Objective To investigate the indication of approach,type of fixation and the clinical outcome of minimally invasive internal fixation for treatment of pelvic anterior ring injury.Methods From January 2012 to August 2016,data of 32 patients with 44 pelvic anterior ring injuries who had been treated with minimally invasive internal fixation were retrospectively analyzed.There were 22 males and 10 females with an average age of 38.2 years old (range,20-65 years).14 patients were injured by traffic accident,12 patients by falling and 6 patients by crush injury.There were 4 cases of pubic symphysis diastasis,27 fractures of anterior ring which included 12 billatral fractures and 1 combined vertical displacement of pubic symphysis associated with pubic fracture.According to AO classification,there were 3 cases in A2.3,3 cases in B1.2,4 cases in B2.2,4 cases in B2.3,2cases in C1.1,1 case in C1.2,5 cases in C1.3,4 cases in C2,6 cases in C3.There were 25 patients associated with other injuries,including brain injury in 2,thoracic injury in 17,abdominal injury in 8,urogenital system injury in 5,lumbosacral nerve plexus injury in 4 and the extremity or lumbar fracture in 19.The average period from injury to operation was 9.2 d (range,5-32 d).4 patients who had the pubic symphysis diastasis,3 had pelvic anterior ring fracture medial obturator foramen and 1 combined vertical displacement of pubic symphysis associated with pubic fracture were reduced by modified Pfannenstiel incision and fixed with cannulated screws,while 36 patients with fractures of lateral obturator foramen were reduced by modified Pfannenstiel incision associated with small ilial crest incision and fixed with locking reconstruction plates,and 25 patients received the fixation of pelvic posterior ring injury simultaneously.Results The average time of operation was 44.5 min (range,30-65 min),and the average amount of blood loss intraoperative was 56.2 ml (range,20-150 ml).All patients were followed up successfully,with an average time of 28.2 months (range,16-42 months).All the fractures were healed with an average time of 4.5 months (range,3-9 months).According to Matta standard of reduction assessment,30 fractures' reduction were excellent,12 were good and 2 were fair,which the rate of satisfaction was 95.5％ (42/44).Neither reduction loss or fixation failure nor infection occurred,and the occurrence rate of complication was 9.1％ (4/44),including one patient with fatal liquefaction and was cured 3 weeks after wound dressing,one patient with lateral femoral cutaneous nerve injury who was cured within 3 months by oral drug and 2 patients who complained discomfort of inguinal area because of the fixation prominence and were lessened by physical therapy.Conclusion Minimally invasive internal fixation can be recommended for treatment of pelvic anterior ring injury because of the advantages of less damage,safer manipulation,less complications and good prognosis.

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 compare the clinical outcomes between minimal-invasive triangular fixation with orthopedic robot and traditional open fixation method for unilateral unstable sacral fracture patients.Methods:Data of 24 consecutive patients with unilateral unstable sacral fracture who were treated from August 2014 to February 2018 were retrospectively analyzed. All patients were associated with anterior ring injuries of pelvis and received magnetic resonance of nerve (MRN) preoperatively to exclude the compression of sacral nerve by bone. All patients received surgical treatment of sacral fractures with triangular fixation and the fixation of pelvic anterior ring injuries simultaneously and two groups were divided according to the different surgical methods of sacral fractures. There were 10 males and 2 females with an average age of 36.3±1.2 years in the orthopaedic robot group. According to Dennis classification, there were 4 type I and 8 type II fractures. Two patients were associated with nerve injuries (Gibbons II 1 case, III 1 case). In traditional posterior-midline open fixation group, there were 11 males and 1 female with an average age of 38.2±1.6 years. According to Dennis classification, there were 3 type I and 9 type II fractures. Three patients were associated with nerve injuries (Gibbons II 2 cases, III 1 case). The clinical data of two group patients were collected and compared statistically. T test was used to compare the operation time, intraoperative bleeding, intraoperative fluoroscopy times, Majeed function assessment which was to evaluate the patients' clinical prognosis and healing time of fracture. χ2 test was used to compare the healing rate of fracture, accuracy assessment of fixation insertion, and Mears radiological assessment which was applied to evaluate the reduction quality of fractures. The rank sum test was used to compare Gibbons score which was applied as the index of neurological deficiency recovery. The Fisher exact test was used to compare the infection rate. Results:All patients were followed up continuously for an average time of 21.2±3.2 months. The average operation time of robot group was 100.3±14.5 minutes, meanwhile the open fixation group was 202.0±18.5 min. The average intraoperative bleeding of robot group was 180.0±17.4 ml, meanwhile the open fixation group was 850.0±15.2 ml. The average intraoperative fluoroscopy time of robot group was 23.3±4.5 s, meanwhile