The Porous Structure of Peripheral Nerve Guidance Conduits: Features, Fabrication, and Implications for Peripheral Nerve Regeneration.

Porous structure is an important three-dimensional morphological feature of the peripheral nerve guidance conduit (NGC), which permits the infiltration of cells, nutrients, and molecular signals and the discharge of metabolic waste. Porous structures with precisely customized pore sizes, porosities, and connectivities are being used to construct fully permeable, semi-permeable, and asymmetric peripheral NGCs for the replacement of traditional nerve autografts in the treatment of long-segment peripheral nerve injury. In this review, the features of porous structures and the classification of NGCs based on these characteristics are discussed. Common methods for constructing 3D porous NGCs in current research are described, as well as the pore characteristics and the parameters used to tune the pores. The effects of the porous structure on the physical properties of NGCs, including biodegradation, mechanical performance, and permeability, were analyzed. Pore structure affects the biological behavior of Schwann cells, macrophages, fibroblasts, and vascular endothelial cells during peripheral nerve regeneration. The construction of ideal porous structures is a significant advancement in the regeneration of peripheral nerve tissue engineering materials. The purpose of this review is to generalize, summarize, and analyze methods for the preparation of porous NGCs and their biological functions in promoting peripheral nerve regeneration to guide the development of medical nerve repair materials.

Polymer Scaffolds for Biomedical Applications in Peripheral Nerve Reconstruction.

The nervous system is a significant part of the human body, and peripheral nerve injury caused by trauma can cause various functional disorders. When the broken end defect is large and cannot be repaired by direct suture, small gap sutures of nerve conduits can effectively replace nerve transplantation and avoid the side effect of donor area disorders. There are many choices for nerve conduits, and natural materials and synthetic polymers have their advantages. Among them, the nerve scaffold should meet the requirements of good degradability, biocompatibility, promoting axon growth, supporting axon expansion and regeneration, and higher cell adhesion. Polymer biological scaffolds can change some shortcomings of raw materials by using electrospinning filling technology and surface modification technology to make them more suitable for nerve regeneration. Therefore, polymer scaffolds have a substantial prospect in the field of biomedicine in future. This paper reviews the application of nerve conduits in the field of repairing peripheral nerve injury, and we discuss the latest progress of materials and fabrication techniques of these polymer scaffolds.

Risk factors for cement leakage and nomogram for predicting the intradiscal cement leakage after the vertebra augmented surgery.

BACKGROUND: Vertebral augmentation is the first-line treatment for the osteoporosis vertebral compression fractures. Bone cement leakage is the most common complication of this surgery. This study aims to assess the risk factors for different types of cement leakage and provides a nomogram for predicting the cement intradiscal leakage. METHODS: We retrospectively reviewed 268 patients who underwent vertebral augmentation procedure between January 2015 and March 2019. The cement leakage risk factors were evaluated by univariate analysis. Different types of cement leakage risk factors were identified by the stepwise logistic analysis. We provided a nomogram for predicting the cement intradiscal leakage and used the concordance index to assess the prediction ability. RESULTS: A total of 295 levels of vertebrae were included, with a leakage rate of 32.5%. Univariate analysis showed delayed surgery and lower vertebral compression ratio were the independent risk factors of cement leakage. The stepwise logistic analysis revealed percutaneous vertebroplasty was a risk factor in vein cement leakage; delayed surgery, preoperative compression ratio, and upper endplate disruption were in intradiscal cement leakage; age, preoperative fracture severity, and intravertebral vacuum cleft were in perivertebral soft tissue cement leakage; no factor was in spinal canal cement leakage. The nomogram for intradiscal cement leakage had a precise prediction ability with an original concordance index of 0.75. CONCLUSIONS: Delayed surgery and more vertebral compression increase the risk of cement leakage. Different types of cement leakage have different risk factors. We provided a nomogram for precise predicting the intradiscal cement leakage.

A special healing pattern in stable metaphyseal fractures.

