Abstract Objective The aim of this study was to evaluate the best timing and feasibility of intrathecal application of sodium monosialoganglioside (GM1) after spinal cord contusion in Wistar rats as an experimental model. Methods Forty Wistar rats were submitted to contusion spinal cord injury after laminectomy. The animals were randomized and divided into four groups: Group 1 - Intrathecal application of GM1 24 hours after contusion; Group 2 - Intrathecal application of GM1 48 hours after contusion; Group 3 - intrathecal application of GM1 72 hours after contusion; Group 4 - Sham, with laminectomy and intrathecal application of 0.5 mL of 0.9% saline solution, without contusion. The recovery of locomotor function was evaluated at seven different moments by the Basso, Beattie, and Bresnahan (BBB) test. They were also assessed by the horizontal ladder, with sensory-motor behavioral assessment criteria, pre-and postoperatively. Results This experimental study showed better functional scores in the group submitted to the application of GM1, with statistically significant results, showing a mean increase when evaluated on known motor tests like the horizontal ladder and BBB, at all times of evaluation (p < 0.05), especially in group 2 (48 hours after spinal cord injury). Also, fewer mistakes and slips over the horizontal ladder were observed, and many points were achieved at the BBB scale analysis. Conclusion The study demonstrated that the intrathecal application of GM1 after spinal cord contusion in Wistar rats is feasible. The application 48 hours after the injury presented the best functional results.

ABSTRACT Objectives: To evaluate the functional and immunohistochemical effects of ganglioside GM1 and erythropoietin following experimental spinal cord injury. Methods: Thirty-two male BALB/c mice were subjected to experimental spinal cord injury using the NYU Impactor device and were randomly divided into the following groups: GM1 group, receiving standard ganglioside GM1 (30 mg/kg); erythropoietin group, receiving erythropoietin (1000 IU/kg); combination group, receiving both drugs; and control group, receiving saline (0.9%). Animals were evaluated according to the Basso Mouse Scale (BMS) and Hindlimb Mouse Function Score (MFS). After euthanasia, the immunohistochemistry of the medullary tissue of mice was analyzed. All animals received intraperitoneal treatment. Results: The GM1 group had higher BMS and MFS scores at the end of the experiment when compared to all other groups. The combination group had higher BMS and MFS scores than the erythropoietin and control groups. The erythropoietin group had higher BMS and MFS scores than the control group. Immunohistochemical tissue analysis showed a significant difference among groups. There was a significant increase in myelinated axons and in the myelinated axon length in the erythropoietin group when compared to the other intervention groups (p < 0.01). Conclusion: Erythropoietin and GM1 have therapeutic effects on axonal regeneration in mice subjected to experimental spinal cord injury, and administration of GM1 alone had the highest scores on the BMS and MFS scales.

RESUMO Na tentativa de compreender melhor a etiologia da necrose da cabeça femoral, existe uma diversidade de modelos experimentais tanto no que diz respeito à variedade das espécies em que é induzida a necrose quanto nas técnicas operatórias utilizadas para o tratamento. Objetivo: Este trabalho tem fundamentalmente dois objetivos: a revisão da literatura concernente aos modelos experimentais da necrose avascular da cabeça do fêmur em crescimento e demonstrar a reprodutibilidade do modelo experimental do suíno por meio de um estudo piloto. Métodos: Foi realizada uma revisão bibliográfica descrevendo as tentativas ao longo do tempo em buscar qual seria a melhor espécie e técnica para indução que reproduzisse a necrose isquêmica da cabeça do fêmur em crescimento nos humanos. Simultaneamente foi feito um estudo piloto para verificar a replicação da indução na espécie suína, o espécime cujo quadril tem mais similaridades com o humano. A análise metodológica do piloto consiste na radiologia convencional e verificação das possíveis alterações anátomo patológicas. Resultados: Nos exames por imagem, foram observadas sub-luxação lateral da cabeça do fêmur e aparência triangular da cabeça, caracterizando o achatamento da mesma; no exame macroscópico, identificamos o achatamento da cabeça femoral com alargamento e encurtamento do colo; na histologia, identificamos a proliferação da cartilagem articular com presença de tecido regenerativo vascular de granulação, com osteoclastos e tecido fibrocartilaginoso na região metafisária do colo femoral. Conclusão: Podemos inferir que o modelo experimental suíno pode servir como ferramenta valiosa para a reprodutibilidade das alterações anátomo patológicas da necrose isquêmica da cabeça femoral em crescimento. O modelo é reprodutível e factível, servindo para estudos futuros sobre a anátomo patologia da necrose da cabeça do fêmur em crescimento. Nível de Evidência III, Revisão da Literatura .

