Improved Abdomen Hypodermic Embedding for Salvage of the Amputated Fingertip from Tip to Lunula (Tamai Zone (cid:0) )

Background To explore the clinical ecacy of a new surgical approach called improved abdomen hypodermic embedding for salvage of the amputated ngertip from tip to lunula (Tamai zone (cid:0) ). Methods From September 2015 to June 2017, we treated 18 ngertips from 15 patients with abdomen hypodermic embedding while all the ngertips were completely amputated and failed to vascular anastomose. After 3 weeks, all the ngertips were taken out from abdomen. After 6 months, outcomes were evaluated with DASH score and static two-point nger discrimination. Results 16 ngertips survived completely, 2 ngertips developed partial loss and scar healed by dressing change. All patients were satised with the appearance of the ngertips while one woman was not satised for ischemic atrophy. The DASH score ranged from 35-46 (average 38), static two-point discrimination was 6--14mm (average 8mm). Conclusions When improved


Background
The hand is the most commonly used organ in daily life and the most vulnerable part for injury. The ngertip is the most important sensory part of the hand. It has a structure such as a nail, which has an important in uence on the pinching and appearance. Amputated ngertip from tip to lunula is common in the emergency department. It usually occurs due to cutting, squeezing, and crushing.
There are many treatments for amputated ngertip: wound care, revision amputation, in situ suture, replantation, ap repair and reconstruction. The amputated ngertip with minor soft tissue defect and without bone exposure can be treated with wound care [1]. It is simple but it cannot treat the severe cases. Revision amputation deserts the amputated section and repairs the residual. It is simple and practical but the nger shortens which means poor function. In situ suture keeps the nger from shortening. However, the survival rate is low and the appearance is atrophic because there is not enough blood supply for the amputated section. Flap repair can ensure that the nger will not shorten, but there are also many kinds of drawbacks such as poor appearance, large damage, and poor recovery of the ap. Reconstruction is rarely used because of the large trauma and the uncertain survival rate. The replantation technique of reconstructing the blood supply is the best choice. However, the anatomical factors, the technical ability of the doctor, the soft tissue conditions and patient selection affect the ngertip survival.
Some scholars such as Wang Bin [2] proposed a novel treatment. They conducted abdominal hypodermic embedding after de-epithelialization, sutured in situ without Kirschner wire xation. Satisfactory appearance and function were obtained. Therefore, in the study, we aim to improve it to explore a relatively simpler and more general approach with higher survival rate, better appearance, less shortening, less cost and higher patient satisfaction. There were various reasons for the inability to perform vascular anastomosis. All patients signed informed consent before surgery.
Our surgery was divided into two parts: emergency surgery and second-stage surgery.

Emergency surgery
Local anesthetic 2% lidocaine was given. After thorough disinfection, the nger root was tied with rubber strips to stop bleeding. After repeated washing with physiological saline and hydrogen peroxide, the ngertip was immersed in 0.02% chlorohexidine for 5 minutes and debrided under the microscope. Probe and mark the vascular and nerve. If the vascular anastomosis could not be performed due to the vascular defect or the distal part avulsion, the epidermis of the amputated ngertip was removed. A scalpel was used to remove the epidermis to the dark purple dermis. The fracture end was properly trimmed and the 9 − 0 or 10 − 0 Plylin was used to suture nger nerve. The broken nger was loosely sutured in situ with the 4 − 0 Plylin and the Kirschner wire xation was not used. Local anesthesia was injected on the ipsilateral abdomen and the incision made was slightly wider than the transverse diameter of the broken nger to reach the subcutaneous fat layer. The subcutaneous fat was bluntly separated to accommodate the distal end of the broken nger. Then, the proximal end of the nger was sutured to the abdomen with the 4 − 0 Plylin. Second-stage surgery 3 weeks after emergency operation, sutures were removed and the nger was removed from the subcutaneous fat space of the abdomen under local anesthesia. The surface was covered with a large amount of granulation tissue, and the excess granulation tissue was appropriately trimmed with reference to the surrounding residual epidermis.
Burn cream was applied to keep the nger wet. The ngertip was exposed without gauze and disinfected every 2 days. The granulation tissue was trimmed again if necessary. Postoperative routine anti-infection, circulation invigorating, shoulder, elbow and wrist joint function exercise were conducted.

