Objective To establish a fluoroscopic percutaneous vertebral augmentation model in dogs by measuring and analyzing canine spinal anatomy.We also assessed the effectiveness and safety of this modeling method by postoperative radiological analysis.Methods Morphological measurements were taken in six dogs,aged approximately 12～24 months,and the following parameters of the lumbar vertebrae were determined:height of the L1～L7 vertebrae,width of the vertebral base,distance from the upper edge of the intervertebral disc to the narrowest part of the vertebra,distance from the vertical line of the spinous process to the upper edge of the intervertebral disc,and vertical distance from the midpoint of the transverse process to the lower edge of the intervertebral disc.These measurements were obtained to clarify the anatomical characteristics of the canine vertebrae and determine the optimal location,direction,and depth for bone-cement injection.A percutaneous vertebral augmentation model was subsequently established in the L4,L5,and L6 vertebrae of six healthy Beagle dogs,weighing 20～25 kg.The dogs were euthanized 4 weeks post-surgery and examined radiologically.Primary observations included the surgical duration,postoperative distribution of the implanted bone cement,and integrity of the vertebral canal and anterior edge of the vertebrae.Results Anatomical observation of the canine vertebrae revealed that the vertebral height increased gradually from L1～L5 and then decreased from L5～L7.The width of the vertebral base increased consistently from L1～L7.The distance from the vertical line of the spinous process to the upper edge of the intervertebral disc showed an increasing trend from L1～L7(1.9～4.0 mm).The distance between the midpoint of the base of the transverse process and the lower edge of the intervertebral disc increased gradually from L1～L5(4.7～6.9 mm).There was no significant difference in the distance between the midpoint of the base of the transverse process and the lower edge of the intervertebral disc in the L4,L5,and L6 segments among the dogs(P=0.925).The midpoint of the root of the transverse process of the spine was taken as the puncture point,and the insertion direction and horizontal plane were at an angle of 20°～30°,with a head tilt of 5°～15° and a puncture depth of 1.2～1.5 cm.If the puncture was directed towards the caudal side of the vertebra,the angle of the needle tail was 30°～35°,with a penetration depth of 1.5～1.8 cm.This technique allowed the successful construction of a canine vertebral puncture surgical model.A total of 15 canine vertebral puncture surgical models were successfully created,with an average surgery time of 22.7±4.6 min(15～30 min)per vertebral segment.During surgery,one vertebral segment experienced spinal cord injury result ing in paralysis of the hind limbs and bowel and bladder incontinence.Two vertebral cortical bones fractured,but there were no deaths due to anesthesia or infection.Four weeks post-surgery,micro-computed tomography-based three-dimensional reconstructions consistently showed bone cement distributed within the trabecular bone of the canine vertebrae,with newly formed bone tissue enveloping the implanted material.There was no leakage,and no complications such as damage to the vertebral canal or the anterior wall of the vertebrae.Conclusions A safe and reliable canine vertebral augmentation puncture model can be successfully established based on the anatomy of the canine lumbar vertebrae(L4～L6)and using the midpoint of the base of the transverse process as a bony landmark.

