Histological evaluation of the effect of low-frequency electric stimulation on healing Achilles tendons in rats

Purpose: Histologically evaluate the effects of low frequency electrical stimulation in the treatment of Achilles tendon injuries in rats. Methods: Thirty-four rats underwent Achilles tendon tenotomy and tenorrhaphy. They were randomly allocated in two groups. Half of the sample constituted the experiment group, whose lesions were stimulated with 2 Hz, nonpolarized current and 1 mA, for 14 days. The other animals formed the control group. They were evaluated at 2, 4 and 6 weeks. The histological study was carried out, the collagen density and the wound maturity index were measured. Results: The healing score was higher in the group stimulated at the 6th week (p = 0.018). The density collagen 1 was higher in the group treated at the three times (p = 0.004) and that collagen 3 was higher in the group treated at 6 weeks (p = 0.004). Together, collagen 1 and 3 were higher in the group stimulated at 4 and 6 weeks (p = 0.009, p = 0.004). The maturity index was higher in this group at the three moments (p = 0.017 p = 0.004 and p = 0.009). Conclusion: Low frequency electric stimulation improved healing and increased the quantity of collagen.(AU)

Tensiometric evaluation of the effect of low frequency electric stimulation on healing Achilles tendons in rats

Purpose: To evaluate the effects of low-frequency electric stimulation on biomechanics following surgical treatment of the Achilles tendon in rats. Methods: Forty-two rats were divided into two groups. One was given electric stimulation and the other was not. All were submitted to Achilles tenotomy and tenorrhaphy performed with a modified Kessler stitch. The experiment group underwent electric stimulation with 2 Hz, a nonpolarized current of 1 mA intensity for 14 days. The animals were euthanized at 2, 4 and 6 weeks for the biomechanical study. Results: The work performed, that is, the tendons capacity to absorb energy until rupture, was greater in the electrically stimulated group in the 2nd (p = 0.032) and in the 6th week (p = 0.010). The maximum tension, which is the capacity to support a load, was higher in the treated group in the 2nd (p = 0.030) and the 6th week (p = 024). These results indicate greater resistance of the electrically stimulated tendons. An analysis of the elastic module showed no differences. Conclusion: Low-frequency electric stimulation increased the resistance of the tendons at 2 and 6 weeks of evolution in rats.(AU)

Effect of low intensity photobiomodulation associated with norbixin-based poly (hydroxybutyrate) membrane on post-tenotomy tendon repair: in vivo study

Purpose: To evaluate the in vivo response of photobiomodulation therapy associated with norbixin-based poly(hydroxybutyrate) membrane (PHB) in tenotomized calcaneal tendon. Methods: Thirty rats were randomly allocated to six groups (n=5 each): LED groups (L1, L2 and L3) and membrane + LED groups (ML1, ML2 and ML3). The right calcaneal tendons of all animals were sectioned transversely and were irradiated with LED daily, one hour after surgery every 24 hours, until the day of euthanasia. At the end of the experiments the tendons were removed for histological analysis. Results: The histological analysis showed a significant reduction in inflammatory cells in the ML1, ML2 and ML3 groups (p=0.0056, p=0.0018 and p 0.0001, respectively) compared to those in the LED group. There was greater proliferation of fibroblasts in the ML1 (p 0.0001) and L3 (p 0.0001) groups. A higher concentration of type I collagen was also observed in the ML1 group (p=0.0043) replacing type III collagen. Conclusion: Photobiomodulation in association with norbixin-based PHB membrane led to control of the inflammatory process. However, it did not favor fibroblast proliferation and did not optimize type I collagen formation in the expected stage of the repair process.(AU)

Effect of norbixin-based poly(hydroxybutyrate) membranes on the tendon repair process after tenotomy in rats

Purpose: To determine the efficacy of norbixin-based poly(hydroxybutyrate) (PHB) membranes for Achilles tendon repair. Methods: Thirty rats were submitted to total tenotomy surgery of the right Achilles tendon and divided into two groups (control and membrane; n = 15 each), which were further subdivided into three subgroups (days 7, 14, and 21; n = 5 each). Samples were analyzed histologically. Results: Histological analysis showed a significant reduction in inflammatory infiltrates on days 7, 14 (p 0.0001 for both), and 21 (p = 0.0004) in the membrane group compared to that in the control group. There was also a significant decrease in the number of fibroblasts in the control group on days 7, 14 (p 0.0001), and 21 (p = 0.0032). Further, an increase in type I collagen deposition was observed in the membrane group compared to that in the control group on days 7 (p = 0.0133) and 14 (p = 0.0107). Conclusion: Treatment with norbixin-based PHB membranes reduces the inflammatory response, increases fibroblast proliferation, and improves collagen production in the tendon repair region, especially between days 7 and 14.(AU)

Uso de enxerto autógeno de fáscia lata no tratamento de defeito segmentar crônico do tendão calcâneo comum em felino doméstico / Use of autogenous fascia lata graft in the treatment of chronic segmental defect of the common calcaneus tendon in domestic feline

Background: The common calcaneus tendon is formed by the common tendon of the femoral biceps muscle, tendon of the superficial digital flexor muscle and gastrocnemius muscle tendon, and its rupture is related to acute traumas in small animals. Among some applications described, surgical repair can be adopted in the correction of tendon ruptures and the use of grafts may be indicated in some severe lesions, where it is not possible to perform tenorrhaphy. This study aims to report the case of a feline with rupture of the common calcaneus tendon in which the tenorrafia associated with the autogenous fascia lata graft was performed as adjuvant to the cicatrization of the same.Case: A 24-month-old, undefined male feline with approximately 3 kg was treated at the FCAV Veterinary Hospital, UNESP Jaboticabal, State of São Paulo, Brazil, with a history of falling, for approximately two weeks, and has since plantigrade posture. Upon physical examination, it was possible to identify a discontinuity of the common calcaneus tendon. The radiographs were performed, which did not show any bone changes. A hemogram and biochemical profile were performed, which were within normal limits. The patient underwent surgery, and a complete lesion of the common calcaneus tendon was identified, with a chronic aspect. Approximation of the stumps was impossible, so a flap of fascia lata, about two centimeters long and one centimeter wide, was removed, which was used as a bed and tendon support for tendon growth. After removal all of the present fibrosis, the tendon stumps were approximated by means of modified Kessler suture with mononylon thread, and fascia lata flap of the ipsilateral limb was sutured with separate single points in both tendon ends and in their lateral and medial portion. In the tibiotarsic joint, the external skeletal fixator type II was used for immobilization, during a period of 30 days.[...]

