Lesions of the deep digital flexor tendon in the digit: a correlative MRI and post mortem study in control and lame horses.
Authors: Blunden, Murray, Dyson
Journal: Equine veterinary journal
Summary
# Editorial Summary This correlative study examined the pathological basis of deep digital flexor tendon (DDFT) lesions in the digit—a recognised cause of lameness—by comparing MRI signal changes with post-mortem histology in sound horses and those with confirmed DDFT pathology. Using transverse sections harvested from three standardized sites within the digit and proximal extensions where lesions were identified, the researchers found that lesions were fundamentally degenerative rather than inflammatory, with no haemorrhage or inflammatory cell infiltration evident in any specimen. Key pathological features distinguishing lame horses included septal thickening, blood vessel occlusion, core necrosis (ranging 0.5–13 cm in length), dorsal splitting, and fibrocartilaginous metaplasia—changes that were absent or minimal in the control group, particularly at the navicular bone level. Notably, increased signal intensity on fat-suppressed MRI sequences correlated with substantial matrix changes rather than frank fluid accumulation or inflammation, which has significant implications for image interpretation; clinicians should recognise that MRI signal changes reflect degenerative matrix disruption and probable vascular compromise rather than classical inflammatory lesions. The vascular occlusion and associated necrosis identified histologically suggest that compromised blood supply may underlie DDFT lesion development in the digit, though the initiating causes remain unclear—highlighting an important gap in understanding that must be addressed to develop effective prevention strategies for this clinically significant condition.
Read the full abstract on PubMed
Practical Takeaways
- •MRI signal intensity changes in the DDFT digit region should be interpreted as degenerative matrix changes rather than acute inflammation, affecting diagnostic and therapeutic approaches
- •Vascular compromise appears to be a key mechanism in DDFT lesion development; focus preventative strategies on maintaining digital blood supply and reducing ischaemic injury
- •Core lesions can extend well proximal to the navicular bone; complete MRI assessment of the entire DDFT is necessary for accurate lesion characterization and prognosis
Key Findings
- •DDFT lesions in lame horses (Group D) showed septal thickening, blood vessel ghosting, occlusion, and core necrosis primarily absent in control horses (Group C)
- •Core necrosis extended 0.5-13 cm proximal to the navicular bone level and correlated with increased signal intensity on fat-suppressed MRI
- •Lesions appear primarily degenerative rather than inflammatory, with no haemorrhage or inflammatory cell infiltration observed in either group
- •Increased MRI signal intensity on fat-suppressed images reflects major matrix changes rather than frank fluid or inflammation