Objective To study the biomechanics of posterior lumbar interbody fusion with unilateral fixation.Methods 15 bovine lumbers were divided into three groups(intact group,spondylolisthesis group,posterior lumbar interbody fusion with unilateral fixation group as experimental group).Nondestructive tests were performed in pure compression,flexion,extension,and lateral bending on every group.Results Compared with intact group and spondylolisthesis group,after posterior lumbar interbody fusion with unilateral fixation,the mean straining of vertebral body in experimental group increased.The value of experimental group had significant difference from spondylolisthesis group(P ＜ 0.01,P ＜0.05).And the value of experimental group was proximal to intact group (P ＞ 0.05).Conclusion After operation with posterior lumbar interbody fusion with unilateral fixation,the stiffness of vertebral body was approached the intact group during axis compression,flexion,extension and lateral bending.And the initial stability was enough after operation.

Objective To explore the influence of interbody fusion intervertebral fixation on adjacent joint degeneration in patients with lumbar diseases .Methods 56 patients with lumbar diseases who were taken interbody fusion intervertebral fixation were selected as the research subjects ,and the adjacent intervertebral joint degeneration in patients were followed up .Results 56 patients were followed up for 24-72 months,the average time was (41.2 ± 8.3)months.The new clinical symptoms were occurred in 12 cases(21.4%),including 8 cases of low back pain, 3 patients with leg pain,1 case of lumbocrural pain.Radiographic changes occurred in 9 cases(16.1%),9 cases of patients with new clinical symptoms ,including 5 cases of osteophyte formation or exacerbation ,2 cases for adjacent segment instability ( I degree of vertebral spondylolisthesis ) ,1 case of small joint hyperplasia stage spinal stenosis , 1 case of protrusion of intervertebral disc .In 9 patients with imaging performance ,internal fixation of upper adjacent segment degeneration in 7 cases,internal fixation of the adjacent segment degeneration in 2 cases.Conclusion Inter-body fusion intervertebral fixation in the treatment of lumbar diseases ,adjacent joint is prone to degeneration ,so the destruction of adjacent joint operation should be reduced .

Objective:By comparing the clinical effect of minimally invasive hollow screw internal fixation Assisted by orthopedic robot (TiRobot) and O-arm navigation in the treatment of pelvic fractures, and practicability and security of both treatments were evaluated.Methods:Retrospective analysis of data of 42 cases of Tile C type pelvic fractures was employed during June 2017 to June 2020. Among them, 32 cases, twenty-four men, eight women, aged 34±6.2 years (range 24-68 years), were treated with percutaneous screw fixation guided by O-arm X wire instrument. According to Tile classification, there were 3 cases of C1.1 type, 8 cases of C1.2 type and 21case of C1.3 type. According to the Denis classification of sacral fractures, 17 cases were in zone I, and 8 cases in zone II. Ten patients, eight males and two females, aged 36±5.2 years (range 19-62 years) were treated by percutaneous screw fixation assisted by orthopedic robot. According to Tile classification, there were 1 case of C1.1 type, 2 cases of C1.2 type and 7 cases of C1.3 type. According to the Denis classification of sacral fractures, there were 5cases in zone I, 2 cases in zone II. For those who got obviously displaced pelvic fractures, Starr frames were used and then internal fixation was used to fix pelvic anterior ring and posterior ring injury respectively. Based on the times of needle adjustments, intraoperative fluoroscopy time, good screw position and incidence of complications two groups were statistically analysed. Matta score was employed to evaluate the quality of fracture reduction, while the Majeed score was employed to evaluate the clinical efficacy. Through the two groups of cases guide needle adjustment times, intraoperative fluoroscopy time, screw position excellent and good rate and the incidence of complications, which were statistically analyzed.Results:All screw positions were confirmed by CT scan after operation. The average time required for each screw placement of the O-arm group was 7.36±2.63 s, of the robot group was 6.80±3.20 s, so difference was not statistically significant ( P<0.05). An average of screw adjustments