Osteochondrosis (OC) is a common joint disease that affects developing cartilage and subchondral bone in humans, and in multiple animal species including horses. It is an idiopathic localized joint disorder characterized by focal chondronecrosis and retention of growing cartilage that can lead to the formation of fissures, subchondral bone cysts or intra-articular fragments. OC is considered a complex multifactorial disease with chondrocyte biogenesis impairment mainly due to biochemical and genetic factors. Likewise, the molecular events involved in the OC are not fully understood. Moreover, the OC pathogenesis seems to be shared across species. In particular, equine OC and human juvenile OC share some symptoms, predilection sites and clinical presentation. In this study, by using the label-free mass spectrometry approach, proteome of chondrocytes isolated from equine OC fragments has been analysed in order to clarify some aspects of cell metabolism impairment occurring in OC.

Equine chondrocytes isolated from 7 healthy articular cartilages (CTRL) and from 7 osteochondritic fragments (OC) (both obtained from metacarpo/metatarsophalangeal joints) were analysed. Proteins were extracted using urea and ammonium bicarbonate buffer, reduced, alkylated and digested with Trypsin/Lys-C Mix. Peptides were analysed using Q Exactive UHMR Hybrid Quadrupole-Orbitrap Mass Spectrometer (Thermo Scientific). All mass spectra of label-free samples analysed was set up to search against SwissProt human database (Homo sapiens) and SwissProt horse database (Equus caballus). One-way ANOVA was used for hypothesis testing. Proteins with a ≥1.5 fold change and with a FDR adjusted p value of ≤0.05 were defined as differentially expressed.

Statistical analysis evidenced 41 proteins up-regulated in OC while 18 were down-regulated with respect to the CTRL. Functional analysis showed that up-regulated proteins in OC were related to extracellular matrix degradation, lysosome, apoptotic execution phase, unfolded protein response, hyaluronan and keratan sulfate degradation, oxidative stress response and negative regulation of BMP signalling pathway. The down-regulated proteins were associated with endochondral ossification, vitamin D in inflammatory disease, Wnt signalling pathway and ECM proteoglycans. Validation assays confirmed these findings

These findings may contribute to clarify the events determining the onset and progression of both equine and human OC. Imaging MS analysis of OC and healthy cartilage to analyse lipid and metabolomic changes occurring in OC cartilage is in progress

Aim: The aim of the study was to assess the correlation of CE angle to the ratios of medial hip joint space width and femoral head diameter to acetabular width.

Material and metod: Measurements were done on 196 AP pelvic radiographs of 10 years old and 20 years old males and females obtained with “siemens lconos r 200 axion^®”. The patients were placed in the supine position with their hips extended and internally rotated 15°. Medial hip joint space width (mJSW), CE angle, femoral head diameter (FD) and acetabular width (AW) were measured. The intraobserver reproducibility was assessed by a randomly chosen subset of 50 radiographs and these were read 1 month apart. The levels of agreement were qualified using the intraclass correlation coefficient. The ratios of mJSW to AW and FD to AW were calculated.

Results: Mean CE angles in 10 years old females and males were 33.87±3.64 ve 32.74±4.21 degrees respectively. CE angle was correlated to mJSW/AW in 10 years old females (r = − 0.446, p=0.043). CE angle was not correlated to mJSW/AW in 10 years old males (r = − 0.293, p=0.146). CE angle was not correlated to mJSW/AW in 20 years old females while CE angle was correlated to mJSW/AW in 20 years old males (r = 0. 694, p=0.001). CE angle was correlated to FD/AW only in 20 years old males (r=0.553, p= 0.002).

Discussion: Ratios of medial hip joint space width and femoral head diameter to acetabular width are not correlated to CE angle in both preadelocent and postade-locent terms depending on sex. The expected inverse correlation of these parameters to CE angle was not dedected, so these parameters can be used in radiologic assessement of subluxation of the hip and acetabular dysplasia together with CE angle.