BACKGROUND AND PURPOSE: Metaphyseal fractures heal in a rapid fashion that is different from the bone shaft healing process. Animal studies have focused on diaphyseal fractures. We investigated the metaphyseal fracture-healing process in rabbits. ANIMALS AND METHODS: 60 rabbits (divided into 12 groups) underwent proximal tibial osteotomy, anatomical reduction, and fixation with screws. After surgery, the proximal tibiae were harvested at different time points for histology. RESULTS: No obvious osteonecrosis or bone resorption were found 2 weeks after surgery. From day 5 to week 5, woven bone or new trabeculae formed. From week 2, remodeling into lamellar bone started and reached a peak at week 6. These 3 stages overlapped. Histomorphometry showed that the structure changed as a unimodal curve. INTERPRETATION: The healing process of metaphyseal fractures appears to differ from the commonly studied healing process in diaphyseal fractures. It is rapid, and can be divided into 4 histological stages: cellular activation and differentiation, formation of woven bone, transformation of woven bone into lamellar bone, and further remodeling.

[Multi-center retrospective analysis of clinical and related sociologic characteristics of postoperative distal radius fracture patients].

OBJECTIVE: To study clinical-related characteristics of sociology of postoperative distal radius fracture patients. METHODS: A multi-center retrospective research was conducted on the information of the case evaluation and follow-up, including the patients' gender, age, habits, history of chronic diseases, conditions of fracture, length of hospital stay and treatments. The epidemiology data were analyzed with SPSS15.0. RESULTS: Of the entire 143 patients, 52 were male (average age: 41), and 91 were female (average age: 61). The different gender and age groups had significant distinction in the characteristics of injury. The length of hospital stay was influenced by the energy of injury. CONCLUSION: To reduce the damage or incidence of distal radius fracture, we should avoid falling, strengthen protection awareness, treat internal medicine diseases or osteoporosis and so on. The knowledge of characteristics of sociology and injury of distal radius fracture is beneficial to the prevention and treatment.

[Surgical treatment of internal fixation failure after clavicular fracture operation].

OBJECTIVE: To investigate the surgical treatment results of implant failure after clavicular fracture open reduction and internal fixation (ORIF). METHODS: Fifteen cases from Jan. 2005 to Jan. 2013 were treated surgically according to fracture classification, time of implant failure and implant type. The fracture union, shoulder function and pain were evaluated postoperatively. RESULTS: All the patients had full follow-up for 5 to 101 months (mean: 43.8 months). All the fractures were united well. The constant scores to assess the shoulder function were 82 to 100 (mean: 93.3 in the fracture side) and were 85 to 100 (mean: 96.7 in the uninjured side); statistically significant difference of the constant scores between the two sides was found (P=0.02). Eight cases did not have shoulder pain in the fracture side, while the other 7 cases had mild pain, The visual analogue scale (VAS) scores to evaluate shoulder pain were 1 to 3 in the fracture side, which were statistically different from those in the uninjured side (P=0.03). CONCLUSION: Implant instability causes early implant failure after clavicular fracture ORIF and re-fixation with stable implant is effective. Fracture nonunion leads to late implant failure, and bridging fixation using locking plate associated with bony autograft with iliac crest is a successful method to treat atrophy clavicular nonunion. Surgical treatment can bring good results.

[Traffic injuries of pre-hospital treatment in the urban area of Beijing].

OBJECTIVE: To evaluate the current condition of urban road traffic injuries (RTIs) according to Beijing Emergency Medical Center (BEMC) from Jan. 1, 2004 to Dec. 31, 2010, analyze the social characteristics and explore the possible methods for prevention and improvement. METHODS: Using data from the Beijing Emergency Medical Center, we collected 19 550 victims who were involved in RTIs in Beijing from Jan. 1, 2004 to Dec. 31, 2010. The personal information, time of the injury event, road user type and striking vehicle type, as well as the site and severity of injury, were analyzed using Excel 2007 and SPSS 17.0 software with ANOVA of variance and Chi-squared tests. RESULTS: The annual rate of RTIs was 120.0 per 100 000 people in Beijing, and the mortality rate was about 4.97 per 100 000 people. Male victims were more than female victims (11 737 persons vs. 7 618 persons).The mean age was (72.92 ± 5.67) years. Overall, RTIs in all the age groups happened in October commonly, and were inclined to daytime, especially at noon. But different age groups had their special hour distribution features of RTIs. Traffic collisions occurred most frequently in pedestrians and cyclists (7 588,38.81%;3 790,19.39%). Majorities of victims presented with head injuries and lower-limb injuries(8 343,42.68%; 6 828,34.93%). These collisions included car striking accidents (11 490, 58.77%). And most of the older adults were classified as medium in severity (11 718, 59.94%). CONCLUSION: The prevention and treatment of RTIs, should focus on targeted prevention solutions and standardized pre-hospital rescue, according to specific population, time interval and vehicle usage.