Uso de enxerto autógeno de fáscia lata no tratamento de defeito segmentar crônico do tendão calcâneo comum em felino doméstico / Use of autogenous fascia lata graft in the treatment of chronic segmental defect of the common calcaneus tendon in domestic feline

Background: The common calcaneus tendon is formed by the common tendon of the femoral biceps muscle, tendon of the superficial digital flexor muscle and gastrocnemius muscle tendon, and its rupture is related to acute traumas in small animals. Among some applications described, surgical repair can be adopted in the correction of tendon ruptures and the use of grafts may be indicated in some severe lesions, where it is not possible to perform tenorrhaphy. This study aims to report the case of a feline with rupture of the common calcaneus tendon in which the tenorrafia associated with the autogenous fascia lata graft was performed as adjuvant to the cicatrization of the same.Case: A 24-month-old, undefined male feline with approximately 3 kg was treated at the FCAV Veterinary Hospital, UNESP Jaboticabal, State of São Paulo, Brazil, with a history of falling, for approximately two weeks, and has since plantigrade posture. Upon physical examination, it was possible to identify a discontinuity of the common calcaneus tendon. The radiographs were performed, which did not show any bone changes. A hemogram and biochemical profile were performed, which were within normal limits. The patient underwent surgery, and a complete lesion of the common calcaneus tendon was identified, with a chronic aspect. Approximation of the stumps was impossible, so a flap of fascia lata, about two centimeters long and one centimeter wide, was removed, which was used as a bed and tendon support for tendon growth. After removal all of the present fibrosis, the tendon stumps were approximated by means of modified Kessler suture with mononylon thread, and fascia lata flap of the ipsilateral limb was sutured with separate single points in both tendon ends and in their lateral and medial portion. In the tibiotarsic joint, the external skeletal fixator type II was used for immobilization, during a period of 30 days.[...](AU)

Hyaluronic acid and synovial fluid in preventing adhesion formation after tenorrhaphy: An in vivo study on rabbit Achilles tendon / Ácido hialurônico e líquido sinovial na prevenção da formação de aderências após tenorrafia: Um estudo in vivo sobre o tendão de Aquiles de coelho

Peritendinous adhesions are a significant problem in tendon surgery. One of the most preferred methods for preventing adhesion formation is anti-adhesive applications. This study aimed to investigate the efficacy of natural synovial fluid as an alternative viscoelastic agent for preventing adhesion in the healing period compared to hyaluronic acid. Thirty adult New Zealand rabbits were used in the study to form three experimental models. In all groups, a rupture was induced in the Achilles tendons. Following tenorrhaphy, hyaluronic acid was applied in one group and synovial fluid in the other group for anti-adhesive purposes. In the control group, no viscoelastic application was made. Bandage was applied to the operated extremities for three weeks post-operatively. At the end of five weeks, euthanasia was performed on the animals using pentobarbital sodium. Surgical sites in all groups were macroscopically examined for healing status as well as the presence and extent of adhesions. Biomechanical tests and histopathological examinations were then performed on the tendons in all groups. Findings established once again the positive contribution of hyaluronic acid to preventing adhesion formation as well as to healing and tensile strength in tendon surgery. Although, we found that it is possible to use synovial fluid, which is a natural source of hyaluronic acid, as a viscoelastic material, it is not superior to commercial hyaluronic acid preparation.(AU)

Asderências peritendinares são um problema significativo na cirurgia tendínea. Um dos métodos mais empregados para evitar a formação de adesão são as aplicações anti-adesivas. Este estudo tem como objetivo investigar a eficácia do líquido sinovial natural como um agente viscoelástico alternativo para prevenir a adesão no período de cicatrização comparado ao ácido hialurônico. Trinta coelhos adultos da Nova Zelândia foram utilizados no estudo para formar três modelos experimentais. Em todos os grupos, uma ruptura foi induzida nos tendões de Aquiles. Após tenorrafia, o ácido hialurônico foi aplicado em um grupo e o líquido sinovial no outro grupo para fins anti-adesivos. No grupo controle, não foi feita qualquer aplicação viscoelástica. A bandagem foi aplicada às extremidades operadas por três semanas pós-operatório. No final de cinco semanas, a eutanásia foi realizada nos animais utilizando pentobarbital sódico. Os locais cirúrgicos em todos os grupos foram examinados macroscopicamente quanto ao estado de cura, bem como a presença e extensão das aderências. Testes biomecânicos e exames histopatológicos foram realizados nos tendões em todos os grupos. Os achados estabeleceram mais uma vez a contribuição positiva do ácido hialurônico para prevenir a formação de aderências, bem como para a cicatrização e resistência à tração na cirurgia do tendão. Embora se tenha constatado que é possível utilizar fluido sinovial, que é uma fonte natural de ácido hialurónico, como material viscoelástico, não é superior à preparação de ácido hialurónico comercial.(AU)

Amniotic membrane as an option for treatment of acute Achilles tendon injury in rats

Purpose: To evaluate the effect of human amniotic membrane (hAM) fragment on inflammatory response, proliferation of fibroblast and organization of collagen fibers in injured tendon. Methods: Sixty rats were divided into 3 groups: C - surgical procedures without tendon lesion and with simulation of hAM application; I - surgical procedures, tendon injury and simulation of hAM application; T - surgical procedures, tendon injury and hAM application. These groups were subdivided into four experimental times (3, 7, 14 and 28 days). The samples underwent histological analysis and ATR-FTIR spectroscopy. Results: Histological analysis at 14 days, the T group showed collagen fibers with better alignment. At 28 days, the I group presented the characteristics described for the T group at 14 days, while this group presented aspects of a mature connective tissue. FT-IR analysis showed a clear distinction among the three groups at all experimental times and groups T and I presented more similarities to each other than to group C. Conclusion: Acute injury of tendon treated with human amniotic membrane fragment showed a faster healing process, reduction in inflammatory response, intense proliferation of fibroblasts and organization of collagen fibers.(AU)

Laserterapia Para Tratamento De Tendinopatia Induzida Em Ratos Wistar: Estudo Histomorfométrico / Laser Therapy For Treatment Of Tendinopathy Induced In Wistar Rats: An Histomorfometric Study / Terapia Con Láser Para Tratamiento De Tendinopatia Inducida En Ratas Wistar: Estudio Histomorfométrico

