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Ring avulsion injuries managed with homodigital and heterodigital venous island conduit (VIC) flaps
RING AVULSION INJURIES MANAGED WITH HOMODIGITAL A N D H E T E R O D I G I T A L V E N O U S I S L A N D C O N D U I T (VIC) FLAPS E C. BEHAN, A. V. CAVALLO and P. TERRILL
From the Department of Plastic, Reconstructive and Hand Surgery, WesternHospital Melbourne, Australia Ring avulsion injury frequently results in vascular insufficienc~ (venous or arterial) and soft tissue injury. We report four cases requiring revascularization where( venous congestion and dorsal skin cover were achieved using a composite pedicled venous flow-through flap. We have termed this a Venous Island Conduit (VIC) Flap. Two types of flaps, homodigital and heterodigital, were used, depending on the severity of the injury. The techniques and results are discussed. Venous island conduit flaps are ideally suited to the management of ring avulsion injury and have several advantages over the alternatives. Journal of Hand Surgery (British and European Volume, 1998) 23B: 4:465-471 method is that vein grafts are not required; instead, flap veins are used, supported by surrounding connective tissue that is thin and pliable yet strong and well vascularized.
Ring avulsion is usually caused by accidently catching the ring on a fixed object and transmitting the body's weight through it whilst falling or jumping from a height. The spectrum of severity has been classified by Urbaniak et al (1981) and a later subclassification was proposed by Kay et al (1989) (Table 1). The more complex avulsions have generally resulted in a poor outcome due to soft tissue contracture and proximal interphalangeal (PIP) joint stiffness. In view of this, we felt it desirable to develop a technique which would achieve supple skin cover and correct venous insufficiency whilst minimizing donor site morbidity. We report four cases in which the problem of simultaneously providing venous reconstruction and well vascularized, pliable soft tissue cover was solved using a composite pedicled venous flow-through flap. The donor site in two cases was the proximal digital skin advanced as a triangle, relying on venous in- and outflow; a homodigital Venous Island Conduit (VIC) flap. In a further two with more extensive damage, an island of skin from the dorsum of the adjacent digit (protected from the avulsive force) was used, pedicled proximally on the dorsal intermetacarpal veins and then transposed to the dorsum of the ring finger; a heterodigital Venous Island Conduit (VIC) flap. In all cases, the congested veins of the degloved digit were then anastomosed to the distal channel ends in the venous flap, which then acted as conduits for the venous blood flow. The advantage of this
CASE REPORTS Homodigital VIC flaps
Case 1 A 37-year-old teacher, suffered a degloving injury to the right ring finger when he jumped from a trailer, catching his ring on a bolt as he fell. Examination revealed that the digit was congested with a brisk capillary return and altered sensation. The middle phalanx was fractured in its distal portion. Debridement was performed and both digital neurovascular bundles were seen to be intact (Kay class 111 v). The fracture was stabilized with K-wires and primary closure of the dorsal defect was achieved by advancement of a homodigital triangular flap, 3 x 2 cm, of proximal dorsal skin abutting the debrided defect (Fig l a) and two venous anastomoses were performed. The donor defect was closed in V-Y pattern and soft tissue healing was rapid (Fig lb).
Case 2 A 47-year-old man caught the ring on the right ring finger on a pipe as he fell from a ladder, dividing all structures except for the flexor digitorum profundus tendon at the midlevel of the middle phalanx (Kay class III). 2.5 cm of the dorsal digital skin was lost to the level of the middle of the proximal phalanx and the digit was devascularized. A fracture of the base of the middle phalanx was fixed with an axial K-wire and the radial and ulnar digital nerves were repaired directly as was the ulnar digital artery. The dorsal defect was too great to allow repair of skin and dorsal veins directly and so a 4 x 2 cm long homodigital triangular flap, with its apex just proximal to the third web, was mobilized from the surrounding tissues except for those veins coursing through it (Fig 2a). It was advanced to close the dorsal defect and two
Table 1--Ring avulsion injuries (modified from Kay et al [19891 and reproduced by the kind permission of Churchill Livingstone Inc., New York)
CLASS 1 CLASS II
CLASS III
CLASS IV
Circulation adequate Circulation inadequate, no skeletal injury (a-arterial insufficiency only) (v-venous insufficiency only) Circulation inadequate, skeletal injury (a-arterial insufficiency only) (v-venous insufficiency only) Complete amputation/degloving 465
466
Fig 1
THE JOURNAL OF HAND SURGERY VOL. 23B No. 4 AUGUST 1998
Case 1. (a) Homodigital Venous island conduit (VIC) flap before advancement. Note background highlighting distal flap vein. (b) Healed homodigital VIC flap (outlined by dots) on right ring finger at 3 months. DIP has extension deficit.
congested veins in the distal digit were anastomosed to the veins in the advanced flap, satisfactorily relieving the problem. The donor defect was closed in a V-Y pattern (Fig 2b). Healing was a little delayed distally due to incomplete ddbridement of the injured digit, however PIP joint function was satisfactory (Figure 2c).
