Biomechanical evaluation of a short-rod technique for lumbar fixation surgery.

Objective: The purpose of this study was to analyze the stability and instrument-related complications associated with fixation of the lumbar spine using the Short-Rod (SR) technique. Methods: Using finite element analysis, this study assessed the stability of a bilateral lumbar fixation system when inserting the pedicle screws at angles of 10°, 15°, and 20° to the endplate in the sagittal plane. Using the most stable construct with a screw angle, the model was then assessed with different rod lengths of 25, 30, 35, and 45 mm. The optimal screw inclination angle and rod length were incorporated into the SR model and compared against traditional parallel screw insertion (pedicle screws in parallel to the endplate, PPS) in terms of the stability and risk of instrument-related complications. The following parameters were evaluated using the validated L4-L5 lumbar finite element model: axial stiffness, range of motion (ROM), stress on the endplate and facet joint, von-Mises stress on the contact surface between the screw and rod (CSSR), and screw displacement. Results: The results showed that the SR model with a 15° screw inclination angle and 35 mm rod length was superior in terms of construct stability and risk of complications. Compared to the PPS model, the SR model had lower stiffness, lower ROM, less screw displacement, and lower stress on the facet cartilage, the CSSR, and screws. However, the SR model also suffered more stress on the endplate in flexion and lateral bending. Conclusion: The SR technique with a 15° screw inclination and 35 mm rod length offers good lumbar stability with a low risk of instrument-related complications.

TiRobot-Assisted Percutaneous Cannulated Screw Fixation in the Treatment of Femoral Neck Fractures: A Minimum 2-Year Follow-up of 50 Patients.

OBJECTIVE: To assess the long-term clinical efficacy of TiRobot-assisted percutaneous cannulated screw fixation in the treatment of femoral neck fractures. METHODS: This retrospective study included 50 patients with unilateral femoral neck fractures who were treated with TiRobot-assisted percutaneous cannulated screw fixation from September 2017 to May 2018. After at least 2 years of follow-up, the results of treatment, including operation duration, frequency of fluoroscopy use, intraoperative bleeding, hospital stay, medical expense, screw placement accuracy, rate of fracture healing and necrosis of the femoral head, and Harris hip scores at the last follow up, were recorded and compared with those of 83 matched patients who underwent conventional manual positioning surgery. RESULTS: The TiRobot group had longer operation duration (83.3 ± 31.2 min vs 44.1 ± 14.8 min) and higher medical expenses (28,407.1 ± 7498.0 yuan vs 22,672.3 ± 4130.3 yuan) than the conventional group. The TiRobot group had significantly less intraoperative bleeding (11.3 ± 7.3 mL vs 51.6 ± 40.4 mL) and shorter hospital stay (8.6 ± 2.8 days vs 11.1 ± 3.41 days) than the conventional group. Screw parallelism (1.32° ± 1.85° vs 2.54° ± 2.99° on anteroposterior radiograph; 1.42° ± 2.25° vs 3.09° ± 3.63° on lateral radiograph) and distance between screws (58.44 ± 10.52 mm vs 39.69 ± 12.17 mm) were significantly improved. No significant difference was found between the two groups in terms of the use of fluoroscopy (40.1 ± 28.5 times vs 38.6 ± 21.0 times) and Harris hip scores at the last follow-up (93.2 ± 10.3 points vs 88.4 ± 11.9 points). Two cannulated screws penetrated the femoral head during manual insertion in the conventional group but not in the TiRobot group. The rate of nonunion and necrosis of the femoral head in the TiRobot group was reduced compared with that in the conventional group (0 vs 7.2%; 6.0% vs 24.1%). CONCLUSION: TiRobot-assisted percutaneous cannulated screw fixation of femoral neck fractures is accurate and minimally invasive and helps in reducing late complications, particularly necrosis of the femoral head and nonunion of fractures.

Controlled Alternate Quantum Walks based Quantum Hash Function.

