3D-printed polylactic acid scaffolds for establishing an animal model of hip impingement syndrome
By placing a personalized 3D-printed polylactic acid scaffold at the edge of the acetabulum of a New Zealand white rabbit, the impact between the acetabulum and the femoral head was simulated, solving the problem of the lack of effective animal models in the existing technology and realizing a simple and effective research model for hip impingement syndrome.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PEKING UNIVERSITY THIRD HOSPITAL (THE THIRD CLINICAL MEDICAL SCHOOL OF PEKING UNIVERSITY)
- Filing Date
- 2025-05-29
- Publication Date
- 2026-07-21
AI Technical Summary
There is a lack of effective animal models for studying hip impingement syndrome in the current technology, and existing surgical methods are highly invasive, difficult to operate, and have uncertain effects.
A personalized 3D-printed polylactic acid scaffold was used to simulate the impact between the acetabulum and the femoral head by placing the scaffold at the edge of the acetabulum of a New Zealand white rabbit. Combined with exercise training, a model of hip impingement syndrome was established.
It provides a simple and effective animal model that can induce osteochondral damage and osteophyte formation in the femoral head, supporting basic research on hip impingement syndrome.
Smart Images
Figure CN120616830B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of medical device technology, and more specifically to a 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome. Background Technology
[0002] Femoroacetabular impingement syndrome (FAI) is a common hip joint disorder primarily caused by abnormal contact between the acetabulum and the femoral head. This abnormal contact may be due to anatomical abnormalities of the femoral head or acetabulum.
[0003] 1. Cam Impingement: The irregular shape of the femoral head (usually an irregular protrusion at the junction of the femoral head and neck) causes abnormal friction between the femoral head and the acetabulum.
[0004] 2. Pincer Impingement: Excessive coverage of the acetabular rim (usually the anterosuperior part of the acetabulum) leads to abnormal contact between the femoral head and the acetabulum.
[0005] 3. Combined Impingement: A combination of cam-type and clamp-type impacts.
[0006] Basic research on femoroacetabular impingement (FAI) requires the use of animal models. Currently, there is no scaffold for establishing animal models of FAI. It is necessary to increase the coverage of the femoral head by acetabular osteotomy (rotation of the acetabulum) to realize the impingement between the acetabulum and the femoral head. However, the surgery is highly invasive, difficult to perform, inconvenient to operate, time-consuming, and the postoperative results are uncertain. Summary of the Invention
[0007] The present invention aims to provide a 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome. The technical problem to be solved includes at least how to establish a personalized 3D-printed polylactic acid scaffold that can be placed at the edge of the acetabulum, and to realize a New Zealand white rabbit model of femoral-acetabulum impingement through the scaffold, so as to provide a new animal model and research method for the pathogenesis and diagnosis of hip impingement syndrome.
[0008] To achieve the above objectives, the present invention provides a 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome, comprising an arc-shaped front wall, an arc-shaped rear wall, a left side wall, a right side wall, a top wall, and a bottom wall. The arc-shaped front wall and the arc-shaped rear wall are spaced apart relative to each other, the left side wall and the right side wall are spaced apart relative to each other, and the top wall and the bottom wall are spaced apart relative to each other. The top wall is provided with a first side hole and a second side hole, both of which are through holes extending from the top wall to the bottom wall. The vertical distance between the center of the first side hole and the left side wall is less than the vertical distance between the first side hole and the right side wall; the vertical distance between the second side hole and the right side wall is less than the vertical distance between the center of the second side hole and the left side wall.
[0009] Preferably, the portion of the internal space enclosed by the arc-shaped front wall, arc-shaped rear wall, left side wall, right side wall, top wall, and bottom wall, except for the first and second side holes, is a solid structure 3D printed from polylactic acid.
[0010] Preferably, the radius of the arc corresponding to the arc front wall is 8.5mm, and the central angle corresponding to the projection of the arc front wall on the horizontal plane is 60°, that is, the arc length of the projection of the arc front wall on the horizontal plane is 1 / 6 of the circumference.
[0011] Preferably, the radius of the arc corresponding to the arc rear wall is 11.5mm, and the central angle corresponding to the projection of the arc rear wall on the horizontal plane is 60°, that is, the arc length of the projection of the arc rear wall on the horizontal plane is 1 / 6 of the circumference.
[0012] Preferably, the centers of the projections of the arc-shaped front wall and the arc-shaped rear wall onto the horizontal plane overlap at a single point.
[0013] Preferably, the left side wall is a rectangular structure with a length of 3mm and a width of 1.5mm.
