Fixing device for modeling limbs of rats and mice

Abstract

The present application relates to a kind of rat limb bone modeling fixing device, belong to the technical field of animal experiment instrument, solve the difficulty of modeling operation field exposure, the soft tissue, blood vessel and nerve that have been exposed are vulnerable, involve the operation of knee joint all need to keep the stability and upright of knee joint, but current can only rely on artificial fixation problem.The present application includes first support, second support and adapter rod, first support and second support are connected by adapter rod, first support and second support can rotate around adapter rod, first support and second support are used to support the forelimb or hind limb of rat, first support and second support rotate around adapter rod and form included angle, to carry out rat knee modeling operation.The length, width, height and angle of the first support and second support of the present application can be adjusted, to be suitable for the forelimb or hind limb of different length of rat, and the angle of knee flexion and knee exposure degree, increase the convenience of operation.

Description

Technical Field

[0001] This invention relates to the field of animal experimental equipment technology, and in particular to a fixation device for modeling the limbs and skeletons of rats and mice. Background Technology

[0002] Fractures are a common clinical condition. Researching the pathophysiological mechanisms of fracture occurrence, healing, and post-fracture bone remodeling requires stable, reliable, standardized, and reproducible animal models. Currently, small animal fracture models mainly include open fracture models and bone defect models.

[0003] However, the drawbacks of open fracture models and bone defect models are that when the long bone shaft is exposed, it is easy to damage major blood vessels and nerves. This requires a certain level of anatomical knowledge and surgical experience. During long bone shaft osteotomy using a wire saw or oscillating saw, it is extremely easy to damage the already exposed soft tissues, blood vessels, and nerves, resulting in a very high surgical risk. Therefore, in order to protect surrounding important tissues to the greatest extent possible, the surgeon must enlarge the incision as much as possible to fully expose the surgical field, which causes significant harm to the experimental animals.

[0004] In addition, the knee joint is the largest weight-bearing organ in the human body, and also one of the most complex. The knee joint has a rich structure and clear anatomy, and is very common in animal models, with the rat model being the most widely used and studied.

[0005] During the rat knee joint modeling surgery, no specialized fixation instruments were used. Assistants were generally chosen to assist with fixation and angle adjustment. During the surgery, the knee joint required multiple adjustments to the flexion angle to observe its internal structure, determine the mobility and anatomical position of the medial femoral condyle, ligaments, and meniscus, and also required knee flexion. A drill or hand drill was also needed. Fixing the knee joint with one hand is unstable and carries safety risks. Therefore, during the surgical construction of the bone defect, an assistant is required to assist in fixing the knee joint, which leads to a narrow surgical space and inconvenience for the surgeon.

[0006] Given the difficulty in exposing the surgical field in open fracture models and bone defect models, which easily damages exposed soft tissues, blood vessels, and nerves, and the fact that surgeries involving the knee joint require maintaining knee stability and uprightness, but currently rely solely on manual fixation, there is an urgent need for a fixation device for rat and mouse limb skeletal models that can be used in both open fracture models and bone defect models as well as surgeries involving the knee joint. Summary of the Invention

[0007] Based on the above analysis, the present invention aims to provide a fixation device for rat and mouse limb skeletal modeling, in order to solve the problem of difficulty in surgical field exposure in open fracture models and bone defect models, the easy damage to exposed soft tissues, blood vessels and nerves, and the problem that current surgeries involving the knee joint require maintaining the stability and upright position of the knee joint, but currently can only rely on manual fixation.

[0008] The objective of this invention is mainly achieved through the following technical solutions:

[0009] A fixation device for creating a rat limb skeleton model includes a first support, a second support, and a connecting rod. The first support and the second support are connected by the connecting rod and can rotate around the connecting rod. The first support and the second support are used to support the forelimbs or hindlimbs of rats for fracture and bone defect modeling surgery. The first support and the second support rotate around the connecting rod and form an angle, which allows the rat to flex its knee and fully expose the knee joint for rat knee joint modeling surgery.

[0010] Furthermore, both the first and second supports include a base frame and a crossbar, with the crossbar mounted on the base frame.

[0011] Furthermore, the two base frames are connected by an adapter rod, and the two base frames can rotate around the adapter rod.

