First web-space defect—a common sequela of hand trauma—can be caused by injuries, burns, paralysis, and infection. This defect has a profound adverse effect on the hand function, as even a slight contracture will result in decreased thumb mobility. The present study investigated the usefulness and postoperative outcomes of a novel, modified SDMA flap technique to treat first web-space soft-tissue defects in eight patients. This modified technique conferred good postoperative outcomes and an acceptable esthetic appearance. The donor area was closed directly in two cases, while those in six cases were resurfaced with skin grafting. The modified SDMA flap technique is timesaving, without causing any flap loss. Moreover, neither flap necrosis nor a web contracture was seen.
When selecting donor sites for the reconstruction of the web-space, the hand itself is preferable to other sites due to various advantages, including “like-with-like” tissues, superior recovery of sensitivity, and the requirement for a limited surgical area in a single anatomic region. Therefore, pedicled flaps remain important in reconstructive first web-space surgeries. The first dorsal metacarpal artery flap was commonly used for web-space defects(15, 16). Doğan described new bio-geometric designs of first dorsal metacarpal artery flap—bilobed or V-Y advancement flap—to reconstruct soft-tissue defects of the first web-space and the proximal dorsal thumb(17). This technique is generally indicated for complex defects. The contraindications of this technique include overlapped injuries to the donor region or to the pathway of the first dorsal metacarpal artery. The first dorsal metacarpal artery flap is also limited by the small size (up to 4 cm), which may not be large enough to cover most of its hand defects(18). Zhang et al. described the use of the SDMA flap to repair thumb defects. The flap sizes ranged from 3.5 cm × 3 cm to 3 cm × 3.5 cm(19). If the flap goes beyond the proximal interphalangeal joint, the flap survival may not be reliable. This technique is more suitable for the coverage of small-sized web-space defects. Zhu reported the use of bilobed SDMA-based island flap for the reconstruction of complex soft-tissue defects around the MCP joint of the thumb, which was harvested from both the index and long fingers(20). The average size of the flaps from the index and long fingers was 2.6 cm × 3.4 cm and 2.8 cm × 3.2 cm, respectively. However, the disadvantages include a relatively complicated procedure and partial sensory impairment at the donor fingers.
To our knowledge, only a few studies have previously reported the use of SDMA flap to cover first web-space defects. Presumably, the limited flap width may restrict its use for larger defects involving the first web-space. However, our technique could offer a reliable chance for the reconstruction of the first web-space defects. The flap margins were outlined proximally and distally to preserve the dorsal skin of the MCP and carpometacarpal joints, respectively, and between the marginal lines of the first and fourth metacarpals. The cutaneous perforators of the SDMA have consistent ascending and descending branches. The adjacent ascending branches were anastomosed with the adjacent descending branches to form the axis of the cutaneous chain, which was parallel to the SDMA(14, 21). Notably, there is a consistent anastomosis between the dorsal metacarpal arteries to form the transverse arterial network. Usually, the flap pedicle is sufficiently wide to cover the recipient area without any tension(14). In this study, 4 × 6-cm flaps were harvested. Moreover, the flaps were narrowly rotated (by over 90°) to cover the web-space defect and to reduce the risk of venous insufficiency. This flap is reliable and versatile, simple and fast, has low donor site morbidity, and provides acceptance appearance cosmetically.
The advantages of this technique are the extended flap length and width, small rotation, low donor site morbidity, appropriate flap thickness, a low rate of flap failure, and almost near-physiological skin texture at the recipient area. Moreover, postoperatively, during the follow-up period, the patients’ thumbs had the freedom of movement in any direction, and there were no sensorial complaints of the resurfaced anatomical parts. However, our study had a limited number of patients to assess the effectiveness of our flaps.