Transfer of deep circumflex iliac flaps to the tarsus by microvascular anastomosis in the horse.

This research piece focuses on an experimental method of flap transfers to the tarsus (ankle) in horses, using deep circumflex iliac flaps elevated from18 adult horses. The study found limited success in this transfer method due to technical issues and the no-reflow phenomenon leading to failure.

Introduction

• The study was focused on exploring the practicability and potential setbacks of transferring deep circumflex iliac flaps to the tarsus in horses. This process involves the repositioning of tissue – specifically the deep circumflex iliac flap – to the tarsus via microvascular anastomosis (the connection of small blood vessels).

Experimentation

• Eighteen healthy adult horses were subjected to the flap transfer procedures. This has created a sizeable sample group for the study, which gives weight to its results.
• The deep circumflex iliac flaps, an area of skin and underlying tissue from the iliac region (top of the horse’s rump), were extracted and then repositioned as islands in some instances and to the tarsus in others.

Findings

• Four island flaps survived and were viable proving the functionality of this method theoretically.
• However, limitations were observed with the orthotopic flaps (flaps transplanted to the same site from where they were extracted), as well as the heterotopic flaps (flaps transplanted to different locations).
• Five orthotopic flaps and nine heterotopic flaps failed post-transfer. This substantial failure rate among transferred flaps underlines significant obstacles in the broader application of this technique in existing forms.
• The paper suggests technical reasons could account for the failure in orthotopic flaps. However, no such reasons were presented for the heterotopic flaps.

Reason for Failure – the No-Reflow Phenomenon

• The failure in heterotopic flaps was credited to the ‘no-reflow phenomenon’. This is a medical condition where the blood fails to reperfuse certain areas of tissue, despite the removal of an obstruction causing ischemia (restricted blood supply causing shortage of oxygen and glucose needed for cellular metabolism).
• This means that despite the technical precision of the transfer and removal of any obstructions, the blood failed to flow into the repositioned flap, leading to flap failure.