BACKGROUND:Intervertebral disc degeneration is clinically considered to be the main cause of low back pain,but due to the unclear pathogenesis of intervertebral disc degeneration,there is still a lack of effective means to delay the progression of the disease.Single-cell RNA sequencing technology can amplify and sequence mRNA at the single-cell level,reveal the gene expression intensity of a single cell,discover different cell subsets in tissues according to the heterogeneity of cells,study the pathogenesis of intervertebral disc degeneration at the molecular level,and provide a new theoretical basis for its early diagnosis and treatment. OBJECTIVE:To introduce the basic principles of single-cell RNA sequencing technology and review the research progress of single-cell RNA sequencing technology in intervertebral disc degeneration in recent years. METHODS:A computer was used to search PubMed,Web of Science,CNKI and WanFang databases for the literature published from 2012 to 2022.Key words were"single-cell RNA sequencing,intervertebral disc degeneration,sequencing Technology"in Chinese and English.Duplicate,poor-quality and irrelevant articles were excluded;a total of 70 articles were eventually included. RESULTS AND CONCLUSION:(1)We identified new cell subsets such as homeostatic chondrocytes,hypertrophy chondrocyte-like nucleus pulposus cells and fibrous nucleus pulposus cells,identified the marker genes and transcription factors of these cell subsets,and described the functions,differentiation paths and cell fate of these cell subsets during the development and progression of intervertebral disc degeneration,and proposed the concept of progenitor nucleus pulposus cells.A cell subpopulation with progenitor nucleus pulposus cells properties was identified and its effectiveness in treating intervertebral disc degeneration was verified in mice.(2)Fibro chondrocyte-like annulus fibrosus cells and annulus fibrosus stem cells with both cartilage and fiber properties were identified,and a new type of composite hydrogel was prepared by combining fibrous cartilage inducers silk fibroin and hyaluronic acid in vitro.Experiments in mice demonstrated that this hydrogel could repair both annulus fibrosus tissue and cartilage matrix,and was remarkably effective in the treatment of intervertebral disc degeneration.(3)Regulatory chondrocytes were found in endplate cartilage.Two distinct fates in the progression of intervertebral disc degeneration were analyzed and the differential genes in the two fates were identified.Intercellular communication analysis indicated that regulatory chondrocytes interact with endothelial cells to promote angiogenesis.(4)Immune cells such as macrophages,T cells,myeloid progenitor cells and neutrophils were identified in the degenerated intervertebral disc tissues,demonstrating the existence of immune response during intervertebral disc degeneration.It was found that apolipoprotein induced the polarization of macrophages M1 and M2 subtypes,and this polarization process affected the activity of progenitor nucleus pulposus cells by amplifying the inflammatory response through the MIF signaling pathway.

BACKGROUND:Hydroxyapatite is the main inorganic component of bone tissue.The polymer has the structure and function of a biomimetic extracellular matrix.The composites of hydroxyapatite and polymer have been widely studied. OBJECTIVE:To summarize the research status of hydroxyapatite composite polymer materials for bone tissue repair. METHODS:The articles collected in PubMed,Web of Science,CNKI and WanFang databases were searched from January 2010 to April 2023.The Chinese and English search terms were"hydroxyapatite,polymer,composites,degradability,bone defect,bone repair".Finally,75 articles were included for review. RESULTS AND CONCLUSION:Polymers often used in composite with hydroxyapatite for bone tissue repair include natural polymers(collagen,chitosan,alginate,serine protein,cellulose,hyaluronic acid,and polyhydroxybutyrate)and synthetic polymers[polylactic acid,polylactic acid-hydroxyacetic acid copolymer,poly(has-lactide),poly(amino acid)and poly(vinyl alcohol)].The mechanical properties and osteoinductivity of hydroxyapatite/polymer composites were improved compared with pure hydroxyapatite.Hydroxyapatite composite with polymers can be made into porous scaffolds,hydrogels,and coatings for bone repair.Hydroxyapatite/polymer composites can accelerate bone reconstruction with a slow release of loaded drugs and cytokines due to their bionic extracellular matrix structure and function.Based on the diversity of causes of bone defects and the fact that bone repair is a complex continuous process involving multiple biological factors and proteins,repair materials with mechanical properties matching bone tissue,degradation processes synchronized with bone repair,and efficient osteogenesis and vascularization need to be further investigated.