O objetivo desse estudo foi avaliar os efeitos da laserterapia na lesão do tendão calcanear comum de ratos Wistar. Foram utilizados 12 ratos machos adultos, distribuídos aleatoriamente em dois grupos (L=laser e C=controle). Todos foram submetidos à tendinopatia unilateral (escolha aleatória) mediante compressão transversal do tendão (10 segundos) com pinça Halstead mosquito, assim como escarificações (com bisturi). Após 24 horas da indução da lesão os animais do grupo L receberam laser (904 nm/3 J/cm²/9s) por 20 dias. Os do grupo C foram manipulados como se fossem receber a radiação. Após 3, 7, 14 e 21 dias da realização da lesão, três ratos de cada grupo foram submetidos à eutanásia, e os tendões obtidos para análise histomorfométrica. As amostras foram processadas como de rotina e os fragmentos corados com hematoxilina-eosina, tricrômico de Masson e Picrosirius Red. Os dados foram analisados por ANOVA, a 5% de probabilidade e análise de regressão. Não houve diferença entre grupos nem entre tempos para as características hemorragia, angiogênese, espessamento do epitendão. Independente do tratamento ocorreu diminuição (p=0,0129) da formação de aderência fibrinosa (do 3o ao 21o dias). Por outro lado, a avaliação morfométrica revelou maiores (p=0,0120) quantidades de fibroblastos no grupo que recebeu laserterapia, não havendo efeito de tempo. Avaliação semiquantitativa, revelou maiores (p=0,0000) quantidades de fibroblastos no grupo tratado, porém nessa análise, a quantidade dessas células aumentou com o tempo (p=0,0001) em ambos os grupos. Diferentemente, ANOVA revelou redução do infiltrado inflamatório do 3o ao 21o dia em ambos os grupos (histologia: p=0,0003; morfometria: p=0,0000).(AU)

The aim of this study was to evaluate the effects of laser therapy in tendinopathy of Achilles tendon of Wistar rats. Thus, 12 adult male rats which were divided into two groups (L=laser and C=control) were used. All animals were submitted to unilateral tendinopathy (random selection) by transverse compression of the tendon (10 seconds) with Halsted forceps, as well as 10 scarifications (using a scalpel). After 24 hours of induction of lesion all animals of Group L received laser (904 nm/3 J/cm²/ 9 s) for 20 days, while Group C were handled as if they would receive radiation. After 3, 7, 14 and 21 days lesion induction, three rats from each group were euthanized, and the tendons obtained for histomorphometric analysis. The samples were processed as routine and the sections stained with hematoxylin-eosin, Masson's trichrome and Picrosirius Red. Data were analyzed by ANOVA, at 5% probability and regression analysis. No differences between groups neither between time for hemorrhage characteristics, angiogenesis, thickening of epitendon. Independently of the treatment there was a decrease (p=0.0129) of fibrinous adhesion (3rd to 21st day). On the other hand, morphometric analysis revealed higher (p=0.0120) amounts of fibroblasts cells in the group receiving laser therapy, with no effect of time. Semiquantitative assessment also showed higher (p=0.0000) amounts of fibroblasts cells in the treated group, but in this analysis, the number of fibroblasts increased with time (p=0.0001) in both group. In contrast, ANOVA revealed a reduction of the inflammatory cells from 3rd to 21st day in both groups (histology: p=0.0003; morphometry: p=0.0000).(AU)

La finalidad de ese estudio fue evaluar los efectos del láser en la lesión del tendón calcáneo común de ratas Wistar. Fueron utilizadas 12 ratas machos adultos, distribuidos al azar en dos grupos (L=láser y C=control). Todos fueron sometidos a tendinopatía unilateral (selección aleatoria) por la compresión transversal del tendón (10 segundos) con una pinza Halstead-Mosquito, y escarificación (con bisturí). Después de 24 horas de la inducción de la lesión los animales del grupo L recibieron láser (904 nm/3J/ cm²/9s) durante 20 días. Los tendones del grupo C fueran manejados como si recibera la radiación. Después de 3, 7, 14 y 21 días de realización de la lesión, tres ratas de cada grupo fueron sacrificadas, y los tendones obtenidos para análisis histomorfométrico. Las muestras fueron procesadas como de rutina y los fragmentos se tiñeron con hematoxilina-eosina, tricrómico de Masson y Picrosirius Red. Los datos fueron analizados por ANOVA, con una probabilidad de 5%, además de análisis de regresión. No hubo diferencias entre los grupos o tiempos para las variables hemorragia, angiogénesis, engrosamiento del epitendón. Independientemente del tratamiento se redujo (p=0,0129) la formación de adherencia fibrinosa (del 3o al 21o días). Por otra parte, la evaluación morfométrica mostró cantidades más altas (p=0,0120) de los fibroblastos en el grupo que recibió el tratamiento con láser, sin efecto del tiempo. Evaluación semicuantitativa reveló mayor (p=0,0000) cantidad de fibroblastos en el grupo tratado, pero en esa análisis la cantidad de esas células aumentó con el tiempo (p=0,0001) en ambos grupos. En contraste, ANOVA reveló reducción del infiltrado inflamatorio entre el 3o y el 21o días, en ambos grupos (histología: p=0,0003; morfometría: p=0,0000). Aunque no hubo diferencias entre grupos en la cantidad de fibras de colágeno (I y III), la morfometría reveló que las ratas del grupo L presentaram mayores cantidades (p=0,0096) de fibras de colágeno.(AU)

Laserterapia Para Tratamento De Tendinopatia Induzida Em Ratos Wistar: Estudo Histomorfométrico / Laser Therapy For Treatment Of Tendinopathy Induced In Wistar Rats: An Histomorfometric Study / Terapia Con Láser Para Tratamiento De Tendinopatia Inducida En Ratas Wistar: Estudio Histomorfométrico

O objetivo desse estudo foi avaliar os efeitos da laserterapia na lesão do tendão calcanear comum de ratos Wistar. Foram utilizados 12 ratos machos adultos, distribuídos aleatoriamente em dois grupos (L=laser e C=controle). Todos foram submetidos à tendinopatia unilateral (escolha aleatória) mediante compressão transversal do tendão (10 segundos) com pinça Halstead mosquito, assim como escarificações (com bisturi). Após 24 horas da indução da lesão os animais do grupo L receberam laser (904 nm/3 J/cm²/9s) por 20 dias. Os do grupo C foram manipulados como se fossem receber a radiação. Após 3, 7, 14 e 21 dias da realização da lesão, três ratos de cada grupo foram submetidos à eutanásia, e os tendões obtidos para análise histomorfométrica. As amostras foram processadas como de rotina e os fragmentos corados com hematoxilina-eosina, tricrômico de Masson e Picrosirius Red. Os dados foram analisados por ANOVA, a 5% de probabilidade e análise de regressão. Não houve diferença entre grupos nem entre tempos para as características hemorragia, angiogênese, espessamento do epitendão. Independente do tratamento ocorreu diminuição (p=0,0129) da formação de aderência fibrinosa (do 3o ao 21o dias). Por outro lado, a avaliação morfométrica revelou maiores (p=0,0120) quantidades de fibroblastos no grupo que recebeu laserterapia, não havendo efeito de tempo. Avaliação semiquantitativa, revelou maiores (p=0,0000) quantidades de fibroblastos no grupo tratado, porém nessa análise, a quantidade dessas células aumentou com o tempo (p=0,0001) em ambos os grupos. Diferentemente, ANOVA revelou redução do infiltrado inflamatório do 3o ao 21o dia em ambos os grupos (histologia: p=0,0003; morfometria: p=0,0000).