per one screw was 1.56±0.02 times by O-arm, and by the robot group was 0.34±0.06 times, so differences between the two groups were statistically significant ( P>0.05). The average operating time of O-arm group was 53.86±15.06 min, while the robot group was 52.52±15.14 min, so differences between the two groups were not statistically significant ( P>0.05). Position distribution of screw placement in two groups, all screws in O-arm group of position evaluations were excellent, excellent rate was 100%, all screw position evaluations by robot were excellent, excellent rate was 100%, so difference in screw distribution between the two groups was not statistically significant ( P>0.05). All cases were followed up for 6-12 months. Fracture healing time: 34.6±8.6 weeks for O-arm group, 33.4±9.4 weeks for robot group. Comparison between the two groups was not statistically significant ( P>0.05). Majeed score of O-arm group was 55-87, including Excellence of 17 cases, goodness of 9, fairness of 6. The rate of excellence and goodness was 81.2%, while robot group was 76-95, and that were excellent 7 cases,1 good, and the excellent and good rate was 80%, there was no significant difference between Matta and Majeed score between the two groups ( P>0.05). The incidence of complications between the two groups were no statistically significant ( P>0.05). Conclusion:Orthopedic robot system and O-arm navigation system assisted by percutaneous hollow screw fixation treatment of pelvic anterior and posterior ring injury, which are accurate, safe, minimally invasive, can reduce radiation damage to patients and surgeons. The efficacy were satisfactory. Both treatments are ideal for minimally invasive treatment of pelvic fractures, and the orthopedic robot have advantages of being programmed, standardized, stable and it’s learning curve is shorter.

Objective: To investigate the feasibility and short term clinical efficacy of early minimally invasive treatment of complex pelvic trauma with Starr reduction frame combined with O-arm navigation system. Methods: From June 2017 to December 2018, thirty two patients with Tile C complex pelvic fractures were prospectively divided into two groups according to the random number table. The open treatment group included 17 cases (open reduction and internal fixation group; 10 males and 7 females, age 24-60 years, average 37±6.5 years; according to Tile classification, 8 cases of C1 type, 8 cases of C2 type and 1 case of C3 type; according to the Denis classification of sacral fractures, 9 cases in zone I, 6 cases in zone II and 2 cases in zone III). The combined treatment group included 15 cases (Starr reduction frame group combined with O-arm navigation system, 8 males and 7 females, age 32-57 years, average 40±5.2 years; according to Tile classification, 8 cases of C1 type, 6 cases of C2 type and 1 case of C3 type; according to the Denis classification of sacral fractures, 8 cases in zone I, 5 cases in zone II and 2 cases in zone III). The ilioinguinal and Stoppa approaches were used in the open treatment group, and the anterior and posterior ring injuries were fixed with reconstruction plate screws and hollow screws, respectively. In the combined treatment group, starr frame was used to assist reduction, combined with "O" arm navigation technique, infix internal fixation frame, superior pubic branch screw, sacroilium screw were used to fix the anterior and posterior ring injury. The quality of pelvic fracture reduction was evaluated by the Matta scoring system, and the Majeed score was used to evaluate the clinical efficacy. Results: All patients were followed up for 6 to 12 months. The hospitalization time (45±11 d), operation time (220.0±49.4 min) and fracture healing time (24.0±5.6 weeks) in the open treatment group were longer than those in the combined treatment group (21±9 d, 180.0±24.2 min, 16.1±3.8 weeks), and the intraoperative blood loss (820.0±140.4 ml) was significantly higher than that in the combined treatment group (24.0±10.4 ml)(t=6.651, 2.772, 6.128, 22.874; all P< 0.05). According to Matta scoring system, in the open treatment group, there are 8 excellent cases, 6 good cases, 2 fair cases, 1 poor case, thus the excellent and good rate was 82.4%(14/17). While 9 cases were excellent, 5 good, 1 fair, and the excellent and good rate was 93.3% (14/15) in the combined treatment group. At the latest follow-up, Majeed score was 51-85 points in the open treatment group, including excellent