New Insights in Diagnosing and Treating Equine SDFT Injuries—What You Need to Know

Clinical Updates on Superficial Digital Flexor Tendon Injuries

Roger K.W. Smith, Michael C. Schramme

Background
Superficial digital flexor tendon (SDFT) tendinopathy is a prevalent cause of lameness in athletic horses. Although acute injuries can result from external trauma, overstrain injuries often arise due to a complex interplay between aging, cumulative microdamage from exercise, and insufficient resolution of inflammation. Tendon healing typically results in fibrous, disorganized tissue with compromised biomechanical function, predisposing horses to reinjury. Emerging evidence emphasizes the need for therapies that resolve inflammation effectively.

Methods
This is a narrative clinical update reviewing recent advancements in the diagnosis and treatment of SDFT tendinopathy in horses. It includes findings from experimental and clinical studies, diagnostic imaging techniques, and therapeutic interventions including regenerative medicine, surgery, and physical therapies.

Results
Key advances in diagnostics include enhanced ultrasonography with off-incidence and non-weightbearing views, Doppler imaging to detect early neovascularization, elastography, and ultrasound tissue characterization. MRI and CT are beneficial in complex cases, while PET scanning shows future promise. Molecular markers (especially from synovial fluid) and limb stiffness assessment tools are emerging technologies.

In terms of therapies, intralesional orthobiologic treatments—particularly mesenchymal stem cells (MSCs)—have shown the strongest evidence for improving tendon healing and reducing reinjury rates. Platelet-rich plasma (PRP) and other hemoderivatives offer variable results. Newer modalities such as microRNA therapy, glycosaminoglycan mimetics, and Class IV laser therapy are under evaluation. Surgical options like accessory ligament desmotomy and tenoscopic removal of manica flexoria tears remain relevant in select cases. Custom-designed limb supports and controlled exercise remain foundational in rehabilitation.

Limitations
Many therapeutic studies lack robust design, with small sample sizes, lack of randomization, or reliance on surrogate rather than clinical endpoints. The variability in lesion types, patient response, and limited long-term follow-up challenge generalizability. There is also insufficient standardization in biologic product preparation and delivery methods.

Conclusions
Substantial progress has been made in imaging technologies and regenerative therapies for SDFT injuries. Among these, stem cell-based treatments currently hold the best evidence for clinical benefit. Future directions should focus on stage-specific interventions that promote resolution of inflammation and address the biomechanical deficits of the healing tendon. Continued development of objective diagnostic tools and controlled clinical trials are essential to optimize treatment outcomes and reduce recurrence.

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