The aim of this study was to evaluate the effects of laser therapy in tendinopathy of Achilles tendon of Wistar rats. Thus, 12 adult male rats which were divided into two groups (L=laser and C=control) were used. All animals were submitted to unilateral tendinopathy (random selection) by transverse compression of the tendon (10 seconds) with Halsted forceps, as well as 10 scarifications (using a scalpel). After 24 hours of induction of lesion all animals of Group L received laser (904 nm/3 J/cm²/ 9 s) for 20 days, while Group C were handled as if they would receive radiation. After 3, 7, 14 and 21 days lesion induction, three rats from each group were euthanized, and the tendons obtained for histomorphometric analysis. The samples were processed as routine and the sections stained with hematoxylin-eosin, Masson's trichrome and Picrosirius Red. Data were analyzed by ANOVA, at 5% probability and regression analysis. No differences between groups neither between time for hemorrhage characteristics, angiogenesis, thickening of epitendon. Independently of the treatment there was a decrease (p=0.0129) of fibrinous adhesion (3rd to 21st day). On the other hand, morphometric analysis revealed higher (p=0.0120) amounts of fibroblasts cells in the group receiving laser therapy, with no effect of time. Semiquantitative assessment also showed higher (p=0.0000) amounts of fibroblasts cells in the treated group, but in this analysis, the number of fibroblasts increased with time (p=0.0001) in both group. In contrast, ANOVA revealed a reduction of the inflammatory cells from 3rd to 21st day in both groups (histology: p=0.0003; morphometry: p=0.0000).

La finalidad de ese estudio fue evaluar los efectos del láser en la lesión del tendón calcáneo común de ratas Wistar. Fueron utilizadas 12 ratas machos adultos, distribuidos al azar en dos grupos (L=láser y C=control). Todos fueron sometidos a tendinopatía unilateral (selección aleatoria) por la compresión transversal del tendón (10 segundos) con una pinza Halstead-Mosquito, y escarificación (con bisturí). Después de 24 horas de la inducción de la lesión los animales del grupo L recibieron láser (904 nm/3J/ cm²/9s) durante 20 días. Los tendones del grupo C fueran manejados como si recibera la radiación. Después de 3, 7, 14 y 21 días de realización de la lesión, tres ratas de cada grupo fueron sacrificadas, y los tendones obtenidos para análisis histomorfométrico. Las muestras fueron procesadas como de rutina y los fragmentos se tiñeron con hematoxilina-eosina, tricrómico de Masson y Picrosirius Red. Los datos fueron analizados por ANOVA, con una probabilidad de 5%, además de análisis de regresión. No hubo diferencias entre los grupos o tiempos para las variables hemorragia, angiogénesis, engrosamiento del epitendón. Independientemente del tratamiento se redujo (p=0,0129) la formación de adherencia fibrinosa (del 3o al 21o días). Por otra parte, la evaluación morfométrica mostró cantidades más altas (p=0,0120) de los fibroblastos en el grupo que recibió el tratamiento con láser, sin efecto del tiempo. Evaluación semicuantitativa reveló mayor (p=0,0000) cantidad de fibroblastos en el grupo tratado, pero en esa análisis la cantidad de esas células aumentó con el tiempo (p=0,0001) en ambos grupos. En contraste, ANOVA reveló reducción del infiltrado inflamatorio entre el 3o y el 21o días, en ambos grupos (histología: p=0,0003; morfometría: p=0,0000). Aunque no hubo diferencias entre grupos en la cantidad de fibras de colágeno (I y III), la morfometría reveló que las ratas del grupo L presentaram mayores cantidades (p=0,0096) de fibras de colágeno.

Effects of the essential oil of Alpinia zerumbet (Pers.) B.L. Burtt & R.M. Sm. on healing and tissue repair after partial Achilles tenotomy in rats

Purpose: To investigate the cellular response to injury, analyzing histopathologic changes associated with increased cellularity, degeneration and disorganization of collagen fibers. Methods: Thirty wistar rats were divided in two groups after partial Achilles tenotomy: the right hind paw were treated with the essential oil of Alpinia zerumbet (EOAz), diluted to 33% (0.3 mL kg-1), and the left hind paw received sunflower oil for 3, 14, 30 and 90 days. Statistical significance was determined using a Chi-square and Pearson Correlation qualitative variables test. Moreover, Mann-Whitney U-test test for comparison between different groups of the same cell, one-way ANOVA, and Tukeys test of quantitative measurement. Results: A decrease hyperemia (p 0.001) was observed in the acute phase of inflammatory cell number (p 0.001), whereas sub-acute phase was marked by significant correlation with macrophages in fibroblasts (r = 0.17, p = 0.03), with probable induction a dense and modeled tissue. At chronic phase, it was found an increase in the number of fibroblasts and a higher percentage of type I collagen fibers (78%) compared with control collagen fibers (55%). Conclusion: Oil of Alpinia zerumbet stimulated the process of maturation, organization and tissue repair which gave it greater resistance.(AU)

Tenorrhaphy of the common calcaneal tendon in dogs and cats

Background: Common calcaneal tendon (CCT) is usually affected by injuries in dogs and less frequently in cats. The Achilles mechanism consists of the convergence of three distinct structures: the tendons of the gastrocnemius muscle, superficial digital flexor muscle and the common tendons of the biceps femoris, gracilis, and semitendinosus muscles. Classification of lesions is based upon their location, severity and chronicity. Clinical signs include lameness, plantigrade stance and various degrees of tarsal hyperflexion according to the injurys severity. The purpose of this study is to report four cases of reconstruction of the common calcaneus in three dogs and a cat. Cases: Case 1. A 10-year-old male canine, Brazilian Terrier, 7.7 kg of body weight, with a 6-month history of nonweightbearing lameness of the right hind limb attended consultation. Orthopedic examination showed plantigrade stance, hyperflexion of the right tibial-tarsal joint (TTJ) and swelling with fibrous thickening of the distal portion of the CCT. Surgical tendon repair was achieved through insertion of a locking screw on the calcaneo-tibial, tenorrhaphy and suture of a titanium plate on the caudal aspect of the CCT. Case 2. A 2-year-old female mongrel canine, with 13.3 kg of body weight was presented with the complaint of chronic left hind leg lameness. The owner described trauma at the area of the hock [...]