ABSTRACT Many experimental models exist to better understand the necrosis of the femoral head etiology, both in terms of the species variety in which necrosis is induced and in the operative techniques used for treatment. Objective: This study has two main objectives, the first is to review the literature concerning experimental models of avascular necrosis of the growing femoral head, the second, to demonstrate the experimental pig model’s reproducibility using a pilot study. Methods: This was a bibliographic review to describe the attempts over time to find the best species and technique for induction that would reproduce ischemic necrosis of the growing femoral head in humans. Simultaneously, a pilot study was performed to verify the replication of induction in pigs, the species that has more similarities with the human hip. The pilot’s methodological analysis consists of conventional radiology and verification of possible anatomical, pathological changes. Results: In imaging exams; lateral sub-dislocation of the femur head and triangular appearance of the head were observed, characterizing its flattening; in macroscopic examination, the femoral head flattening with femoral neck widening and shortening was identified; in histology, the proliferation of articular cartilage with the presence of vascular granulation regenerative tissue, with osteoclasts and fibrocartilaginous tissue in the metaphyseal femoral neck region was identified. Conclusion: The experimental pig model can be used as a valuable tool for the reproducibility of anatomical, pathological changes in ischemic necrosis of the growing femoral head. The model is reproducible and feasible and can be beneficial for future studies on the anatomical pathology of necrosis of the growing femoral head. Level of Evidence III, Literature Review .

RESUMO Objetivo: Avaliar as alterações histológicas nos nervos periféricos após neurorrafia do nervo ciático de ratos, de acordo com o tempo de exposição ao tratamento com câmara hiperbárica de oxigênio. Métodos: Vinte e cinco ratos da raça Wistar foram divididos em cinco grupos conforme o tempo de exposição ao tratamento com câmara hiperbárica de oxigênio. O grupo 1 não recebeu o tratamento; o grupo 2 recebeu uma semana de terapia; o grupo 3, duas semanas; o grupo 4, três semanas; e o grupo 5, quatro semanas. Após quatro semanas de pós-operatório, os animais foram submetidos à eutanásia e uma amostra do nervo ciático foi enviada para análise histológica. Foram feitas contagens do número de axônios proximalmente e distalmente à neurorrafia, com medição do índice de regeneração axonal. Resultados: Observamos que o aumento do número de axônios distais à neurorrafia foi diretamente proporcional ao tempo de exposição à câmara hiperbárica de oxigênio, sendo mais expressivo a partir da terceira semana de tratamento. Entretanto, a análise estatística não encontrou diferença significativa entre os grupos. Conclusão: A análise descritiva sugere benefício do uso da câmara hiperbárica de oxigênio. Porém, devido à amostra reduzida, o estudo não apresentou resultados estatisticamente relevantes, sendo necessária a realização de estudos subsequentes com amostragem mais significativa. Nível de Evidência II, Estudo Prospectivo Comparativo.

ABSTRACT Objective: To evaluate histological changes in peripheral nerves of rats after sciatic nerve neurorrhaphy, according to the time of exposure to hyperbaric oxygen chamber treatment. Methods: Twenty-five Wistar rats were divided into 5 groups according to the amount of exposure to hyperbaric oxygen chamber treatment. Group 1 was the control and there was no use of hyperbaric oxygen chamber; group 2 received one week of therapy; group 3, two weeks; group 4, three weeks; and group 5, four weeks. After the fourth postoperative week, the animals were submitted to euthanasia and a sciatic nerve sample sent for histological analysis. Axons proximal and distal to the neurorrhaphy were counted with axonal regeneration index measurement. Results: We observed that the number of axons distal to neurorrhaphy increases with the amount of hyperbaric oxygen chamber exposure, the results were more expressive from the third week of treatment. However, the statistical analysis found no significant difference between the groups. Conclusion: The descriptive analysis suggests benefit of using hyperbaric oxygen chamber directly proportional to the time of therapy. The study, however, did not present statistically relevant results, probably due to the reduced sample size. Subsequent studies with more significant sampling would be of great value. Level of Evidence II, Prospective Comparative Study.

