Distally based cross-finger flaps for amputation stumps in avulsion amputations.

BACKGROUND: Though advances in microsurgery have resulted in better survival rates of replants, replanting crushed and avulsed digits are difficult. If replantation is not possible these digits need local tissue cover to retain length. PATIENTS AND METHODS: Twenty seven patients underwent distally based cross finger flaps for coverage of exposed vital structures over the amputation stumps.
RESULTS: All the flaps survived well. They provide good quality thin pliable tissue over the fingertips and help in achieving near normal range of movements in injured digits.
CONCLUSION: Distally based cross finger flap gives tissues of right dimensions, at the most desired site, making reconstruction of these difficult problems quiet easy.

INTRODUCTION

Distal digital replantations have become possible following advances in microsurgery. Although replantation should be attempted for all the amputated digits, sometimes it is not possible. Some relative contraindications are excessive crushing, contamination, multilevel injury, other associated injuries, and a few times due to lack of expertise. Survival rates are poor in cases of crush and avulsion amputations of digits.[1] Terminalisation of digit and coverage with locoregional flaps are the mainstay of management when replantation is not possible.

Many authors have pointed out that the amount of tissue required for coverage of near a circumferential defect at the tip is more than what is perceived.[2] The problem becomes more prominent in crush amputations with element of degloving. These injuries will have exposed bone devoid of any soft tissue at the tip. These injuries would need even more soft tissue for adequate cover and retaining the length.

Fingertip injuries have the potential for significant morbidity. There are principles on which the surgeon can base a sound management plan. The goal is to replace like with like. A stable, durable, preferably sensate cover is a deciding factor for a functional finger. Length should be preserved as much as possible, especially in the thumb. Treatment should be expeditious, simple, reliable, and cost-effective. It should take into consideration the age, gender, occupation, hobbies, hand dominance, health and needs of the patient. A thorough understanding of the limitations, possible complications and likely outcomes of the treatment options is a must. This knowledge, guided by sound judgment, can transform a potentially debilitating injury into a functional hand.

We have been using distally based cross-finger flaps (CFFs) from the dorsum of adjacent finger for coverage of these amputation stumps. It is useful when near-circumferential coverage of the defect for preserving the available skeletal finger length is required. This orientation makes the flap come from the most suitable place for comfortable post-operative positioning. Although most of the flaps have similar dimensions to that of conventional CFFs, the effective positioning makes it reach the most desired position and provide important part of the cover.

PATIENTS AND METHODS

Twenty-seven patients underwent distally based CFF for coverage of the exposed bones over fingertips from January 2010 till July 2011. The most common indication for the flap was nonreplantable crush avulsion amputations of digits at various levels with near-circumferential exposure bone at the tip. Later it was tried for 2 cases with soft tissue loss of dorsum of the digits and 2 cases with large volar defects. Demographic data such as age, gender, indication for flap cover, outcome and complications if any, were noted from the patients’ medical records.

Operative procedure

The procedure is performed under local anaesthesia and finger tourniquet control. Whole skin over the dorsum of the finger between the mid-lateral lines can be elevated as flap. After debridement, as shown in Figure 1 (a and b), the flap is planned over dorsum of the adjacent finger [Figure 1c]. The base of the flap is planned just distal to the extent of defect over the injured finger. The communication between the volar and the dorsal digital arterial systems around the joints has been well described.[3-5] We routinely try and plan the flap base around the joint so as to include this communication. Planning in reverse is done and the final flap dimensions are marked. The flap is elevated as usual CFF just above the paratenon over the extensor tendons carefully controlling the dorsal veins and transposed to cover the defect over the injured finger. No specific attempt is made to skeletonise the above-mentioned communication. Some subcutaneous tissue around the joints is preserved on the side of the injured finger to preserve these communications.[4] With the flap based distally, around 80%-90% in-setting is possible, and the excess portion can be tubed if required. The injured and the donor digits are anchored to each other with an additional suture proximally to be sure about position post-operatively. The donor site is then covered with split thickness skin graft with a tie over dressing. We usually harvest graft from the mid-dorsal aspect of the proximal forearm (so as to keep it out of site of the patient) after infiltration of local anaesthesia. The position of the flap can be adjusted precisely to avoid any tension on the flap or pedicle. Post-operative splinting was not required in any of the patients. The fingers were covered with a small dressing and additional small dressing was applied for the donor site. The average operative time has been a little less than an hour for all cases. The graft dressing (flap donor site) was opened on 7th day. The flaps were divided at 2 weeks (14 days) on outpatient basis and excess flap was replaced over the donor finger if required.