Heterodigital VIC flaps Case 3
A 39-year-old left handed truck driver, caught the left ring finger on the tailgate of his truck while dismounting. Examination showed gross destruction of the proximal half of the dorsal digital skin. The distal part of the finger was cyanotic and congested (Fig 3a). Sensation was normal. There was loss of extension at the proximal and distal interphalangeal joints. X-Ray showed no fracture but there was disruption of the DIP joint. D6bridement of the devitalized tissue resulted in a dorsal defect, 2 x 4 cm, with exposed and damaged tendon and proximal interphalangeal joint. The circumferential laceration had caused complete division of the venous drainage of the digit, with division of the ulnar digital artery; however both digital nerves and the radial digital artery were intact (Kay class 11 lv). The DIP joint was stabilized with axial K-wires. The dorsal veins of the distal segment were dissected to expose three proximal ends. A longitudinally oriented elliptical venous flap, 2 x 6 cm was then planned on the dorsum of the adjacent middle finger extending from the dorsum of the hand and crossing the PIP and MP joints. The pivot point was placed just proximal to the third web (Fig 3b), adjacent to the metacarpal necks, in the region
of the deep metacarpal perforating vessel. The flap was elevated just above the paratenon, commencing distally, and proceeding proximally toward the dorsum of the intermetacarpal head region where the veins were preserved. The dermis was divided completely and the proximal dorsal venous channels were carefully preserved in a cuff of adventitia, except for one lateral vein which was divided to allow adequate transposition (Fig 3c). The flap was then transposed on to the dorsum of the ring finger where the proximal intact skin bridge on the dorsum of the hand was split to allow insetting of the flap. Anastomoses were then performed between the two largest draining venous channels in the degloved digit and the two largest channels in the distal end of the flap using 10/0 nylon interrupted sutures. The overlying wound was closed directly without tension as was the laceration on the palmar aspect of the finger, and the donor site was covered with a full thickness graft (Fig 3d). Postoperatively, venous circulation rapidly stabilized and the wounds healed swiftly. PIP movement could be commenced early as a result. Long-term follow-up confirms durable, pliable soft tissue cover with full range of movement of PIP in both ring and middle fingers (Figs 3e, f). Case 4
A 30-year-old man caught his wedding ring on a post when attempting to climb over a fence, resulting in a Kay class 111 ring avulsion injury. This involved a circumferential laceration with complete division of both digital arteries and all veins. The digital nerves were stretched but intact. There was a dorsally angulated fracture through the neck of the middle phalanx. The flexor and extensor tendons were intact.
RING AVULSION INJURIES
Fig 2
467
Case 2. (a) Congested digit with Homodigital VIC flap planned on proximal digital skin. (b) VIC flap advanced to close soft tissue defect with resolution of the congestion following single level flap vein anastomoses. (c) Kay class 111 ring avulsion injury, displaying flexion 4 months after operation.
At operation, the fracture was reduced and stabilized using K-wires. The radial digital artery was repaired with a vein graft and palmar soft tissue cover was achieved with direct apposition, but there was insufficient dorsal skin following d6bridement to achieve primary closure and to relieve venous congestion. A venous island conduit flap was raised from the dorsum of the adjacent (undamaged) middle finger (Fig 4a) and transposed to the dorsum of the ring finger, pivoting proximally on the third web (Fig 4b). Two single level venous anastomoses were then performed. A full thickness skin graft was placed on the secondary defect. Postoperatively, healing was rapid, a satisfactory range of motion was achieved by 3 months, and he returned to pre-injury activities (Fig 4c). DISCUSSION Ring avulsion presents a spectrum of injury and the treatment varies accordingly from simple suture to amputation. Urbaniak et al (1981) suggested a practical classification in an attempt to guide treatment to these injuries and to assess their functional outcome: class I, where there is circumferential soft tissue injury but the circulation and innervation remain intact or minimally damaged; class II, where incomplete digital degloving is accompanied by circulatory interruption requiring revascularization, nerve repair and soft tissue cover; and class
III, where there is digital amputation or else complete soft tissue degloving leaving nothing but bare bone, joint and tendon. Kay et al (1989) modified class II by determining whether there was arterial [a] or venous Iv] insufficiency, and added an extra category [class 111- also a and v] when bone or joint injury occurred, as the prognosis was significantly worsened. Digital amputation and total degloving injury was changed to class IV (Table 1). In Kay class II and III injuries in which significant dorsal skin loss and destruction is accompanied by severe venous congestion, the situation can be approached using a composite flap of skin and subcutaneous soft tissue vascularized by its contained veins - a so called "venous flap". Venous flaps were introduced clinically in 1984 by Honda et al. The initial description was "the cutaneous vein graft", which is now known as the venous flowthrough flap. The vascular input was venous, (preferably with a high venous 02 tension and pressure to aid in the nutrition of the soft tissue component (Fukui et al, 1989), and the outflow was also venous: a V-V flap. In an attempt to increase the reliability of these flaps, "arterialized" venous flaps were introduced, using an arterial inflow to the flap. In these flaps the vein graft could be used as a bridge to reconstruct an arterial defect: an A-A flap (Inoue et al, 1990). When no outflow arteries are available, the flap can be connected to a draining vein creating a small A-V fistula: an A-V flap (Yoshimura et al, 1987).