[0014] Preferably, the shape and structure of the right side wall are exactly the same as those of the left side wall.
[0015] Preferably, the left and right side walls have rounded chamfers on all four sides.
[0016] Preferably, the diameter of the first side hole and the second side hole is 2 mm.
[0017] Preferably, the minimum straight-line distance between the circumferential walls of the first side hole and the second side hole is 4.45 mm.
[0018] Preferably, the minimum straight-line distance between the circumferential wall of the first side hole and the left side wall is 0.93 mm; the minimum straight-line distance between the circumferential wall of the first side hole and the arc front wall is 0.48 mm; and the minimum straight-line distance between the circumferential wall of the first side hole and the arc rear wall is 0.52 mm.
[0019] Preferably, the minimum straight-line distance between the circumferential wall and the right side wall of the second side hole is 0.93 mm; the minimum straight-line distance between the circumferential wall and the front arc wall of the second side hole is 0.48 mm; and the minimum straight-line distance between the circumferential wall and the rear arc wall of the second side hole is 0.52 mm.
[0020] Preferably, the bottom wall contacts the acetabular rim, and the arc-shaped anterior wall contacts the femoral head and neck region.
[0021] Compared with the prior art, the beneficial effects of the present invention are:
[0022] This invention marks the first use of personalized 3D-printed polylactic acid (PLA) scaffolds to establish an animal model of hip impingement syndrome. This model allows for the use of acetabular rim capping surgery on New Zealand white rabbits, effectively mitigating the impingement between the acetabulum and femoral head. The animals underwent eight weeks of exercise training, starting three weeks post-surgery. Postoperative imaging, gross assessment, and histological evaluation revealed damage to the osteochondral bone of the femoral head and the formation of osteophytes. This animal model is simple to operate, relatively novel, and provides an effective animal model for basic research on hip impingement syndrome. Attached Figure Description
[0023] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the specific embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.
[0024] Figure 1 This is a top view of the 3D-printed polylactic acid scaffold used to establish an animal model of hip impingement syndrome, as described in this invention.
[0025] Figure 2 This is a side view of the 3D-printed polylactic acid scaffold used to establish an animal model of hip impingement syndrome according to the present invention. Detailed Implementation
[0026] The invention is described in more detail below to aid in understanding it.
[0027] like Figure 1 and Figure 2As shown, the 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome according to the present invention is arc-shaped, including an arc-shaped front wall 1, an arc-shaped rear wall 2, a left side wall 3, a right side wall 4, a top wall 7, and a bottom wall 8. The arc-shaped front wall 1 and arc-shaped rear wall 2 are arranged with relative intervals, the left side wall 3 and right side wall 4 are arranged with relative intervals, and the top wall 7 and bottom wall 8 are arranged with relative intervals. The top wall 7 is provided with a first side hole 5 and a second side hole 6. The first side hole 5 and the second side hole 6 are both through holes that pass from the top wall 7 to the bottom wall 8. The vertical distance between the center of the first side hole 5 and the left side wall 3 is less than the vertical distance between the first side hole 5 and the right side wall 4. The vertical distance between the second side hole 6 and the right side wall 4 is less than the vertical distance between the center of the second side hole 6 and the left side wall 3.
[0028] Preferably, the portion of the internal space enclosed by the arc-shaped front wall 1, arc-shaped rear wall 2, left side wall 3, right side wall 4, top wall 7, and bottom wall 8, except for the first side hole 5 and the second side hole 6, is a solid structure made of polylactic acid 3D printed.
[0029] Polylactic acid (PLA) is a biodegradable polymer commonly used in the manufacture of medical products such as sutures, stents, bone repair materials, and implants. Its biodegradability and biocompatibility allow it to gradually degrade in the body without causing negative effects on the human body.
[0030] Preferably, the radius of the arc corresponding to the arc front wall 1 is 8.5mm, and the central angle corresponding to the projection of the arc front wall 1 on the horizontal plane is 60°, that is, the arc length of the projection of the arc front wall 1 on the horizontal plane is 1 / 6 of the circumference.
[0031] Preferably, the radius of the arc corresponding to the arc rear wall 2 is 11.5mm, and the central angle corresponding to the projection of the arc rear wall 2 on the horizontal plane is 60°, that is, the arc length of the projection of the arc rear wall 2 on the horizontal plane is 1 / 6 of the circumference.
[0032] Preferably, the centers of the projections of the arc-shaped front wall 1 and the arc-shaped rear wall 2 onto the horizontal plane overlap at a single point.
[0033] Preferably, the left side wall 3 is a rectangular structure with a length of 3mm and a width of 1.5mm.