Objective:To compare the efficacy of the horizontal plate plus raft screws above the acetabulum and fixation with screws only for acetabular fractures combined with dome impaction in the aged patients.Methods:A retrospective cohort study was conducted to analyze the clinical data of 20 aged patients with acetabular fractures combined with dome impaction, who were admitted to Tianjin hospital between May 2013 and January 2023, including 5 males and 15 females, aged 61-84 years [(72.2±7.3)years]. According to Letournel and Judet classification, 13 patients had anterior column fracture, 5 anterior column fracture combined with posterior transverse fracture and 2 two-column fracture. All the patients underwent open reduction and internal fixation through an anterior approach. Of them, 11 patients were treated with the fixation with the horizonal plate plus raft screws above the acetabulum (plate plus raft screw group) and 9 with the screws only (screw only group). The operative time, intraoperative blood loss, and intraoperative fluoroscopy times were compared between the two groups. The quality of fracture reduction was evaluated with the Matta′s radiographic criteria at 3 days after surgery and the function of the hip joint was assessed with Merle D′Aubigné and Postel scoring system at 3 months after surgery and at the last follow-up as well as the excellent and good rate at te last follow-up. The occurrence of postoperative complications was observed.Results:All the patients were followed up for 6-18 months [(13.1±3.1)months]. There were no significant differences in the operative time, intraoperative blood loss or intraoperative fluoroscopy times between the two groups ( P>0.05). According to the Matta′s radiographic criteria at 3 days after surgery, patients with anatomical reduction and satisfactory reduction accounted 6 and 5 in the plate plus raft screw group, compared to 5 and 4 respectively in the screw only group ( P>0.05). The values of Merle D′Aubigné and Postel score at 3 months after surgery and at the last follow-up were (14.0±2.4)points and (15.8±2.2)points in the plate plus raft screw group, which were higher than those in the screw only group [(11.0±2.6)points and (13.0±3.1)points] ( P<0.01). The values of Merle D′Aubigné and Postel score at the last follow-up of both groups were further enhanced from those at 3 months after surgery ( P<0.01). At the last follow-up, 3 patients were rated excellent, 6 good, 1 fair and 1 poor in the plate plus raft screw group, with an excellent and good rate of 81.8%, while in the screw only group, 3 were rated good, 2 fair and 4 poor, with an excellent and good rate of 33.3% ( P<0.05). One patient in the plate plus raft screw group and 5 in the screw only group had displacement of the dome impaction fragment combined with traumatic arthritis after surgery ( P<0.05). Conclusion:For acetabular fractures combined with dome impaction in the aged patients, the horizontal plate plus raft screw above the acetabulum can effectively improve the function restoration of the hip joint and reduce the occurrence of the displacement of the dome impaction fragment and traumatic arthritis after surgery compared to the fixation with screws only.

Objective:To evaluate the clinical outcome of Robot-assisted sacroiliac screw fixation in the treatment of fragility fracture of the sacrum in the elderly.Methods:From March 2016 to June 2022, a retrospective analysis was performed on 30 patients with fragility fractures of the sacrum in the elderly who accepted robot-assisted sacroiliac screw to treat fragility fractures of the sacrum in our hospital. There were 12 males and 18 females with average age 71.03±8.25 years (range, 60-89 years). According to the classification of fragility fractures of the pelvis (FFP) in the elderly, there were 22 patients with FFP II, 2 patients with FFP III, and 6 patients with FFP IV. Surgical planning was based on the average CT value of S 1 channel and whether there is a transsacral screw channel. Robot-assisted sacroiliac screw fixation was performed during surgery. The pain of pre-operation and post-operation was evaluated using the visual analogue scale (VAS), the position of sacroiliac screws was evaluated by Gras grading, and the degree of functional recovery after surgery was evaluated using the Majeed function score. Results:All 30 patients successfully completed the operation. The mean operation time was 27.00±6.68 min (range, 18-35 min), the mean fluoroscopy times were 27.13±5.16 (range, 18-34), and the mean blood loss was 30.53±6.61 ml (range, 23-38 ml). All patients were followed up, and the mean follow-up time was 19.03±7.8 months (range, 8-25 months). The VAS was 5(5, 6), 4(3, 4), 3(2, 3), 0(0, 1) points before surgery, 1 week, 2 months and 6 months after surgery, respectively, and the difference was statistically significant ( H=103.26, P<0.001). After the surgery of 2 months, 6 months and the last follow-up time, the Majeed function scores were 88(83, 90), 91(87, 92), 92(90, 93) points, respectively, and the difference was statistically significant ( H=19.59, P<0.001). Screw position was evaluated according to Gras grading at 3 days after surgery, including 28 cases of level I, 2 cases of level II, and no screw penetrated the cortical bone or entered the sacral canal or sacral foramen. No vascular or nerve injury occured during the operation. 28 patients with FFS met the fracture healing criteria, and the healing time was 4.54±1.57 months (range, 3-7 months). Two patients had bone nonunion, one of whom underwent anterior ring plate removal due to infection of the pelvic anterior wound, and one month later, pelvic CT scan revealed loosening of the sacroiliac screw; the other one is considered to be related to too early weight bearing. Conclusion:For fragility fractures of the sacrum in elderly, Robot-assisted sacroiliac screw is an effective minimally invasive treatment, with high accuracy of screw placement, effective pain reduction, improved fracture healing rate, and achieve the satisfactory clinical efficacy.