468
THE JOURNAL OF HAND SURGERY VOL. 23B No. 4 AUGUST 1998
b ~[
lr J
l
C
~sv
d Fig 3
Case 3. (a) Kay class 11 lv ring avulsion injury (b) Heterodigital VIC flap planned on middle finger adjacent to injured ring digit. (c) VIC flap islanded and transposed to ring finger pivoting on dorsal intermetacarpal veins. (d) VIC flap inset with congestion relieved, and a fenestrated full thickness skin graft on the donor site. (e) Digital flexion at 3 months. (f) Digital extension at 3 months.
R I N G AVULSION INJURIES
Fig 4
469
Case 4. (a) HeterodigitalVIC flap planned for treatment of Kay class 111 ring avulsion. (b) Flap elevatedon third web vesselswith arrows indicating veins. (c) HeterodigitalVIC flap and donor site at 3 months.
D o n o r sites for these composite flaps include the dorsum of the foot, the flexor aspect of the forearm, and the dorsum of the finger. The latter is probably the best suited for use in finger injuries because of the venous network characteristics, the size of the channels and the pliability of the skin. Venous flaps have been used to resurface defects of the dorsum of the hands and fingers. Due to their thinness and pliability they do not interfere with flexion and extension. In the case of ring avulsion, they present the ideal mechanism for reconstructing the thin, flexible, dorsal skin with healthy similar tissue, giving good quality durable cover to the underlying venous anastomoses, as well as providing enclosed and supported vein "grafts" to enable drainage of the congested periphery. Pedicled venous flaps have also been described. Foucher and Norris (1988) introduced the "neutral flap" a skin island transposed to cover a defect based purely on the venous connections at its proximal margin for both inflow and outflow, relying on the resulting eddy
currents to supply the metabolic requirements of the soft tissue. Inada et al (1991) described a "sliding" bipedicled venous flow-through flap in which a dorsal digital flap was elevated completely except for its proximal and distal veins, the lateral mobility allowing it to slide across the digit to cover a complex lateral digital defect. Thus venous flaps can be classified as pedicled or free with further subdivisions depending on the pattern of vascular hook-up and blood flow (Table 2). The transposition and advancement pedicled venous flow-through flaps (or venous island conduit flaps) presented here have not been previously described but have evolved in our practice and we have also used them successfully in digital replantation surgery. The advantages of these over free venous flaps in the management of Class II and III ring avulsion injuries are threefold. Firstly, anastomoses are required at only one level, resulting in a decrease in operating time and complications; secondly, the vascular supply of the flap is more reliable, presumably due to perivenous adventitial
Table 2~-Classification of venous flaps Pedicled
a) Venousisland flap (Neutral flap) b) Venousflow-throughflap i) Sliding (bipedicled) ii) Venousisland conduit (VIC) flaps Advancement HomodigitalVIC flap - Transposition - HeterodigitalVIC flap Free
a) Venousflow-through(V-Vflap) b) Arterializedvenous flap i) A-A flap ii) A-V fistula flap
T H E J O U R N A L OF H A N D SURGERY VOL. 23B No. 4 AUGUST 1998
470
arterioles (Noreldin et al, 1992) that are otherwise divided in free transfer; and thirdly, the heterodigital VIC flap avoids the zone of injury as its origin is external to the line of the damaging avulsive force. We find that islanding the heterodigital flap makes insetting the flap easier. It also removes the potential for the dog ear which results from simple transposition to kink and obstruct the venous drainage. It has been shown that division of the dermal blood supply in pedicled and free island flaps has little effect on flap survival (O'Brien and Morrison, 1987). The added advantages over a similar local flap such as the deepithelialized cross finger flap in which contained veins can be used to relieve the venous congestion are that VIC flaps are single stage and do not require skin grafts on the damaged digit. Whilst it may be possible to avoiding splitting the skin bridge by tunnelling the flap, we have been reluctant to do this for two reasons. Firstly, if the venous network were to be taken with a sufficient surrounding layer of subcutaneous tissue, there would always be potential for compression in the tunnel. Secondly, it would be difficult to skeletonize a portion of the flap once elevated and marked after tunnelling down to the venous network without the possibility of damage. The alternative of skeletonizing the flap in situ on the donor finger before elevation may result in inaccuracy in preparation that may limit the insetting options after transfer and alter the tension on the microvenous anastomoses. When planning the length of the heterodigital flap, it should be made as short as possible to avoid unnecessary sacrifice of skin over the PIP joint of the donor finger. Following d6bridement and joint repair this can be calculated using simple principles of transposition. The flap is pivoted midway between the metacarpal heads, close to which lies the perforating branch of the dorsal metacarpal artery. Although we have not seen this vessel during VIC flap elevation, we only divide those structures necessary to allow flap advancement, commencing with the skin which is divided with the scalpel and then the subcutaneous tissues which are stretched by opening the scissors. In practice there is little visible tissue anchoring the flap at its base other than the axial veins. If necessary, further advancement of the flap may be possible in a V-Y fashion.
