Validation of the ultrasonographic assessment of the femoral trochlea epiphyseal cartilage in foals at osteochondrosis predilected sites with MRI and histology

BACKGROUND: Non-invasive imaging tools are needed to screen foal femoropatellar joints to detect subclinical osteochondrosis lesions due to focal failure of endochondral ossification to enhance early management to optimise intrinsic healing events. Recently investigations employing 3T susceptibility-weighted MRI (3T SWI MRI) and CT have demonstrated their capacity for early osteochondrosis diagnosis, but these technologies are not practical for field screening. We postulate that ultrasonography is a valuable field tool for the detection of subclinical osteochondrosis lesions.

OBJECTIVES: The goals were 1) to describe the sonographic features of the femoral trochlea of healthy and osteochondrosis-predisposed neonatal foals, 2) to validate the capacity of ultrasound to assess cartilage canal vascular archictecture and the ossification front and 3) to evaluate field feasibility in a pilot study.
STUDY DESIGN: Experimental study.

METHODS: Ultrasonographic evaluation of osteochondrosis predisposed (n = 10) and control (n = 6) femoral trochleas was performed ex vivo and compared with site-matched histological sections and 3T SWI MRI. The articular and epiphyseal cartilage thickness, the ossification front indentation and the cartilage canal vascular archictecture were assessed at each ROI. Femoral trochleae of foals (n = 3) aged 1, 3 and 6 months were also evaluated with ultrasonography in field.

RESULTS: Ultrasonographic measurements strongly correlated with the histological measurements. There was no difference in the cartilage thickness or ossification front indentation between control and osteochondrosis-predisposed specimens. The cartilage canal vascular archictecture on ultrasonograms corresponded with the vessel pattern observed on site-matched histology and 3T SWI MRI.

MAIN LIMITATIONS: The number of specimens for study was limited, and no early osteochondrosis lesions were present within the predilected group, but a field study is now underway.

CONCLUSION: Ultrasonographic examination of the femoral trochlea permitted accurate evaluation of cartilage thickness, cartilage canal vascular archictecture and ossification front indentation in young foals and is a promising, practical tool for screening subclinical osteochondrosis and monitoring and managing lesions at important clinical sites. This article is protected by copyright. All rights reserved.