[0012] Furthermore, the adapter rod includes a first support rod, a first nut, and a first sleeve.

[0013] Furthermore, the first support rod is disposed inside the first sleeve, and the first support rod can extend and retract within the first sleeve.

[0014] Furthermore, the first nut is screwed to one end of the first sleeve.

[0015] Furthermore, the bottom frame includes two first rods and a second rod, with the two first rods connected by the second rod.

[0016] Furthermore, the first rod includes a second support rod, a second nut, and a second sleeve.

[0017] Furthermore, one end of the second sleeve is rotatably connected to one end of the adapter rod, and the second support rod is disposed inside the second sleeve, allowing it to extend and retract within the second sleeve.

[0018] Furthermore, the second nut is screwed to one end of the second sleeve.

[0019] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0020] (1) The first bracket, the second bracket and the adapter rod of the fixation device provided by the present invention can be used to support the forelimbs or hindlimbs of mice and rats. It is suitable for fixing the forelimbs or hindlimbs of mice and rats during fracture and bone defect modeling surgery. The first bracket and the second bracket rotate around the adapter rod and form an angle, which can make the rat flex its knee and fully expose the knee so as to perform rat knee joint modeling surgery.

[0021] (2) The length, width, height and angle of the first and second brackets of the fixation device provided by the present invention can be adjusted to suit different lengths of forelimbs or hindlimbs of mice and rats, as well as the angle of knee flexion and the degree of knee exposure, thereby increasing the convenience of surgical operation;

[0022] (3) The lifting component of the fixation device provided by the present invention can lift and fix the forelimbs and hindlimbs of mice and rats without manual support, saving personnel and facilitating surgical operations;

[0023] (4) The hook of the fixation device provided by the present invention is used to lift the forelimbs of mice and rats, while isolating the bone shaft from soft tissues and nerves, thus preventing damage to the soft tissues and nerves of the forelimbs during leg bone modeling surgery.

[0024] (5) The fixing device provided by the present invention can change and fix the included angle between the first bracket and the second bracket by snapping the bottom frame into different positioning slots;

[0025] (6) The traction component of the fixation device provided by the present invention can keep the forelimbs and hindlimbs of mice and rats in a traction and fixation state, without the need for a special person to support the limbs, which facilitates surgical operations. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 This is a schematic diagram of the overall structure of the fixing device of the present invention;

[0028] Figure 2 This is a schematic diagram of the overall structure of the adapter rod;

[0029] Figure 3 This is a schematic diagram of the overall structure of the first rod;

[0030] Figure 4 This is a schematic diagram of the overall structure of the second rod;

[0031] Figure 5 This is a schematic diagram of the overall structure of the hook assembly;

[0032] Figure 6 This is a schematic diagram of the overall structure of the limit switch;

[0033] Figure 7 This is a schematic diagram of the overall structure of the traction component.

[0034] Figure label:

[0035] 1-First support; 2-Second support; 3-Adapter rod; 4-First rod; 5-Second rod; 6-T-connector; 7-Lifting assembly; 8-Limiter; 9-Tethering assembly; 11-Base frame; 12-Horizontal frame; 31-First support rod; 32-First nut; 33-First sleeve; 41-Second support rod; 42-Second nut; 43-Second sleeve; 51-Third support rod; 52-Third nut; 53-Third sleeve; 71-Hook; 72-Cantilever; 73-Cantilever seat; 74-Groove; 75-Screw; 81-Positioning groove. Detailed Implementation

[0036] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0037] A specific embodiment of the present invention, such as Figure 1 As shown, a fixation device for rat and mouse limb skeletal modeling (hereinafter referred to as fixation device) is disclosed, including a first support 1, a second support 2 and a connecting rod 3. The first support 1 and the second support 2 are connected by the connecting rod 3. The first support 1 and the second support 2 can rotate around the connecting rod 3. The first support 1, the second support 2 and the connecting rod 3 are used to support the forelimbs or hindlimbs of rats and mice for fracture and bone defect modeling surgery. The first support 1 and the second support 2 rotate around the connecting rod 3 and form an angle, which allows the rat to flex its knee and fully expose the knee joint for rat knee joint modeling surgery.

