OBJECTIVE: To investigate the hemodynamic changes of the end-to-end anastomosed arteries with nitinol clips. METHODS: Fifteen New Zealand rabbits were divided into anastomosis clip group, suture group and control group randomly. The carotid arteries were resected and end-to-end anastomosis were carried out with nitinol clips in anastomosis clip group and with traditional suture in suture group. The carotid arteries remained undamaged in control group. On the days of 3, 9, 21 and 30 postoperatively, mean blood velocity (Vm), pulsatility index (PI) and resistance index (RI) of anastomosed arteries were determined by Ultrasonography Doppler. RESULTS: On the days of 8 and 9 postoperatively, there were no significant differences of VM, PI and RI between two experimental groups (P gt; 0.05). On the days of 20 and 30 postoperatively, the differences of Vm and RI were significant (Vm: P lt; 0.01, P lt; 0.05: RI: P lt; 0.01, P lt; 0.05). The hemodynamic restoration of the anastomosis clip group was better than that of the suture group. CONCLUSION: The hemodynamics of arteries anastomosed with nitinol clips is better than that with traditional suture. This technique has practical value clinically.
【Abstract】 Objective To develop a new internal fixator Ni-Ti shape memory alloy scaphoid arc nail (NT-SAN)for fracture of the scaphoid waist and to test the biomechanical characteristics of NT-SAN so as to provide the biomechanicalproofs for cl inical appl ication. Methods According to the acquired measurements and anatomic features of the scaphoid in Chinese population, a special internal fixator—— NT-SAN was designed. The biomechanical intensity experiment: The 32 specimens of fractures of the waist of scaphoid were divided randomly into 4 groups (n =8). Reduction and internal fixation were carried out in each specimen, with Kirschner wires (Group A), with Kirschner wires stapl ing (Group B), with screw (Group C) and with NT-SAN (Group D). Their fixed strength was tested by a hydrol ic pressure biomechanical system AG-1. The biomechanical fatigue experiment: The models of 24 waist scaphoid fracture of adult upper l imbs specimens were made and randomly divided into 3 groups (n =8). Fracture was fixed with Kirschner wire stapl ing (Group E), with screw(Group F) and with NTSAN(Group G). Wrist joint was vertically pressured load of 98 N, palmar flexion and dorsal extension motion was simulated;the range of movement was from palmar flexion 5° to dorsal extension 30° and the frequency was 2 000 cycles. Displace data offragment were measured at every 500 cycles. Finally, the biomechanical features of NT-SAN were evaluated according to thetested data. NT-SAN was used to treated 1 patient with fracture of the waist of scaphoid, who was typed as Ⅱ b according to Herbert classification. Results The biomechanical tests showed that the traction forces were (15.18±3.55), (36.04±4.30),(64.88±11.62), (65.84±12.22) N and (20.28±12.09), (75.95±47.64), (120.91±26.68), (130.21±31.55) N when the displacements of the fracture l ines distracted in 1 mm/min were 1 mm and 2 mm; showing significant differences between Group D and groups A, B (P lt; 0.05), and showing no significant difference between Group D and Group C (P lt; 0.05). The biomechanical fatigue experiment showed that there were significant differences between Group G and groups E, F(P lt; 0.05) according to the measuredresults of the displacements of the fracture l ines. When wrist joint were circularly moved; showing significant differences between Group G and Group E(P lt; 0.05) after 500 circular movements, and showing significant differences between Group G and Group F(P lt; 0.05) after 1 500 circular movements according to the measured results of the “stage-shape” displacements in the fracture position. Incision healed by first intention and the X-ray films showed good NT-SAN fixation 3 months after followup.Conclusion The design of NT-SAN is in accordance with the anatomic features of the scaphoid. The fixed strength can meet the demand of the biomechanics and the range of fatigue strength can meet the demand of bony union.
Objective To investigate the effectiveness of acetabular tridimensional memory alloy-fixation system (ATMFS) combined with autologous il iac bone in the treatment of old acetabular posterior wall fracture with bone defect. Methods Between January 2002 and February 2009, 17 patients with old acetabular posterior wall fracture and bone defect were treated, including 11 males and 6 females with an average age of 41.7 years (range，20-60 years). The time from fracture to admission was 14-180 days (mean, 63 days). The displacement of the acetabular articular surface was more than or equal to 3 mm. According to the America Association of Orthopedic Surgeon (AAOS) acetabular fracture and defectclassification standard, there were 4 cases of type I, 6 cases of type II, 5 cases of type III, and 2 cases of type IV. After the residual fracture fragments of the acetabular posterior wall and soft tissue hyperplasia were removed, the femoral head was reducted, and posterior wall defect was repaired with autologous il iac bone graft; ATMFS was used to fix acetabular posterior wall and artificial capsular l igament to reconstruct the hip so as to prevent re-dislocation of the femoral head. Results According to Matta imaging assessment standard, the results were excellent in 8 cases, good in 6 cases, fair in 2 cases, and poor in 1 case with an excellent and good rate of 82.3%. All incisions healed by first intention, and no sciatic nerve injury occurred. All patients were followed up 1-8 years (mean, 3.9 years). The mean time of fracture union was 3.6 months (range, 2-6 months). Avascular necrosis of femoral head occurred in 1 case, heterotopic ossification around the acetabulum in 1 case. According to Merle d’ Aubigné-Postel scoring system evaluation, the cl inical results were excellent in 9 cases, good in 6 cases, fair in 1 case, and poor in 1 case with an excellent and good rate of 88.2%. Conclusion ATMFS combined with autologous il iac bone graft and artificial l igament reconstruction of the hip joint capsule is a good choice for the treatment of old acetabular posterior wall fractures with bone defect, which can resume the posterior hip joint stabil ity and prevent re-dislocation of the femoral head.