OBJECTIVES: This study proposed a structured microsurgical training program and evaluated it with the assistance of a large sample of surgeons. METHODS: The practical course comprised 16 sessions of approximately 4 hours each. This included two sessions for suturing rubber gloves and two sessions for suturing arteries, veins, and nerves in chicken thighs. The other sessions were performed on the femoral vessels of rats: 5 sessions for end-to-end arterial anastomosis, 5 for end-to-end venous anastomosis, 1 for arterial grafting, and 1 for end-to-side anastomosis. We conducted a structured assessment of the microsurgical skills in each training session. RESULTS: In this study, 89 surgeons were evaluated. The mean scores for the different procedures were as follows: glove suturing, 33.3±0.59; chicken nerve end-to-end anastomosis, 40.3±0.49; chicken artery suturing, 40.9±0.36; chicken vein suturing, 42.3±0.36; graft interposition, 44.8±0.7; and end-to-side anastomosis, 43.7±0.63 (p<0.05 for all). The chicken thigh suturing scores were significantly higher than the rubber gloves suturing scores (p<0.01). There were no differences between scores of the rat artery and chicken thigh suturing procedures (p=0.24). The rat venous anastomosis scores were higher than the rat arterial anastomosis scores (p=0.02), as were graft interposition scores when compared with end-to-end venous anastomosis scores. The end-to-side anastomosis scores did not differ significantly from the grafting scores (p=0.85). The most common errors were inadequate knotting technique and suture rupture due to inadequate technique (both n=88 [98.9%]). CONCLUSION: We propose a 16-step, progressive microsurgical training program to learn the basic microsurgical techniques comprehensively and reliably. The program was evaluated in a large sample of trainees, and it demonstrated the adequacy of the training sequence and results.

RESUMO Objetivo: Avaliar, em coelhos, qual é a influência do desenho da alça de veia femoral com anastomose na artéria femoral, na presença de fluxo (patência) após sete dias. Método: 39 coelhos foram submetidos à microanastomose arteriovenosa com técnica microcirúrgica. As alças foram acomodadas em dois desenhos, um circular e outro, o mais alongado possível sem dobras na alça. Os parâmetros avaliados foram: presença ou não de fluxo, sinais de hemólise, alterações hemodinâmicas. Resultados: após sete dias, o fluxo estava presente em 68% das alças anguladas e em 75% das alças circulares (p > 0,05). Houve, intragrupo, diminuição estatisticamente significante da pCO 2 e aumento estatisticamente significante do pH. Não houve diferença estatística no restante dos parâmetros avaliados entre os dois modelos de alça. Conclusões: apresentamos um modelo reprodutível de alça vascular. Não houve diferença estatística quanto à presença de fluxo após sete dias nos dois modelos de alça vascular. Nível de Evidência V, Estudo experimental em animais.

ABSTRACT Objective: To evaluate the effect of the design of a femoral vascular loop with anastomosis in the femoral artery of rabbits on the presence of flow (patency) after seven days. Methods: A total of 39 rabbits underwent arteriovenous microanastomosis using the microsurgical technique. Two loop designs were used: one circular and the other angled. The parameters evaluated were presence or absence of flow, signs of hemolysis and hemodynamic changes. Results: After seven days, flow was present in 68% of the angled loops and 75% of the circular loops (p > 0.05). There was a significant intragroup decrease in pCO2 and a significant increase in pH. For the other parameters evaluated, no significant differences between the two loop models were found. Conclusions: A reproducible vascular loop model was shown. There was no significant difference between the two vascular loop models about the presence of flow after seven days. Level of Evidence V, Animal experimental study.

OBJECTIVE: To evaluate the effects of interleukin-6 (IL-6) and erythropoietin (EPO) in experimental acute spinal cord injury (SCI) in rats. METHODS: Using standardized equipment, namely, a New York University (NYU) Impactor, a SCI was produced in 50 Wistar rats using a 10-g weight drop from a 12.5-mm height. The rats were divided into the following 5 groups of 10 animals each: “Group EPO”, treated with erythropoietin only; “Group EPO + IL-6”, treated with both substances; “Group IL-6”, receiving IL-6 administration only; “Group Placebo”, receiving a placebo solution; and “Group Sham”, submitted to an incomplete procedure (only laminectomy, without SCI). All drugs and the placebo solution were administered intraperitoneally for three weeks. The animals were followed up for 42 days. Functional motor recovery was monitored by the Basso, Beattie, and Bresnahan (BBB) scale on days 2, 7, 14, 21, 28, 35 and 42. Motor-evoked potential tests were performed on the 42nd day. Histological analysis was performed after euthanasia. RESULTS: The group receiving EPO exhibited superior functional motor results on the BBB scale. IL-6 administration alone was not superior to the placebo treatment, and the IL-6 combination with EPO yielded worse results than did EPO alone. CONCLUSIONS: Using EPO after acute SCI in rats yielded benefits in functional recovery. The combination of EPO and IL-6 showed benefits, but with inferior results compared to those of isolated EPO; moreover, isolated use of IL-6 resulted in no benefit.