[0038] Preferably, both the first support 1 and the second support 2 include a base frame 11 and a crossbar 12. The crossbar 12 is disposed on the base frame 11, and the two base frames 11 are connected by a connecting rod 3. The two base frames 11 can rotate around the two ends of the connecting rod 3. The crossbar 12 is used to support the forelimbs and hindlimbs of the rat, and the base frame 11 allows the rat to flex its knees.

[0039] Preferably, such as Figure 2 As shown, the adapter rod 3 is a telescopic rod, including a first support rod 31, a first nut 32 and a first sleeve 33. The first support rod 31 is set inside the first sleeve 33 and can extend and retract inside the first sleeve 33. The first nut 32 is screwed to one end of the first sleeve 33 and is used to adjust the extension and retraction of the telescopic rod and fix the adjusted length of the telescopic rod.

[0040] Preferably, the first support rod 31 is a straight rod that can extend and retract in a straight line within the first sleeve 33. After loosening the first nut 32, the first support rod 31 can extend and retract, allowing adjustment of the length of the adapter rod 3. After tightening the first nut 32, the first support rod 31 and the first sleeve 33 are locked together, preventing the first support rod 31 from extending and retracting, thus maintaining the length of the adapter rod 3. The length of the adapter rod 3 is both adjustable and fixed.

[0041] Preferably, such as Figure 1 As shown, the bottom frame 11 includes two first rods 4 and a second rod 5. The two first rods 4 are connected by the second rod 5. Both the first rods 4 and the second rod 5 are telescopic rods.

[0042] Preferably, such as Figure 3 As shown, the first rod 4 includes a second support rod 41, a second nut 42, and a second sleeve 43. One end of the second sleeve 43 is rotatably connected to one end of the adapter rod 3. The second support rod 41 is disposed inside the second sleeve 43 and can extend and retract inside the second sleeve 43. The second nut 42 is screwed to one end of the second sleeve 43 and is used to adjust the extension and retraction of the telescopic rod and fix the adjusted length of the telescopic rod.

[0043] Preferably, the second support rod 41 is a straight rod that can extend and retract in a straight line within the second sleeve 43. After loosening the second nut 42, the second support rod 41 can extend and retract, allowing adjustment of the length of the first rod 4. After tightening the second nut 42, the second support rod 41 and the second sleeve 43 are locked together, preventing the second support rod 41 from extending and retracting, thus maintaining the length of the first rod 4. The length of the first rod 4 is adjustable and can be fixed.

[0044] Preferably, such as Figure 4 As shown, the second rod 5 includes a third support rod 51, a third nut 52, and a third sleeve 53. The third support rod 51 is disposed inside the third sleeve 53 and can extend and retract within the third sleeve 53. The third nut 52 is screwed to one end of the third sleeve 53 and is used to adjust the extension and retraction of the telescopic rod and to fix the adjusted length of the telescopic rod. The length of the second rod 5 is adjustable and can be fixed.

[0045] The lengths of the adapter rod 3, the first rod 4, and the second rod 5 are all adjustable and can be fixed. The length and width of the base frame 11, which is composed of the adapter rod 3, the first rod 4, and the second rod 5, are adjustable and can be fixed to accommodate different lengths of forelimbs or hindlimbs of rats and mice. At the same time, the included angle between the two base frames 11 can also be adjusted through the adapter rod 3, so that the knee flexion angle of the rat can be adjusted, which facilitates surgical operation.

[0046] Preferably, the fixing device of the present invention further includes a three-way connector 6, which is disposed at both ends of the second rod 5, and the second rod 5 is connected to the first rod 4 through the three-way connector 6.

[0047] Preferably, the tee connector 6 is T-shaped, including a horizontal tube and a vertical tube; the horizontal tube is hollow and open between its two ends; one end of the vertical tube is connected to the horizontal tube, and it is hollow inside, while the other end is open. One end of the second rod 5 is inserted into the vertical tube and fixedly connected to it, ensuring that the second rod 5 will not detach from the tee connector 6; the second support rod 41 passes through the horizontal tube and is movably connected to it.

