Objective To explore the effect of persistent stress on the ultrastructure of cancellous bone in the process of fracture healing.Method A transverse osteotomy on both sides of the femoral tuberositas was performed in 20 adult dogs. One side was fixed with a self-designed tuberositas memofy-pressure connector (TMC) which was made of NiTi shape memory alloy, and the other with compressive steel-wire (SW) cerclage.Five animals in each group were sacrificed at 2, 4, 8, 12 weeks after operation and observed under transmission electron microscope.Results The fracture healing was accelerated in the TMC group.The osteoblasts, chondroblasts and collagen fibers at the fracture sites showed significantly different morphology between the 2 groups at every observation time.Most cells and collagen fibers in the TMC group grew along the same direction as the stress, but those in the SW group grew in disorder.Both the number and functional activity of the osteoblasts and chondroblasts were higher in the TMC group than in the SW group.Conclusion Persistent stress can enhance healing and bone reconstruction following a cancellous bone fracture.

Objective To develop a new method of treating fractures and nonunion of radial and ulnar diaphyses. Methods We designed a kind of radius-ulna shape memory connector (RSMC) on the basis of the shape memory property of nitinol alloy and the anatomic characteristics of radial and ulnar diaphyses. It is capable of providing 3-D fixation and exerting continually longitudinal compression upon fracture sites. It was used in 31 cases (57 bones) of fresh fractures and 39 cases (53 bones) of nonunion, totaling 70 cases (110 bones). Results The mean follow-up time was 1.5 years(from 7 months to 2 years). In the fresh fracture group, no delayed union or nonunion was observed, and the solid bone healing time averaged 2.3 months. In the nonunion group, all the cases were cured at one time and the solid bone healing time averaged 3.5 months, but two cases were complicated with slight skin infection which had little influence on the internal fixation and bone healing. Conclusion RSMC can provide a new and efficacious method for the treatment of fracture and nonunion of radial and ulnar diaphyses.

Objective To introduce a new technique for treatment acetabular fractures with nitinol tridimensional internal fixation system. Methods According to the characteristics of nitinol and acetabular anatomy, a new internal fixation system for acetabular fracture, acetabular tridimensional memoryalloy-fixation system (ATMFS), was designed. This system consisted of anterior column, posterior column, arch teeth and trochanter device. During operation, these devices were transformed in iced water first, after fracture reduction they were inserted into bones, finally, these devices were reverted to their original shape by warm saline. Till October 2001, 41 cases acetabular fractures were treated with this system. All these cases were followed from 6 to 28 months. Results This system could transform the complicated and comminuted fracture to its anatomic position, and was easy to use in operation. Bone healing time averaged 1.6 months in 38 cases, and the hip function recovered time averaged 2.5 months. Heterotopic ossification which led to joint functional disturbance in one case, and myositis ossificans which caused joint dysfunction in two cases. One case was complicated by infection which was cured and good function was reserved. Conclusion ATMFS provides a new and efficacious method for the anatomic reduction or reconstruction of comminuted acetabular fractures.

Nickel titanium shape memory alloys(NiTi-SMA) are thought to be the promising biomaterials of biological osteosynthesis(BO) with regard to biomedical applications. However, a critical concern is the release of harmful Ni ions from the implants into the living tissues. And little is known about the influences of surface modifications on the biocompatibility of these alloys. The emphasis was focused on the recent developments, the related questions, surface treatments, future directionsin.

0.05). Conclusion The injured peripheral nerve is able to regenerate after side-to-side neurorrhaphy.

BACKGROUND:Swan-like memory connector (SMC) can form a three-dimensional fixation on long bone shaft,ensure the stability of fracture ends,and produce a continuous dynamic compressive stress on the fracture ends.Insulin-like growth factorⅠ (IGF-Ⅰ) regulates bone development and metabolism,cell differentiation,as well as mitosis.During the union process of fracture,IGF-I is effective to promote cellular proliferation,stimulate bone formation and result in chondrogenesis.OBJECTIVE:To quantitatively determine the effect of SMC and conventional dynamic compression plate (DCP) on the concentration of local IGF-Ⅰ in the union duration of rabbit humerus fracture.DESIGN,TIME AND SETTING:A controlled observational animal study was performed in the laboratory,Department of Orthopaedics,Changhai Hospital,the Second Military Medical University of Chinese PLA from January to May in 2007.MATERIALS:SMC was Ni-Ti alloy panel,comprising 50%-53% Ni,was customized by Lanzhou Seemine Shape Memory Alloy Co.,Ltd.The temperature of shape recovery was (33±2) ℃.METHODS:Thirty adult New Zealand rabbits were used in this study and were processed into osteotomy.The experiment sides of rabbit humerus were cut and fixed with SMC at random,serving as SMC group,and the other sides were cut at the same position and fixed with DCP,serving as DCP group.Each five animals were put to death at the time points of 2,3,4,6,8,and 12 weeks after internal fixation.Specimens were obtained from the areas that were 0.5 cm besides the fracture line.MAIN OUTCOME MEASURES:Following internal fixation,the contents of local IGF-Ⅰ in the specimens of different time points (2,3,4,6,8,and 12 weeks) were determined in both SMC group and DCP group.RESULTS:In the SMC-treated group,the contents of IGF-I increased 2 weeks after internal fixation,reached the maximum at 6 weeks,and then decreased at 8-12 weeks.In the DCP-treated group,the contents of IGF-Ⅰincreased 2 weeks after internal fixation,reached the maximum at 8 weeks,and then decreased at 12 weeks.No significant differences were found between the SMC group and the DCP group at 2,8,12 weeks after internal fixation (P ＞ 0.05).Compared with the DCP group,the SMC group had a remarkably higher content of IGF-Ⅰ at the time points of 3,4 and 6 weeks (P ＜ 0.05).The difference was the most statistically significant at 4 weeks.CONCLUSION:Compared with conventional DCP,the SMC could better promote the secretion of IGF-Ⅰin fracture and facilitate the fracture union due to the continuous dynamic compressive stress and three-dimensional fixation.