Homodigital flaps are technically simpler but the amount of advancement is less than 2 cm and so they should be used only for a laceration from the ring rather than an extensive avulsive injury. It may be necessary to graft one side of the donor defect if V-Y closure adds circumferential tension to the existing ischaemic injury, although this is unlikely if the apex is situated over the intermetacarpal groove. In our cases, healing was rapid in cases i, 3 and 4, but was delayed in case 2 due to some necrosis on the dorsum in und6brided skin adjacent to the flap. In retrospect, selection of a heterodigital VIC flap would have allowed more substantial d6bridement. Long-term results reveal durable cover and satisfactory range of motion in the injured and donor digits (Table 3). Venous island conduit flaps provide a simple and convenient solution to the combined problems of relieving venous insufficiency and obtaining pliable skin cover in Kay Class II and III ring avulsion injuries, by transferring a single composite unit of thin skin and soft tissue vascularized by the same vessels that decompress the congested veins.
Acknowledgements I would like to thank Mr R. J. Ratcliffe, (Plastic and H a n d Surgeon, Canniesburn, Glasgow), and Mr A. Breidahl (Plastic Surgeon, Western Hospital, Melbourne) for their advice and the Canniesburn Department of Medical Illustration for their aid in preparation of the illustrations.
References Foucher G, Norris RW (1988). The venous dorsal digital island flap or the "neutral" flap. British Journal of Plastic Surgery, 41:337 343. Fukui A, Inada Y, Maeda M e t al (1989). Pedicled and "flow-through" venous flaps: clinical applications. Journal of Reconstructive Microsurgery, 5: 235~43. Honda T, Nomura S, Yamauchi S, Shimamura K, Yoshimura M (1984). The possible applications of a composite skin and subcutaneous vein graft in the replantation of amputated digits. British Journal of Plastic Sm-gery, 37:607 612. Inada Y, Fukui A, Tamai S, Kakihana T, Maeda M (1991). The sliding venous flap for covering skin defects with poor blood supply on the lateral aspects of fingers. British Journal of Plastic Surgery, 44:368-371. Inoue G, Maeda N, Suzuki K (1990). Resurfacing of skin defects of the hand using the arterialised venous flap. British Journal of Plastic Surgery, 43: 135-139. Kay S, Werntz J, Wolff T (1989). Ring avulsion injuries: classification and prognosis. Journal of Hand Surgery, 14A: 204-213. Noreldin A, Fukuta K, Jackson I (1992). Role of perivenous areolar tissue in the viability of venous flaps: an experimental study on the inferior epigastric venous flap of the rat. British Journal of Plastic Surgery, 45: 18-22.
Table 3~Results Case
Class
Flap
PIP AROM* Injured Donor
Complication
1
11 l v
Homo VIC
10°40 °
N/A
40 ° e x t e n s i o n deficit at t h e D I P
2
111
Homo VIC
20°-90 °
N/A
S u p e r f i c i a l necrosis
3
11 l v
Hetero VIC
0 ° 80 °
0 ° 90 °
Nil
4
111
Hetero VIC
20 ° 85 °
0°-90 °
Nil
*Active Range of Movement at the Proximal Interphalangeal Joint. N/A = not applicable.
R I N G AVULSION INJ URIES O'Brien B. McC, Morrison WA. Reconstructive microsurgery, 2nd edn, Melbourne, Churchill Livingstone, 1987. Urbaniak JR, Evans JP, Bright DS (I 981). Microvascular management of ring avulsion injuries. Journal of Hand Surgery, 6:25 30. Yoshimura M, Shimada T, Imura S, Shimamura K, Yamauchi S (1987). The venous skin graft method for repairing skin defects of the fingers. Plastic and Reconstructive Surgery, 79: 243-248.