Figure 1

(a and b) Amputation of tip of index finger in a 19-year-old male (case 15) with the defect over the tip exposing bone. (c) To avoid deformity of nail, pulp and for reconstruction of the tip, a distally based flap was planned. (d) The flap was transposed and is seen sitting comfortably without undue tension and without the need of a splint

RESULTS

There were 23 male and 4 female patients with average age of 33.6 years (±12.8). Twenty-three flaps were used for covering stumps of amputated digits, whereas 2 each were used for dorsal and large volar defects. All the 27 flaps survived without any problem at the recipient site. Graft take were acceptable in all the cases. Average time taken for complete wound healing was 23.6 days (±2.9). Average size of the defect were 19 × 16 mm, whereas the average flap dimensions were 21 × 16 mm. Average follow-up period was 13 months (maximum 28 months and minimum 4 months). In all of the patients stable cover was achieved and none so far has reported any complication. The donor finger recovered full range of movements (ROM) in all the cases. Most of the patients recovered near-normal ROM in injured digits. Table 1 summarises the patient-related information, including the defect site, size, injury and the movements achieved till the last follow-up visit.

Table 1

Patient information

Cases

A 19-year-old male (case 15), presented with amputation of tip of his index finger when his finger got caught in door. Exposed distal phalanx and the defect over the tip was covered with distally based CFF from middle finger [Figure 1]. The flap settled well and the patient recovered full range of movements (ROM) as can be appreciated in Figure 2.

Figure 2

(a-d) Well-settled flap with full range of movement. The nail is short but is free of any deformity (e.g., hooking deformity)

A 18-year-old male (case 1), with worksite injury and crush amputation of index and middle fingers [Figure 3a and b]. Defect after debridement has been shown from dorsal and volar aspect in Figure 3c and d, respectively. Index finger soft tissues were re-arranged and the remaining defect was covered with volar V–Y flap [Figure 4a]. Middle phalanx of middle finger can be seen exposed over the stump. As can be appreciated in Figure 3d, the base of middle phalanx was uninjured with intact motors. Distally based flap was used to cover the defect [Figure 4a]. The flap settled well without any complication. Three weeks post-operative and long-term results have been shown in [Figure 4b–d. His movements, two and half years following the surgery have been shown in Figure 5a–d. The donor site colour match, the flap colour, and texture and the durable cover can be appreciated. He has got protective sensations with static 2PD of 6 mm and has been able to use the hand for all his activities.

Figure 3

(a and b) Machine crush injury in an 18-year-old male (case 1) from volar and dorsal aspect (c and d) following the debridement the middle phalanx of middle finger was found to be completely devoid of soft tissues. The index finger had segmental defect

Figure 4

(a) Immediate postoperative photo following the flap inset. Index finger defect was covered with a V-Y flap while that on middle finger with distally based cross-finger flap (CFF). (b, c) showing the extent of the flap over the dorsal and the volar aspect and well-settled donor site after 3 weeks. The flap over the index finger (V-Y) also has settled well. The donor site raw area is similar to that of a conventional CFF, and has been shown by arrows. (d) shows long-term result in the same patient

Figure 5

(a-d) Long-term results and the range of movements at individual finger joints. Soft and supple tissue, durable cover without any complications and excellent colour and texture, match of both the donor and recipient site can be appreciated

A 63-year-old man (case 18) presented with avulsion amputation of his thumb when his thumb got caught in rope while controlling cow. The amputated part was crushed and was not suitable for replantation. He had exposed distal phalanx over the tip of the stump. Distally based CFF from index finger was used to cover the defect [Figure 6]. He recovered near-normal movements of his thumb while there was normal function of his donor finger [Figure 7]. Video enclosed along shows the donor and recipient digits in motion (video 1).

