An optimised injection technique for the navicular bursa that avoids the deep digital flexor tendon.
Authors: Daniel A J, Goodrich L R, Barrett M F, Werpy N M, Morley P S, McIlwraith C W
Journal: Equine veterinary journal
Summary
# Editorial Summary: Optimised Lateral Approach to Navicular Bursal Injection Traditional palmar-approach navicular bursal injections inevitably penetrate the deep digital flexor tendon, raising questions about potential iatrogenic damage and therapeutic efficacy. Daniel and colleagues evaluated a radiographically-guided lateral injection technique across 71 cadaveric and clinical equine limbs, using contrast studies and magnetic resonance imaging to map needle trajectory and synovial penetration patterns. The lateral approach successfully achieved navicular bursal access in all cases whilst completely avoiding DDFT puncture; however, the risk of inadvertent distal interphalangeal joint penetration increased 19-fold when that joint was distended, and digital flexor tendon sheath puncture risk nearly tripled when that structure was distended. Practitioners should consider this lateral technique as the preferred method for routine navicular bursa injections, particularly in sound limbs, but must exercise heightened caution—or potentially employ alternative imaging modalities—when concurrent synovial pathology of the DIP joint or flexor tendon sheath is suspected or confirmed. The 47% successful synovial fluid retrieval rate also suggests diagnostic potential for this approach in investigating navicular bursa involvement in distal limb lameness.
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Practical Takeaways
- •The lateral injection approach is a reliable alternative to traditional palmar injection that eliminates deep digital flexor tendon damage, improving safety and reducing iatrogenic injury risk
- •Exercise caution when injecting horses with concurrent distal interphalangeal joint or digital flexor tendon sheath pathology, as distension significantly increases risk of unintended synovial penetration
- •Radiographic guidance is recommended during navicular bursa injection to confirm needle placement and avoid complications, particularly in clinically affected limbs
Key Findings
- •Lateral injection technique successfully achieved navicular bursal injection in all 71 limbs without deep digital flexor tendon penetration
- •Risk of distal interphalangeal joint puncture was 19 times higher when the joint was distended (9/10 limbs) versus normal limbs (0/10 limbs)
- •Risk of digital flexor tendon sheath puncture was 2.7 times higher when distended (8/10 limbs) compared to normal limbs (3/7 limbs)
- •Synovial fluid was successfully aspirated from 47% of navicular bursae in clinical cases using the lateral technique