471 Received: 1 January 1997 Accepted after revision: 5 January 1998 Mr A, V. Cavallo, 30 Newton Street, Surrey Hills, Melbourne, Austrolia 3127 © 1998The British Society for Surgery of the Hand
From the Department of Plastic, Reconstructive and Hand Surgery, WesternHospital Melbourne, Australia Ring avulsion injury frequently results in vascular insufficienc~ (venous or arterial) and soft tissue injury. We report four cases requiring revascularization where( venous congestion and dorsal skin cover were achieved using a composite pedicled venous flow-through flap. We have termed this a Venous Island Conduit (VIC) Flap. Two types of flaps, homodigital and heterodigital, were used, depending on the severity of the injury. The techniques and results are discussed. Venous island conduit flaps are ideally suited to the management of ring avulsion injury and have several advantages over the alternatives. Journal of Hand Surgery (British and European Volume, 1998) 23B: 4:465-471 method is that vein grafts are not required; instead, flap veins are used, supported by surrounding connective tissue that is thin and pliable yet strong and well vascularized.
Ring avulsion is usually caused by accidently catching the ring on a fixed object and transmitting the body's weight through it whilst falling or jumping from a height. The spectrum of severity has been classified by Urbaniak et al (1981) and a later subclassification was proposed by Kay et al (1989) (Table 1). The more complex avulsions have generally resulted in a poor outcome due to soft tissue contracture and proximal interphalangeal (PIP) joint stiffness. In view of this, we felt it desirable to develop a technique which would achieve supple skin cover and correct venous insufficiency whilst minimizing donor site morbidity. We report four cases in which the problem of simultaneously providing venous reconstruction and well vascularized, pliable soft tissue cover was solved using a composite pedicled venous flow-through flap. The donor site in two cases was the proximal digital skin advanced as a triangle, relying on venous in- and outflow; a homodigital Venous Island Conduit (VIC) flap. In a further two with more extensive damage, an island of skin from the dorsum of the adjacent digit (protected from the avulsive force) was used, pedicled proximally on the dorsal intermetacarpal veins and then transposed to the dorsum of the ring finger; a heterodigital Venous Island Conduit (VIC) flap. In all cases, the congested veins of the degloved digit were then anastomosed to the distal channel ends in the venous flap, which then acted as conduits for the venous blood flow. The advantage of this
CASE REPORTS Homodigital VIC flaps
Case 1 A 37-year-old teacher, suffered a degloving injury to the right ring finger when he jumped from a trailer, catching his ring on a bolt as he fell. Examination revealed that the digit was congested with a brisk capillary return and altered sensation. The middle phalanx was fractured in its distal portion. Debridement was performed and both digital neurovascular bundles were seen to be intact (Kay class 111 v). The fracture was stabilized with K-wires and primary closure of the dorsal defect was achieved by advancement of a homodigital triangular flap, 3 x 2 cm, of proximal dorsal skin abutting the debrided defect (Fig l a) and two venous anastomoses were performed. The donor defect was closed in V-Y pattern and soft tissue healing was rapid (Fig lb).
Case 2 A 47-year-old man caught the ring on the right ring finger on a pipe as he fell from a ladder, dividing all structures except for the flexor digitorum profundus tendon at the midlevel of the middle phalanx (Kay class III). 2.5 cm of the dorsal digital skin was lost to the level of the middle of the proximal phalanx and the digit was devascularized. A fracture of the base of the middle phalanx was fixed with an axial K-wire and the radial and ulnar digital nerves were repaired directly as was the ulnar digital artery. The dorsal defect was too great to allow repair of skin and dorsal veins directly and so a 4 x 2 cm long homodigital triangular flap, with its apex just proximal to the third web, was mobilized from the surrounding tissues except for those veins coursing through it (Fig 2a). It was advanced to close the dorsal defect and two
Table 1--Ring avulsion injuries (modified from Kay et al [19891 and reproduced by the kind permission of Churchill Livingstone Inc., New York)
CLASS 1 CLASS II
CLASS III
CLASS IV
Circulation adequate Circulation inadequate, no skeletal injury (a-arterial insufficiency only) (v-venous insufficiency only) Circulation inadequate, skeletal injury (a-arterial insufficiency only) (v-venous insufficiency only) Complete amputation/degloving 465
466
Fig 1
THE JOURNAL OF HAND SURGERY VOL. 23B No. 4 AUGUST 1998
Case 1. (a) Homodigital Venous island conduit (VIC) flap before advancement. Note background highlighting distal flap vein. (b) Healed homodigital VIC flap (outlined by dots) on right ring finger at 3 months. DIP has extension deficit.
congested veins in the distal digit were anastomosed to the veins in the advanced flap, satisfactorily relieving the problem. The donor defect was closed in a V-Y pattern (Fig 2b). Healing was a little delayed distally due to incomplete ddbridement of the injured digit, however PIP joint function was satisfactory (Figure 2c).