OBJECTIVE: To standardize a spinal cord lesion mouse model. METHODS: Thirty BALB/c mice were divided into five groups: four experimental groups and one control group (sham). The experimental groups were subjected to spinal cord lesion by a weight drop from different heights after laminectomy whereas the sham group only underwent laminectomy. Mice were observed for six weeks, and functional behavior scales were applied. The mice were then euthanized, and histological investigations were performed to confirm and score spinal cord lesion. The findings were evaluated to prove whether the method of administering spinal cord lesion was effective and different among the groups. Additionally, we correlated the results of the functional scales with the results from the histology evaluations to identify which scale is more reliable. RESULTS: One mouse presented autophagia, and six mice died during the experiment. Because four of the mice that died were in Group 5, Group 5 was excluded from the study. All the functional scales assessed proved to be significantly different from each other, and mice presented functional evolution during the experiment. Spinal cord lesion was confirmed by histology, and the results showed a high correlation between the Basso, Beattie, Bresnahan Locomotor Rating Scale and the Basso Mouse Scale. The mouse function scale showed a moderate to high correlation with the histological findings, and the horizontal ladder test had a high correlation with neurologic degeneration but no correlation with the other histological parameters evaluated. CONCLUSION: This spinal cord lesion mouse model proved to be effective and reliable with exception of lesions caused by a 10-g drop from 50 mm, which resulted in unacceptable mortality. The Basso, Beattie, Bresnahan Locomotor Rating Scale and Basso Mouse Scale are the most reliable functional assessments, and but the horizontal ladder test is not recommended.

OBJECTIVES:To evaluate the functional and histological effects of estrogen as a neuroprotective agent after a standard experimentally induced spinal cord lesion.METHODS:In this experimental study, 20 male Wistar rats were divided into two groups: one group with rats undergoing spinal cord injury (SCI) at T10 and receiving estrogen therapy with 17-beta estradiol (4mg/kg) immediately following the injury and after the placement of skin sutures and a control group with rats only subjected to SCI. A moderate standard experimentally induced SCI was produced using a computerized device that dropped a weight on the rat's spine from a height of 12.5 mm. Functional recovery was verified with the Basso, Beattie and Bresnahan scale on the 2nd, 7th, 14th, 21st, 28th, 35th and 42nd days after injury and by quantifying the motor-evoked potential on the 42nd day after injury. Histopathological evaluation of the SCI area was performed after euthanasia on the 42nd day.RESULTS:The experimental group showed a significantly greater functional improvement from the 28th to the 42nd day of observation compared to the control group. The experimental group showed statistically significant improvements in the motor-evoked potential compared with the control group. The results of pathological histomorphometry evaluations showed a better neurological recovery in the experimental group, with respect to the proportion and diameter of the quantified nerve fibers.CONCLUSIONS:Estrogen administration provided benefits in neurological and functional motor recovery in rats with SCI beginning at the 28th day after injury.

OBJECTIVES : To evaluate the neuroprotective effect of epidural hypothermia in rats subjected to experimental spinal cord lesion. METHODS: Wistar rats (n = 30) weighing 320-360 g were randomized to two groups (hypothermia and control) of 15 rats per group. A spinal cord lesion was induced by the standardized drop of a 10-g weight from a height of 2.5 cm, using the New York University Impactor, after laminectomy at the T9-10 level. Rats in the hypothermia group underwent epidural hypothermia for 20 minutes immediately after spinal cord injury. Motor function was assessed for six weeks using the Basso, Beattie and Bresnahan motor scores and the inclined plane test. At the end of the final week, the rats' neurological status was monitored by the motor evoked potential test and the results for the two groups were compared. RESULTS: Analysis of the Basso, Beattie and Bresnahan scores obtained during the six-week period indicated that there were no significant differences between the two groups. There was no significant difference between the groups in the inclined plane test scores during the six-week period. Furthermore, at the end of the study, the latency and amplitude values of the motor evoked potential test were not significantly different between the two groups. CONCLUSION: Hypothermia did not produce a neuroprotective effect when applied at the injury level and in the epidural space immediately after induction of a spinal cord contusion in Wistar rats.