the open fixation group was 90.0±7.7 s. All fractures were healed and no loss of reduction or fail of fixation occurred in both groups. The healing time of fracture of robot group was 8.5±1.9 months, meanwhile the open fixation group was 12.8±2.4 months. The satisfaction rates of reduction which was based on Mears-Velyvis radiological criterion of both groups were 91.7%. The accuracy rate of fixation insertion of robot group was 100% meanwhile the open fixation group was 77.78%. Majeed function assessment score of robot group was 86.2±3.4, meanwhile the open fixation group was 84.2±2.7. There was no infection occurred in robot group, meanwhile 3 patients infected in open fixation group. The Gibbons score of one patient changed from II preoperative to I postoperative and one case changed from III preoperative to II postoperative in robot group, meanwhile two patients changed from II preoperative to I postoperative and one case changed from III preoperative to II postoperative in open fixation group. The healing rate of fracture, infection rate, Majeed function assessment, Mears-Velyvis radiological evaluation criterion and Gibbons score of two groups had no significant statistical difference ( P >0.05), meanwhile the operation time ( t=14.99), intraoperative bleeding ( t=100.46), intraoperative fluoroscopy time ( t=32.13), healing time of fracture ( t=4.87) and accuracy rate of fixation insertion ( χ2=9.00) of orthopedic robot group were better than traditional open group and had the significant difference ( P< 0.05). Conclusion:The minimal-invasive triangular fixation with orthopedic robot for unilateral unstable sacral fracture had the advantages of less operation time, less intraoperative bleeding and less times of fluoroscopy, more accurate of fixation insertion and less healing time of sacral fractures compared to traditional open fixation method and should be recommended as an effective and advanced choice.

Objective:To explore the efficacy of posterior iliac screw rod for unilateral unstable Denis I and II sacral fractures.Methods:Data of 50 patients with unilateral unstable Denis I, II sacral fractures treated from March 2016 to October 2018 were retrospectively analyzed. According to fixation methods, the patients were divided into posterior iliac screw rod group (Iliac screw rod group) and robot-assisted iliosacral screw group (Iliosacral screw group). There were 20 patients in the Iliac screw rod group, 13 males and 7 females, with an average age of 41.10±14.07 years (range, 22-76 years), and there were 5 cases of Denis type I and 15 cases of type II sacral fractures. All of them had anterior pelvic ring injuries, and according to pelvic Tile classification, there were 2 B1 type, 12 B2 type, 6 C1 type, and 3 cases of Gibbons grade II sacral nerve injuries. There were 30 patients in the Iliosacral screw group, 18 males and 12 females, with an average age of 44.70±13.35 years (range,16-78 years), and there were 6 cases of type I and 24 cases of type II sacral fractures. There were 2 cases of type B1, 20 cases of B2, 8 cases of C1 pelvic fractures, 4 cases combined with sacral nerve injuries including 3 cases of Gibbons grade II and 1 case of grade III. The patients’ age, operation time, amount of bleeding, times of fluoroscopy, postoperative Majeed score were compared by the independent t test. The quality of fracture reduction was compared by Chi-square test, and the postoperative Gibbons grade was compared by the rank sum test.Results:All patients were followed up for 22.8 months (range, 12-40 months). In the Iliac screw rod group, the operation time was 41.40±7.30 min, intraoperative blood loss 105.00±61.94 ml, intraoperative times of fluoroscopy 19.10±7.33, and according to Mears and Velyvis valuation criterion, there were 9 cases of anatomical reduction, 10 cases of satisfactory reduction, and 1 case of unsatisfactory reduction, with the Majeed score of 84.25±8.29. There were 3 cases with Gibbons grade II sacral nerve injury, and 2 of them recovered to grade I. In the Iliosacral screw group, the operation time was 18.27±5.89 min, intraoperative blood loss 33.00±17.54 ml, intraoperative times of fluoroscopy 14.93±4.49, and according to Mears and Velyvis valuation criterion, there were 15 cases of anatomical reduction, 13 cases of satisfactory reduction and 2 cases of unsatisfactory reduction, with the Majeed score of 86.43±7.43. There were 3 cases with Gibbons grade II sacral nerve injury, and 2 of them recovered to grade I, and 1 case with grade III recovered to grade II postoperation. Compared to Iliosacral screw group, the Iliac screw rod group has longer operation time ( t=-12.36, P<0.001), more blood loss ( t=-6.04, P<0.001) and more intraoperative times of fluoroscopy ( t=-2.50, P=0.016). There were no statistical differences for quality of fracture reduction ( χ2=0.23, P=0.89), Majeed score ( t=0.97, P=0.34), and the Gibbons grade ( Z=-0.224, P=0.82) between the two groups. In the Iliac screw rod group, 1 patient had a unilateral superficial wound infection and 1 patient complained of discomfort because of the nail. In the Iliosacral screw group 1 patient had iatrogenic S 1 neurological injury. Conclusion:For the unstable sacral fractures, who are not suitable for iliosacral screw fixation, posterior iliac screw rod fixation is an effective alternative with similar clinical effect as robot assisted iliosacral screw fixation.