Results
There were 9 males of 10 ngers and 6 females of 8 ngers with aged between 25-56 years old with an average age of 41 years. Among them, 8 cases of 9 ngers were of cut, 3 cases of 4 ngers were of crush injury, and 5 cases of 5 ngers were of punching injury, which gave a total of 2 Thumb nger, 9 index nger, 6 middle nger, 1 ring nger. The time from injury was between 1-6 hours, with an average of 2.3 hours.
In this sample, the ngertip healed about 2 weeks after second-stage surgery. 15 cases of 18 ngers all survived, and 2 cases had partial soft tissue necrosis at the time of removal. About 4 weeks after the removal of the broken ngers, all of them epithelialized. One female patient was dissatis ed with the appearance due to atrophy of the ngertip, and the remaining patients were satis ed. After six months, DASH [3] scores ranged from 35-46, with an average of 38 points. According to the Chinese Medical Association upper limb function evaluation trial standard, excellent performance was recorded in 9 cases, good in 5 cases, and general in 1 case [3]. The patient's static two-point nger discrimination was 6-14 mm, with an average of 8 mm.
Typical case: Patient, Chen XX, male, 39 years old, was admitted to the hospital in emergency due to cable twist trauma 2 hours after the accident. Physical examination: The left index nger was completely amputated from radialis middle part of the nail to the ulnaris distal part. The bone was exposed and the soft tissue was severely crushed. The radialis digital artery could not be found after debridement under the microscope. After the patient's consent was obtained, the epidermis was removed and the ngertip was embedded in the abdomen. The nger was removed from the abdomen 3 weeks after the operation, and the broken nger survived well. After 3 months, the appearance was similar to the uninjured and the function was good. (Figs. 1-8)

