4.1 Research status of flap repair for finger pulp defect
With the development of handicraft industry and the popularization of mechanical operation, hand injury, especially finger pulp defect, is more and more common in clinic, and the treatment technology is becoming mature. Hand is not only a motor organ, but also an important cosmetic organ, so the repair of hand defects strive to achieve both appearance and function. Refers to the finger pulp skin is composed of dense connective tissue, containing rich nerve endings and sensory corpuscles, and there are many vertical fibers in the dermis to fix the skin to the phalanx and deep fascia, so the skin in the pulp of the finger has low slippage, good wear resistance and sensitive sensation[8–9]. The pedicled skin flap and free skin flap used routinely in clinical practice are quite different from the skin of the finger pulp in texture and nerve distribution, and are unable to restore its sensation and wear resistance. Therefore, at present, it is the best to use the lateral flap of the toe (finger) to repair the finger pulp defect[10–13]. Due to the high difficulty of operation, great trauma and high probability of failure, some patients are unwilling to accept the free toe lateral skin flap. When the finger pulp defect combined with serious injury of the proximal middle phalanx of the finger, or vascular injury, inflammatory edema and poor skin condition, the local island flap and free flap cannot be used to repair. When the finger pulp defect exceeds the distal interphalangeal joint, the island flap of the digital artery of the same finger cannot be used for repair because of the damage of the distal digital artery arch. The vascular pedicle of the island flap of adjacent finger artery needs to be separated to the common digital artery. With a large incision, the palm will be left with a large scar, which is easy to cause scar contracture[14].
It has been reported that bridge transfer of digital artery retrograde island flap was used to repair adjacent finger defect, but additional rectangular flaps were designed at the vascular pedicle. This vascular pedicle treatment can cause a waste of finger skin. Zhang Gonglin et al.[15–16]. repaired skin and soft tissue defects of the leg with free skin flap bridge transfer: The vascular pedicle of the free skin flap was exposed and anastomosed with the posterior tibial artery of the contralateral leg, and the exposed vascular pedicle was covered with reticular skin grafting. This greatly simplifies the operation, saves the amount of skin used in the leg, and the legs can be placed in parallel, the postoperative position is comfortable, and all the flaps survive, and eliminates the concern of the vascular crisis caused by the exposed vascular pedicle. Due to the small area of the lateral flap of the finger, in order to reduce the damage to the donor area of the finger, we exposed the finger artery pedicle of the flap and covered it with a skin flap. This operation method does not need to cut the skin on the side of the finger to make a skin tube to wrap the vascular pedicle, which can greatly reduce the trauma to the donor finger, simple operation and shorten the operation time. Compared with the conventional island flap of the adjacent digital artery that needs to be separated to the common digital artery, this procedure requires a secondary pedicle amputation, but it has no collateral damage to the palm. In addition, the flap has a large contact area with the donor area, and the blood supply is reliable. The pedicle can be broken in advance, and it is easy to break the pedicle. The pedicle can be broken without suturing or with only 1–2 stitches, and the shape is beautiful[17–18].
4.2 The advantages and disadvantages of this operation
In this study, retrograde island flap bridge transfer of adjacent finger artery combined with vascular pedicle tubular skin graft was used to finger pulp defect, which has the following advantages: 1. The donor area is concealed, and the texture of the skin flap is close to the recipient area. The dorsal branch of digital nerve can be carried to anastomose with the proper digital nerve of the recipient area. The appearance of the flap is beautiful after repair, and the feeling of the finger pulp can be restored. 2. The flap with the main finger artery, reliable blood supply, fast wound healing, can be cut to take a longer vessel pedicle, easy to care, the patient's position is comfortable, and can make the finger after surgery on an axis flexion and extension function exercise. 3. The operation was performed in the same surgical field, with simple operation and no need for vascular anastomosis, and the success rate was high after operation. 4. The flap pedicle is narrow, the pedicle is easy to be cut off, the contact area is large, and the pedicle can be cut off in advance. 5. There is no damage to the proximal injury tissue of the finger body, and it will not cause necrosis of the skin and soft tissue of the finger body or even necrosis of the finger body because of new trauma. 6. Compared with other parts of the island flap, the injured finger has no open subcutaneous tunnel, and the scar is small.
However, this technique also has some shortcomings:1. The flap was cut in a small area and could only repair two fingers pulp defect at the same time. 2.It is necessary to sacrifice the digital artery on one side of the finger in the donor area. In order to restore the sensation of the flap, it is necessary to carry the dorsal branch of the digital nerve, and the sensation on the side of the finger may decrease after operation.
4.3 Precautions for surgery and postoperative management
we should pay attention to the following points when using this operation:1. The pedicle of finger artery skin flap should carry a fascia pedicle of about 0.5cm-1.0cm to facilitate venous return and pedicle skin grafting, while avoiding vascular spasm caused by artery injury. 2. Do not twist the pedicle when the flap is transferred, cover the vascular pedicle with a thin layer of skin during skin grafting, and suture with fine nylon thread to avoid damage to the vascular pedicle. 3. Do not transfer the proper finger nerve with the skin flap to avoid damaging the function of the donor finger nerve.
In summary, this paper used the retrograde island flap bridge transfer of adjacent finger artery combined with vascular pedicle tubular skin graft to repair finger pulp defect and achieved good results. It is a safe and effective operation. The flap has the advantages of simple cutting, good texture and concealed donor area, which is convenient for early functional exercise of the finger body.