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.

Objective:To evaluate the clinical outcomes of traumatic spinopelvic dissociation treated with robot-assisted bilateral triangular fixation.Methods:From March 2016 to March 2020, 30 patients with traumatic spinopelvic dissociation were retrospectively analyzed. According to operation and fixation methods, the patients were divided into robot-assisted minimally invasive bilateral triangular fixation group (Robot triangular group) and traditional open reduction lumbopelvic fixation group (Lumbopelvic group). There were 16 patients in the Robot triangular group, 4 males and 12 females, average age 35.7±13.3 years (range, 16-58 years). There were 10 cases of U-shaped, 4 cases of H-shaped, 2 cases of Y-shaped sacral fractures according to shape classification of sacral fractures. According to ROY-Camille classification, there were 4 cases of type I, 9 cases of type II, 3 cases of type III. There were 13 cases with sacral nerve injuries, including 10 cases of Gibbons grade II, 3 cases of grade III. There were 14 patients in the Lumbopelvic group, 4 males and 10 females, average age 37.4±15.1 years (range, 18-66 years), there were 10 cases of U-shaped, 3 cases of H-shaped, 1 case of Y-shaped sacral fractures according to shape classification of sacral fractures. According to ROY-Camille classification, there were 1 case of type I, 10 cases of type II, 3 cases of type III. There were 10 cases with sacral nerve injuries, 7 cases of Gibbons grade II, 3 cases of grade III. The patients' age, operation time, intraoperative blood loss, and Majeed score of the two groups were compared by independent sample t-test; gender, sacral fracture classification, ROY-Camille classification, fracture reduction quality, postoperative wound infection, and sacral nerve recovery were compared by Chi-square test. Results:All patients were followed up for 23.6 months (range, 12-54 months). In the Robot triangular group, the operation time was 95.3±27.5 min (range, 70-180 min), and intraoperative blood loss was 98.7±47.5 ml (range, 50-250 ml). According to Mears and Velyvis imaging evaluation criteria, anatomical reduction was achieved in 6 cases, satisfactory reduction was achieved in 9 cases and unsatisfactory reduction in 1 case. The Majeed score was 85.5±7.7 points. 8 cases of Gibbons grade II sacral nerve injury were recovered to grade I after surgery, 1 case of grade III recovered to grade I, and 1 case recovered to grade II. In the Iliolumbar fixation group, the operation time was 148.6±59.1 min (range, 90-240 min), and intraoperative blood loss was 582.1±244.6 ml (range, 300-1 200 ml). According to Mears and Velyvis imaging evaluation criteria, anatomical reduction was achieved in 7 cases, satisfactory reduction was achieved in 6 case and unsatisfactory in 1 case. The Majeed score was 77.6±7.7 points. 5 of 7 cases of Gibbons grade II sacral nerve injury were recovered to grade I after surgery, and 2 of 3 cases of grade III recovered to grade I. Compared with the Iliolumbar fixation group, the Robot triangular group has shorter operation time ( t=3.23, P<0.05), less bleeding ( t=7.76, P<0.05), and higher postoperative Majeed score ( t=2.83, P<0.05). There are statistical differences in the above indicators significance. Conclusion:For traumatic spinopelvic dissociation, especially fractures involving the lumbosacral junction, those who do not require sacral nerve decompression, Robot-assisted bilateral triangular fixation shows satisfactory clinical outcomes, which is minimally invasive, with fewer postoperative complications.

