Anatomy of the Posterior Interosseous Artery Flap in Adult Vietnamese Cadavers: Skin Mapping and Surgical Landmarks for Clinical Applications.

Background: The Posterior Interosseous Artery Flap (PIA) is widely used in soft tissue reconstruction of the wrist and hand due to its consistent vascularity, long pedicle, and favorable donor site. However, anatomical variations in the vascular pedicle, perforator distribution, and flap dimensions remain limitations for clinical use.

Objective: This study aims to provide a detailed anatomical evaluation of the PIA flap in adult Vietnamese cadavers to support surgical planning.

Methods: A observational study was conducted on 30 forearm specimens from 15 adult Vietnamese cadavers. Methylene blue was injected into the PIA to evaluate its origin, perforator distribution, pedicle length, and perfused skin territory. Measurements were made using anatomical landmarks, and data were analyzed with SPSS 26.0.

Results: The PIA originated from the common interosseous artery in 93.3% (28/30) and from the ulnar artery in 6.7% (2/30). The reverse-flow pedicle length averaged 12.8 ± 1.6 cm. Perforators were concentrated in intervals 4-8, especially intervals 5 and 8. Pattern II was the most prevalent of the three identified perforator patterns, accounting for 70% of specimens. The methylene blue-stained skin territory measured 20.6 ± 2.0 cm in length, 8.4 ± 1.4 cm in width, and 175.9 ± 41.8 cm² in area. The stained area was located 1.9 ± 1.2 cm from the distal ulna (A1), 2.9 ± 1.2 cm from the anterior midline (A2), 0.8 ± 0.9 cm below the lateral epicondyle (A3), and 0.03 ± 0.18 cm from the posterior ulnar border (A4).

Conclusion: The PIA flap demonstrates a reliable vascular supply and a wide perfusion range. It should be designed > 2 cm distal to the ulna, ≥ 3 cm lateral to the anterior midline, ~1 cm below the lateral epicondyle, and not extend beyond the posterior ulnar border.