Heterodigital VIC flaps Case 3
A 39-year-old left handed truck driver, caught the left ring finger on the tailgate of his truck while dismounting. Examination showed gross destruction of the proximal half of the dorsal digital skin. The distal part of the finger was cyanotic and congested (Fig 3a). Sensation was normal. There was loss of extension at the proximal and distal interphalangeal joints. X-Ray showed no fracture but there was disruption of the DIP joint. D6bridement of the devitalized tissue resulted in a dorsal defect, 2 x 4 cm, with exposed and damaged tendon and proximal interphalangeal joint. The circumferential laceration had caused complete division of the venous drainage of the digit, with division of the ulnar digital artery; however both digital nerves and the radial digital artery were intact (Kay class 11 lv). The DIP joint was stabilized with axial K-wires. The dorsal veins of the distal segment were dissected to expose three proximal ends. A longitudinally oriented elliptical venous flap, 2 x 6 cm was then planned on the dorsum of the adjacent middle finger extending from the dorsum of the hand and crossing the PIP and MP joints. The pivot point was placed just proximal to the third web (Fig 3b), adjacent to the metacarpal necks, in the region
of the deep metacarpal perforating vessel. The flap was elevated just above the paratenon, commencing distally, and proceeding proximally toward the dorsum of the intermetacarpal head region where the veins were preserved. The dermis was divided completely and the proximal dorsal venous channels were carefully preserved in a cuff of adventitia, except for one lateral vein which was divided to allow adequate transposition (Fig 3c). The flap was then transposed on to the dorsum of the ring finger where the proximal intact skin bridge on the dorsum of the hand was split to allow insetting of the flap. Anastomoses were then performed between the two largest draining venous channels in the degloved digit and the two largest channels in the distal end of the flap using 10/0 nylon interrupted sutures. The overlying wound was closed directly without tension as was the laceration on the palmar aspect of the finger, and the donor site was covered with a full thickness graft (Fig 3d). Postoperatively, venous circulation rapidly stabilized and the wounds healed swiftly. PIP movement could be commenced early as a result. Long-term follow-up confirms durable, pliable soft tissue cover with full range of movement of PIP in both ring and middle fingers (Figs 3e, f). Case 4
A 30-year-old man caught his wedding ring on a post when attempting to climb over a fence, resulting in a Kay class 111 ring avulsion injury. This involved a circumferential laceration with complete division of both digital arteries and all veins. The digital nerves were stretched but intact. There was a dorsally angulated fracture through the neck of the middle phalanx. The flexor and extensor tendons were intact.
RING AVULSION INJURIES
Fig 2
467
Case 2. (a) Congested digit with Homodigital VIC flap planned on proximal digital skin. (b) VIC flap advanced to close soft tissue defect with resolution of the congestion following single level flap vein anastomoses. (c) Kay class 111 ring avulsion injury, displaying flexion 4 months after operation.
At operation, the fracture was reduced and stabilized using K-wires. The radial digital artery was repaired with a vein graft and palmar soft tissue cover was achieved with direct apposition, but there was insufficient dorsal skin following d6bridement to achieve primary closure and to relieve venous congestion. A venous island conduit flap was raised from the dorsum of the adjacent (undamaged) middle finger (Fig 4a) and transposed to the dorsum of the ring finger, pivoting proximally on the third web (Fig 4b). Two single level venous anastomoses were then performed. A full thickness skin graft was placed on the secondary defect. Postoperatively, healing was rapid, a satisfactory range of motion was achieved by 3 months, and he returned to pre-injury activities (Fig 4c). DISCUSSION Ring avulsion presents a spectrum of injury and the treatment varies accordingly from simple suture to amputation. Urbaniak et al (1981) suggested a practical classification in an attempt to guide treatment to these injuries and to assess their functional outcome: class I, where there is circumferential soft tissue injury but the circulation and innervation remain intact or minimally damaged; class II, where incomplete digital degloving is accompanied by circulatory interruption requiring revascularization, nerve repair and soft tissue cover; and class
III, where there is digital amputation or else complete soft tissue degloving leaving nothing but bare bone, joint and tendon. Kay et al (1989) modified class II by determining whether there was arterial [a] or venous Iv] insufficiency, and added an extra category [class 111- also a and v] when bone or joint injury occurred, as the prognosis was significantly worsened. Digital amputation and total degloving injury was changed to class IV (Table 1). In Kay class II and III injuries in which significant dorsal skin loss and destruction is accompanied by severe venous congestion, the situation can be approached using a composite flap of skin and subcutaneous soft tissue vascularized by its contained veins - a so called "venous flap". Venous flaps were introduced clinically in 1984 by Honda et al. The initial description was "the cutaneous vein graft", which is now known as the venous flowthrough flap. The vascular input was venous, (preferably with a high venous 02 tension and pressure to aid in the nutrition of the soft tissue component (Fukui et al, 1989), and the outflow was also venous: a V-V flap. In an attempt to increase the reliability of these flaps, "arterialized" venous flaps were introduced, using an arterial inflow to the flap. In these flaps the vein graft could be used as a bridge to reconstruct an arterial defect: an A-A flap (Inoue et al, 1990). When no outflow arteries are available, the flap can be connected to a draining vein creating a small A-V fistula: an A-V flap (Yoshimura et al, 1987).