Objective:To investigate the clinical efficacy of MIPO combined with non-contact bridging periprosthesis fracture plate (NCB.PP) in the treatment of re-fracture around the nail after intramedullary fixation of intertrochanteric fracture.Methods:From October 2015 to January 2020, 12 patients with re-fracture around the nail after intramedullary fixation of intertrochanteric fracture were treated in our hospital. There were 7 males and 5 females with an average age of 74.88±12.1 years (range, 65-83 years old); 8 patients on the left side and 4 patients on the right side received short nail of proximal femoral nail (PFN), 6-36 months after operation, they fell down and caused closed fracture around the nail body. According to Vancouver classification system, all the patients were Vancouver type B; preoperative bone mineral density examination showed that 1 case had normal bone mass, 10 cases had osteoporosis, and 1 case had low bone mass. All patients were treated with minimally invasive plate osteosynthesis (MIPO) technique for reduction and fixation, and fixed with proximal femur NCB.PP. The visual analogue scale (VAS) and Harris hip score at 1 day, 3 months and the last follow-up were compared.Results:The average operation time was 68.7±4.33 min (range, 65-75 min); the average intraoperative blood loss was 291.67±114.48 ml (range, 150-400 ml); the average postoperative drainage volume was 79.17±17.17 ml (range, 50-100 ml). After fracture reduction, all patients were able to obtain 2-5 bicortical screws fixation, with an average of 3.25±0.96. Among them, 3 cases were fixed with additional binding straps; 3 cases underwent autologous iliac bone grafting during the operation. All cases were followed up for 9-60 months, with an average of 16 months. At the last follow-up, 10 patients had fracture healing, the healing time was 7.75±2.83 months (range, 4-13 months), and the fracture healing rate was 83.3% (10/12). Among the other two patients, one was an 83 years old patient with severe osteoporosis, who was bedridden after operation and remained unhealed after 12 months of follow-up; a 68 years old patient had bone restoration at the broken end of the fracture 6 months after operation. The second operation was performed. Iliac combined with allogeneic bone graft was taken from the broken end. At the end of 13 months after operation, the fracture was partially healed. The VAS at one week, three months and the last follow-up were 8.00 (8.00, 9.00), 2.50 (2.00, 3.00) and 0.00 (0.00, 0.75), respectively. There were significant differences in VAS scores between 1 week after operation and 3 months after operation, 1 week after operation and the last follow-up, and 3 months after operation and the last follow-up ( Z=-3.129, -3.097, -3.134, all P < 0.05). The Harris scores at 3 months after operation and at the last follow-up were 72.50±2.91 and 86.67±5.30 respectively. After statistical analysis, the difference was statistically significant ( t=8.857, P< 0.001). At the last follow-up, except for 1 case of fracture nonunion and 1 case of reoperation, the Harris score of hip joint of the other 10 patients was excellent in 6 cases and good in 4 cases, and the excellent and good rate was 83.3% (10/12). One case of superficial wound infection was healed by intravenous drip of sensitive antibiotics. One patient had incision fat liquefaction and was given local dressing change to heal the incision. Conclusion:MIPO combined proximal femoral NCB.PP in the treatment of re-fracture around the nail after intramedullary fixation of intertrochanteric fracture has the advantage of less surgical damage, less blood loss, higher healing rate, and it can obtain satisfactory short and medium-term clinical efficacy.

