Características planimétricas y estereológicas de los nervios palmar lateral y medial en manos de equinos con y sin síndrome navicular / Planimetric and stereological characteristics of lateral and medial palmar nerves in hands of equine with and without navicular syndrome

El Síndrome Navicular (SN) es una de las patologías claudicógenas mas frecuentes en la práctica clínica equina. Se ha descrito, cierta susceptibilidad individual respecto a ésta presentación clínica, es decir, algunos equinos con SN claudican y otros, con similares hallazgos radiográficos en mano no lo hacen sugiriendo que existen diferencias cuantitativas, entre equinos con y sin SN, en las características de las fibras nerviosas de los nervios periféricos que inervan la mano. El objetivo del estudio fue describir las características morfológicas cuantitativas de los nervios palmar lateral y medial en equinos con SN. Se obtuvo manos mediante un muestreo dirigido y diagnosticadas por inspección visual y evaluación radiográfica. Se conformó dos grupos: "No afectadas" (n= 6) y "Síndrome Navicular" (n= 8). Para determinar diferencias cuantitativos entre ambos grupos se realizó: i) Estudio 1, evaluó las características morfológicas, planimétricas y estereológicas de los nervios palmar lateral y medial, ii) Estudio 2: evaluó la cantidad de axones mielinizados y no mielinizados. En ambos estudios, el análisis de los datos morfológicos, estereológicos y planimétricos, en general, no detectó diferencias significativas entre grupos. En conclusión, los resultados obtenidos en el estudio no entregan evidencia morfológica respecto a diferencias entre nervios palmares entre equinos con y sin SN.

Navicular Syndrome (NS) is one of the most frequent claudicogen pathologies in the equine clinical practice. Certain individual susceptibility has been described in this clinical presentation, that is, some horses with SN halt, while others with similar radiographic findings in hand do not, suggesting that there are quantitative differences, between horses with and without clinical presentation of SN, on the characteristics of the nerve fibers of the peripheral nerves of the hand. The aim of this study was to describe the morphologic quantitative characteristics of the lateral and medial palmar in horses with SN nerves. Hands were obtained by sampling directed and diagnosed by visual inspection and radiographic evaluation. Two groups were formed: "Not affected" (n= 6) and "Navicular Syndrome" (n = 8). To determine quantitative differences between two groups we performed: i) Study 1: evaluated the morphological, planimetric and stereological lateral and medial palmar nerves, ii) Study 2: evaluated the number of unmyelinated and myelinated axons. In both studies, analysis of stereological, morphological and planimetric data generally detected no significant differences between groups. In conclusion, the results of the study do not provide morphological evidence for differences between palmar nerves between horses with and without SN.

Alterações radiográficas do aparato podotroclear de equinos da Polícia Militar de Minas Gerais sem sinais clínicos de doença do osso navicular / Radiographic changes in the podotroclear apparatus from Minas Gerais State Military horses without clinical signs of navicular disease

Os objetivos deste experimento foram identificar e associar alterações radiográficas do aparato podotoclear de equinos do Regimento de Cavalaria Alferes Tiradentes da Policia Militar do estado de Minas Gerais sem histórico e sinais clínicos de doença do osso navicular. Foi avaliado um total de 33 equinos, de ambos os sexos, com idade entre 10 e 20 anos. Os dígitos torácicos foram radiografados de forma padronizada nas projeções lateromedial (LM), dorsoproximal palmarodistal 65º (DPPD) e palmaroproximal palmarodistal (SK). A radiopacidade medular aumentada em projeção SK foi a principal alteração radiográfica detectada. Essa alteração foi associada a maior número de invaginações sinovais, a maior espessura de cortical em relação à medular em exposição SK e a maior relação corticomedular em exposição LM (P<0,05). Esses achados indicam uma predisposição da população equina para desenvolver a síndrome do osso navicular, possivelmente associada ao trauma repetitivo promovido pelo constante trabalho em piso duro.

The aims of this study were to identify and associate radiographic changes of podotoclear apparatus in horses from the Tiradentes Calvary Regiment of the Military Police of Minas Gerais State without history and clinical signs of navicular disease. 33 horses from both sexes, aged between 10 and 20 years were evaluated. The thoracic digits were radiographed in a standardized manner in lateralmedial (LM), palmaroproximal-distodorsal 65o(DPPD) and palmaroproximal-distopalmar (SK) projections. The increased medullary radiopacity in SK projection was the main radiological change detected and was associated with a higher number of synoval invaginations, increased cortical thickness in relation to medulla in SK exposure and increased corticomedullar in LM exposure (P < 0.05). These findings indicate a predisposition of this population to develop navicular syndrome, which is possibly associated with repetitive trauma promoted by constant work on hard floors.

Estudio histoquímico de la distribución de las fibras de colágeno en hueso sesamoídeo distal de equinos con y sin síndrome navicular / Histochemical study of the distribution of collagen fibers on distal sesamoid bone in equine with and without navicular syndrome

La significancia funcional de cualquier relación que exista entre la orientación de las fibras de colágeno y la tensión ejercida sobre una estructura ósea dependerá de la influencia de estos parámetros microestructurales sobre las propiedades biomecánicas del hueso y su capacidad de adaptarse. Se estudió la localización del colágeno en el hueso sesamoídeo distal (HSD) de la mano en equinos con Síndrome Navicular para observar cómo este refleja las demandas biomecánicas ejercidas por la tensión que ejerce el tendón del músculo flexor digital profundo sobre la articulación interfalángica distal. Se utilizaron las tinciones hematoxilina-eosina-azul alcián, y Rojo Picrosirius de Junqueira. La birrefringencia de colágeno óseo fue determinada utilizando microscopía de luz polarizada. La remodelación del HSD resultó en la formación de osteonas secundarias transversales orientados en una dirección lateral a medial y el colágeno óseo se orientó de manera similar. Estos resultados proporcionan evidencia de la existencia de una relación entre la función mecánica de un hueso con su arquitectura, incluso demuestra que esta se extiende hasta el nivel molecular.