[0048] Preferably, the horizontal tube is provided with an anti-slip layer, which provides damping while maintaining the movable connection between the horizontal tube and the second support rod 41. The user can apply force to make the second support rod 41 slide inside the horizontal tube. Once the external force applied by the user is lost, the second support rod 41 cannot slide or displace inside the horizontal tube, thus preventing the fixing device of the present invention from deforming after the position and state are set, which would affect the surgical effect.

[0049] Preferably, such as Figure 1 As shown, three second rods 5 form a crossbar 12, which supports and fixes the forelimbs or hindlimbs of mice and rats. By adjusting the length of the second rods 5, the height and length of the crossbar 12 can also be adjusted to accommodate forelimbs or hindlimbs of different lengths for mice and rats. The length, width, height, and angle of the first support 1 and the second support 2 can all be adjusted to accommodate forelimbs or hindlimbs of different lengths for mice and rats, as well as the angle of knee flexion and the degree of knee exposure, increasing the convenience of surgical procedures.

[0050] Preferably, the fixation device of the present invention further includes a lifting component 7, which is disposed on the crossbar 12. The lifting component 7 is used to lift and fix the forelimbs and hindlimbs of mice and rats, eliminating the need for manual support, saving personnel space, and facilitating surgical operations.

[0051] Preferably, such as Figure 5 As shown, the lifting assembly 7 includes a hook 71, a cantilever 72 and a cantilever seat 73. One end of the cantilever 72 is connected to the hook 71, and the other end of the cantilever 72 is connected to the cantilever seat 73.

[0052] Preferably, the hook 71 is plate-shaped, and more preferably, the hook 71 is a curved plate. The hook 71 is used to lift the forelimbs and hindlimbs of mice and rats, while isolating the bone shaft from soft tissues and nerves, thus preventing damage to the soft tissues and nerves of the forelimbs and hindlimbs during leg bone modeling surgery.

[0053] Preferably, the hook 71 includes a groove 74.

[0054] Preferably, the groove 74 is a trough, including a hollow part with an opening at one end, the hollow part leaving operating space for surgical instruments, which facilitates the surgical instruments to penetrate the bone shaft for operation; or, the groove 74 is a slot, including a hollow part with openings at both ends, which not only facilitates the surgical instruments to penetrate the bone shaft for operation, but also allows the soft tissue isolated by the hook 71 to be observed through the slot.

[0055] Preferably, the cantilever 72 is a universal movable cantilever, which can bend at any curvature, and can be suspended and fixed at any time, making it convenient to position and keep the hook 71 fixed.

[0056] Preferably, the hook 71 and the cantilever 72 are connected by a ball joint, and the hook 71 can rotate flexibly relative to the cantilever 72.

[0057] Preferably, the cantilever seat 73 is mounted on the second rod 5. The cantilever seat 73 can slide or rotate on the second rod 5, thereby driving the cantilever 72 and the hook 71 to move along the second rod 5. The hook 71 can be adjusted in six directions (up, down, left, right, front, and back) to adapt to the surgical requirements of different body shapes and postures of experimental animals.

[0058] Preferably, the cantilever seat 73 is provided with a screw 75, which passes through the cantilever seat 73 and is connected to the second rod 5. Loosening the screw 75 allows the cantilever seat 73 to slide or rotate on the second rod 5; tightening the screw 75 fixes the cantilever seat 73 on the second rod 5, thereby fixing the position of the cantilever 72.

[0059] Preferably, each base frame 11 is provided with two crossbars 12, and each of the two crossbars 12 is provided with a lifting component 7, so that the lifting and fixation of the forelimbs and hindlimbs of the mouse and rat are more stable.

[0060] The first bracket 1 and the second bracket 2 can rotate around the adapter rod 3, but the angle between the first bracket 1 and the second bracket 2 is not easy to fix. Preferably, as follows: Figure 6 As shown, the fixing device of the present invention also includes a limiter 8, with two ends of the limiter 8 connected to two bottom frames 11 respectively. The limiter 8 is used to restrict the rotation of the first bracket 1 and the second bracket 2 and fix the included angle between the first bracket 1 and the second bracket 2.