Objective:To investigate the clinical efficacy of robot-assisted sacroiliac screw implantation in the treatment of proximal dysplasia sacral fractures.Methods:A retrospective analysis was conducted on 191 patients admitted to the Pelvic Department of Tianjin Hospital from May 2016 to January 2021 who underwent robot assisted sacroiliac screw implantation with sacral fractures, including 105 males and 86 females, aged 38.5±6.5 years (ranging from 19 to 69 years old). Among them, there were 85 patients with dysplasia of proximal sacrum. According to the classification of proximal sacral dysplasia, the patients were divided into five groups: the steep sacral alar slope group ( n=60), the mastoid protrusion group ( n=30), the lumbar sacralization group ( n=25), the sacral foramen oval degeneration group ( n=23) and the S 1 anterior cortical depression group ( n=10). The remaining 106 patients were normal group. Iliac cortical density (ICD) line typing was recorded in the 85 patients. The the completion of sacroiliac screw implantation, the Gras score of screw position after operation, the postoperative complications, the minimum diameter of S 1 screw channel (R1), the angle ∠A between the S 1 sacroiliac screw in the coronal plane and the cephalic side, and the angle ∠B between the S 1 sacroiliac screw in the water plane and the ventral side were recorded and compared with those of normal development patients. Results:The incidence of steep sacral alar slope was the highest (31.4%, 60/191). There were 2 or more developmental abnormalities in 24 cases. In 85 cases with dysplasia of proximal sacrum, ICD line type I was found in 8 cases, type II in 12 cases and type III in 65 cases. 49 patients (58.8%, 49/85) were able to complete the implantation of S 1 sacroiliac screw, while 36 patients (35.3%, 36/85) were only able to complete the implantation of S 2 sacroiliac screw. The Gras score of postoperative screw position was 90.05% for grade I, 9.94% for grade II, and 0 for grade III. In 1 case the sacroiliac screw pierced through the anterior cortex of the sacrum, and in 1 case the screw partially threaded into the sacral foramen, and there were no symptoms of iatrogenic nerve injury. The R1 values of the preoperative steep sacral alar slope group, the mastoid protrusion group, the sacral foramen oval degeneration group, the lumbar sacralization group, the sacral foramen oval degeneration group and normal development patient group were 11.4±3.0, 11.6±3.2, 9.8±3.0, 8.8±4.2, 6.5±4.4, and 11.4±3.4 mm, respectively. The differences between the lumbar sacralization group, the sacral foramen oval degeneration group, and the S1 anterior cortical depression group with the normal development patients were statistically significant, respectively ( t=-3.05, P=0.005; t=-2.32, P=0.022; t=-3.45, P=0.006). The postoperative angle ∠A of the above six groups were 33.8°±4.2°, 20.8°±3.5°, 25.8°±2.5°, 35.5°±4.5, 27.8°±3.5° and 26.8°±5.0°, respectively. The postoperative angle ∠B of the above six groups were 27.8°±3.5°, 36.2°±3°, 26.3°±1.8°, 29.8°±2.7°, 14.8°±1.5° and 37.2±4.2°, respectively. The differences between the ∠A of the steep sacral alar slope group, the mastoid protrusion group, and tthe lumbar sacralization group with that of the normal development patients were statistically significant, respectively ( t=9.17, -7.48, 7.97, P<0.001). The differences between the ∠B of the steep sacral alar slope group, the lumbar sacralization group, the sacral foramen oval degeneration group, and the S 1 anterior cortical depression group with that of the normal development patients were statistically significant, respectively ( t=-14.68, -10.93, -19.79, -35.8, P<0.001). Conclusion:This study proposes the "absolute stenosis" of the S 1 screw channel; In the treatment of patients with abnormal proximal sacral fracture, attention should be paid to S 1 anterior cortical depression and lumbar sacralization, and robot-assisted sacroiliac screw implantation can further improve the safety and accuracy of sacroiliac screw implantation.

