Comparação de dois parafusos de interferência bioabsorvíveis: estudo in vivo em ovinos
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Data
2019-12-06
Autores
Scorsato, Paulo Sérgio
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Universidade Estadual Paulista (Unesp)
Resumo
O trabalho teve por objetivo comparar, por meio de exames de imagem e avaliações histológicas, dois parafusos de interferência bioabsorvíveis implantados em ovinos. Foram utilizados 22 ovinos, misto de Santa Inês, adultos, fêmeas, com massa corpórea média de 42,3 kg. Em todos os animais, o membro pélvico direito recebeu o parafuso de PDLLA (70% de L-lactídeo e 30% de DL-lactídeo) e o membro pélvico esquerdo recebeu parafuso de PDLLA 70/30 + β-TCP (30% de beta fostato tricálcico), os quais foram aplicados na região metafisária distal do fêmur por acesso lateral. Os animais foram submetidos à eutanásia, de acordo com o tempo de observação e permanência dos implantes, como segue: 1 mês (n=6), 4 meses (n=5), 7 meses e meio (n=6), 18 meses (n=5). Pelo exame radiográfico, o local de inserção do parafuso PDLLA mostrava-se inicialmente como área radiolucente circular, que progressivamente apresentou-se menos definido e com presença de radiopacidade central. Pela tomografia computadorizada (TC) havia área de hipodensidade no período inicial, que com o passar do tempo apresentou aumento da densidade no eixo central. No último tempo de avaliação, a microTC mostrou acentuado aumento da densidade do parafuso, principalmente nas regiões corticais. Na avaliação histologia o parafuso estava degradado, com áreas de formação óssea discretas e outras mais evidentes. O parafuso de PDLLA/β-TCP foi facilmente identificado nas avaliações iniciais pelos exames de imagem, sendo tanto radiopaco como hiperdenso, havendo perda progressiva da definição pelo exame radiográfico e alteração da densidade pela TC. Na última avaliação este permaneceu hipodenso e envolto por discreto tecido ósseo na microTC, sendo que histologicamente foi evidente o preenchimento da cavidade central por tecido característico da região (osso e medula óssea). Foi possível concluir que o parafuso de PDLLA/β-TCP mostrou sinais de processo de degradação, com substituição discreta por tecido ósseo; ao passo que o parafuso de PDDLA apresentou menor degradação, porém com produção óssea ao redor, pelas perfurações laterais e dentro do seu canal central.
This study aimed to compare two bioabsorbable interference screws implanted in sheep. Twenty-two Santa Inês mixed sheep, adults, females, mean body mass of 42.3 kg were used. In all sheep, the right hind limb received PDLLA screw (70% L-lactide and 30% D,L-lactide) and the left hind limb received PDLLA70/30 + β-TCP (30% beta-tricalcium phosphate) screw, which were applied in the distal metaphyseal region of the femur by lateral access. The animals were submitted to euthanasia, according to observation time and permanence of the implants, as follows: 1 month (n = 6), 4 months (n = 5), 7.½ months (n = 6), 18 months (n = 5). On radiographs, the PDLLA screw insertion site was initially visibilized as a circular radiolucent area, which progressively was less defined and had central radiopacity. Computed tomography (CT) showed an area of hypodensity in the early period, and over time showed increased density in the central axis. At the last evaluation time, the microCT showed a marked increase in screw density, especially in the cortical regions. In the histology, the screw was degraded, with discrete bone formation areas and others more evident. The PDLLA/β-TCP screw was easily identified in the initial evaluations by imaging exams, being radiopaque and hyperdense, with progressive loss of definition by radiographic examination and density change on CT. In the last evaluation, the screw remained hypodense and surrounded by discrete bone tissue on microCT. Histologically, its central cavity was filled by tissue characteristic of the region (bone and bone marrow). In conclusion, the PDLLA/β-TCP screw showed signs of degradation process, with discrete bone tissue replacement; whereas the PDDLA screw presented less degradation, but with bone production around, through the lateral perforations and within its central canal.
This study aimed to compare two bioabsorbable interference screws implanted in sheep. Twenty-two Santa Inês mixed sheep, adults, females, mean body mass of 42.3 kg were used. In all sheep, the right hind limb received PDLLA screw (70% L-lactide and 30% D,L-lactide) and the left hind limb received PDLLA70/30 + β-TCP (30% beta-tricalcium phosphate) screw, which were applied in the distal metaphyseal region of the femur by lateral access. The animals were submitted to euthanasia, according to observation time and permanence of the implants, as follows: 1 month (n = 6), 4 months (n = 5), 7.½ months (n = 6), 18 months (n = 5). On radiographs, the PDLLA screw insertion site was initially visibilized as a circular radiolucent area, which progressively was less defined and had central radiopacity. Computed tomography (CT) showed an area of hypodensity in the early period, and over time showed increased density in the central axis. At the last evaluation time, the microCT showed a marked increase in screw density, especially in the cortical regions. In the histology, the screw was degraded, with discrete bone formation areas and others more evident. The PDLLA/β-TCP screw was easily identified in the initial evaluations by imaging exams, being radiopaque and hyperdense, with progressive loss of definition by radiographic examination and density change on CT. In the last evaluation, the screw remained hypodense and surrounded by discrete bone tissue on microCT. Histologically, its central cavity was filled by tissue characteristic of the region (bone and bone marrow). In conclusion, the PDLLA/β-TCP screw showed signs of degradation process, with discrete bone tissue replacement; whereas the PDDLA screw presented less degradation, but with bone production around, through the lateral perforations and within its central canal.
Descrição
Palavras-chave
Ácido poli-D L-láctico, Beta fosfato tricálcico, Histologia, Estudo de imagem, Poly-D, L-lactic acid, Beta-tricalcium phosphate, Histology, Imaging study