The Delay Phenomenon: Is One Surgical Delay Technique Superior?

Background: Surgical delay remains a common method for improving flap survival. However, the optimal surgical technique has not been determined. In this article, we compare flap perfusion, viable surface area, and flap contraction of 2 surgical delay techniques.

Methods: Male Sprague-Dawley rats were divided into 3 groups. In the incisional surgical delay group (n = 9), a 9 × 3 cm dorsal flap was incised on 3 sides without undermining, leaving a cranial pedicle. In the bipedicle surgical delay group (BSD, n = 9), a 9 × 3 cm dorsal flap was incised laterally and undermined, leaving cranial and caudal pedicles. Control group (n = 16) animals did not undergo a delay procedure. Ten days following surgical delay, all flaps for all groups were raised, leaving a cranial pedicle. A silicone sheet separated the flap and the wound bed. On postoperative day (POD) 7, viable surface area was determined clinically. Contraction compared to POD 0 was measured with ImageJ software. Perfusion was measured with Laser Doppler Imaging. The Kruskal-Wallis with Dunn's multiple comparisons test was performed for group comparisons.

Results: BSD preserved significantly more viable surface area on POD 7 (13.7 ± 4.5 cm2 ) than Control (8.7 ± 1.8 cm2 ; P = 0.01). BSD also showed significantly less contraction (21.0% ± 13.5%) than Control (45.9% ± 19.7%; P = 0.0045). BSD and incisional surgical delay showed significantly increased perfusion compared with Control on POD 0 ( P = 0.02 and 0.049, respectively), which persisted on POD 3. This trend resolved by POD 7.

Conclusion: BSD showed improved early perfusion, increased viable surface area, and reduced contraction compared to control, suggesting that BSD is the superior flap design for preclinical modeling.