RESUMO
OBJECTIVE: To investigate the effect of decellularized cartilage-derived matrix (CDM) scaffolds, by itself and as a composite scaffold with a calcium phosphate (CaP) base, for the repair of osteochondral defects. It was hypothesized that the chondral defects would heal with fibrocartilaginous tissue and that the composite scaffold would result in better bone formation. METHODS: After an 8-week pilot experiment in a single horse, scaffolds were implanted in eight healthy horses in osteochondral defects on the medial trochlear ridge of the femur. In one joint a composite CDM-CaP scaffold was implanted (+P), in the contralateral joint a CDM only (-P) scaffold. After euthanasia at 6 months, tissues were analysed by histology, immunohistochemistry, micro-CT, biochemistry and biomechanical evaluation. RESULTS: The 8-week pilot showed encouraging formation of bone and cartilage, but incomplete defect filling. At 6 months, micro-CT and histology showed much more limited filling of the defect, but the CaP component of the +P scaffolds was well integrated with the surrounding bone. The repair tissue was fibrotic with high collagen type I and low type II content and with no differences between the groups. There were also no biochemical differences between the groups and repair tissue was much less stiff than normal tissue (P < 0.0001). CONCLUSIONS: The implants failed to produce reasonable repair tissue in this osteochondral defect model, although the CaP base in the -P group integrated well with the recipient bone. The study stresses the importance of long-term in vivo studies to assess the efficacy of cartilage repair techniques.
Assuntos
Cartilagem Articular/patologia , Cartilagem/metabolismo , Alicerces Teciduais , Animais , Cartilagem Articular/diagnóstico por imagem , Cartilagem Articular/lesões , Modelos Animais de Doenças , Cavalos , Microtomografia por Raio-XRESUMO
REASONS FOR PERFORMING STUDY: Treadmill locomotion is frequently used for training of sport horses, for diagnostic purposes and for research. Identification of the possible biomechanical differences and similarities between the back movement during treadmill (T) and over ground (O) locomotion is essential for the correct interpretation of research results. OBJECTIVES: To compare the kinematics of the thoracolumbar vertebral column in treadmill and over ground locomotion in healthy horses. METHODS: Six sound Dutch Warmblood horses trotted on a T and O during 10 s at their own preferred velocity (mean +/- s.d. 3.6 +/- 0.3 m/s T and 3.6 +/- 0.1 m/s O), which was the same in both conditions. Kinematics of the vertebral column was captured by infrared cameras using reflective skin markers attached over the spinous processes of selected vertebrae and other locations. Flexion-extension and lateral bending range of motion (ROM), angular motion pattern (AMP) and intravertebral pattern symmetry (IVPS) of 5 vertebral angles (T6-T10-T13, T10-T13-T17, T13-T17-L1, T17-L1-L3 and L1-L3-15) were calculated. Neck angle, linear and temporal stride parameters and protraction-retraction angles of the limbs were also calculated. RESULTS: The vertical ROM (flexion-extension) was similar in both conditions, but the horizontal ROM (lateral bending) of the lumbar angles T17-L1-L3 and L1-L3-L5 was less during T locomotion (mean +/- s.d. difference of 1.8 +/- 0.6 and 1.7 +/- 0.9 degrees, respectively, P > 0.05). During O locomotion, the symmetry pattern of the lumbar vertebral angles was diminished from 0.9 to 0.7 (1 = 100% symmetry) indicating increased irregularity of the movement (P > 0.05). No differences were found in the basic linear and temporal stride parameters and neck angle. POTENTIAL RELEVANCE: Vertebral kinematics during treadmill locomotion is not identical to over ground locomotion, but the differences are minor. During treadmill locomotion lumbar motion is less, and caution should be therefore taken when interpreting lumbar kinematics.
Assuntos
Dorso/fisiologia , Marcha/fisiologia , Cavalos/fisiologia , Animais , Fenômenos Biomecânicos , Teste de EsforçoRESUMO
This article describes a case of massive mortality among horses which was probably due to intoxication by pyrrolizidine alkaloids from Heliotropium indicum. Over 4 years more than 75% of a population of about 110 horses on a farm in Costa Rica died after showing nervous neurological symptoms. Two clinical manifestations were encountered, an acute and a chronic one, both with a fatal outcome. Pathological findings in 2 horses coincided with those reported in the literature for intoxication by pyrrolizidine alkaloids and were not specific for VEE. However Venezuelan equine encephalitis (VEE) was the main differential diagnosis and could not completely be excluded because this disease was endemic in the region and VEE titres were found to be high. Taxonomic and toxicological investigations implicated Heliotropium indicum as the most probable principal cause of the intoxication.