Tenorrhaphy of the common calcaneal tendon in dogs and cats

Background: Common calcaneal tendon (CCT) is usually affected by injuries in dogs and less frequently in cats. The Achilles mechanism consists of the convergence of three distinct structures: the tendons of the gastrocnemius muscle, superficial digital flexor muscle and the common tendons of the biceps femoris, gracilis, and semitendinosus muscles. Classification of lesions is based upon their location, severity and chronicity. Clinical signs include lameness, plantigrade stance and various degrees of tarsal hyperflexion according to the injurys severity. The purpose of this study is to report four cases of reconstruction of the common calcaneus in three dogs and a cat. Cases: Case 1. A 10-year-old male canine, Brazilian Terrier, 7.7 kg of body weight, with a 6-month history of nonweightbearing lameness of the right hind limb attended consultation. Orthopedic examination showed plantigrade stance, hyperflexion of the right tibial-tarsal joint (TTJ) and swelling with fibrous thickening of the distal portion of the CCT. Surgical tendon repair was achieved through insertion of a locking screw on the calcaneo-tibial, tenorrhaphy and suture of a titanium plate on the caudal aspect of the CCT. Case 2. A 2-year-old female mongrel canine, with 13.3 kg of body weight was presented with the complaint of chronic left hind leg lameness. The owner described trauma at the area of the hock [...](AU)

Common calcaneal tendon repair with glycerin-preserved carotid artery xenografts and autologous bone marrow mononuclear cells in rabbits / Reparo de tendão calcanear comum de coelhos com xenoimplante de artéria carótida preservada em glicerina associado a células mononucleares da medula óssea autólogas

Fifteen adult rabbits were used to evaluate the repair of experimental common calcaneal tendon defects treated with glycerin-preserved canine carotid artery xenografts alone or associated with autologous mononuclear bone marrow cells (AMCs). Rabbits were submitted to daily clinical examination; implanted sites were analyzed under light microscopy within 15, 30 and 60 days of surgery. Pelvic limbs receiving xenografts associated with AMCs had better physical performance as well as higher collagen fiber, fibroblast, lymphocyte and new vessel counts at all postoperative time points considered. Glycerin-preserved canine carotid artery xenografts associated with AMCs constituted an effective method for common calcaneal tendon repair in rabbits.(AU)

Utilizou-se 15 coelhos adultos para avaliar o reparo de lesão do tendão calcanear comum com implante de artéria carótida de cães, preservada em glicerina, associado ou não a células mononucleares autólogas da medula óssea (CMAs). Os animais foram observados diariamente por meio de avaliações clínicas e o local do implante foi analisado sob microscopia de luz decorridos 15, 30 e 60 dias de pós-operatório. Notou-se em todos os períodos de observação, com o implante associado às CMAs, melhor desempenho físico dos membros pélvico e maior intensidade de fibras colágenas, fibroblastos e linfócitos e neovascularização. A utilização de xenoimplante de artéria carótida de cães preservada em glicerina associado à administração de células mononucleares da medula óssea foi eficiente no reparo do tendão calcanear comum de coelhos.(AU)

Common calcaneal tendon repair with glycerin-preserved carotid artery xenografts and autologous bone marrow mononuclear cells in rabbits / Reparo de tendão calcanear comum de coelhos com xenoimplante de artéria carótida preservada em glicerina associado a células mononucleares da medula óssea autólogas

Fifteen adult rabbits were used to evaluate the repair of experimental common calcaneal tendon defects treated with glycerin-preserved canine carotid artery xenografts alone or associated with autologous mononuclear bone marrow cells (AMCs). Rabbits were submitted to daily clinical examination; implanted sites were analyzed under light microscopy within 15, 30 and 60 days of surgery. Pelvic limbs receiving xenografts associated with AMCs had better physical performance as well as higher collagen fiber, fibroblast, lymphocyte and new vessel counts at all postoperative time points considered. Glycerin-preserved canine carotid artery xenografts associated with AMCs constituted an effective method for common calcaneal tendon repair in rabbits.(AU)

Utilizou-se 15 coelhos adultos para avaliar o reparo de lesão do tendão calcanear comum com implante de artéria carótida de cães, preservada em glicerina, associado ou não a células mononucleares autólogas da medula óssea (CMAs). Os animais foram observados diariamente por meio de avaliações clínicas e o local do implante foi analisado sob microscopia de luz decorridos 15, 30 e 60 dias de pós-operatório. Notou-se em todos os períodos de observação, com o implante associado às CMAs, melhor desempenho físico dos membros pélvico e maior intensidade de fibras colágenas, fibroblastos e linfócitos e neovascularização. A utilização de xenoimplante de artéria carótida de cães preservada em glicerina associado à administração de células mononucleares da medula óssea foi eficiente no reparo do tendão calcanear comum de coelhos.(AU)

Common calcaneal tendon repair with glycerin-preserved carotid artery xenografts and autologous bone marrow mononuclear cells in rabbits / Reparo de tendão calcanear comum de coelhos com xenoimplante de artéria carótida preservada em glicerina associado a células mononucleares da medula óssea autólogas

Fifteen adult rabbits were used to evaluate the repair of experimental common calcaneal tendon defects treated with glycerin-preserved canine carotid artery xenografts alone or associated with autologous mononuclear bone marrow cells (AMCs). Rabbits were submitted to daily clinical examination; implanted sites were analyzed under light microscopy within 15, 30 and 60 days of surgery. Pelvic limbs receiving xenografts associated with AMCs had better physical performance as well as higher collagen fiber, fibroblast, lymphocyte and new vessel counts at all postoperative time points considered. Glycerin-preserved canine carotid artery xenografts associated with AMCs constituted an effective method for common calcaneal tendon repair in rabbits.