Figure 6

A 63-year-old male (case 18) presenting with nonreplantable thumb tip amputation. (a-d) Sequentially summarises the injury, the planned flap, the flap being executed and the final in-setting

Figure 7

The donor and the recipient site from the volar and dorsal aspect can be seen in a and b, respectively. The patient could achieve near-normal movements of donor and the injured finger within 4 weeks as can be seen in (c and d)

A 22-year-old male with defect over thumb distal phalanx with partial loss of nail plate and bed including part of root (case 5) and a 34-year-old male (case 7) with complete loss of dorsal soft tissues over DPX of little finger following knife cut injury were successfully resurfaced with the distally based flaps. The donor and recipient site functions can be appreciated as shown in Figure 8.

Figure 8

Details of 2 patients with dorsal defects. Pictures (a) and (b) are showing defect over the DPX of thumb (case 5) that was reconstructed successfully with distally based cross-finger flap from index finger, whereas c and d are showing defect over the DPX of little finger (case 7) successfully reconstructed with flap from ring finge

A 23-year-old male with complete soft tissue degloving of right thumb exposing distal phalanx following blast injury. A flap from index finger was planned and executed [Figure 9]. The flap settled and as can be seen the patient did not require any splint after the surgery and was having near-normal movement of donor finger on 3rd post-operative day [Figure 10a and b]. After flap division he recovered full ROM in the donor digit while the flap on thumb was settled well [Figure 10c and d]. In Figure 11 full ROM both in donor and recipient digits, minimal donor morbidity, and excellent soft tissue contour of the distal phalanx of thumb can be appreciated.

Figure 9

A 23-year-old male with blast injury of both hands. He had soft tissue degloving over distal phalanx of right thumb (a and b). A flap from index finger was used for cover (c and d)

Figure 10

The hand was left without splint postoperatively (a and b) and after division of the flap the index finger recovered movements very soon (c and d)

Figure 11

The final colour and texture of both donor and recipient site and the movements were near normal

DISCUSSION

Replantation is ideal treatment of amputated digits when the facilities are available. Although some recent publications have shown favourable results following avulsion amputations and crush amputations in selected cases,[1] failure rates are high. Numbers of publications still include these in the list of contraindications for digital replantation.[6] When replantation is not possible, retaining as much length as possible is the next best option.[78] This warrants soft tissue cover of sufficient dimensions to cover exposed bone at the tip.

Possible local options for coverage of exposed phalanges over the fingertips include the CFF, thenar flaps and volar advancement flaps such as TranquilliLeali, Segmuller flap and Venkataswami flap.[29] Local flaps in the hand though, should be chosen carefully taking care not to borrow too much tissue, achieving early primary healing and promoting early motion; as pain may prevent patient from using his hand. Conventional CFF works well for the volar defects but has insufficient dimensions for covering near-circumferential defects and needs uncomfortable positioning in case of terminal digital defects. For dorsal defects the modification of CFF by Thatte et al. (i.e, de-epithelialised CFF)[10] works equally well. for dorsal defects but again has insufficient dimensions for larger defects. Thenar flaps cover the fingertip defects over distal phalanges. Thenar flaps have multiple limitations: (1) Proximal level amputations cannot be made to reach thenar area; (2) Width of the flap has to be limited for primary closure of donor site; (3) Donor site scar in the palm can remain tender; and (4) Finger stiffness due to unphysiological position. Volar advancement flaps are more suitable for dorsal oblique defects and do not have sufficient dimensions for circumferential defects. Multiple variations of distally based flaps also have been described – mainly distally based adipofacsial flaps,[9] distally based island flaps[4] and distally based flaps from hemidorsum[5] – but all have limitations of tissue available for coverage of circumferential defects.

