Intraosseous gentamicin perfusion of the distal metacarpus in standing horses.
Authors: Mattson Shawn, Bouré Ludovic, Pearce Simon, Hurtig Mark, Burger John, Black William
Journal: Veterinary surgery : VS
Summary
# Intraosseous Gentamicin Perfusion of the Distal Metacarpus in Standing Horses Orthopaedic infections of the equine distal limb present a significant clinical challenge, and achieving adequate antibiotic penetration into synovial structures and bone remains difficult through systemic routes alone. Mattson and colleagues investigated intraosseous (IO) perfusion as a targeted delivery method by inserting a cannulated cortical bone screw into the dorsolateral metacarpus of twelve sedated horses, applying a proximal tourniquet, and infusing gentamicin (2.2 mg/kg) whilst sequentially euthanising pairs of horses at 0, 2, 6, 12, 24, and 36 hours to measure antibiotic concentrations in synovial fluid and bone using fluorescence polarization immunoassay. Peak gentamicin concentrations substantially exceeded minimum inhibitory concentrations for common equine pathogens, with synovial fluid levels reaching 385 µg/mL in the metacarpophalangeal joint, 382 µg/mL in the digital flexor tendon sheath, and bone concentrations of 55 µg/g in the distal metacarpus, demonstrating superior local delivery compared to systemic administration. These findings suggest IO perfusion represents a viable treatment option for suspected or confirmed orthopaedic infections in the distal limb, offering practitioners a technique that can be performed under standing sedation with realistic potential to achieve bactericidal drug levels at the infection site.
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Practical Takeaways
- •Standing IO perfusion offers a practical alternative to systemic antibiotic therapy for distal limb infections, achieving local concentrations that kill common pathogens without anesthesia
- •This technique can simultaneously treat multiple structures (joints, tendons, bursa, bone) in the distal limb with a single procedure
- •Consider IO perfusion early in distal limb infection management, particularly for metacarpophalangeal joint, digital flexor tendon sheath, and navicular bursa infections
Key Findings
- •Intraosseous gentamicin perfusion achieved synovial fluid concentrations of 215-385 μg/mL across distal limb joints, exceeding minimum inhibitory concentrations for common pathogens
- •Bone gentamicin concentrations ranged from 16-55 μg/g in distal metacarpal and phalangeal sites
- •Highest antibiotic concentrations were achieved at 2-12 hours post-infusion in metacarpophalangeal joint and digital flexor tendon sheath
- •Standing IO perfusion technique successfully delivered therapeutic antibiotic levels to multiple distal limb structures without general anesthesia