468
THE JOURNAL OF HAND SURGERY VOL. 23B No. 4 AUGUST 1998
b ~[
lr J
l
C
~sv
d Fig 3
Case 3. (a) Kay class 11 lv ring avulsion injury (b) Heterodigital VIC flap planned on middle finger adjacent to injured ring digit. (c) VIC flap islanded and transposed to ring finger pivoting on dorsal intermetacarpal veins. (d) VIC flap inset with congestion relieved, and a fenestrated full thickness skin graft on the donor site. (e) Digital flexion at 3 months. (f) Digital extension at 3 months.
R I N G AVULSION INJURIES
Fig 4
469
Case 4. (a) HeterodigitalVIC flap planned for treatment of Kay class 111 ring avulsion. (b) Flap elevatedon third web vesselswith arrows indicating veins. (c) HeterodigitalVIC flap and donor site at 3 months.
D o n o r sites for these composite flaps include the dorsum of the foot, the flexor aspect of the forearm, and the dorsum of the finger. The latter is probably the best suited for use in finger injuries because of the venous network characteristics, the size of the channels and the pliability of the skin. Venous flaps have been used to resurface defects of the dorsum of the hands and fingers. Due to their thinness and pliability they do not interfere with flexion and extension. In the case of ring avulsion, they present the ideal mechanism for reconstructing the thin, flexible, dorsal skin with healthy similar tissue, giving good quality durable cover to the underlying venous anastomoses, as well as providing enclosed and supported vein "grafts" to enable drainage of the congested periphery. Pedicled venous flaps have also been described. Foucher and Norris (1988) introduced the "neutral flap" a skin island transposed to cover a defect based purely on the venous connections at its proximal margin for both inflow and outflow, relying on the resulting eddy
currents to supply the metabolic requirements of the soft tissue. Inada et al (1991) described a "sliding" bipedicled venous flow-through flap in which a dorsal digital flap was elevated completely except for its proximal and distal veins, the lateral mobility allowing it to slide across the digit to cover a complex lateral digital defect. Thus venous flaps can be classified as pedicled or free with further subdivisions depending on the pattern of vascular hook-up and blood flow (Table 2). The transposition and advancement pedicled venous flow-through flaps (or venous island conduit flaps) presented here have not been previously described but have evolved in our practice and we have also used them successfully in digital replantation surgery. The advantages of these over free venous flaps in the management of Class II and III ring avulsion injuries are threefold. Firstly, anastomoses are required at only one level, resulting in a decrease in operating time and complications; secondly, the vascular supply of the flap is more reliable, presumably due to perivenous adventitial
Table 2~-Classification of venous flaps Pedicled
a) Venousisland flap (Neutral flap) b) Venousflow-throughflap i) Sliding (bipedicled) ii) Venousisland conduit (VIC) flaps Advancement HomodigitalVIC flap - Transposition - HeterodigitalVIC flap Free
a) Venousflow-through(V-Vflap) b) Arterializedvenous flap i) A-A flap ii) A-V fistula flap
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arterioles (Noreldin et al, 1992) that are otherwise divided in free transfer; and thirdly, the heterodigital VIC flap avoids the zone of injury as its origin is external to the line of the damaging avulsive force. We find that islanding the heterodigital flap makes insetting the flap easier. It also removes the potential for the dog ear which results from simple transposition to kink and obstruct the venous drainage. It has been shown that division of the dermal blood supply in pedicled and free island flaps has little effect on flap survival (O'Brien and Morrison, 1987). The added advantages over a similar local flap such as the deepithelialized cross finger flap in which contained veins can be used to relieve the venous congestion are that VIC flaps are single stage and do not require skin grafts on the damaged digit. Whilst it may be possible to avoiding splitting the skin bridge by tunnelling the flap, we have been reluctant to do this for two reasons. Firstly, if the venous network were to be taken with a sufficient surrounding layer of subcutaneous tissue, there would always be potential for compression in the tunnel. Secondly, it would be difficult to skeletonize a portion of the flap once elevated and marked after tunnelling down to the venous network without the possibility of damage. The alternative of skeletonizing the flap in situ on the donor finger before elevation may result in inaccuracy in preparation that may limit the insetting options after transfer and alter the tension on the microvenous anastomoses. When planning the length of the heterodigital flap, it should be made as short as possible to avoid unnecessary sacrifice of skin over the PIP joint of the donor finger. Following d6bridement and joint repair this can be calculated using simple principles of transposition. The flap is pivoted midway between the metacarpal heads, close to which lies the perforating branch of the dorsal metacarpal artery. Although we have not seen this vessel during VIC flap elevation, we only divide those structures necessary to allow flap advancement, commencing with the skin which is divided with the scalpel and then the subcutaneous tissues which are stretched by opening the scissors. In practice there is little visible tissue anchoring the flap at its base other than the axial veins. If necessary, further advancement of the flap may be possible in a V-Y fashion.