Discussion
There are many treatments for amputated ngertip: wound care, revision amputation, in situ suture, replantation, ap repair and reconstruction [4,5]. The amputated ngertip with minor soft tissue defect and without bone exposure can be treated with wound care [1]. Revision amputation is a simple and practical method. It can achieve almost normal sensibility and satisfactory motion [6]. However, it also has many disadvantages, such as frequent cold intolerance [7], painful neuroma formation [8], shortening of the ngers and poor appearance. It cannot be accepted by many Asians especially female patients.
Some scholars believe that if condition of the disconnected ngertip is good and the wound is at, the success rate of in situ suture can reach more than 60% [9]. However, in actual clinical situations, it is often unsatisfactory. The success rate is extremely low because of seriously grinded soft tissue.
Moreover, the disconnected ngertip atrophies for lack of blood supply. The above three methods all result in shortened ngers and atrophy which cannot be accepted by Asians for cultural factors [10]. Their satisfaction with the operation largely depends on appearance such as length and the nail maintaining [11,12]. It means that their obsession with appearance outweighs their need for function. Sometimes this obsession manifests itself simply as a desire for physical integrity, even if both the appearance and function are poor.
The ap repair can ensure that the nger will not shorten, but there are also many kinds of drawbacks such as poor appearance, large damage, poor sensitivity [7] and poor mechanical properties of the ap. Reconstruction of blood supply by microsurgery is still the best treatment at present, but the technical di culty is high, especially the identi cation of vessel ends, anastomosis of the submillimeter vessels and ngertip's highly specialized anatomy [13]. Moreover, the appropriate conditions for the amputated nger are also required [14,15].
For ngertips which vascular anastomosis cannot be performed, scholars have adopted various techniques. We once successfully replanted amputated ngertip (Tamai zone ) without venous anastomosis, all of which were treated with artery-only anastomosis and postoperative venous out ow [16]. Emin Sir introduced a novel method called reposition ap repair, which could preserve the length and sensory functions of the ngertip [17]. Akito Nakanishi discovered that reconstruction using a digital artery ap and microsurgical replantation were comparable regarding postoperative activities of daily living and hand performance, but reconstruction gave better objective functional outcomes such as strength, digital sensitivity and nger mobility [18]. Although the above method is effective, the large trauma to the nger and the bloated appearance are also unsatisfactory. Wang Bin et al [2] took the lead to report in China that the subcutaneous embedding method was used to treat the distal segmental disconnection. Many scholars have improved it and achieved satisfactory results in this technology. Like abdomen hypodermic embedding, some scholars used other nger [19] or palm [20] to foster the smaller amputated ngertip. All of them have their respective advantages and disadvantages.
The bilateral digital arteries beyond the distal deep exor tendon insertion form the distal transverse arterial arch, then give off branches [21]. The distal digital dorsal veins in the proximal nail root con uence into the terminal veins. Palmar digital veins only exist in the nger pulp or the slant ulnar side and the outer diameter is wee. According to this feature, the Tamai partition method divides the ngertip into two zones, the Zone I: the lunula (methyl) to the nger end; the Zone II: the distal interphalangeal joint to the lunula (methyl) [22]. All of our cases were belonged to Zone I. Combining the above various methods and improving them, we have adopted the method of de-epithelial embedding to provide an effective surgical method for the distal injury beyond the lunula.
The early survival of the amputated nger can be achieved through the exchange of plasma and dialysate in the abdomen, as well as the penetration of the bone marrow cavity blood. Similar to the abdominal subcutaneous fostering, the survival of the amputated nger was ensured, and the formation of capillary network gradually establishes blood supply. In the previous abdomen hypodermic embedding methods, it was usually xed with a fracture reduction and Kirschner wire, and then embedded in the palm, forearm or abdomen. We improved it in the following aspects. Firstly, we did not recommend the use of Kirschner wire for xation, which is one of our strengths. For the amputated ngertip from tip to lunula, the demand of Kirschner wire xation is not very high. When it does not cross the distal interphalangeal joint, it is easy to loosen and slip off after 3 weeks. When the joint is xed, the joint stiffness is easy to occur. Long-term Kirschner wire internal xation increases the likelihood of infection.
Though there was no Kirschner wire xation accompanied by a risk of fracture nonunion, there was no painful discomfort during follow-up. Secondly, we sutured the abdominal skin with amputated nger at 2 mm proximity from the wound instead of at the distal or proximal interphalangeal joint surface.
Excessive soft tissue containment is unnecessary and it increases the likelihood of infection and joint stiffness. Considering that ipsilateral abdominal embedding can better help perform functional rehabilitation of shoulder and elbow after surgery, ipsilateral abdominal embedding was adopted to replace contralateral abdominal embedding. Among the 15 patients we treated, 2 patients had necrosis of some soft tissues during the second operation. The possible reason of oversized nger or excessive soft tissue squeezing was not ruled out. However, both of them scarring healed after the dressing change.
The purpose of surgery is to restore appearance and function, so postoperative rehabilitation is as important as surgery. Many patients fail to perform rehabilitation in time, resulting in tendon adhesions and joint stiffness. It is recommended to start the functional exercise of the shoulder and elbow joint on the rst day after emergency surgery. After the second operation, rehabilitation can be gradually transited from the passive activity to the active activity. All of our patients didn't remain movement disorder.
To sum up, we believe that subcutaneous embedding method can integrate the advantages and disadvantages of all aspects. When the replantation of amputated nger cannot be performed due to poor soft tissue conditions, it can feed the amputated nger to the greatest extent, so as to save the amputated nger. And for ngertip defects, we do not recommend the use of ap repair. The ap is bloated and poor in appearance, which hinders the postoperative functional recovery especially the ne motor. At the same time, the sensory function of donor skin is not as good as ngertip skin, and nerve regeneration is di cult. All of them lead to the dissatisfactory recovery of ngertip sensory function after surgery. Moreover, the ap has a great damage to the donor area, poor resistance to compression and abrasion, intolerance to physicochemical stimulation and di culty to bear the function of nger.
Whereas, removing the epidermis and embedding on the abdomen can perfectly solve these problems. Since the dermis is not damaged, the new epidermis is almost the same as the original ngertip skin, which can replace the original ngertip skin in appearance, mechanical characteristics and motor functions. In addition, after half a year of follow-up, we found that there was little effect on the static twopoint discrimination for the neurorrhaphy, and some scholars also had similar views through research [23,24].
Our surgical method is convenient, reliable and it is suitable for primary hospitals. However, there are also some shortcomings. There were 2 cases of soft tissue necrosis which scarring healed after the dressing change. It was probably because both of their amputated ngertips were larger, which wound reached the vicinity of lunula. We embedded the ngertip for 3 weeks according to abdominal pedicled ap, but our embedding didn't need vascularization. Therefore, we cannot be sure if the embedding time could be shortened without avascular necrosis. The level of amputation which can survive through the abdomen embedding has not been reported in china or abroad. Our follow-up time was also a little short, the recovery, appearance and sensory reconstruction also required further follow-up observation.

Conclusion
When vascular anastomosis is not feasible in ngertip replantation, improved abdomen hypodermic embedding is a simple and feasible operation for the amputated ngertip from tip to lunula.