Various trauma often leaves the hand surgeon with a complex defect in the hand, and the small defect (especially multiple digital defects) is always challenging for reconstruction. The ideal reconstruction of digital defects is the preservation function of hand as much as possible, meanwhile, providing an aesthetic appearance both in recipient and donor region. So among the various options for reconstruction of small soft tissue defects in the fingers, the free flaps have been recognized as the best reconstructive option.[1–3]
The radial forearm flap has been first descripted by Yang in 1978,[10] and this pedicle flap has been established its role in plastic reconstructive field by surgeons.[13–15] Howerer, either free or pedicle radial forearm flap remains the main disadvantage is that the sacrifice of a major artery to the upper extremity. Generally, sacrifice of the radial artery doesn’t cause an ischemic problem unless the ulnar artery has been previously injuried in the upper extremity. However, several studies have reported serious complication (eg. hypothenar hammer syndrome; dry gangrene of fingers) after harvesting a radial forearm flap.[19–20] Based on the the anatomical study of proximal perforators of radial artery in forearm,[11–12] Lin and Omer attempted preliminarily to havest this perforator free flap in order to preserve of the radial artery in clinic,[16–17] and then there are few literature to describe and use the proximal perforator from radial artery of forearm for free tansfer. We design this study is to locate a constant anastomosable perforator of radial artery on the proximal forarm using ultrasonography, and then raise a free flap based on this single perforator in clinical cases to assess the flap’s potential application for reconstruction of the digital soft tissue defect.
Several previous studies about the perforators analysis of radial artery have confirmed that two main clusters perforators (≥ 0.5 mm diameter; distal cluster and proximal cluster) in forarm could be potentionally used for flap transfer in clinic.[11, 14] Michel et al. have futher detamined that the proximal cluster perforators of radial artery located at a distance of 61.7 percent along the radial styloid-to-lateral epicondyle interval in an anatomical cadaver study. The perforators
reveal no statistical difference in either radial or ulnar distribution originated from the radial artery. In our study, an anastomosable perforator originated from the radial artery can be always detected in all volunteers’ proximal forarm. This perforator location at about 8.8 cm far from the elbow crease, and the relative distance is about 37.2% along the elbow crease to wrist crease interval, which is consistent with the previous study. Furthermore, this perforator is an intermuscular septal type coursing between the brachioradialis and the pronator teres muscles, and the pedicle length is 12 mm, the internal diameter is 0.7 mm under ultrasonography. These ultrasonography data illustrate the perforator is consistently located at the radial artery in the proximal half of forarm, and designing a free flap based on this single perforator could be achieved. Furthermore, the diameter of the perforator can match with digit artery well in the reconstruction of finger. The multiple superficial veins in forarm can be harvested as an alternative donor vein for venous drainage. Our study is also proved the importance of ultrasonography preoperatively. Ultrasonography is an simple and noninvasive inspection method to locate an small perforaor for desiging a flap. So we suggest the perforator inspection and location using ultrasonography should be an routine examination before a flap operation.
How much aera could the free flap based on a single perforator of radial artery be done? According the anatomical study about proximal perforators of radial artery, several perforators coming off the radial artery travel to the skin and form linking networks with each other along the radial arter as axis (about 2 cm wide).[11] This network of vessels between the fascia and the dermis ensure the adequate blood supply for designing a long free flap(10 cm-18 cm reported by Lin JY[16]), meanwhile, the wide of free flap is limited (usually ≤ 4 cm). This shape feature of an oblong flap is especially suit to reconstruct the defect in long finger. There are some other more advantages of the radial artery proximal perforator free flap: fitstly, the single perforator flap haversting preserves the radial artery avoiding the potentional ischemic problem of upper extremity; secondly, the flap can provide the similar colour and texture match and aesthetic apperance of the finger; thirdly, the lateral antebrachial cutaneous nerve can be havested into the flap to recovery excellent sensory of finger; lastly, the operation can be one stage performed in a single operative field.
There are also some disadvantages of the radial artery proximal perforator free flap, including: non-concealed enough morbidity in donor site, bulkiness of the flap in the reconstructive finger, dissection and anastomosis of microvessels. The main morbidity in donor site is the presence of a longitudinal scar in the forarm, so the patients in our study evaluate the flap as an average grade of ‘somewhat satisfied’ during a period of 12 months follow-up. Due to the small diameter of perforator (0.7 mm), meticulous dissection is required for flap elevation, and anastomosis requires supermicrosurgical skills.
There are several limitations in this report. First, we could not perform objective examination for precise marking the perforator directly and evaluating blood supply area of a single perforator. Second, the population sample is not large enough in ultrasonography study, and the clinical implications of radial artery proximal perforator free flap are limited.