Utilizou-se 15 coelhos adultos para avaliar o reparo de lesão do tendão calcanear comum com implante de artéria carótida de cães, preservada em glicerina, associado ou não a células mononucleares autólogas da medula óssea (CMAs). Os animais foram observados diariamente por meio de avaliações clínicas e o local do implante foi analisado sob microscopia de luz decorridos 15, 30 e 60 dias de pós-operatório. Notou-se em todos os períodos de observação, com o implante associado às CMAs, melhor desempenho físico dos membros pélvico e maior intensidade de fibras colágenas, fibroblastos e linfócitos e neovascularização. A utilização de xenoimplante de artéria carótida de cães preservada em glicerina associado à administração de células mononucleares da medula óssea foi eficiente no reparo do tendão calcanear comum de coelhos.

Histomorphometric analysis of the Achilles tendon of Wistar rats treated with laser therapy and eccentric exercise / Análise histomorfométrica do tendão calcanear comum de ratos Wistar tratado com laserterapia e exercício excêntrico

Low-level laser therapy is recommended for the treatment of tendinopathies despite the contradictory results related to the ideal dose of energy, wavelength and time of application. This study aimed to assess the effects of laser therapy and eccentric exercise on tendinopathy of the Achilles tendon of Wistar rats. Forty-eight adult male rats were randomly distributed into four groups (L= laser; E= eccentric exercise; LE = laser and eccentric exercise; and R= rest). Laser therapy (904nm/3J/cm2) and/or eccentric exercise (downhill walking; 15o incline treadmill; 12m/min; 50min/day) was started 24h after induction of unilateral tendinopathy and remained for 20 days. At 3, 7, 14 and 21 days after lesion induction, three rats from each group were euthanized and the tendons were collected for histological and morphometric analyses. There was no difference among groups or among times for the characteristics hemorrhage (p=0.4154), fibrinous adhesion formation (p=0.0712), and organization of collagen fibers (p=0.2583) and of the connective tissue (p=0.1046). For these groups, regardless of the time, eccentric exercise led to epitenon thickening (p=0.0204), which was lower in the group treated with laser therapy. Histological analysis revealed differences (p=0.0032) in the number of inflammatory cells over time. They were more numerous in the group that only exercised. This result was confirmed by morphometric analysis, which showed a significant interaction (groups x time) for this characteristic. Eccentric exercise increased (p=0.0014) the inflammatory infiltrate over time (3 and 21 days). However, association with laser therapy reduced inflammatory reaction. On the other hand, the combination of the treatments increased angiogenesis in morphometric (p=0.0000) and histological (p=0.0006) analyses compared with the other groups, while the isolated application of low-level laser reduced this characteristic over time. Animals maintained at rest presented the lowest amount (p=0.0000) of fibroblasts, according to the morphometric analysis. However, histological evaluation showed a significant group x time interaction (p=0.0024). Greater amounts of fibroblasts were observed in groups E, L and LE on the 7th, 14th and 21st days, respectively. The animals that received laser therapy and were exercised showed a greater (p=0.0000) amount of collagen fibers over time. Laser therapy at a dose of 3J and at a wavelength of 904nm, starting 24h after surgical induction of tendinopathy in Wistar rats, is suitable for angiogenesis and prevention of tendon thickening, which can be associated with the intensity of inflammatory process. When associated with eccentric exercise, the therapy has the advantage of increasing the amount of collagen fibers, reducing fibrinous adhesions and inflammatory infiltrate, despite prolonging angiogenesis. Therefore, eccentric exercise performed concomitantly with laser therapy improves the histological properties of the injured tendon.(AU)

O laser de baixa potência é recomendado para o tratamento das tendinopatias apesar dos resultados contraditórios no que se refere a dose de energia ideal, comprimento de onda e tempo de aplicação. O objetivo desse estudo foi avaliar os efeitos da laserterapia e do exercício excêntrico na tendinopatia do tendão calcanear comum de ratos Wistar. Foram utilizados 48 ratos machos adultos. Os animais foram distribuídos aleatoriamente em quatro grupos (L=laser; E=exercício excêntrico; LE=laser e exercício excêntrico, e R=repouso). Após 24h da indução de tendinopatia unilateral, foi iniciada laserterapia (904nm/3J/cm2) e/ou exercício excêntrico (caminhada em declive; esteira com 15o de inclinação; 12m/min; 50min/dia) que permaneceu por 20 dias. Aos 3, 7, 14 e 21 dias após indução da lesão, três ratos de cada grupo foram submetidos à eutanásia, e os tendões foram obtidos para análises histológica e morfométrica. Não houve diferença entre grupos nem entre tempos nas características hemorragia (p=0,4154), formação de aderência fibrinosa (p=0,0712) e organização das fibras colágenas (p=0,2583) e do tecido conjuntivo (p=0,1046). Considerando os grupos, independentemente do tempo, foi observado que o exercício excêntrico ocasionou espessamento do epitendão (p=0,0204), que foi menor no grupo submetido à laserterapia. A análise histológica revelou diferença (p=0,0032) na quantidade de células inflamatórias ao longo do tempo, sendo observado em maior quantidade no grupo apenas exercitado. Esse resultado foi confirmado pela análise morfométrica, que demonstrou haver interação significativa (grupos x tempo) nessa característica, na qual o exercício excêntrico aumentou (p=0,0014) o infiltrado inflamatório ao longo do tempo (3 e 21 dias), porém, quando associado à laserterapia, ocorreu redução da reação inflamatória. Por outro lado, a associação dos tratamentos ocasionou maior angiogênese observada nas análises morfométrica (p=0,0000) e histológica (p=0,0006), quando comparada com os demais grupos, enquanto a aplicação isolada do laser de baixa potência reduziu essa característica ao longo do tempo. Os animais mantidos em repouso foram os que apresentaram menor (p=0,0000) quantidade de fibroblastos, na análise morfométrica, porém na avaliação histológica foi observada interação significativa entre grupo e tempo (p=0,0024). Maior quantidade de fibroblastos foi observada nos grupos E, L e LE, no 7o, 14o e 21o dias, respectivamente. Os animais que receberam laserterapia e foram exercitados apresentaram maior (p=0,0000) quantidade de fibras colágenas ao longo do tempo. A laserterapia na dose de 3J e comprimento de onda de 904nm, iniciada 24h após indução cirúrgica de tendinopatia em ratos Wistar é adequada para angiogênese e para evitar o espessamento do tendão, que pode estar relacionado com a intensidade do processo inflamatório. Quando associada ao exercício excêntrico, a terapia apresenta a vantagem de aumentar a quantidade de fibras colágenas, reduzir a aderência fibrinosa e infiltrado inflamatório, apesar de prolongar a angiogênese. Portanto, o exercício excêntrico realizado concomitantemente com a laserterapia melhora as propriedades histológicas do tendão lesionado.(AU)