Objective To investigate the clinical results and summarize the advantages and surgical indications in the treatment of femoral head fractures (Pipkin type Ⅰ and Ⅱ) via medial hip approach.Methods From October 2014 to August 2015,sixteen patients of femoral head fracture (Pipkin type Ⅰ and Ⅱ) surgically treated via medial hip approach were retrospectively analyzed in our Hospital.There were 13 males and 3 females with an average age of 44.8 years (range,22-62 years old).According to Pipkin classification,12 femoral head fractures were classified as type Ⅰ and 4 type Ⅱ.Thirteen patients were injured by traffic accidents,two patients by falling down from height and one patient was injured by collapses of a heavy objective.All femoral head fractures were combined with posterior hip dislocation.The skeletal traction was performed in each patient after successful close reduction of the hip joint under general anesthesia.Computed Tomography scans of hip joints were performed routinely.All femoral head fractures were fixed with absorbable screws via medial hip approach.The mean time from injury to operation was 5.3 days (range,2-14 days).Results The average duration of the operations was 75 min (range,60-110 min).The average length of incisions was 7.1 cm (range,6-9 cm).The average blood loss was 160 ml (range,80-300 ml).All the patients were followed up for an average period of 26.3 months (range,24 to 30 months).Eight femoral head fractures with Pipkin Ⅰ and three with Pipkin Ⅱ were union and the healing time was 3-12 months,with an average time of 8.8 months.Three femoral head fractures with Pipkin Ⅰ were incomplete union at the latest follow-up of 24 months after surgery.One femoral head fracture with Pipkin Ⅰ and one with Pipkin Ⅱ didn't get union at the latest follow-up of 24 months after surgery.According to Thompson and Epstein function evaluation,the clinical outcomes were rated as excellent in 12 cases,good in 1,fair in 3.The excellent and good rate was 81.3％ (13/16).According to Merled'Aubigne-Postel evaluation criterion,there were 13 cases excellent,1 good and 2 fair.The excellent and good rate was 87.5％ (14/16).There were no intraoperative complications in all patients such as neurovascular injury injuries.No incision infection,fat liquefaction and other incision related complications occurred postoperatively.Avascular necrosis of the affected femoral head occurred in one case whose symptom didn't aggravate after appropriate conservation.Fractures were nonunion in 2 cases but the patients' functions were satisfactory in daily living.Traumatic arthritis of the affected hip occurred in 2 cases.The patients felt uncomfortable with long walking but could get better after taking NSAIDs.The fracture fragment absorption occurred in 3 cases but these patients had a good function and needed no further treatment.Conclusion Good exposure could be achieved for reduction and fixation in the treatment of femoral head fractures (Pipkin Ⅰ、Ⅱ) via hip medial approach.The operation is a minimally invasive procedure and the treatment outcome is satisfactory,but the indication should be strictly controlled.

Objective: To explore the treatment outcome of triangular osteosynthesis (TOS) for the treatment of unilateral Isler type II lumbosacral junction injuries (LSJIs). Methods: Data of sixteen patients with unilateral Isler type II LSJIs surgically who were treated in our Hospital from March 2015 to February 2017 were retrospectively analyzed. There were 13 males and 3 females with an average age of 35.5 years (range, 24-61 years). Seven patients were multiple injuries including head, thoracic, musculoskeletal and nerve injuries. According to Isler classification of LSJIs, there were 5 cases of type IIa, 9 of type IIb and 2 of type IIc. All the LSJIs combined with ipsilateral sacral fractures. The sacral fractures were classified by Denis classification with 1 case of zone I, 13 cases of zone II and 2 cases of zone III. According to Tile classification of pelvic fractures, there were 3 cases of type B2, 11 of type C1 and 2 of type C3. There were 3 cases combined with sacral nerve injury among which there were 2 cases of grade II and 1 case of grade III according to Gibbons classification of neurologic deficits. All cases were surgically treated with triangular osteosynthesis. There were 14 cases combined with iliosacral screws fixation in S₁ and 2 cases combined with posterior locking plates. Results: All patients were followed up for 20.6 months (range, 16-30 months). CT scan was conducted 12 to 24 months after surgery which showed all the sacral fractures were union, and 2 cases achieved bony fusion in L₅S₁ facets while the other 14 didn’t. According to Majeed’s pelvic injury evaluation, clinical outcomes were rated with excellent in 12 cases, good in 2 cases, fair in 2 cases. The excellent and good rate was 87.5% (14/16) . According to Mears-Velyvis evaluation criterion, there were 14 cases with anatomical reduction and 2 cases with satisfactory reduction. Among the 3 cases with sacral nerve injury, 2 cases were improved from Gibbons grade II to grade I and the other 1 case was improved from Gibbons grade III to grade II, still feeling numbness on the lateral foot. There were no intraoperative complications in all patients such as neurovascular injuries. No incision infection, fat liquefaction and other incision related complications occurred postoperatively. Irritation and pain in iliac spine about prominent implant occurred in 1 case and lumboscaral stiffness in 1 case, in which the symptom relieved and disappeared after implants removal. Conclusion Triangular osteosynthesis can provide enough stabilization for Isler type II LSJIs and achieve satisfactory outcomes.

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.