The functional significance of any relationship exists between the orientation of the collagen fibers and the strain on a bone structure depend on the influence of these microstructural parameters on the biomechanical properties of bone and its ability to adapt. Localization of collagen was studied in the distal sesamoid bone (DSB) in in equine foot with Navicular Syndrome to see how this reflects the biomechanical demands by the tension exerted by the tendon of the deep digital flexor muscle on the joint distal interphalangeal. Hematoxylin-eosin-alcian blue staining, and Red Picrosirius of Junqueira were used. The birefringence of bone collagen was determined using polarized light microscopy. The remodeling of DSB resulted in the formation of transverse secondary osteons oriented lateral to medial and bone collagen was oriented in similar direction. These results provide evidence for the existence of a relationship between the mechanical function of a bone with the architecture, and shows further that this extends up to the molecular level.

Morfometría, planimetría y estereología en el hueso sesamoídeo distal en manos de equinos con y sin síndrome navicular / Morphometry, planimetry and stereology in the distal sesamoid bone in equine foot with and without navicular syndrome

El Síndrome Navicular (SN) es una patología claudicógena bilateral crónica, degenerativa y progresiva, que compromete alhueso sesamoídeo distal (HSD), labolsa podotroclear, ligamentosy a las superficies adyacentes al tendón del músculo flexor digitalprofundo en manos de equinos. La hipótesis de que las características morfológicas del HSD en la mano de equinos varían en aquellos que presentan SN fue evaluada en este estudio. Para determinar cambios morfológicos en el HSD en manos de equinos con SN se realizó un estudio morfométrico, planimétrico y estereológico. Fueron evaluados dos grupos: No Afectadas (n=11) y Síndrome Navicular (n=11). Se evaluaron variables tales como peso, volumen, mediciones lineales, área y parámetros estereológicos tales como densidad de número (NA), volumen (VV) y superficie (SV). Los resultados obtenidos indican que a pesar de existir un proceso patológico e inflamatorio en la región del HSD que induce cambios mesoscópicos y microscópicos atribuibles a SN, no lograrían modificar sus características macroscópicas.

Navicular Syndrome (NS) is a chronic, degenerative and progressive bilateral claudication pathology, compromising the distal sesamoid bone (DSB), the podotrochlear bursa, ligaments and adjacent surfaces of the tendon of the deep digital flexor muscle of equine foot. The hypothesis that morphological characteristics of HSB in hand of horses vary in those with SN was evaluated in this study. A study was carried out to determine the morphological changes in the DSB in 22 left foot of horses with NS. We realized morphometrical, planimetrical and stereological studies in two groups of horses feet: Not Affected (n=11) and Navicular Syndrome (n=11). The following variables were quantified: weight, volume, linear measurements, area and stereological parameters: densities of number (NA), volume (VV) and surface (SV). Results indicate that although there is a pathological and inflammatory process in the region of DSB which induces mesoscopic and microscopic changes attributable to SN, their gross morphological features were not modified.

Avaliação radiográfica e ultrassonográfica do aparato podotroclear de cavalos Quarto de Milha diagnosticados com síndrome do navicular / Radiographic and ultrasonographic evaluation of the podotrochlear apparatus in American Quarter horses diagnosed with navicular syndrome

O objetivo deste estudo foi avaliar as alterações do aparato podotroclear de 22 cavalos da raça Quarto de Milha acometidos pela síndrome do navicular utilizando o acesso transcuneal. Esses equinos foram submetidos ao exame radiográfico e ultrassonográfico. No exame radiográfico foi observado a presença de invaginação sinovial de diferentes tipos, além de calcificação da bursa podotroclear e tendão flexor digital profundo, entesiófitos, osteófitos e alteração do limite córtico-medular. No exame ultrassonográfico observou-se alterações da bursa podotroclear, aderência e irregularidades nos bordos do tendão flexor digital profundo, diminuição do coxim digital, calcificação do ligamento sesamóide distal ímpar e irregularidade da superfície flexora do osso sesamóide distal. Todos os equinos que apresentavam alterações radiográficas também apresentaram alterações no exame ultrassonográfico compatíveis com a síndrome do navicular. O exame ultrassonográfico utilizando o acesso transcuneal foi um método prático e eficiente para avaliação das lesões do aparato podotroclear dos eqüinos, sendo um método complementar ao exame radiográfico.

The objective of this study was to evaluate radiographically and ultrasonographically the podotrochlear apparatus using a transcuneal approach in 22 American Quarter horses suffering from navicular syndrome. On the radiographs, different forms of synovial invaginations, calcification of the podotrochlear bursa and deep digital flexor tendon, enthesophyte and osteophyte formation, and changes in the cortical-medullary margin were observed. On the ultrasound scans, changes of the podotrochlear bursa, adhesions and irregularities at the surface of the deep digital flexor tendon, the digital cushion area reduction, calcification of the impar distal sesamoideal ligament, and irregularities of the flexor surface of the distal sesamoid bone were observed. Radiographic and ultrasonographic abnormalities compatible with navicular syndrome were present in all patients. Ultrasonography using transcuneal approach was a practical and efficient method to evaluate podotrochlear apparatus injuries in equine, thus being a complementary method to radiography.