Degradation of Proteoglycans and Collagen in Equine Meniscal Tissues.

Investigate meniscal extracellular matrix degradation. Equine menisci (n = 34 from 17 horses) were studied. Site-matched sections were cut and scored from three regions (ROIs; n = 102) and stained for histology, proteoglycan (safranin O and fast green), aggrecan, and collagen cleavage (NITEGE, DIPEN, and C1,2C antibodies, respectively). Picrosirius red and second harmonic generation microscopy were performed to investigate collagen ultrastructure. A total of 42 ROIs met the inclusion criteria and were included in the final analysis. The median (range) ROI histological score was 3 (0-9), providing a large spectrum of pathology. The median (range) proteoglycan score was 1 (0-3), representing superficial and central meniscal loss. The median (range) of DIPEN, NITEGE, and C1,2C scores was 1 (0-3), revealing immunostaining of the femoral and tibial surfaces. The proteoglycan scores exhibited significant positive associations with both histologic evaluation (p = 0.03) and DIPEN scores (p = 0.02). Additionally, a robust positive association (p = 0.007) was observed between the two aggrecanolysis indicators, NITEGE and DIPEN scores. A negative association (p = 0.008) was identified between NITEGE and histological scores. The C1,2C scores were not associated with any other scores. Picrosirius red and second harmonic generation microscopy (SHGM) illustrated the loss of the collagen matrix and structure centrally. Proteoglycan and collagen degradation commonly occur superficially in menisci and less frequently centrally. The identification of central meniscal proteoglycan and collagen degradation provides novel insight into central meniscal degeneration. However, further research is needed to elucidate the etiology and sequence of degradative events.

Maturation of the Meniscal Collagen Structure Revealed by Polarization-Resolved and Directional Second Harmonic Generation Microscopy.

We report Polarization-resolved Second Harmonic Generation (P-SHG) and directional SHG (forward and backward, F/B) measurements of equine foetal and adult collagen in meniscus, over large field-of-views using sample-scanning. Large differences of collagen structure and fibril orientation with maturation are revealed, validating the potential for this novel methodology to track such changes in meniscal structure. The foetal menisci had a non-organized and more random collagen fibrillar structure when compared with adult using P-SHG. For the latter, clusters of homogeneous fibril orientation (inter-fibrillar areas) were revealed, separated by thick fibers. F/B SHG showed numerous different features in adults notably, in thick fibers compared to interfibrillar areas, unlike foetal menisci that showed similar patterns for both directions. This work confirms previous studies and improves the understanding of meniscal collagen structure and its maturation, and makes F/B and P-SHG good candidates for future studies aiming at revealing structural modifications to meniscus due to pathologies.

Partial resection of bilateral ulnar remnants for treatment of carpus valgus in a 3-week-old Hanoverian foal.

A 3-week old Hanoverian foal was presented with bilateral moderate to severe carpal valgus. The deviations were 10 and 14 degrees, respectively for the left and right carpi and orthogonal radiographs of both front limbs highlighted bilateral persistent ulnar remnants. A partial resection of the ulnar remnants and periosteal transection on the disto-lateral aspect of the radius were performed bilaterally under general anesthesia. The valgus deviations began to improve within the first month and the limbs were almost straight (2 degrees for the left and right carpi) 5 1/2 months after surgery. This is the first report of successful surgical correction of bilateral carpal valgus secondary to persistent ulnar remnants in a large breed foal. The combination of partial ulnar remnant resection and radial disto-lateral periosteal transection, detailed in this report, should be considered for treatment of foals with this condition.

Résection ulnaire bilatérale partielle comme traitement d'un valgus des carpes chez un poulain Hanovrien de 3 semaines d'âge. Un poulain Hanovrien de 3 semaines d'âge a été présenté avec un valgus bilatéral des carpes. Les déviations étaient de 10 et 14 degrés, pour les carpes gauche et droit respectivement. Des projections radiographiques orthogonales des deux membres antérieurs ont mis en évidence un ulna persistant bilatéralement. Une résection partielle des ulnas persistants et une section périostée de l'aspect disto-latéral de chaque radius a été effectuée sous anesthésie générale. Une amélioration des déviations a d'abord été observé durant le premier mois et les deux membres antérieurs étaient quasi droits (2 degrés pour chacun des carpes) 5 1/2 mois après la chirurgie. Ceci est le premier rapport de cas à décrire la correction chirurgicale d'un valgus bilatéral des carpes secondaire à la présence d'ulnas persistants, chez un poulain de grande taille. La combinaison de la résection ulnaire partielle et de la section périostée disto-latérale du radius présentée ici devraient être considérée comme traitement des poulains présentant cette condition.(Traduit par Dre Julia Dubuc).