Objective To find out an ideal method of internal fixation for the treatment of fractures of proximal radius. Methods From August 2001 to April 2004, 24 patients suffering from fractures of proximal radius were treated with NiTi shape memory alloy embracing fixator. Of 24 patients, there were 19 males and 5 females, aging from 16 to 48 years; there were 9 cases of wrestling injury, 5 cases of crush injury, 4 cases of traffic accident injury, 3 cases of direct violence impact injury and 3 cases of high falling injury. All patients were given operation according to fix method of the shape memory alloy embracing fixator. All cases were regularly followed up to observe the fracture healingand functional recovery. Results All cases were followed up postoperatively from 4 months to 21 months with an average of 10 months. No complication occurred during operation and after operation. Healing by first intention was achieved. X－ray showed that all cases achieved clinical union 8－12 weeks after operation. According to Anderson’scriteria and the results were excellent in 18 cases, good in 5 cases, and fairin 1 case. The excellent and good rate was 95.83 %. Conclusion The internal fixation with shape memory alloy embracing fixator has as follows adventages: less trauma, esay－to－do, stable fixation, better tissue compatibility and less complication in treating fractures of proximal radius. This method can enhance the fracture healing and functional recovery. So it is a better method to treat fractures of proximal radius.
Objective To evaluate initial experience with shape memory alloy stent as an alterative to colostomy in patients with intestinal obstruction of rectal cancer. Methods Twenty-one patients with acute and chronic rectal obstructions from malignant causes underwent stent placement. After rectal stent was slenderized in ice water, it was inserted into the strictured rectum by hand or sigmoidoscope. Nitinol mesh stent were deployed in hot water. Results Eighteen patients who had underwent rectal stent placement achieved clinical decompression within 5 hours. Colostomy underwent in 3 patients due to stent failure. Eighteen patients with stent were followed-up, 14 cases died in 56-720 days and 4 other cases were still alive without intestinal obstruction in 2-15 months. Conclusion Nitinol mesh stent may be useful in the management of terminal or high-risk surgical patients for palliative purposes shuning colostomy. Palliation of stent combined with chemotherapy and immunotherapy can be performed to improve survival.
ObjectiveTo investigate the technique and short-term effectiveness of the umbrella-shaped memory alloy femoral head support device (umbrella-shaped support device for short) for the treatment of avascular necrosis of femoral head (ANFH). MethodsThe umbrella-shaped support device was fabricated with Ni-Ti alloy, and its biomechanics characteristics were tested by three-dimensional finite element analysis with pro/mechanica software. Between October 2009 and December 2012, 10 patients (18 hips) with ANFH were treated. There were 7 males (12 hips) and 3 females (6 hips), aged 21-53 years (mean, 40.6 years). The disease duration was 1-5 years (mean, 3.3 years). According to Ficat staged criteria, 10 hips were rated as stage Ⅱ, 6 hips as stage Ⅲ, and 2 hips as stage IV. Microtrauma methods were used to erase the necrotic tissue of the femoral head, and the umbrella-shaped support device, autogenous iliac bone graft, and artificial bone were implanted to support the collapsed femoral head. ResultsThree-dimensional finite element analysis showed that the largest stress of umbrella-shaped support device was 1 500 MPa and the largest displacement was 1.75 mm. Operation was successfully completed in the other 10 patients (17 hips) except 1 failure hip (total hip arthroplasty was performed after 6 months). The average follow-up period was 19.7 months (range, 15-26 months). At last follow-up, the results were excellent in 5 hips, good in 9 hips, fair in 2 hips, and poor in 1 hip; the excellent and good rate was 82.35%. The Ficat stage had no change when compared with preoperative stages. ConclusionThe advantages of the umbrella-shaped support device for the treatment of ANFH are to thoroughly remove the sequestrum, to rebuild blood circulation of the femoral head, to increase the machinery supporting of subchondral bone in weight-bearing area of femoral head, and to decrease the localized stress, and it has good short-term effectiveness, but long-term effectiveness needs further observation.