OBJECTIVE: The objective of this study was to compare two four-strand techniques: the traditional Strickland and cruciate techniques. METHODS: Thirty-eight Achilles tendons were removed from 19 rabbits and were assigned to two groups based on suture technique (Group 1, Strickland suture; Group 2, cruciate repair). The sutured tendons were subjected to constant progressive distraction using a universal testing machine (Kratos®). Based on data from the instrument, which were synchronized with the visualized gap at the suture site and at the time of suture rupture, the following data were obtained: maximum load to rupture, maximum deformation or gap, time elapsed until failure, and stiffness. RESULTS: In the statistical analysis, the data were parametric and unpaired, and by Kolmogorov-Smirnov test, the sample distribution was normal. By Student's t-test, there was no significant difference in any of the data: the cruciate repair sutures had slightly better mean stiffness, and the Strickland sutures had longer time-elapsed suture ruptures and higher average maximum deformation. CONCLUSIONS: The cruciate and Strickland techniques for flexor tendon sutures have similar mechanical characteristics in vitro.

OBJETIVOS: Avaliar os efeitos de monossialogangliosídeos (GM1) administrados com laser por via transdérmica na recuperação da lesão da medula espinal de ratos. MÉTODOS: Quarenta ratos Wistar machos foram submetidos a contusão da medula espinal usando NYU Impactor. No Grupo 1, os ratos receberam 0,2 ml de solução salina diária por via intraperitoneal; no Grupo 2, GM1 foi administrada intraperitonealmente em concentração de 30 mg/kg por dia; no Grupo 3, os ratos foram tratados diariamente com o laser a baixa temperatura sobre a pele, e no Grupo 4, a sessão de laser diária também continha GM1. Todos os grupos foram tratados durante 42 dias. Os animais foram avaliados pela escala funcional de Basso, Baettie e Bresnahan (BBB) nos dias 7, 14, 21, 28, 35 e 42 após a lesão, e por histopatologia e potencial motor evocado 42 dias depois da lesão. RESULTADOS: Os animais do Grupo 4 apresentaram escores BBB mais elevados em comparação com os outros grupos. Não houve diferenças entre os grupos ou nas comparações ao longo do tempo. A avaliação histológica não mostrou diferenças, e tampouco foram encontradas diferenças significativas no potencial evocado. CONCLUSÃO: A GM1 associada ao uso de laser a baixa temperatura não mostra resultados superiores no tratamento de lesões da medula espinal de ratos. Nível de Evidência I, Experimental, Estudo Controlado de Animais.

OBJECTIVES: to evaluate the effects of monosialoganglioside (gm1) administered transdermally with laser in the recovery of spinal cord injury in rats. METHODS: forty male wistar rats underwent spinal cord contusion using the nyu impactor. in group 1, the rats received 0,2 ml of saline intraperitoneally daily; in group 2, gm1 was administered intraperitoneally at a concentration of 30 mg/kg per day; in group 3, rats were treated daily with laser at low temperature on the skin, and in group 4, the daily laser session also contained gm1. all the groups were treated for 42 days. the animals were evaluated by the Basso, Baettie and Bresnahan (BBB) functional scale on days 7, 14, 21, 28, 35 and 42 after the injury, and by histopathology and motor evoked potential after 42 days of injury. RESULTS: the animals in group 4 had higher BBB scores compared with the other groups. there were no differences between the groups, or in the comparisons over time. Histological evaluation showed no differences, and no differences were found in the motor evoked potential tests either. CONCLUSION: gm1 associated with the use of low-temperature laser shows no superior functional, neurological or histological results in the treatment of spinal cord lesions in rats. Evidence Level I, Experimental, Controlled, Animal Study.