Homodigital flaps are technically simpler but the amount of advancement is less than 2 cm and so they should be used only for a laceration from the ring rather than an extensive avulsive injury. It may be necessary to graft one side of the donor defect if V-Y closure adds circumferential tension to the existing ischaemic injury, although this is unlikely if the apex is situated over the intermetacarpal groove. In our cases, healing was rapid in cases i, 3 and 4, but was delayed in case 2 due to some necrosis on the dorsum in und6brided skin adjacent to the flap. In retrospect, selection of a heterodigital VIC flap would have allowed more substantial d6bridement. Long-term results reveal durable cover and satisfactory range of motion in the injured and donor digits (Table 3). Venous island conduit flaps provide a simple and convenient solution to the combined problems of relieving venous insufficiency and obtaining pliable skin cover in Kay Class II and III ring avulsion injuries, by transferring a single composite unit of thin skin and soft tissue vascularized by the same vessels that decompress the congested veins.
Acknowledgements I would like to thank Mr R. J. Ratcliffe, (Plastic and H a n d Surgeon, Canniesburn, Glasgow), and Mr A. Breidahl (Plastic Surgeon, Western Hospital, Melbourne) for their advice and the Canniesburn Department of Medical Illustration for their aid in preparation of the illustrations.
References Foucher G, Norris RW (1988). The venous dorsal digital island flap or the "neutral" flap. British Journal of Plastic Surgery, 41:337 343. Fukui A, Inada Y, Maeda M e t al (1989). Pedicled and "flow-through" venous flaps: clinical applications. Journal of Reconstructive Microsurgery, 5: 235~43. Honda T, Nomura S, Yamauchi S, Shimamura K, Yoshimura M (1984). The possible applications of a composite skin and subcutaneous vein graft in the replantation of amputated digits. British Journal of Plastic Sm-gery, 37:607 612. Inada Y, Fukui A, Tamai S, Kakihana T, Maeda M (1991). The sliding venous flap for covering skin defects with poor blood supply on the lateral aspects of fingers. British Journal of Plastic Surgery, 44:368-371. Inoue G, Maeda N, Suzuki K (1990). Resurfacing of skin defects of the hand using the arterialised venous flap. British Journal of Plastic Surgery, 43: 135-139. Kay S, Werntz J, Wolff T (1989). Ring avulsion injuries: classification and prognosis. Journal of Hand Surgery, 14A: 204-213. Noreldin A, Fukuta K, Jackson I (1992). Role of perivenous areolar tissue in the viability of venous flaps: an experimental study on the inferior epigastric venous flap of the rat. British Journal of Plastic Surgery, 45: 18-22.
Table 3~Results Case
Class
Flap
PIP AROM* Injured Donor
Complication
1
11 l v
Homo VIC
10°40 °
N/A
40 ° e x t e n s i o n deficit at t h e D I P
2
111
Homo VIC
20°-90 °
N/A
S u p e r f i c i a l necrosis
3
11 l v
Hetero VIC
0 ° 80 °
0 ° 90 °
Nil
4
111
Hetero VIC
20 ° 85 °
0°-90 °
Nil
*Active Range of Movement at the Proximal Interphalangeal Joint. N/A = not applicable.
R I N G AVULSION INJ URIES O'Brien B. McC, Morrison WA. Reconstructive microsurgery, 2nd edn, Melbourne, Churchill Livingstone, 1987. Urbaniak JR, Evans JP, Bright DS (I 981). Microvascular management of ring avulsion injuries. Journal of Hand Surgery, 6:25 30. Yoshimura M, Shimada T, Imura S, Shimamura K, Yamauchi S (1987). The venous skin graft method for repairing skin defects of the fingers. Plastic and Reconstructive Surgery, 79: 243-248.
471 Received: 1 January 1997 Accepted after revision: 5 January 1998 Mr A, V. Cavallo, 30 Newton Street, Surrey Hills, Melbourne, Austrolia 3127 © 1998The British Society for Surgery of the Hand