Objective:To investigate the clinical outcomes of fragility fractures of the pelvis (FFP) treated with robot-assisted screws, minimally reduction according to the pelvic osseous pathways.Methods:A retrospective analysis was performed on the data of 50 elderly patients with FFP treated by the Department of Trauma and Pelvic Trauma of Tianjin Hospital from March 2016 to October 2021, and the 50 patients with FFP were divided into robotic-assisted screw fixation group (robot group) and open reduction steel plate fixation group (open group) according to the fixation method. There were 30 patients in the Robot group, 6 males and 24 females, average age 75.03±7.32 years (range, 60-90 years). According to Rommens and Hofmann FFP classification, there were 4 cases of IIc type, 8 cases of IIIa type, 1 case of IIIb type, 12 cases of IIIc type, 3 cases of IVa type, 2 cases of IVb type. There were 20 patients in the open group, 5 males and 15 females, average age 71.90±5.51 years (range, 62-85 years). According to Rommens and Hofmann FFP classification, there were 2 cases of IIc type, 6 cases of IIIa type, 9 cases of IIIc type, 3 cases of IVa type. The two groups were compared with age, pelvic fracture classification, operation time, intraoperative blood loss, fracture reduction quality, visual analogue scale (VAS), Majeed score, and wound healing or not.Results:All patients were followed up for 12.72 months (range, 6-24 months). In the robot group, the operation time was 50.17±19.32 min (range, 30-120 min), and intraoperative blood loss was 55.50±28.60 ml (range, 10-150 ml); in the open group, the operation time was 92.25±27.55 min (range, 60-180 min), and intraoperative blood loss was 217.50±67.20 ml (range, 150-400 ml), there were statistical differences ( t=6.36, P<0.001; t=11.72, P<0.001). According to Mears and Velyvis imaging evaluation criteria, in the robot group, anatomical reduction were achieved in 10 cases, satifactory reduction were achieved in 20 cases; in the open group, anatomical reduction were achieved in 14 cases, satifactory reduction were achieved in 6 cases, there were statistical differences (χ 2=6.46, P=0.011). In the robot group, VAS for pelvic pain was 7.33±1.32 points (range, 4-9 points) before operation, 4.13±1.07 points (range, 3-8 points) one week after surgery, and 2.30±0.84 points (range, 1-5 points) at the last follow-up; in the open group, VAS for pelvic pain was 7.45±1.23 points (range, 5-9 points) before operation, 5.25±1.25 points (range, 3-8 points) one week after surgery, and 2.80±1.24 points (range, 1-6 points) at the last follow-up, the difference between the two groups was statistically significant ( F=162.18, P<0.001; F=70.18, P<0.001), the difference between the two groups was statistically significant 1 week after surgery ( t=3.37, P=0.001), and there was no statistically significant difference between the two groups before surgery and the last follow-up ( P>0.05). The Majeed score was 82.10±4.80 (range, 65-95) in the robot group, 77.60±5.40 (range, 70-93) in the open group at the last follow-up, there were statistical differences ( t=3.09, P=0.003). There was no wound complication in the robot group, there were 4 cases with wound infection or rupture in the open group. One LC-II screw loosen in the robot group, which needed reoperation with cement, there was also 1 screw of plate loosening in the open group with no reoperation. Conclusion:Robot-assisted screws fixation with minimally reduction based pelvic osseous pathways shows satisfactory clinical outcomes, satisfactory reduction, effective pain relief, and fewer postoperative complications in treatment of elderly FFP.