Growth factors: Bioactive macromolecular drugs for peripheral nerve injury treatment - Molecular mechanisms and delivery platforms.

Bioactive macromolecular drugs known as Growth Factors (GFs), approved by the Food and Drug Administration (FDA), have found successful application in clinical practice. They hold significant promise for addressing peripheral nerve injuries (PNIs). Peripheral nerve guidance conduits (NGCs) loaded with GFs, in the context of tissue engineering, can ensure sustained and efficient release of these bioactive compounds. This, in turn, maintains a stable, long-term, and effective GF concentration essential for treating damaged peripheral nerves. Peripheral nerve regeneration is a complex process that entails the secretion of various GFs. Following PNI, GFs play a pivotal role in promoting nerve cell growth and survival, axon and myelin sheath regeneration, cell differentiation, and angiogenesis. They also regulate the regenerative microenvironment, stimulate plasticity changes post-nerve injury, and, consequently, expedite nerve structure and function repair. Both exogenous and endogenous GFs, including NGF, BDNF, NT-3, GDNF, IGF-1, bFGF, and VEGF, have been successfully loaded onto NGCs using techniques like physical adsorption, blend doping, chemical covalent binding, and engineered transfection. These approaches have effectively promoted the repair of peripheral nerves. Numerous studies have demonstrated similar tissue functional therapeutic outcomes compared to autologous nerve transplantation. This evidence underscores the substantial clinical application potential of GFs in the domain of peripheral nerve repair. In this article, we provide an overview of GFs in the context of peripheral nerve regeneration and drug delivery systems utilizing NGCs. Looking ahead, commercial materials for peripheral nerve repair hold the potential to facilitate the effective regeneration of damaged peripheral nerves and maintain the functionality of distant target organs through the sustained release of GFs.

Strategies for Treating Traumatic Neuromas with Tissue-Engineered Materials.

Neuroma, a pathological response to peripheral nerve injury, refers to the abnormal growth of nerve tissue characterized by disorganized axonal proliferation. Commonly occurring after nerve injuries, surgeries, or amputations, this condition leads to the formation of painful nodular structures. Traditional treatment options include surgical excision and pharmacological management, aiming to alleviate symptoms. However, these approaches often offer temporary relief without addressing the underlying regenerative challenges, necessitating the exploration of advanced strategies such as tissue-engineered materials for more comprehensive and effective solutions. In this study, we discussed the etiology, molecular mechanisms, and histological morphology of traumatic neuromas after peripheral nerve injury. Subsequently, we summarized and analyzed current nonsurgical and surgical treatment options, along with their advantages and disadvantages. Additionally, we emphasized recent advancements in treating traumatic neuromas with tissue-engineered material strategies. By integrating biomaterials, growth factors, cell-based approaches, and electrical stimulation, tissue engineering offers a comprehensive solution surpassing mere symptomatic relief, striving for the structural and functional restoration of damaged nerves. In conclusion, the utilization of tissue-engineered materials has the potential to significantly reduce the risk of neuroma recurrence after surgical treatment.

[Minimal invasive internal fixation with U-shaped break-off pedicle screws for treatent of thoracolumbar fractures].

