# First dorsal metacarpal artery (FDMA) flaps: A novel classification system incorporating various modifications and subtypes—a 5 year retrospective comparative study

## TL;DR

This paper introduces a new classification system for FDMA flaps to improve thumb reconstruction outcomes based on a 5-year study of 29 patients.

## Contribution

A novel, clinically applicable classification system for FDMA flap modifications is proposed to guide flap selection and improve outcomes.

## Key findings

- Flap survival was highest in peninsular and split-skin flaps.
- Type IIIt flaps had the highest complication rate (OR 5.0, p = 0.03).
- 79.3% of patients reported high satisfaction at 6 months.

## Abstract

The first dorsal metacarpal artery (FDMA) flap, including its extended versions, is a reliable and versatile option for reconstructing thumb defects. However, a structured and practical classification system for its various modifications has been lacking.

This study aimed to assess the versatility of the FDMA flap and its modifications in managing a range of thumb defects and to propose a novel, clinically applicable classification system to facilitate flap selection and improve outcomes.

A retrospective observational study was conducted over five years at a tertiary care referral hospital with a specialized hand unit. A total of 29 patients with thumb defects underwent FDMA flap reconstruction. Flaps were classified into five types:•Type I Islanded flap, up to PIP joint; subtypes It (tunneled) Is (split skin)•Type II Peninsular flap, up to PIP joint•Type III Extended islanded flap beyond PIP joint; subtypes IIIt (tunneled), IIIs (split skin),•Type IV Extended peninsular flap beyond PIP joint, and•Type V Other modifications, e.g., reverse flaps or bilobed flaps (not used in this study).•Data on flap survival, complications, hospital stay, and 6-month patient satisfaction were analyzed.

Type I Islanded flap, up to PIP joint; subtypes It (tunneled) Is (split skin)

Type II Peninsular flap, up to PIP joint

Type III Extended islanded flap beyond PIP joint; subtypes IIIt (tunneled), IIIs (split skin),

Type IV Extended peninsular flap beyond PIP joint, and

Type V Other modifications, e.g., reverse flaps or bilobed flaps (not used in this study).

Data on flap survival, complications, hospital stay, and 6-month patient satisfaction were analyzed.

Defect sizes ranged from 2 × 3.5 cm to 4 × 5.5 cm. The majority of patients were young male industrial and carpentry workers. Flap distribution was as follows: Type I (12 cases: 9 It, 3 Is), Type II (4 cases), Type III (7 cases: 4 IIIt, 3 IIIs), and Type IV (6 cases). Flap survival was highest in peninsular and split-skin flaps, while Type IIIt flaps showed the highest complication rate (odds ratio [OR] 5.0, p = 0.03). Overall, 79.3 % of patients reported high satisfaction at 6 months.

The FDMA flap, including its various modifications, remains a versatile and reliable option for thumb reconstruction. The proposed classification system offers a simple, clinically relevant framework to guide flap selection based on defect characteristics, which may help minimize complications and improve clinical outcomes.