Traumatic spinopelvic dissociation is trauma-induced complete separation of the pelvis and spine anatomy. It is characterized by longitudinal fracture lines on both sides of the sacral bone with transverse fractures, multiplane unstable fractures, more common in high-energy violent injury, more combined injuries, high incidence of sacral nerve injury, improper treatment can easily lead to fracture re-displacement, painful deformity healing, secondary nerve injury, dysfunction and other adverse consequences. The difficulty in the surgical treatment of traumatic spinopelvic dissociation lies in the reduction and fixation of fractures. Among them, it is still controversial whether the reduction method of fracture should be open reduction or closed minimally invasive reduction, the internal fixation should be simple sacroiliac screw or plate, iliolumbar fixation or triangular fixation, and whether the sacral nerve injury needs direct decompression. With the improvement of the understanding of spinopelvic dissociation injuries and clinical application of closed minimally invasive reduction technology, minimally invasive sacroiliac screws, iliolumbar fixation, and triangular fixation are increasingly used in clinical treatment, postoperative wound complications are significantly reduced, patient function prognosis is good, indirect decompression of the injured sacral nerve after fracture reduction helps to restore nerve function, but when the fracture displacement is large with a narrow sacral canal and the nerve is compressed by the fracture or free bone mass, direct decompression by laminectomy is recommended.

Objective:To measure the anatomical parameters of three-dimensional available space of S 1 and S 2 vestibules on Chinese adults by imaging methods, and discuss their clinical values. Methods:Data of 200 cases of pelvic CT with complete posterior ring were collected from January 2015 to January 2021, included 110 males and 90 females. The ages ranged from 21 to 63 years (average, 40.72±10.70 years). Then the parameters of both the left vestibule and the right vestibule of S 1 and S 2 such as vestibular width, vestibular height and vestibular area were measured by the three-dimensional CT reconstructions. Statistical analyses were performed among the groups which were classified according to the gender, side of vestibule to compare the difference of vestibular morphological characteristics among different groups. Results:The average vestibular area of S 1 was 425.71± 45.07 mm 2 (range, 296.3-604.4 mm 2), which was 449.80±28.62 mm 2 (range, 338.3-604.4 mm 2) in males and 388.25±34.01 mm 2 (range, 296.3-498.4 mm 2) in females. The average vestibular width was 28.52±4.34 mm (range, 17.1-36.3 mm), 31.77±2.33 mm (range, 22.46-36.30 mm) in males and 24.55±2.55 mm (range, 17.1-26.1 mm) in females. The mean vestibular height was 21.05±2.29 mm (range, 17.5-32.0 mm), with 21.34±2.37 mm (range, 18.5-32.0 mm) of men and 20.69±1.60 mm (range, 17.5-25.6 mm) of women. The mean S 2 vestibular area was 230.19±35.57 mm 2 (range, 142.5-297.3 mm 2), which was 258.91±28.04 mm 2 (range, 218.3-297.3 mm 2) in males and 205.61±24.12 mm 2 (range, 142.5-258.6 mm 2) in females. The average vestibular width was 15.94±1.72 mm (range, 12.4-20.3 mm), 16.51±1.59 mm (range, 14.4-20.3 mm) in male and 15.25±1.63 mm (range, 12.4-18.1 mm) in female. The mean vestibular height was 14.30±1.20 mm (range, 12.9-17.8 mm), 15.49±1.46 mm (range, 13.6-17.8 mm) in males and 13.73±0.93 mm (range, 12.9-16.1 mm) in females. There were significant differences in vestibular width, height and area between S 1 and S 2 (vestibular width t=3.934, P< 0.001; vestibular height t=3.692, P< 0.001; vestibular area t=4.816, P< 0.001). There were significant differences in S 1 vestibular width, S 1 vestibular height, S 1 and S 2 vestibular area between male groups and female groups (S 1 vestibular width: t=2.969, P=0.003; S 1 vestibular height: t=0.316, P=0.049; S 1 vestibular area: t=1.975, P=0.049; S 2 vestibular area: t=2.023, P=0.044). While there was no significant difference in S 2 vestibular width and height between the two gender groups. There were significant differences in S 1 and S 2 vestibular width, height and area between male and female groups ( P < 0.001). There were no significant difference in parameters between the left and right values of the same vestibular site. Conclusion:The parameters of S 1 sacral vestibule are larger than that of S 2. It implies that S 1 was more feasible to insert iliosacral screws than S 2; lesser diameter iliosacral screws should be selected to insert into S 2. The female S 1 vestibule is smaller than the male, so the iliosacral screws placement has more stringent requirements on the selection of the insertion point and the direction of the screw. And the surgeon can utilize the intact contralateral sacral vestibule as the damaged side to proceed the iliosacral screw inserted simulation.

