Ex vivo effects of corticosteroids on equine deep digital flexor and navicular fibrocartilage explant cell viability.
Authors: S. Sullivan, S. Cole, M. Stewart, M. Brokken, S. Durgam
Journal: American journal of veterinary research
Summary
# Editorial Summary: Corticosteroid Effects on Navicular and Deep Digital Flexor Fibrocartilage Sullivan and colleagues examined whether two commonly injected corticosteroids—triamcinolone acetonide (TA) and methylprednisolone acetate (MPA)—damage the resident cells of the fibrocartilage associated with the navicular apparatus in horses. Using tissue explants harvested from five cadaver forelimbs, the researchers exposed samples of deep digital flexor fibrocartilage and navicular fibrocartilage to each drug at clinical and supra-clinical concentrations for 6 and 24 hours, measuring cell metabolic activity and cell death rates. TA showed a reassuring safety profile for deep digital flexor fibrocartilage at both concentrations tested, but demonstrated concentration-dependent toxicity to navicular fibrocartilage cells at the higher dose (6 mg/mL); MPA proved more problematic overall, reducing metabolic activity and increasing cell death in both tissues by 24 hours, with significant damage to navicular fibrocartilage appearing even at 6 hours with the higher concentration (5 mg/mL). For practitioners considering intra-articular corticosteroid injection in the navicular bursa or DDFT sheath, these findings suggest TA may present less risk of direct cytotoxic injury to local fibrocartilage cells than MPA, though the authors appropriately call for further investigation into concentration-dependent effects at lower doses and the longer-term functional consequences of partial cell damage.
Read the full abstract on PubMed
Practical Takeaways
- •If intra-articular corticosteroid injection to the navicular bursa is necessary, triamcinolone acetonide may be a safer choice than methylprednisolone based on lower cell toxicity in laboratory conditions
- •Methylprednisolone's rapid cytotoxic effects suggest particular caution with this agent near sensitive soft tissues like the DDFT and navicular fibrocartilage
- •These are laboratory findings in isolated tissue; clinical outcomes may differ—discuss risks/benefits with your veterinarian before injection decisions
Key Findings
- •Triamcinolone acetonide (TA) at high concentration (6 mg/mL) significantly reduced metabolic activity and increased dead cells in navicular fibrocartilage but not in DDFT fibrocartilage
- •Methylprednisolone acetate (MPA) was more cytotoxic than TA to both tissue types, showing reduced metabolic activity and increased cell death at 24 hours with both concentrations tested
- •MPA at 5 mg/mL demonstrated cytotoxic effects as early as 6 hours, whereas TA effects required 24 hours
- •TA demonstrated lower overall cytotoxicity compared to MPA in equine fibrocartilage explants