OBJECTIVE: To investigate the clinical outcome of minimal invasive internal fixation with U-shaped break-off pedicle screws through paraspinal muscle sparing approach to treat thoracolumbar fractures, and to discuss its advantages. METHODS: From August 2010 to June 2012, we had 40 thoracolumber fractures patients (27 males and 13 females). Their ages ranged from 22 to 60 years. Of the 40 cases, 4 were T11 fractures, 13 T12 fractures ,17 L1 fractures,6 L2 fractures. According to Denis classification,all of them were burst fractures, with vertebral canal compromise less than 1/3. According to AO classification they were type A or type B1 injuries. All the cases had no nerve injury. The patients were randomly divided into two groups. With Group A (20 cases) we took the method of minimal invasive internal fixation with U-shaped break-off pedicle screws to fix one level above and below the injured vertebra through the parespinal muscle sparing approach. With Group B (20 cases), we took the traditional posterior midline approach and open procedure. Then we compared the two groups by operation time, blood loss, drainage, Visual Analogue Scales and X-ray exposure. RESULTS: Minimal invasive group had obvious advatages in operation time, bleeding control and early pain relief of post-operation. The X-ray exposure and long-term follow-up outcome were almost the same. CONCLUSION: Through paraspinal muscle sparing approach minimal invasive internal fixtation with U-shaped break-off pedicle screws to treat thoracolumber has more advantages than traditional procedure in blood control and quick recovery. The method needs no special instruments and don't increase X-ray exposure.

[Surgical treatment of deltoid ligament injury associated with ankle fractures].

OBJECTIVE: To observe the clinical outcome after the surgical treatment of the deltoid ligament injury associated with ankle fractures. METHODS: From January 2005 to December 2009, 16 deltoid ligament ruptures associated with ankle fractures were repaired. According to the AO/OTA system, 2 cases belonged to fracture A, 8 to B, and 6 to C. Radiographs, American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scores and visual analogue scale (VAS) were used for the outcome measurements. RESULTS: The 16 patients were followed up for 30 to 84 months,with the mean follow-up of 47 months. All wounds healed at the first stage. The mean time of bone union was 12.8 weeks (range: 10-14 weeks). The mean AOFAS ankle-hindfoot score in the last follow-up was 93 points (range: 85-100 points). The mean score of VAS was 0.94 points (range: 0-2 points). CONCLUSION: Surgical treatment of ankle fractures associated with deltoid ligament rupture can achieve satisfactory outcomes, but it is important to decide the operation indication.

[Generation and characterization of peripheral nerve animal model of pure motor/sensory nerve fibers].

OBJECTIVE: To generate peripheral nerve animal model of pure motor nerve fibers/pure sensory nerve fibers, and identify them. METHODS: The SPF SD rats were adopted in this study, and divided into 3 groups. In group A, we ablated L2-L4 ventral roots (VRs) to generate peripheral nerve animal model of pure sensory fibers. In group B, we ablated L2-L4 dorsal root ganglions (DRGs) to generate peripheral nerve animal model of pure motor fibers. Two time end-points were set as 2 weeks and 4 weeks. Neuron cells in lumbar spinal cords were detected by immunohistochemical staining with antibody of neuronal nuclei (NeuN). Motor neuron cells in lumbar spinal cords of pure motor fiber animal models and sensory neuron cells in lumbar spinal cords of pure sensory fiber animal models were counted respectively, and then compared to that of normal animals. Femoral nerves distal to the furcation were stained in osmium tetroxide, and then myelinated nerve fibers in the muscle branch and cutaneous branch of femoral nerve were counted respectively. RESULTS: The mean numbers of sensory neuron cells and motor neuron cells in normal lumbar spinal cords were 62.57 ± 1.02 and 29.73 ± 3.03 per 10 × 20 visual field respectively. For different end-points, the mean numbers of sensory neuron cells after ablating vental foots were 62.12 ± 1.77 (2 weeks), 62.15 ± 1.32 (4 weeks) per 10 × 20 visual field respectively; the mean numbers of motor neuron cells after ablating DRGs were 30.12 ± 0.44 (2 weeks), 30.00 ± 1.87 (4 weeks) per 10 × 20 visual field respectively. In group A, motor axons in muscle branch were degenerated as the sensory axons in muscle branch and cutaneous branch were not changed. The senory axons in femoral nerve for the two end-points were 1 558.17 ± 50.14 (2 weeks) and 1 544.00 ± 47.42 (4 weeks). In group B, sensory axons in muscle branch were degenerated as the motor axons were reserved. The motor axons in muscle branch for the two end-points were 387.67 ± 48.50 (2 weeks) and 393.50 ± 27.86 (4 weeks). There was no statistically significant difference in these mean numbers for the two end-points. The degenerating axons and myelin sheath had not been totally eliminated by the endpoint of 2 weeks. CONCLUSION: Peripheral nerve animal model of pure motor fibers can be generated by ablating L2-L4 DRGs; peripheral nerve animal model of pure sensory fibers can be generated by ablating L2-L4 ventral roots. The degenerating axons and myelin sheath have been totally eliminated by the end-point of 4 weeks. Ablating the ventral roots does not influence the survival of sensory neuron cells; and ablating the DRGs does not influence the survival of motor neuron cells.

