Osteochondrosis lesions of the lateral trochlear ridge of the distal femur in four ponies

Evaluation of the appearance of osteochondrosis lesions by two radiographic examinations in sport horses aged from 12 to 36 months

Osteochondrosis is a developmental orthopedic disease characterized by a defect of enchondral ossification. This pathological condition develops and evolves during growth and is influenced by various factors, in particular genetic and environmental. However, little research has been conducted on the dynamic of this condition in horses after the age of 12 months. The retrospective study presented here investigates changes in osteochondrosis lesions through two standardized radiographic examinations carried out on young Walloon sport horses after one year of age (mean age at first and second examination was 407 (±41) and 680 (±117) days respectively). Each examination, analyzed independently by three veterinarians, included latero-medial views of the fetlocks, hocks, stifles, plantarolateral-dorsomedial hocks view and additional radiograph if the operator deemed it necessary. Each joint site was graded as healthy, osteochondrosis (OC) or osteochondrosis dissecans (OCD) affected. A group of 58 horses was studied, among them 20 presented one or more osteochondrosis lesions for a total of 36 lesions present during at least one examination. In this population, 4 animals (6.9%) presented osteochondrosis during only one examination (2 at the first examination and 2 at the second one). Moreover, it was possible to demonstrate the appearance, disappearance and more generally the evolution of 9/36 lesions (25%) within the different joints. The results of the study suggest that, although substantial main limitations, osteochondrosis lesions can evolve after the age of 12 months in sport horses. Knowing this is useful in helping to decide the appropriate radiographic diagnosis timing and management.

Multipotent Stromal Cells Outperform Chondrocytes on Cartilage-Derived Matrix Scaffolds

OBJECTIVE

Although extracellular matrix (ECM)-derived scaffolds have been extensively studied and applied in a number of clinical applications, the use of ECM as a biomaterial for (osteo)chondral regeneration is less extensively explored. This study aimed at evaluating the chondrogenic potential of cells seeded on cartilage-derived matrix (CDM) scaffolds in vitro.

DESIGN

Scaffolds were generated from decellularized equine articular cartilage and seeded with either chondrocytes or multipotent stromal cells (MSCs). After 2, 4, and 6 weeks of in vitro culture, CDM constructs were analyzed both histologically (hematoxylin and eosin, Safranin-O, collagen types I and II) and biochemically (glycosaminoglycan [GAG] and DNA content).

RESULTS

After 4 weeks, both cell types demonstrated chondrogenic differentiation; however, the MSCs significantly outperformed chondrocytes in producing new GAG-containing cartilaginous matrix.

CONCLUSION

These promising in vitro results underscore the potency of CDM scaffolds in (osteo)chondral defect repair.

Alterations in sclerostin protein in lesions of equine osteochondrosis

Osteochondrosis (OC) is a common and clinically important joint disease that occurs in many species, including humans, pigs, chickens and horses. It has been described as a focal failure of endochondral ossification (EO), but no cellular/molecular mechanisms are fully described that explain the cause of this condition. Recently a Wnt signalling inhibitor, sclerostin, has been described in osteoarthritic cartilage, where it has been proposed to protect damaged cartilage from degradation. Cartilage degradation is a key event in EO, thus, abnormalities of sclerostin in growth cartilage could, potentially, lead to a failure of EO and, thus, OC. The aim of this study was to describe the distribution of sclerostin protein in normal and OC growth cartilage.

Immunohistochemistry (IHC) was used to localise sclerostin protein in normal and OC growth cartilage. Growth cartilage was harvested from the distal femur of horses aged between 6 and 18 months. Cartilage was classified as normal or having lesions consistent with a diagnosis of early OC. IHC was used to identify sclerostin protein in cartilage sections. Sclerostin protein distribution was semiquantified using a grading system and shown to be upregulated throughout all three zones of cartilage in lesions of OC (IHC score 8.1 compared to IHC score of 0.88). These results indicate that sclerostin may be contributing to the development of OC lesions by inhibiting extracellular matrix remodelling or may reflect the response of damaged cartilage. Clearly, further work is required to fully characterise this observation but, with antisclerostin antibodies used to treat human osteoporosis, the possibility of development of a systemic treatment of OC remains a potential goal.