[0061] Preferably, one end of the limiter 8 is rotatably connected to a base frame 11, and the other end of the limiter 8 is provided with a positioning groove 81. Multiple positioning grooves 81 are arranged sequentially starting from one end of the limiter 8. The second rod 5 of another base frame 11 can be inserted into the positioning groove 81 to realize the connection between the base frame 11 and the limiter 8. By inserting the base frame 11 into different positioning grooves 81, the included angle between the first bracket 1 and the second bracket 2 can be changed and fixed.

[0062] Preferably, the fixation device of the present invention further includes a traction component 9, one end of which is connected to the bottom frame 11, and the other end of which is connected to the paw of the mouse or rat. The traction component 9 is used to pull the paw of the mouse or rat, so that the forelimbs and hindlimbs of the mouse or rat are in a traction and fixation state, which facilitates the surgical operation.

[0063] Preferably, such as Figure 7As shown, the traction assembly 9 includes a fixing ring 91, a pull ring 92, and an elastic connecting part 93. The elastic connecting part 93 connects the fixing ring 91 and the pull ring 92. The fixing ring 91 is movably connected to the base frame 11, and the pull ring 92 is connected to and fixed to the paw of the mouse or rat to prevent the paw from loosening. The elastic connecting part 93 is a spring or rubber band. The elastic connecting part 93 enables the traction assembly 9 to keep the forelimbs and hindlimbs of the mouse or rat in a traction and fixed state at all times, without the need for a special person to support the limbs, which facilitates surgical operations.

[0064] In use, place the forelimbs or hindlimbs of the mouse or rat on the first support 1 and the second support 2, with the knees or elbows on the adapter rod 3. Use the traction component 9 to pull and fix the paws of the mouse or rat. Adjust the length, width, and height of the base frame 11 and the crossbar 12 so that the crossbar 12 is slightly higher than the limb. When performing modeling surgery on the leg bone, the surgical incision needs to be opened and the bone shaft separated. The surgeon holds one end of the hook 71 and guides it along the curve of the bone shaft, closely following the bone shaft and circling it approximately half a turn, that is, from the opposite side of the surgical field through the bone shaft down to the side of the surgical field, to protect the blood vessels passing under the bone shaft. The nerves are not affected, and the surgical operation above the bone shaft is not affected. Finally, after adjusting the hook 71, if the cantilever 72 obstructs the surgical operation, the overall height of the cross frame 12 or the position of the cantilever seat 73 can be readjusted to adapt to the depth of the surgical incision and the needs of surgical field exposure. After confirming that there is no obstruction, tighten the screw 75 to fix the cantilever seat 73. When performing knee surgery, the hook 71 lifts the hind limb and the bottom frame 11 is inserted into different positioning slots 81 to change the angle between the first support 1 and the second support 2, so that the knee is fully exposed and the angle of limb flexion is suitable for the surgical requirements.