Histomorphometric analysis of the Achilles tendon of Wistar rats treated with laser therapy and eccentric exercise

Abstract: Low-level laser therapy is recommended for the treatment of tendinopathies despite the contradictory results related to the ideal dose of energy, wavelength and time of application. This study aimed to assess the effects of laser therapy and eccentric exercise on tendinopathy of the Achilles tendon of Wistar rats. Forty-eight adult male rats were randomly distributed into four groups (L= laser; E= eccentric exercise; LE = laser and eccentric exercise; and R= rest). Laser therapy (904nm/3J/cm2) and/or eccentric exercise (downhill walking; 15o incline treadmill; 12m/min; 50min/day) was started 24h after induction of unilateral tendinopathy and remained for 20 days. At 3, 7, 14 and 21 days after lesion induction, three rats from each group were euthanized and the tendons were collected for histological and morphometric analyses. There was no difference among groups or among times for the characteristics hemorrhage (p=0.4154), fibrinous adhesion formation (p=0.0712), and organization of collagen fibers (p=0.2583) and of the connective tissue (p=0.1046). For these groups, regardless of the time, eccentric exercise led to epitenon thickening (p=0.0204), which was lower in the group treated with laser therapy. Histological analysis revealed differences (p=0.0032) in the number of inflammatory cells over time. They were more numerous in the group that only exercised. This result was confirmed by morphometric analysis, which showed a significant interaction (groups x time) for this characteristic. Eccentric exercise increased (p=0.0014) the inflammatory infiltrate over time (3 and 21 days). However, association with laser therapy reduced inflammatory reaction. On the other hand, the combination of the treatments increased angiogenesis in morphometric (p=0.0000) and histological (p=0.0006) analyses compared with the other groups, while the isolated application of low-level laser reduced this characteristic over time. Animals maintained at rest presented the lowest amount (p=0.0000) of fibroblasts, according to the morphometric analysis. However, histological evaluation showed a significant group x time interaction (p=0.0024). Greater amounts of fibroblasts were observed in groups E, L and LE on the 7th, 14th and 21st days, respectively. The animals that received laser therapy and were exercised showed a greater (p=0.0000) amount of collagen fibers over time. Laser therapy at a dose of 3J and at a wavelength of 904nm, starting 24h after surgical induction of tendinopathy in Wistar rats, is suitable for angiogenesis and prevention of tendon thickening, which can be associated with the intensity of inflammatory process. When associated with eccentric exercise, the therapy has the advantage of increasing the amount of collagen fibers, reducing fibrinous adhesions and inflammatory infiltrate, despite prolonging angiogenesis. Therefore, eccentric exercise performed concomitantly with laser therapy improves the histological properties of the injured tendon.

Resumo: O laser de baixa potência é recomendado para o tratamento das tendinopatias apesar dos resultados contraditórios no que se refere a dose de energia ideal, comprimento de onda e tempo de aplicação. O objetivo desse estudo foi avaliar os efeitos da laserterapia e do exercício excêntrico na tendinopatia do tendão calcanear comum de ratos Wistar. Foram utilizados 48 ratos machos adultos. Os animais foram distribuídos aleatoriamente em quatro grupos (L=laser; E=exercício excêntrico; LE=laser e exercício excêntrico, e R=repouso). Após 24h da indução de tendinopatia unilateral, foi iniciada laserterapia (904nm/3J/cm2) e/ou exercício excêntrico (caminhada em declive; esteira com 15o de inclinação; 12m/min; 50min/dia) que permaneceu por 20 dias. Aos 3, 7, 14 e 21 dias após indução da lesão, três ratos de cada grupo foram submetidos à eutanásia, e os tendões foram obtidos para análises histológica e morfométrica. Não houve diferença entre grupos nem entre tempos nas características hemorragia (p=0,4154), formação de aderência fibrinosa (p=0,0712) e organização das fibras colágenas (p=0,2583) e do tecido conjuntivo (p=0,1046). Considerando os grupos, independentemente do tempo, foi observado que o exercício excêntrico ocasionou espessamento do epitendão (p=0,0204), que foi menor no grupo submetido à laserterapia. A análise histológica revelou diferença (p=0,0032) na quantidade de células inflamatórias ao longo do tempo, sendo observado em maior quantidade no grupo apenas exercitado. Esse resultado foi confirmado pela análise morfométrica, que demonstrou haver interação significativa (grupos x tempo) nessa característica, na qual o exercício excêntrico aumentou (p=0,0014) o infiltrado inflamatório ao longo do tempo (3 e 21 dias), porém, quando associado à laserterapia, ocorreu redução da reação inflamatória. Por outro lado, a associação dos tratamentos ocasionou maior angiogênese observada nas análises morfométrica (p=0,0000) e histológica (p=0,0006), quando comparada com os demais grupos, enquanto a aplicação isolada do laser de baixa potência reduziu essa característica ao longo do tempo. Os animais mantidos em repouso foram os que apresentaram menor (p=0,0000) quantidade de fibroblastos, na análise morfométrica, porém na avaliação histológica foi observada interação significativa entre grupo e tempo (p=0,0024). Maior quantidade de fibroblastos foi observada nos grupos E, L e LE, no 7o, 14o e 21o dias, respectivamente. Os animais que receberam laserterapia e foram exercitados apresentaram maior (p=0,0000) quantidade de fibras colágenas ao longo do tempo. A laserterapia na dose de 3J e comprimento de onda de 904nm, iniciada 24h após indução cirúrgica de tendinopatia em ratos Wistar é adequada para angiogênese e para evitar o espessamento do tendão, que pode estar relacionado com a intensidade do processo inflamatório. Quando associada ao exercício excêntrico, a terapia apresenta a vantagem de aumentar a quantidade de fibras colágenas, reduzir a aderência fibrinosa e infiltrado inflamatório, apesar de prolongar a angiogênese. Portanto, o exercício excêntrico realizado concomitantemente com a laserterapia melhora as propriedades histológicas do tendão lesionado.

