are controlled to be consistent. Under the premise of ensuring that the medial and lateral pressures are consistent, the changes in the medial and lateral gap distance are observed and recorded. The pressure and distance data from the pressure sensor are obtained and sent to the surgeon. The surgeon uses the measured data to perform ligament release or tibial resection, fine-tuning the gap and pressure. Then, the surgeon uses a stepper motor to rotate the medial and lateral movable detection plates in and out to ensure they are in full contact with the post-osteotomy surface of the femur. The modified medial and lateral soft tissue tension and gap are measured until the medial and lateral soft tissue tension and gap reach a satisfactory state.
[0030] (2) In the gap and insertion mode, priority is given to controlling the size of the gap displacement to keep the gap consistent. The surgeon measures the pressure changes on the detection plate by flexing and extending the knee joint according to the range of motion of the knee joint during the operation. The most common approach is the tibial-priority gap balancing method. First, the surgeon performs a tibial osteotomy at the desired angle. Based on the patient's tibial and femoral size, appropriate sizes of the fixed and movable detection plates are selected. These plates are inserted into the joint space, ensuring the fixed plate fully contacts the proximal surface of the tibial osteotomy. The movable plates are adjusted by rotating them in and out using a stepper motor, ensuring full contact with the most prominent part of the femoral condyle. Next, the patient's knee is moved in and out, and pressure sensors detect the pressure in the medial and lateral compartments of the knee joint. The stepper motor provides the gap distance between the medial and lateral compartments. The obtained pressure and distance data are sent to the surgeon, who prioritizes maintaining a consistent gap distance while simultaneously measuring changes in medial and lateral pressure. This guides ligament release or tibial resection until the medial and lateral soft tissue tension and gap reach a satisfactory state. The generated information is then used to guide virtual planning of the femoral prosthesis position, optimizing the required gap size and ligament / soft tissue tension.
[0031] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A knee soft tissue tension gap measurer characterized by: It includes a handheld end body, a fixed detection plate, a tension and gap measuring device 1, a tension and gap measuring device 2, a movable detection plate 1, and a movable detection plate 2. The lower part of the fixed detection plate is fixedly connected to the inside of the handheld end body. The lower parts of the tension and gap measuring device 1 and the tension and gap measuring device 2 are located in the handheld end body and their bottoms are fixedly connected to the bottom of the fixed detection plate. The movable detection plate 1 and the movable detection plate 2 are respectively connected to the middle parts of the tension and gap measuring device 1 and the tension and gap measuring device 2.
2. A soft tissue tension gap measurement device for the knee according to claim 1, wherein: The handheld device includes an outer shell, an outer shell cover, a bottom fixing block, a plug fixing plate, an outer shell cover support plate, and an upper sealing ring. The bottom of the bottom fixing block is fixedly connected to the bottom of the outer shell, the top of the bottom fixing block is fixedly connected to the bottom of the fixed detection plate, the plug fixing plate is fixedly connected to the bottom fixing block, the outer shell cover support plate is fixedly connected to the lower part of the outer shell cover, the outer shell cover is inserted into the upper part of the outer shell, and there is an upper sealing ring between the outer shell cover and the outer shell.
3. A soft tissue tension gap measurement device for the knee according to claim 2, wherein: There is a sealing ring at the lower end of the outer shell between the outer shell and the bottom fixing block.
4. The soft tissue tension gap measurement device of claim 1, wherein: The tension and gap measuring device one and the tension and gap measuring device two have the same structure.
5. A soft tissue tension gap measurement device for the knee according to claim 4, wherein: The tension and gap measuring device two includes a pressure sensor, a stepper motor, a bottom guide housing of the moving end, a sealing ring for the bottom guide housing of the moving end, a lower slider of the moving end, a nut, an upper slider of the moving end, a connecting rod, a top cover assembly, and a stepper motor screw. The pressure sensor is mounted on top of a fixed detection plate at its bottom, and its top is fixedly connected to the stepper motor. The stepper motor has a stepper motor screw. The bottom guide housing of the moving end is fixedly connected to the top of the stepper motor at its bottom. One end of the sealing ring for the bottom guide housing of the moving end is connected to the upper part of the bottom guide housing of the moving end, and the other end is connected to the upper part of the housing cover. The center of the lower slider of the moving end is threadedly connected to the stepper motor screw, and its exterior is slidably connected to the bottom guide housing of the moving end. The second movable detection plate is located above the lower slider of the moving end and is threadedly connected to the stepper motor screw. The nut is located above the second movable detection plate, and the upper slider of the moving end is located above the nut. The connecting rod connects the upper slider of the moving end, the nut, the second movable detection plate, and the lower slider of the moving end together. The upper part of the top cover assembly is connected to the stepper motor screw, and the lower part is connected to the upper slider of the moving end.
6. A soft tissue tension gap measurement device for the knee according to claim 5, wherein: The sliding block of the moving end is sealed to the bottom guide shell of the moving end by a bottom sealing ring.
7. The soft tissue tension gap measurement device of claim 5, wherein: The top cover assembly includes a rubber cover, a top limiting spring, a bottom sealing ring, and a cover body. The upper part of the cover body is threadedly connected to the rubber cover, the top limiting spring is engaged with the stepper motor screw, and the lower part of the cover body is sleeved with the upper slider of the moving end and sealed by the bottom sealing ring.