Objective:To investigate the clinical outcomes of unstable pelvic fractures in adolescents treated with robot-assisted posterior pelvic channel screw.Methods:From October 2016 to October 2020, 14 adolescent patients with unstable pelvic fractures were retrospectively analyzed. There were 8 males and 6 females, average age of 14.57±1.69 years (range, 12-17 years). Pelvic fracture classification: according to Tile classification, 2 cases of B1, 3 cases of B2, 1 case of B3, 2 cases of C1, 5 cases of C2, 1 case of type C3. According to Torode-Zieg classification, 2 cases of type IIIb, 12 cases of type IV. According to Young-Burgess classification, 1 case of APC II, 1 case of APC III, 2 cases of LC I, 2 cases of LC III, 8 cases of VS type. The diameter of the sacroiliac screw channel, operation time, intraoperative blood loss, fracture reduction quality, pelvic asymmetry, pain visual analogue scale (VAS), Majeed score, screw placement accuracy, postoperative complications were analyzed. The pelvic asymmetry and VAS at presurgery, one week after surgery and the last follow-up were statistically analyzed.Results:There were 8 cases of robot-assisted sacroiliac screw placement and 6 cases of robot-assisted triangular fixation. All patients were followed up for 24.85±10.26 months (range, 12-51 months). The average height of S 1 sacroiliac screw channel was 14.85±3.59 mm (range, 8-22 mm). The average width was 13.78±2.64 mm (range, 9-19 mm). The average height of S 2 sacroiliac screw channel was 14.07±3.08 mm (range, 8-21 mm), and the average width was 12.64±2.84 mm (range, 7-19 mm). The operation time was 63.57±21.61 min (range, 20-120 min), and the intraoperative blood loss was 65.71±41.83 ml (range, 20-200 ml). According to Mears and Velyvis imaging evaluation criteria, 7 cases were anatomically reduced, 6 cases were satisfactory, and 1 case was unsatisfactory, and the satisfactory reduction rate was 93% (13/14). The pelvic asymmetry was 18.14±6.07 mm (range, 9-33 mm) before surgery, while one week after surgery, it was 5.43±2.44 mm (range, 3-13 mm), and it was 4.64±2.27 mm (range, 3-12 mm) in the last follow-up. One week after surgery, the last follow-up, and preoperative pelvic asymmetry was statistically different ( F=50.21, P<0.001); As for VAS for pelvic pain, the score was 6.93±1.21 points (range, 5-9 points) preoperative, 3.93±0.99 points (range, 3-6 points) one week after surgery, and 1.21±0.97 points (range, 0-3 points) at the last follow-up. There was statistical difference between 1 week after operation, the last follow-up and preoperative VAS ( F=100.89, P<0.001). The Majeed score was 86.14±7.35 points (range, 70-95 points), and the excellent and good rate was 93%(13/14). All the robot-assisted screws were located in the bone, the screw placement accuracy was 100%. No postoperative complications such as wound infection occurred, and only 1 patient complained of discomfort because of the nail tail. Conclusion:For unstable pelvic fractures in adolescents, robot-assisted pelvic posterior channel screws shows satisfactory postoperative clinical effects, which is minimally invasive, with fewer postoperative complications.