Sinocutaneous fistula repair with a masseter muscle transposition flap combined with wound matrix and cancellous bone graft in a horse: A new technique.
Authors: Yoshimura Seiji, Barber Spencer M, Tucker Michelle L, Bracamonte José L, Mund Suzanne J K, Thomas Keri L
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Sinocutaneous Fistula Repair Using Masseter Muscle Transposition Chronic sinocutaneous fistulas—abnormal tracts connecting the maxillary sinus to the skin surface—present significant surgical challenges in equine practice, particularly when defects are large or conventional closure methods have failed. This case report documents a novel surgical approach combining three complementary techniques: placement of a commercial wound matrix over the bone defect, cancellous bone grafting harvested from the tuber coxa, and transposition of the superficial masseter muscle as a vascularised flap to reinforce the repair, with a rotational skin flap for final closure. The technique was applied to a 13-year-old thoroughbred stallion with a 3.5 × 6 cm fistula over the right caudal maxillary sinus, with the pedicled masseter flap based at the facial crest and transposed dorsally to provide living tissue coverage. Although seroma formation and partial skin flap dehiscence occurred postoperatively, the muscle flap remained viable and the fistula achieved complete closure with excellent cosmetic and functional outcomes. For equine practitioners, this case demonstrates that transposition of the superficial masseter muscle warrants consideration as a surgical option for large, recurrent, or difficult maxillary sinocutaneous fistulas where standard primary closure is insufficient. The vascularised muscle flap provides biological support for bone healing whilst offering superior soft tissue coverage compared to simple suturing alone, potentially improving long-term success rates in complicated cases.
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Practical Takeaways
- •For large chronic sinocutaneous fistulas over the maxilla, consider masseter muscle transposition as an alternative to conventional closure methods—it can provide durable tissue coverage with good functional results.
- •The technique combines three components (wound matrix, bone graft, and muscle flap) to address the defect; minor complications like seroma may occur but don't necessarily compromise success.
- •This is an advanced surgical technique requiring referral to an experienced equine surgeon; not suitable for first-opinion practice.
Key Findings
- •Masseter muscle transposition flap combined with wound matrix and cancellous bone graft successfully closed a 3.5 × 6 cm chronic sinocutaneous fistula in a thoroughbred stallion.
- •Despite minor complications (seroma formation and skin flap dehiscence), the transposed muscle flap survived and achieved excellent cosmetic and functional outcome.
- •This novel technique represents a viable surgical option for large maxillary sinocutaneous fistulas in horses.