in 8 cases, good in 6 cases, fair in 2 cases, poor in 1 case, thus the excellent and good rate 82.4% (14/17), and the Majeed score was 75-95 points in the combined treatment group, including excellent in 9 cases, good in 5 cases, fair in 1 case, thus excellent and good rate 93.3% (14/15). There was a statistically significant difference between the two groups of Matta score and Majeed score (χ²=0.034, 0.040; P< 0.05). Surgical infection occurred in 4 cases in the open treatment group and healed after debridement and treatment with sensitive antibiotics. The incidence of complications was 23.5% (4/17). In the combined treatment group, 2 cases had anterolateral thigh skin sensory loss after operation, and the symptoms were relieved after mannitol, mecobalamine treatment and removal of internal fixations. One patient had hematoma of the gluteus maximus muscle after operation. The result of angiography showed that the INFIX screw was too long and perforated near the foramen of the ischium, resulting from the injury of the superior gluteal artery. After stopping the use of anticoagulant, intravenous infusion of tranexamic acid, blood transfusion, etc., the patient was cured and discharged from hospital. The incidence of complications was 20.0% (3/15). There was no significant difference in the incidence of complications between the two groups. Conclusion With the help of starr reduction frame, the early reduction and minimally invasive treatment of pelvic fracture can be realized, and the amount of intraoperative bleeding can be reduced. The combined application of "o" arm navigation can improve the accuracy and safety of sacroiliac screw and anterior column screw placement, reduce the radiation dose and frequency of operators and patients, shorten the operation time and improve the curative effect.

Objective: To investigate the incidence of complications following minimal invasive subcutaneous internal fixator (INFIX) for the treatment of anterior pelvic ring instability, and to analyze control measures. Methods: Data of 42 patients with anterior pelvic ring instability who were treated by anterior subcutaneous internal fixation in our hospital from January 2016 to December 2017 were retrospectively analyzed. There were 15 females and 27 males with an average age of 45.4 years (range, 18-67 years). There were 26 traffic injuries, 10 falling injuries, 3 crush injuries and 3 low energy injuries. According to Tile classification, 24 cases of B2 type, 16 cases of B3 type, 1 case of C1 type and 1 case of C2 type. According to Young-Burgess classification, there were 20 cases of LCI, 18 cases of LCII, 1 case of LCIII, 1 case of APCI, 1 case of APCII, and 1 case of VS. Fourteen cases were combined with limb fractures, and 11 cases were combined with thoracic or abdominal injuries requiring surgical treatment, while 16 cases were with brain injuries. For type APC2, LC1, and some LC2 fractures, fixation for the anterior pelvic ring is enough with INFIX technique alone. For some LC2, LC3, or VS fractures, the anterior and posterior ring were both fixed. Postoperative reduction was evaluated by Matta radiological criteria. Lateral thigh numbness and pain, quadriceps muscle power were recorded during follow-up, and clinical efficacy was evaluated by Majeed score at 6 months after operation. Results: All the 42 patients were followed up for 6 to 12 months, with an average of 9.3 months. Matta standard evaluation for fracture reduction showed that 28 cases were excellent, 14 cases good, and the excellent and good rate was 100%. The early complication rate (within 3 month after operation) was 23.8% (10/42) including 6 cases of lateral femoral cutaneous nerve injury and 2 cases of femoral nerve injury. The symptoms were obviously relieved after the treatment of nutrient nerve and hyperbaric oxygen; 1 case had incision infection which was healed after anti-infection therapy and internal plant removal; 1 case suffered from superior gluteal artery injury which was controlled by pressure hemostasis. Six months after surgery, no case had lost reduction. At 6 months follow-up, the Majeed score was 72-96, with an average of 84.96, of which 32 were excellent and 10 were good, thus the excellent and good rate was 100% (42/42). Conclusion INFIX is an effective internal fixation method for the treatment of unstable anterior pelvic ring injury. However, it has a high rate of early complications, among which nerve injury has the highest incidence.