[0065] Compared with the prior art, the fixation device provided by the present invention, consisting of a first support 1, a second support 2, and a connecting rod 3, is used to support the forelimbs or hindlimbs of mice and rats for fracture and bone defect modeling surgery. The first support 1 and the second support 2 rotate around the connecting rod 3 and form an angle, allowing the rat to flex its knee and fully expose the knee joint for knee joint modeling surgery. The length, width, height, and angle of the first support 1 and the second support 2 are all adjustable to accommodate forelimbs or hindlimbs of different lengths, as well as the angle of knee flexion and the degree of knee exposure, increasing the convenience of surgical operation. The lifting component 7 is used to lift and fix the forelimbs and hindlimbs of mice and rats without manual support, saving personnel and facilitating surgical operations. The hook 71 is used to lift the forelimbs and hindlimbs of mice and rats, while isolating the bone shaft from soft tissues and nerves, preventing damage to the soft tissues and nerves of the forelimbs and hindlimbs during leg bone modeling surgery. By inserting the base frame 11 into different positioning slots 81, the angle between the first support 1 and the second support 2 can be changed and fixed. The traction component 9 can keep the forelimbs and hindlimbs of mice and rats in a traction and fixed state without the need for special personnel to support the limbs, facilitating surgical operations.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A fixation device for modeling the limb skeleton of rats and mice, characterized in that, It includes a first support (1), a second support (2), a connecting rod (3), a lifting component (7), a limiter (8), and a traction component (9). The first support (1) and the second support (2) are connected by the connecting rod (3). The first support (1) and the second support (2) can rotate around the connecting rod (3). The first support (1) and the second support (2) are used to support the forelimbs or hindlimbs of rats and mice for fracture and bone defect modeling surgery. The first support (1) and the second support (2) rotate around the connecting rod (3) and form an angle, which allows the rat to flex its knee and fully expose its knee for rat knee joint modeling surgery. The first bracket (1) and the second bracket (2) both include a base frame (11); the base frame (11) includes a second rod (5); by inserting the base frame (11) into different positioning slots (81) of the limiter (8), the included angle between the first bracket (1) and the second bracket (2) can be changed and fixed; The lifting assembly (7) includes a hook (71), a cantilever (72), and a cantilever seat (73). One end of the cantilever (72) is connected to the hook (71), and the other end of the cantilever (72) is connected to the cantilever seat (73). The hook (71) is used to isolate the bone shaft from soft tissues and nerves, preventing damage to the soft tissues and nerves of the fore and hind limbs during leg bone modeling surgery. The hook (71) includes a groove (74). The groove (74) is a trough, including a hollow part with an opening at one end. The hollow part provides operating space for surgical instruments, facilitating the insertion of surgical instruments through the bone shaft. Alternatively, the groove (74) is a slot, including a hollow part with openings at both ends, which not only facilitates the insertion of surgical instruments through the bone shaft but also allows observation through the slot. The hook (71) isolates the soft tissue; the hook (71) and the cantilever (72) are connected by a ball joint, and the hook (71) can rotate relative to the cantilever (72); the cantilever seat (73) can slide or rotate on the second rod (5), thereby driving the cantilever (72) and the hook (71) to move along the second rod (5); the cantilever seat (73) is provided with a screw (75), the screw (75) passes through the cantilever seat (73) and is connected to the second rod (5); loosening the screw (75) allows the cantilever seat (73) to slide or rotate on the second rod (5); tightening the screw (75) fixes the cantilever seat (73) on the second rod (5), thereby fixing the position of the cantilever (72); The traction assembly (9) includes a fixing ring (91), a pull ring (92), and an elastic connecting part (93). The elastic connecting part (93) connects the fixing ring (91) and the pull ring (92) respectively. The fixing ring (91) is movably connected to the bottom frame (11), and the pull ring (92) is connected to and fixed to the paws of the mouse and rat. The elastic connecting part (93) enables the traction assembly (9) to keep the forelimbs and hindlimbs of the mouse and rat in a traction and fixed state.

2. The fixation device for rat and mouse limb skeleton modeling according to claim 1, characterized in that, The first bracket (1) and the second bracket (2) both include a crossbeam (12), which is mounted on the bottom frame (11).

3. The fixation device for rat and mouse limb skeleton modeling according to claim 2, characterized in that, The two base frames (11) are connected by a connecting rod (3), and the two base frames (11) can rotate around the connecting rod (3).

4. The fixation device for rat and mouse limb skeleton modeling according to claim 1, characterized in that, The adapter rod (3) includes a first support rod (31), a first nut (32), and a first sleeve (33).

5. The fixation device for rat and mouse limb skeleton modeling according to claim 4, characterized in that, The first support rod (31) is disposed inside the first sleeve (33), and the first support rod (31) can extend and retract inside the first sleeve (33).

6. The fixation device for rat and mouse limb skeleton modeling according to claim 4, characterized in that, The first nut (32) is screwed to one end of the first sleeve (33).

7. The fixation device for modeling the limb skeleton of rats and mice according to claim 2, characterized in that, The bottom frame (11) also includes two first rods (4), which are connected by a second rod (5).

8. The fixation device for modeling the limb skeleton of rats and mice according to claim 7, characterized in that, The first rod (4) includes a second support rod (41), a second nut (42), and a second sleeve (43).

9. A fixation device for modeling the limb skeleton of rats and mice according to claim 8, characterized in that, One end of the second sleeve (43) is rotatably connected to one end of the adapter rod (3), and the second support rod (41) is set inside the second sleeve (43). The second support rod (41) can extend and retract inside the second sleeve (43).

10. A fixation device for modeling the limb skeleton of rats and mice according to claim 8, characterized in that, The second nut (42) is screwed to one end of the second sleeve (43).

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