[Treatment of comminuted clavicle shaft fractures with provisional intra-medullary K-wire fixation and bridging plate internal fixation].

OBJECTIVE: To discuss the operation effect of comminuted clavicle shaft fractures with provisional intramedullary K-wire fixation and bridging plate internal fixation. METHODS: From Mar. 2008 to Jul. 2012, 22 cases of comminuted clavicle shaft fractures was treated with open reduction, and provisional intramedullary K-wire fixation and bridging plate internal fixation. The fracture healing was investigated through X-rays. The 22 cases were followed up to evaluate the function of the affected shoulder with Constant score. RESULTS: Through the follow-up for average 15 months, all the fractures healed and the average healed time was 14.6 weeks. The average Constant score of the affected shoulder was 95.3. There were 13 excellent cases, 7 good cases, and 2 fair cases. The fineness rate was 90.9% (20/22). Soft tissue problem resulting from plate tilting occurred in 2 cases. At last, they accepted second operation to remove the implant. CONCLUSION: Applying provisional intramedullary K-wire fixation and bridging plate internal fixation in comminuted clavicle shaft fractures, makes procedure simple, improves healing rate and decreases the complications.

[Radix hedysari extract promotes peripheral nerve regeneration].

Treatment of peripheral nerve injury is a major challenge in clinical practice. With advances in molecular biology and development of microsurgical techniques and tissue engineering, peripheral nerve repair procedures have been greatly improved. In the last 10 decades, most treatments for peripheral nerve injury in animal models have achieved histological and functional recovery, the treatments in humans, however, produce insufficient recovery, especially for proximal nerve injury. Increasing attention has been paid to the Traditional Chinese Medicine (TCM) for promoting peripheral nerve regeneration, since these remedies often display effective clinical outcome, minor side effects and effectiveness for multiple targets. Although TCM has complex ingredients and the specific pharmacological mechanisms for their effectiveness are still unclear, an effective clinical outcome is welcomed by many clinicians. In the past 20 years, we have made a series of detailed studies including the toxicity tests, pharmacodynamic tests, pharmacological experiments etc, about a new traditional formula which mainly contains the Radix hedysari, Epimedium etc. RESULTS have shown that this formula is safe to be used in both animals and humans with no toxicity and adverse effect, and systemic administration of this formula could enhance the peripheral nerve regeneration.

[Pain assessment of biological conduit small gap tubulization in rat sciatic nerve multilation model].