Distant pedicle flap options for coverage of fingertip defects are groin flap, sub-axillary and abdominal flaps. This is much extensive exercise for small-and medium-sized fingertip defects. We feel that these should be preserved for larger defects. Although these flaps provide tissue of adequate dimension, they have multiple disadvantages, such as (1) Hand needs to be attached to the donor site for extended period of time; (2) The flap is always bulky and needs de-bulking procedures; and (3) Colour and texture of skin is different than local flaps. Other possible option could be a free tissue transfer. Free tissue can provide tissue of exact dimensions at the most desired site and also can potentially be colour and texture matched and sensate. This surgery is technically demanding and costly when compared with local flaps.

Distally based CFFs proposed in this study were planned in such a way that the base of the flap is just distal to the defect. The level of injury and the condition of adjacent fingers were assessed before the surgery. The flap can be safely harvested even from an injured finger if the adjacent finger has got amputated at a sufficiently proximal level than the donor finger. Presented flap design has the following advantages: It provides well-vascularised tissue at the most desired place and avoids wastage of tissue in transit to the defect. Flaps of smaller dimensions can be planned to avoid donor site morbidity and still providing adequate cover. The fingers lie in their normal resting position reducing un-physiological positioning of digits and tension over the flap. This also eliminates the need for any splint. All the flaps done in this series survived, suggesting good vascularity of the flap even if it is harvested from whole dorsum of digit (between two mid-lateral lines), unlike suggested by some authors.[5] Back cut can be given up to dorsal midline of the digit in case the flap is not reaching the defect.

This flap can be very useful in few other situations. This flap can easily cover dorsal digital defects if the adjacent finger is sufficiently long. They can be transposed without de-epithelialisation, and thus would reduce the operative time as shown in 2 cases in Figure 8. In cases of large volar defects or irregular defects where planning a conventional CFF is difficult, distally based CFF has better reach and orientation. Additionally, while the conventional CFF has limited area available for in-setting, modified flap allows near complete in-setting and thus can help in achieving complete coverage of exposed vital structures. The most distinct advantage of this flap design is its versatility, making the flap of conventional dimensions to reach and cover large defects adequately. Donor site morbidity in the form of colour variation and contour deformity were explained to the patients preoperatively in later part of the series, patients still preferred local flaps over distant flaps. The flap provides durable cover, with good quality, soft and supple local tissue. The terminal part of the fingers (now lined by the flaps) are usually the pressure-bearing points, still none of the patients came with problems commonly noted in insensate fingers, such as burns, injuries, pressure-related blisters, and ulcers. Though have not tested sensations objectively, we believe that patients must have regained at least protective sensations over the flaps.

In this series of patients, flap division was always done as outpatient. As the base of the flap is very small, division is a minor procedure making it a virtually single-stage operation. At the time of flap division we mobilise all the joints of the attached digits under local anaesthesia. As the position is more physiological, none of our patients experienced stiffness of fingers. With dark complexion of our patients the dorsal grafts settles well; what remains is a mild contour defect. In patients with fair complexion the split graft over donor site may become obvious; full-thickness grafting would be a better alternative in those patients. Also early scar massage and silicon-lined pressure garments would help reducing this scar.

For dorsal defects this flap is technically easier than a reverse CFF as it doesn’t need de-epithelialisation of the skin. It also has better vascularity than such adipo-facial flaps. Other options like cross-digital island flaps have the potential of being sensate but it requires extensive dissection and neurolysis of the fascicles supplying the flap from the rest of the nerve. The dissection has to be continued in the web and additionally one sacrifices one side digital artery. This morbidity of extra dissection we feel is unwarranted as thin tissue of dorsal digit usually regains protective sensations.[8]

CONCLUSION

The distally based CFFs provide durable cover of suitable dimensions at a most appropriate area, enabling the salvage of the skeletal length of amputated digits without undue donor site morbidity.