Histological study of fresh versus frozen semitendinous muscle tendon allografts

OBJECTIVE: The purpose of this study was to histologically analyze allografts from cadaveric semitendinous muscle after cryopreservation at -80°C in comparison to a control group kept at only -4°C to test the hypothesis that the histological characteristics of the tissue are maintained when the tendons are kept at lower temperatures. METHODS: In a tissue bank, 10 semitendinous tendons from 10 cadavers were frozen at -80ºC as a storage method for tissue preservation. They were kept frozen for 40 days, and then a histological study was carried out. Another 10 tendon samples were analyzed while still "fresh". RESULTS: There was no histological difference between the fresh and frozen samples in relation to seven variables. CONCLUSIONS: Semitendinous muscle tendon allografts can be submitted to cryopreservation at -80ºC without suffering histological modifications.

Physicochemical and structural analysis of three regions of the deep digital flexor tendon of pigs

Few studies have discussed the relationship between the molecular organization and the physicochemical and biomechanical properties of pig tendons. In this work, we examined the extracellular matrix of the deep digital flexor tendon of pigs, which was subjected to tensional (proximal region) and compressive (distal and terminal regions) forces. The three regions of the tendon were used for swelling tests and their glycosaminoglycan content was determined. Longitudinal sections of the tendon were stained and observed using polarized light microscopy. The distal and terminal regions were swole more in water than the proximal region. After staining with toluidine blue the metachromasy was more intense in the distal and terminal regions, indicating an accumulation of proteoglycans in these regions. Analysis of the glycosaminoglycans by agarose gel electrophoresis showed that dermatan sulfate was present in all regions, whereas chondroitin sulfate occurred only in the regions of compression. The shape of the fibroblasts changed along the tendon: rounded cells occurred in regions under compression, while in the region under tension, elongated cells predominated. The organization and distribution of the collagen bundles were different for each region. Birefringence analysis revealed a more regular crimp pattern in the region under tension than in the regions under compressive forces. The elastic fibers also showed a different distribution in each region. These results indicate that the regional differences in the structure and composition of the deep digital flexor tendon of pigs are related to the biomechanical properties of the tendon.

Ideal concentration of growth factors in rabbit's flexor tendon culture

Growth factors have the ability to stimulate matrix synthesis and cell proliferation in rabbit flexor tendon. Maximal stimulation effects of growth factors have a wide variation. It depends upon the different anatomic sites of the tendon segment, the kinds of growth factor, the concentration of growth factors, and the time sequence. Since proliferation was an early component of intrinsic tendon healing, we investigated the short-term dose response to four different growth factors on in vitro rabbit's tendon culture. We evaluated the effects according to the various concentrations of recombinant human insulin-like growth factor 1 (IGF), recombinant human epidermal growth factor (EGF), fibroblast growth factor (FGF), and recombinant human platelet-derived growth factor-BB (PDGF). Fetal calf serum was the most potent stimulator of cell proliferation and protein synthesis in in vitro rabbit's tendon culture. Matrix synthesis and cell proliferation were stimulated dose-dependently by IGF between the doses of 50 and 150 ng/ml. The maximum mitogenic effect of EGF was observed at the concentration of 100 ng/ml (1.3 times more than the media-only control culture). The rabbit's tendon responded significantly dose-dependently to PDGF, whereas there was no significant response to FGF.

Estudo ultra-sonográfico e morfológico do tendäo patelar doador na reconstruçäo intra-articular do ligamento cruzado anterior / Ultrasonographic and morphologic study of the patellar tendon donor in the intra-articular reconstruction of the anterior cruciate ligament

Em 63 pacientes submetidos a reconstruçao intra-articular do ligamento cruzado anterior com enxerto autógeno do tendao patelar, os autores analisam as dimensoes do tendao patelar do joelho operado e do contralateral nao operado por meio de exame ultra-sonográfico. Cinqüenta e um pacientes sao do sexo masculino e doze, do feminino. As idades variaram de 23 a 47 anos, com média de 30,5 anos. O período do pós-operatório em que os exames foram realizados variou de um a 50 meses, com média de 18,8 meses. Oito pacientes foram submetidos a estudo histológico do tendao patelar remanescente através de biópsia da área doadora de enxerto. O momento do pós-operatório em que as biópsias foram realizadas variou de 33 a 56 meses, com média de 40,8 meses. Observou-se, pela ultra-sonografia, que a largura do tendao patelar doador se equivale à do joelho contralateral a partir do 19§ mês do pós-operatório. A espessura dotendao patelar doador na fase precoce do pós-operatório é de 235 por cento da espessura do tendao patelar contralateral; decresce progressivamente mas mantém-se maior que o lado nao operado em todos os períodos pós-operatório estudados no trabalho. As observaçoes morfológicas demonstraram que o tecido cicatricialformado, embora se assemelhe muito ao normal, nao alcança o mesmo grau de organizaçao original tanto à microscopia de luz quanto à microscopia eletrônica. Observou-se que a reestruturaçao completa dos fascículos nunca foi alcançada nos tendoes patelares operados e que sua composiçao tissular encontrava-se alterada.

Estudo morfológico e biomecânico dos tendöes do músculo supra-espinhoso e porçäo longa do píceps braquial / Morphplogical biomechanical study the tendons of the supraspinatus and biceps brachii

Tendöes do músculo supre-espinhoso e biceps braquial de 57 adultos submetidos a autópsia foram estudados para avaliar-se a freqüência de rotura tendinosa, comprimento do tendäo e resistência à traçäo. No grupo com idade entre 20 e 50 anos, nenuma rotura tendinosa foi observada, contrastando com a pecentagem de 66,7 por cento, observada na faixa etária entre 71 e 80 anos. O comprimento dos tendöes apresentou aumento com o avanço da idade e a resistência à traçäo nos grupos com idade entre 61 e 80 anos era 40 por cento menor do que nos grupos com idade entre 20 e 40 anos. A resistência à traçäo do tendäo do músculo bíceps braquial estava nos grupos etários mais avançados 28 por cento reduzida, em relaçäo aos mais jovens