Histomorphometric analysis of the Achilles tendon of Wistar rats treated with laser therapy and eccentric exercise

Abstract: Low-level laser therapy is recommended for the treatment of tendinopathies despite the contradictory results related to the ideal dose of energy, wavelength and time of application. This study aimed to assess the effects of laser therapy and eccentric exercise on tendinopathy of the Achilles tendon of Wistar rats. Forty-eight adult male rats were randomly distributed into four groups (L= laser; E= eccentric exercise; LE = laser and eccentric exercise; and R= rest). Laser therapy (904nm/3J/cm2) and/or eccentric exercise (downhill walking; 15o incline treadmill; 12m/min; 50min/day) was started 24h after induction of unilateral tendinopathy and remained for 20 days. At 3, 7, 14 and 21 days after lesion induction, three rats from each group were euthanized and the tendons were collected for histological and morphometric analyses. There was no difference among groups or among times for the characteristics hemorrhage (p=0.4154), fibrinous adhesion formation (p=0.0712), and organization of collagen fibers (p=0.2583) and of the connective tissue (p=0.1046). For these groups, regardless of the time, eccentric exercise led to epitenon thickening (p=0.0204), which was lower in the group treated with laser therapy. Histological analysis revealed differences (p=0.0032) in the number of inflammatory cells over time. They were more numerous in the group that only exercised. This result was confirmed by morphometric analysis, which showed a significant interaction (groups x time) for this characteristic. Eccentric exercise increased (p=0.0014) the inflammatory infiltrate over time (3 and 21 days). However, association with laser therapy reduced inflammatory reaction. On the other hand, the combination of the treatments increased angiogenesis in morphometric (p=0.0000) and histological (p=0.0006) analyses compared with the other groups, while the isolated application of low-level laser reduced this characteristic over time. Animals maintained at rest presented the lowest amount (p=0.0000) of fibroblasts, according to the morphometric analysis. However, histological evaluation showed a significant group x time interaction (p=0.0024). Greater amounts of fibroblasts were observed in groups E, L and LE on the 7th, 14th and 21st days, respectively. The animals that received laser therapy and were exercised showed a greater (p=0.0000) amount of collagen fibers over time. Laser therapy at a dose of 3J and at a wavelength of 904nm, starting 24h after surgical induction of tendinopathy in Wistar rats, is suitable for angiogenesis and prevention of tendon thickening, which can be associated with the intensity of inflammatory process. When associated with eccentric exercise, the therapy has the advantage of increasing the amount of collagen fibers, reducing fibrinous adhesions and inflammatory infiltrate, despite prolonging angiogenesis. Therefore, eccentric exercise performed concomitantly with laser therapy improves the histological properties of the injured tendon.

Resumo: O laser de baixa potência é recomendado para o tratamento das tendinopatias apesar dos resultados contraditórios no que se refere a dose de energia ideal, comprimento de onda e tempo de aplicação. O objetivo desse estudo foi avaliar os efeitos da laserterapia e do exercício excêntrico na tendinopatia do tendão calcanear comum de ratos Wistar. Foram utilizados 48 ratos machos adultos. Os animais foram distribuídos aleatoriamente em quatro grupos (L=laser; E=exercício excêntrico; LE=laser e exercício excêntrico, e R=repouso). Após 24h da indução de tendinopatia unilateral, foi iniciada laserterapia (904nm/3J/cm2) e/ou exercício excêntrico (caminhada em declive; esteira com 15o de inclinação; 12m/min; 50min/dia) que permaneceu por 20 dias. Aos 3, 7, 14 e 21 dias após indução da lesão, três ratos de cada grupo foram submetidos à eutanásia, e os tendões foram obtidos para análises histológica e morfométrica. Não houve diferença entre grupos nem entre tempos nas características hemorragia (p=0,4154), formação de aderência fibrinosa (p=0,0712) e organização das fibras colágenas (p=0,2583) e do tecido conjuntivo (p=0,1046). Considerando os grupos, independentemente do tempo, foi observado que o exercício excêntrico ocasionou espessamento do epitendão (p=0,0204), que foi menor no grupo submetido à laserterapia. A análise histológica revelou diferença (p=0,0032) na quantidade de células inflamatórias ao longo do tempo, sendo observado em maior quantidade no grupo apenas exercitado. Esse resultado foi confirmado pela análise morfométrica, que demonstrou haver interação significativa (grupos x tempo) nessa característica, na qual o exercício excêntrico aumentou (p=0,0014) o infiltrado inflamatório ao longo do tempo (3 e 21 dias), porém, quando associado à laserterapia, ocorreu redução da reação inflamatória. Por outro lado, a associação dos tratamentos ocasionou maior angiogênese observada nas análises morfométrica (p=0,0000) e histológica (p=0,0006), quando comparada com os demais grupos, enquanto a aplicação isolada do laser de baixa potência reduziu essa característica ao longo do tempo. Os animais mantidos em repouso foram os que apresentaram menor (p=0,0000) quantidade de fibroblastos, na análise morfométrica, porém na avaliação histológica foi observada interação significativa entre grupo e tempo (p=0,0024). Maior quantidade de fibroblastos foi observada nos grupos E, L e LE, no 7o, 14o e 21o dias, respectivamente. Os animais que receberam laserterapia e foram exercitados apresentaram maior (p=0,0000) quantidade de fibras colágenas ao longo do tempo. A laserterapia na dose de 3J e comprimento de onda de 904nm, iniciada 24h após indução cirúrgica de tendinopatia em ratos Wistar é adequada para angiogênese e para evitar o espessamento do tendão, que pode estar relacionado com a intensidade do processo inflamatório. Quando associada ao exercício excêntrico, a terapia apresenta a vantagem de aumentar a quantidade de fibras colágenas, reduzir a aderência fibrinosa e infiltrado inflamatório, apesar de prolongar a angiogênese. Portanto, o exercício excêntrico realizado concomitantemente com a laserterapia melhora as propriedades histológicas do tendão lesionado.

Experimental model of Achilles tendon injury in rats

PURPOSE: To describe an effective experimental model to study the Achilles tendon healing. METHODS: Forty male Rattus norvegicus albinus, Wistar lineage adult male weighing 250 to 300g were used for this experiment and thirty were surgically submitted to bilateral partial transverse section of the Achilles tendon. The right tendon was treated with radio waves (RF) whereas the left tendon served as control. On the third postoperative day, the rats were divided into four experimental groups consisting of ten rats each which were treated with monopolar RF adjusted to 650 kHz and 2w, for two minutes twice a week and a group of normal animals without any intervention, until they were sacrificed on the 7th, 14th and 28th days, respectively. Tendons were weighed and collagen quantification was evaluated by hydroxyprolin content. RESULTS: Significant reduction in collagen content on day 7, 14 and 28 was related to control experiment to normal tendon (7 days, p<0.01; 14 e 28 days, p<0.05). CONCLUSION: The experimental model has been effective and available to be used to study Achilles tendon healing.(AU)