[0034] Preferably, the shape and structure of the right side wall 4 are exactly the same as those of the left side wall 3.
[0035] Preferably, the left side wall 3 and the right side wall 4 have rounded chamfers on all four sides.
[0036] Preferably, the diameter of the first side hole 5 and the second side hole 6 is 2 mm.
[0037] Preferably, the minimum straight-line distance between the circumferential wall of the first side hole 5 and the circumferential wall of the second side hole 6 is 4.45 mm.
[0038] Preferably, the minimum straight-line distance between the circumferential wall of the first side hole 5 and the left side wall 3 is 0.93 mm; the minimum straight-line distance between the circumferential wall of the first side hole 5 and the arc front wall 1 is 0.48 mm; and the minimum straight-line distance between the circumferential wall of the first side hole 5 and the arc rear wall 2 is 0.52 mm.
[0039] Preferably, the minimum straight-line distance between the circumferential wall of the second side hole 6 and the right side wall 4 is 0.93 mm; the minimum straight-line distance between the circumferential wall of the second side hole 6 and the arc front wall 1 is 0.48 mm; and the minimum straight-line distance between the circumferential wall of the second side hole 6 and the arc rear wall 2 is 0.52 mm.
[0040] Preferably, the bottom surface (i.e., bottom wall 8) of the 3D-printed polylactic acid scaffold used to establish an animal model of hip impingement syndrome contacts the acetabular rim, and the short side arc (i.e., the anterior arc wall 1) contacts the femoral head and neck region.
[0041] This invention aims to establish a New Zealand white rabbit model of femoral-acetabulum impingement by placing a personalized 3D-printed polylactic acid scaffold at the edge of the acetabulum, providing a new animal model and research method for the pathogenesis and diagnosis of hip impingement syndrome.
[0042] In a preferred embodiment, 24 six-month-old male New Zealand white rabbits were selected for the animal model design. The surgery was performed on the right hip, with the left hip serving as a normal control. All animals were allowed normal cage activity post-surgery. Eight weeks post-surgery, the animals were assessed for acetabular overcoverage and secondary cartilage damage.
[0043] Existing techniques increase the coverage of the acetabulum over the femoral head through acetabular osteotomy (acetabular rotation) to achieve impact between the acetabulum and the femoral head, but the surgery is highly invasive and difficult to perform.
[0044] This invention aims to describe and validate a novel surgical method for establishing an animal model of hip impingement syndrome (FAI) in adult rabbits. By placing a personalized 3D-printed polylactic acid scaffold at the edge of the acetabulum, the anatomical developmental abnormality of hip impingement syndrome patients, namely acetabular over-coverage, is simulated to establish a model of FAI.
[0045] The surgical procedure was as follows: The animal was anesthetized with 3% isoflurane. After routine disinfection and draping, a 2cm longitudinal incision was made directly above the greater trochanter. The lateral fascia and gluteal muscles were incised and retracted to expose the acetabulum. The hip joint capsule was then incised along the acetabular rim. Using a 1.8mm Kirschner wire, two holes were drilled at the 11 o'clock and 1 o'clock positions, penetrating the entire thickness of the acetabulum, approximately 3mm from the acetabular rim. The drilling direction should be at a 45° angle to the acetabulum. Throughout the drilling process, gentle traction was used to separate the joint space, avoiding damage to the femoral head.
[0046] The 3D-printed polylactic acid scaffold used to establish an animal model of hip impingement syndrome was placed in the acetabulum at the 11 o'clock to 2 o'clock position. The bottom surface of the scaffold (i.e., bottom wall 8) was in contact with the acetabular rim, and the short side arc (i.e., the anterior arc wall 1) was in contact with the femoral head and neck region.
[0047] Pass both ends of suture #2 through the two holes (at the 11 o'clock and 1 o'clock positions of the acetabulum) and remove it from the joint cavity. Figure 1 The polylactic acid (PLA) scaffold is then passed through the side holes (i.e., the first side hole 5 and the second side hole 6) of the 3D-printed PLA scaffold and secured at the acetabular rim. The PLA scaffold is tightly pressed against the acetabular rim with minimal mobility, leading to over-coverage of the acetabulum and resulting in bony impingement with the femoral head. Finally, the deep fascia and skin are sutured with 3-0 non-absorbable sutures. Immediately postoperatively, 0.1 mg of butorphanol is administered subcutaneously for analgesia, and penicillin is administered subcutaneously for 5 consecutive days postoperatively to prevent infection.