OBJECTIVE: To explore the pain sensation recovery discipline of 2 mm small gap biological conduit tubulization and epineurial neurorrhaphy in rat sciatic nerve multilation model. METHODS: Based on the rat sciatic nerve multilation model, 2 mm small gap biological conduit tubulization and epineurial neurorrhaphy were applied and the 50% paw withdrawal threshold was observed after 2, 4, 5, 6, 8 and 12 weeks. The data were analyzed by two-way ANOVA and chi-square criterion. RESULTS: Obvious hyperalgesia was observed in week 2 in both experimental group and control group, and 50% paw withdrawal threshold was improved significantly even to 15 g. The 50% paw withdrawal threshold began to decline week 4 and the 50% paw withdrawal threshold of small gap tubulization group was obviously lower than that of control group, which may imply that the pain sensation recovery of small gap tubulization group was earlier than that of control group. The 50% paw withdrawal threshold of small gap tubulization group began to increase to the plateau period [week 5: (12.70 ± 5.64) g; week 6: (12.20 ± 3.26) g; week 8: (12.31 ± 4.19) g; week 12: (13.95 ± 2.58) g]. The 50% paw withdrawal threshold of control group declined gradually [week 5: (10.47 ± 7.02) g; week 6: (9.42 ± 6.86) g; week 8: (8.50 ± 7.15) g; week 12: (8.06 ± 5.93) g]. The difference was statistical significant between small gap tubulization group and control group in 12th week. CONCLUSION: Compared with the traditional epineurial neurorrhaphy for peripheral nerve multilation, 2 mm small gap biological conduit tubulization can improve the 50% paw withdrawal threshold during peripheral nerve regeneration process and reduce the pain incidence.

Micron track chitosan conduit fabricated by 3D-printed model topography provides bionic microenvironment for peripheral nerve regeneration.

The micron track conduit (MTC) and nerve factor provide a physical and biological model for simulating peripheral nerve growth and have potential applications for nerve injury. However, it has rarely been reported that they synergize on peripheral nerves. In this study, we used bioderived chitosan as a substrate to design and construct a neural repair conduit with micron track topography using threedimensional (3D) printing topography. We loaded the MTC with neurotrophin-3 (NT-3) to promote the regeneration of sensory and sympathetic neurons in the peripheral nervous system. We found that the MTC@NT3 composite nerve conduit mimicked the microenvironment of peripheral nerves and promoted axonal regeneration while inducing the targeted growth of Schwann cells, which would promote functional recovery in rats with peripheral nerve injury. Artificial nerve implants with functional properties can be developed using the strategy presented in this study.

Tissue-Engineered Nanomaterials Play Diverse Roles in Bone Injury Repair.

Nanomaterials with bone-mimicking characteristics and easily internalized by the cell could create suitable microenvironments in which to regulate the therapeutic effects of bone regeneration. This review provides an overview of the current state-of-the-art research in developing and using nanomaterials for better bone injury repair. First, an overview of the hierarchical architecture from the macroscale to the nanoscale of natural bone is presented, as these bone tissue microstructures and compositions are the basis for constructing bone substitutes. Next, urgent clinical issues associated with bone injury that require resolution and the potential of nanomaterials to overcome them are discussed. Finally, nanomaterials are classified as inorganic or organic based on their chemical properties. Their basic characteristics and the results of related bone engineering studies are described. This review describes theoretical and technical bases for the development of innovative methods for repairing damaged bone and should inspire therapeutic strategies with potential for clinical applications.

Multifunctional wet-adhesive chitosan/acrylic conduit for sutureless repair of peripheral nerve injuries.

The incidence of peripheral nerve injury (PNI) is high worldwide, and a poor prognosis is common. Surgical closure and repair of the affected area are crucial to ensure the effective treatment of peripheral nerve injuries. Despite being the standard treatment approach, reliance on sutures to seal the severed nerve ends introduces several limitations and restrictions. This technique is intricate and time-consuming, and the application of threading and punctate sutures may lead to tissue damage and heightened tension concentrations, thus increasing the risk of fixation failure and local inflammation. This study aimed to develop easily implantable chitosan-based peripheral nerve repair conduits that combine acrylic acid and cleavable N-hydroxysuccinimide to reduce nerve damage during repair. In ex vivo tissue adhesion tests, the conduit achieved maximal interfacial toughness of 705 J m-2 ± 30 J m-2, allowing continuous bridging of the severed nerve ends. Adhesive repair significantly reduces local inflammation caused by conventional sutures, and the positive charge of chitosan disrupts the bacterial cell wall and reduces implant-related infections. This promises to open new avenues for sutureless nerve repair and reliable medical implants.