Through introducing controlled alternate quantum walks, we present controlled alternate quantum walks (CAQW) based quantum hash function. CAQW based quantum hash function have excellent security, outstanding statistical performance and splendid expansibility. Furthermore, due to the structure of alternate quantum walks, implementing CAQW based quantum hash function significantly reduces the resources necessary for its feasible experimental realization than implementing other quantum hash functions.

[Treatment of sternoclavicular joint dislocation with sternoclavicular hook plate fixation].

OBJECTIVE: To evaluate the technique and therapeutic effect of sternoclavicular hook plate fixation in treating sternoclavicular joint (SCJ) dislocation. METHODS: From January 2010 to March 2014,6 patients with SCJ dislocation were treated with sternoclavicular hook plate fixation in our hospital. Among the 6 patients, 5 patients were male and 1 patient was female, and the average age was 34 years, ranging from 26 to 48 years. The course of the disease ranged from 3 to 20 days. All the SCJ dislocations were caused by external injury and accompanied with the symptoms of swelling pain and obvious shoulder joint activity restricted in affected side. All SCJ dislocations were anterior dislocation by the diagnosis of X-ray and CT scan. The postoperative curative effect was evaluated according to Rockwood score. RESULTS: All the patients' operative incision were healed well and in good appearance. X-ray showed that the dislocated SCJ was well reduced and the plate was on right position. All the 6 patients were followed up for 4 to 18 months, with an average of 12 months. The results were evaluated according to Rockwood score, 4 got excellent results, 1 good and 1 fair. No fixation loosening, redislocation or side injury such as vessel, nerve or pleura injury were found. CONCLUSION: With sternoclavicular hook plate fixation, SCJ dislocation could be reduced while keeping its amphiarthrodial function and the completeness of the cartilage surface. Sternoclavicular hook plate fixation has advantages of safety and stabilization in fixation, and patients can begin function exercises earlier.

[Case-control study on hidden blood loss in perioperative period of femoral intertrochanteric fractures in elderly patients treated with intramedullary nailing].

OBJECTIVE: To analyze the neglected hidden blood loss before and after operations in the elderly patients with intertrochanteric fractures and strengthen the treatment and clinical nursing in the perioperative period in order to ensure clinical effects. METHODS: The clinical data of 99 patients with intertrochanteric fracture treated with intramedullary nailing from January 2010 to January 2014 were retrospectively analyzed (47 males and 52 females). Forty-seven cases got blood transfusion supporting and 52 cases were not (blood transfusion group and no-blood transfusion group respectively). According to the Gross equation, the average hemoglobin (Hb) and hematocrit (HCT) were used to analyze blood loss in perioperative period and assess the patients' hidden blood loss situation. RESULTS: There were 22 males and 30 females in blood transfusion group. The average operative time was (62.13±4.01) min; intraoperative visible blood loss and postoperative drainage were 215 ml, totally; preoperative Hb was (103.22±9.01) g/L and postoperative was (81.13±6.20) g/L; preoperative HCT was (96.93±3.38) I/L and postoperative was (308.00±11.81) I/L. There were 25 males and 22 females in no-blood transfusion group. The average operative time was (60.12±3.27) min; intraoperative visible blood loss and postoperative drainage were 196 ml, totally; the average blood transfusion were 621 ml; preoperative Hb was (92.15±5.46) g/L and preoperative was (95.20±8.93) g/L; preoperative HCT was (96.52±3.63) I/L and preoperative was (392.70±14.03) I/L. According to the Gross equation, the blood loss of no-blood transfusion group and blood transfusion group in peroperative period were (937.29±63.04) ml and (706.43±35.02) ml, respectively. The hidden blood loss was dominant. At 1, 3 months after operation, Harris score of blood transfusion group was better than that of no-blood transfusion group, and 12 months after operation, there was no significant difference between two groups. CONCLUSION: The hidden blood loss of intramedullary nailing for intertrochanteric fracture should be emphasized in perioperative period, it can avoid the perioperative complications caused by anemia and affect the prognosis of patients.