[0048] Exercise training began 3 weeks post-surgery, with six days of training per week. Each rabbit trained for 10 minutes at a speed of 50 cm / min for 8 and 12 weeks; all rabbits trained at a 0° incline. Researchers observed treadmill usage daily to ensure the rabbits received effective exercise.
[0049] The imaging evaluation process was as follows: After sampling, a micro-CT scan was performed on the operated hip joint to assess the extent of induced acetabular over-coverage. Multiplanar reconstruction was performed using RadiAnt DICOM Viewer to generate coronal and axial images, along with three-dimensional reconstruction.
[0050] The macroscopic assessment process is as follows: After completing the imaging assessment, the joint capsule is incised and the ligamentum teres is cut to expose the articular surface. The femoral head cartilage is graded according to the modified Outerbridge scoring system as follows: Grade 0 = smooth surface, normal color; Grade 1 = rough surface, with slight fibrillation or slight yellowing; Grade 2 = cartilage erosion extends to the superficial or middle layer; Grade 3 = cartilage erosion extends to the deep layer; Grade 4 = complete cartilage erosion, exposing the subchondral bone.
[0051] Femoral head specimens were fixed in 4% paraformaldehyde for 24 hours, decalcified in 10% formic acid solution for one week, dehydrated with graded ethanol, embedded in paraffin, and sectioned. After baking for 2 hours, the sections were dewaxed in xylene, rehydrated with graded ethanol, and stained with hematoxylin and eosin (HE), safranin and fast green, and toluidine blue.
[0052] The aforementioned animal model is the first to use a personalized 3D-printed polylactic acid scaffold to perform a rim capping surgery on the acetabulum of New Zealand white rabbits, achieving impingement between the acetabulum and the femoral head through acetabular capping. The animals underwent eight weeks of exercise training three weeks post-surgery. Postoperative imaging, gross assessment, and histological evaluation all revealed damage to the osteochondral bone of the femoral head and the formation of osteophytes. This animal model is simple to operate, relatively novel, and provides an effective animal model for basic research on hip impingement syndrome.
[0053] This invention utilizes a personalized 3D-printed polylactic acid scaffold to perform a laparoscopic procedure on the edge of the acetabulum in New Zealand white rabbits, followed by postoperative exercise training. This model effectively induces impingement between the acetabular edge and the femoral head, providing an effective animal model for basic research on hip impingement syndrome.
[0054] The preferred embodiments of the present invention have been described above, but are not intended to limit the invention. Those skilled in the art can make modifications and variations to the embodiments disclosed herein without departing from the scope and spirit of the invention.
Claims
1. A 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome, characterized in that, The 3D-printed polylactic acid scaffold used to establish an animal model of hip impingement syndrome includes an arc-shaped front wall, an arc-shaped rear wall, a left side wall, a right side wall, a top wall, and a bottom wall. The arc-shaped front wall and the arc-shaped rear wall are spaced apart, the left side wall and the right side wall are spaced apart, and the top wall and the bottom wall are spaced apart. The top wall has a first side hole and a second side hole, both of which are through holes extending from the top wall to the bottom wall. The vertical distance between the center of the first side hole and the left side wall is less than the vertical distance between the first side hole and the right side wall; the vertical distance between the second side hole and the right side wall is less than the vertical distance between the center of the second side hole and the left side wall. The internal space enclosed by the arc-shaped front wall, arc-shaped rear wall, left side wall, right side wall, top wall, and bottom wall, except for the first side hole and the second side hole, is a solid structure made of polylactic acid 3D printing. The centers of the projections of the front and rear arc walls onto the horizontal plane overlap at a single point. The radius of the arc corresponding to the arc front wall is 8.5mm, and the central angle corresponding to the projection of the arc front wall on the horizontal plane is 60°. That is to say, the arc length of the projection of the arc front wall on the horizontal plane is 1 / 6 of the circumference. The radius of the arc corresponding to the arc rear wall is 11.5mm, and the central angle corresponding to the projection of the arc rear wall on the horizontal plane is 60°. That is to say, the arc length of the projection of the arc rear wall on the horizontal plane is 1 / 6 of the circumference. The left side wall is a rectangular structure with a length of 3 mm and a width of 1.5 mm. The shape and structure of the right side wall are exactly the same as those of the left side wall; The left and right walls are all rounded with chamfered edges. The minimum straight-line distance between the circumferential walls of the first side hole and the second side hole is 4.45 mm.
2. The 3D-printed polylactic acid scaffold for establishing an animal model of hip impingement syndrome according to claim 1, characterized in that, The diameter of the first side hole and the second side hole is 2mm.