OBJETIVOS: Determinar modelo de contusão medular padronizado e método de avaliação motora em ratos com quadro de paraplegia. MÉTODOS: Utilizados 20 ratos Wistar divididos em quatro grupos, diferenciado o nível de gravidade da lesão raquimedular; realizadas lesões intermediárias padronizadas, através do sistema "MASCIS IMPACTOR" (Multicenter Animal Spinal Cord Injury Study): grupo 1 - 12,5 mm (lesão leve); grupo 2 - 25 mm (lesão moderada); grupo 3 - 50 mm (lesão grave); grupo 4 - animais que não sofreram lesão (grupo controle). Após 48 horas foi avaliada função motora, segundo escala proposta por Basso, Beattie e Bresnahan. RESULTADOS: Utilizando o modelo, notamos que as contusões leves (12,5mm de altura) foram efetivas, e os animais apresentaram infecção urinária na fase aguda uma semana após a contusão. As contusões intermediárias (25 mm de altura) foram efetivas, os animais apresentaram infecção urinária até duas semanas após a contusão. As contusões graves (50mm de altura) foram efetivas, os animais apresentaram infecção urinária durante três a quatro semanas e autofagia. CONCLUSÃO: O modelo de lesão medular utilizando o sistema MASCIS IMPACTOR e a avaliação funcional proposta por Basso, Beattie e Bresnahan é reprodutível, podendo ser utilizada, propiciando troca de informações entre os diferentes pesquisadores.

OBJECTIVES: To determine a standardized spinal cord contusion model and a method for motor assessment in rats with paraplegia. METHODS: This study used 20 Wistar rats divided into 4 groups according to level of severity of spinal cord injury; standardized intermediate lesions were made through system MASCIS IMPACTOR (Multicenter Animal Spinal Cord Injury Study): group 1, 12.5mm (mild injury); group 2,25mm (moderate injury); group 3,50mm (severe injury; in the group 4 the animals suffered no injury (control group). Motor function was assessed after 48 hours, using the scale proposed by Basso, Beattie and Bresnahan. RESULTS: Using the model, we observed that the mild contusions (12.5mm height) were effective, and the animals presented acute urinary tract infection one week after the injury. Moderate contusions (25mm height) were effective, and the animals presented urinary infection until 2 weeks after injury. The severe contusions (50mm height) were effective, and the animals presented urinary infection for 3 to 4 weeks and autophagy. CONCLUSION: The model of spinal cord injury using the system MASCIS IMPACTOR and the functional assessment proposed by Basso, Beattie and Bresnahan is reproducible and can be used, enabling information exchange among different researchers.

OBJETIVO: Realizar estudo histológico comparando o crescimento axonal após neurorrafia término-lateral com e sem epineurectomia. MÉTODOS: foram utilizados vinte ratos Wistar, machos, divididos em dois grupos de 10 ratos cada. Um segmento de 1,0cm do nervo tibial e, foi transposto para o lado contralateral, sendo suturado no nervo ciático D. No grupo I, a sutura foi realizada diretamente no epineuro, enquanto que no grupo II foi realizado epineurectomia. Após 4 semanas foi realizado avaliação histológica do segmento transposto e no nervo ciático D, no sitio distal à lesão. RESULTADOS: demonstrou-se baixa quantidade de fibras remielinizadas, variando de 7 a 51 fibras no Grupo I e de 10 a 91 fibras no Grupo II. Utilizou-se o teste U de Mann-Whitney, com p=0,31, demonstrando que não há diferença estatisticamente significante entre os dois grupos. Não há relação positiva entre o número de fibras remielinizadas no enxerto e no sitio distal à lesão do ciático. CONCLUSÃO: A neurorrafia término-lateral, com e sem janela epineural, não promove remielinização eficiente. Nivel de evidência: Nível II: Estudo prospectivo comparativo

OBJECTIVE: The aim of this study was to histologically compare the axonal sprouting after end-to-side neurorrhaphy with or without epineurotomy. METHODS: twenty male Wistar rats were used, divided into two groups of 10 rats each. A 1.0cm segment of the tibial nerve E was dried and sutured on the opposite side, where it was sutured into the sciatic nerve D. In Group I, the suture was made directly in the epineurium and in Group II, epineurotomy was performed. After 4 weeks, histological evaluation was carried out of the transposed segment and the sciatic nerve distal to the suture. RESULTS: the results showed a small number of remyelinated fibers, varying from 7 to 51 fibers in Group I and from 10 to 91 fibers in Group II. The Mann-Whitney U test was used, with p=0.311, showing there is no statistically significant difference between the two groups. There was no positive relation between the number of remyelinated fibers in the graft and in the suture site distal to the sciatic lesion. CONCLUSION: lateral-ending neurorrhaphy, with or without epineural window, does not promote efficient remyelinization. Level of Evidence: Level II, prospective comparative study.