Objective To research on the new technique and method of bone grafting for nonunion of four limbs. Methods A new method of bone grafting was developed to take advantage of Nitinol Shape Memory Connector. It included splinting mode, padding mode and seeding mode. 148 cases of bone nonunion in 134 patients were treated with the modified method. Results The patients were followed up for 5.5 months to 6 years, with an average period of 2.25 years. On the average, the nonunion healed with lamellar bone 3.5 months after the operation. The healing rate was 99.3% . Conclusion The author s modified bone grafting provides a new and efficacious method for treatment of the limb nonunion.

Objective To discuss the biomechanical factors in the nonunion of femoral fractures and raise corresponding measures. Methods Sixty eight cases with nonunion of femoral shaft fractures were treated with interlocking intramedullary nailing and 13 with nonunion of distal femoral fractures fixated with dynamic condylar screw (DCS). Inner and outer intramedullary bone graft was performed simultaneously. Results The follow up time was 8 24 months with an average of 14 months in all cases. Sixty eight cases got bone healing except for five cases with breakage of nail or lock nail, which were all cured with again interlocking intramedullary nailing combined with bone graft. Thirteen cases with nonunion of distal femoral fractures were healed after DCS internal fixation treatment. The healing time averaged 6.5 months in 81 cases. According to synthetic standards including bone healing and function recovery, 54 cases won excellent bone healing, 21 good and 6 poor, with an excellence rate of 92.6%. Conclusions The failed femoral fracture operation is mainly due to the failed internal fixation caused by the biomechanical factor of the abductor muscles. Therefore, intramedullary nailing system should be the first choice for internal fixation of femoral shaft fractures and nonunion; and DCS should be used for condylar fractures and nonunion.

Objective: To analyze the design of Nitinol Patellar Concentrator (NT-PC) and its biomechanic characteristics for treating comminuted patellar fractures.Methods:NT-PC and patellar was analyzed by ANSYS software,the finite element was three dimension brick unit with 20 nodes, 8 faces, and the degree of freedom was 6.In NT-PC,10 483 units were divided and the number of nodes was 17 959;In Patellar,8 775 units were divided and the number of nodes was 15 847.The patellar model was loaded according to the 5 converging directions of NT-PC.Results:NT-PC had tension force on its internal face and pressure force in its external face.The maximum value was 195.8 MPa and -18 MPa,which was far from its utmost stress and fatigue limit.The memory converging force of NT-PC was 134 N.The stress (0.8 MPa) was evenly distributed on the patellar surface.Stress calculation of every node indicated that positive stress was the main stress.Conclusion: The design of NT-PC is reasonable and has good reusing character.After fixation, exercise is allowed immediately after operation.The continual positive stress is good for the stability of fracture end and fracture healing.

OBJECTIVE: To compare the clinical effect between Gamma nail and proximal femoral nail (PFN) on the treatment for femoral intertrochanteric fractures in the elderly.METHODS: A total of 131 cases (39 males and 92 females; aged 70?81 years, mean age of 76 years) with femoral intertrochanteric fractures were collected from the Department of Orthopaedics, the Affiliated Changhai Hospital of the Second Military Medical University of Chinese PLA from January 2005 to January 2008. Femoral intertrochanteric fractures were classified based on AO system, including type A1 (n=56) and type A2 (n=75). All cases were randomly divided into Gamma nail group (n=65) and PFN group (n=66). Pre- and post-operative blood loss, blood transfusion volume, operating time, and length of stay were recorded, while the complications were detected following nail implantation. Functional changes of injured limbs were detected after 9 months.RESULTS: At 9 months after following up, there was no significant difference in blood loss, blood transfusion volume, operating time, and length of stay between the two groups before and after implantation (P> 0.05). Furthermore, complications did not occur during or after implantation. Six cases in the PFN group had infection in which of them had diabetes mellitus. There were no complications such as cutting out of femoral head, femoral shaft fractures, breakage of internal device or pushing out phenomenon. All cases got bone union at the final follow-up of nine months and did not get nonunion, delayed union of fractures or shortening of injured extremity.CONCLUSION: Gamma nail and PFN have equal effect on the treatment of femoral intertrochanteric fractures in the elderly.