A retrospective study of posterior malleolus fractures.

PURPOSE: In this retrospective study, we evaluated the treatment effect of ankle joint fracture surgery involving the posterior malleolus, and discuss relevant factors influencing the occurrence of traumatic arthritis of the ankle joint. METHODS: A total of 102 cases of ankle joint fractures involving the posterior malleolus in five large-scale skeletal trauma centres in China, from January 2000 to July 2009, were retrospectively analysed in terms of surgical treatment and complete follow-up. Ankle joint mobility, posterior malleolus fragment size, articular surface evenness, Ankle-Hindfoot Scale of the American Orthopedic Foot and Ankle Society (AOFAS) score, and imaging scale score for arthritis were recorded. The degree of fracture pain during rest, active movement, and weight-bearing walking, and satisfaction with treatment were evaluated using a visual analogue scale (VAS). RESULTS: The average AOFAS score was 95.9, excellence rate was 92.2 %, and average VAS scores for degree of fracture pain during rest, active movement, and weight-bearing walking were 0.15, 0.31, and 0.68, respectively. Thirty-six cases showed arthritic manifestations. Ankle joint mobility along all directions on the injured side was lower than that on the unaffected side. There was no obvious difference in treatment effect between the fixed and unfixed posterior malleolus fragment groups for all and for fragment size of < 25 %; between fixing the posterior malleolus fragment from front to back or from back to front; or between elderly patients (≥ 60 years old) and young patients (< 60 years old). There was a distinct difference in the treatment effect between articular surface evenness and unevenness for all and for fragment size of ≥ 25 %. CONCLUSIONS: For all 102 cases of ankle joint fracture involving the posterior malleolus, the treatment effect was satisfactory. Restoration of an even articular surface, especially when fragment size ≥ 25 %, should be attempted during treatment.

[Establishment and evaluation of animal model for studying the effect of traumatic brain injury on bone fracture healing].

OBJECTIVE: To establish a stable animal model for studying the effect of traumatic brain injury on bone fracture healing. METHODS: Eighty adult male Sprague-Dawley rats were randomly divided into fracture combined brain injury group (A) and simple fracture group (B). Animals of the two groups were killed 6 hours, 1 week, 2 weeks, 1 month and 2 months after trauma, respectively. Their brain histopathology changes were observed and neurological severity scores (NSS, 0 through 25 from no injury to severe injury) determined to measure the brain injury after head trauma, and fracture-healing was assessed by measuring callus volume and X ray examination at the scheduled time points after trauma. The callus volumes were compared between the groups using independent-samples t test 1 week, 2 weeks, 1 month and 2 months after trauma respectively. A value of P<0.05 was considered statistically significant. RESULTS: Ninety percent of the rats of group A presented with hemiplegia and the mortality rate was 10% (4/40) . The survived rats developed decorticated flexion deformity of the forelimbs, with behavioral depression, and lost some reflexes and muscle tone. The NSS were 10.83±1.94, 9.33±0.82, 8.17±1.17, 7.83±0.75 and 8.07±0.82 with 6 hours, 1 week, 2 weeks, 1 month and 2 months after trauma, respectively. It showed that the animals received moderate head injury, which tended to be stable from 2 weeks after trauma. Brain pathology showed that blood brain barrier was destroyed, and neurons were degenerative and necrotic at and around the trauma sites. The callus volumes(unit: mm(3)) of the two groups 1 week, 2 weeks, 1 month and 2 months after trauma were 60.03±28.05 and 32.80±11.04, 78.54±15.16 and 51.36±23.02, 93.01±10.65 and 72.38±20.38, 115.26±40.00 and 60.30±13.34, respectively. The callus volumes of the two groups 2 weeks, 1 month and 2 months after trauma were statistically and significantly different (P values were 0.036, 0.006 and 0.01 respectively), and there was no difference 1 week after trauma (P=0.065). CONCLUSION: This model is capable of producing accurately quantified brain injury. The animal model is credible, stable and reproducible, so it is an effective platform for studying the effect of traumatic brain injury on fracture.