COMBINATION OF POSTERIOR INTEROSSEOUS AND HYPOGASTRIC FLAP FOR SKIN DEFECT RECONSTRUCTION IN HAND INJURIES

INTRODUCTION

A combination of degloving injury of the fingers and mutilation of other fingers with skin defects may be treated urgently with a combination of arterialised pedicle flaps from the forearm and distant axial pattern flap.

CASE REPORT

A 26-year-old engine driver sustained a right hand injury during his work as the driver of locomotive. His right hand was injured by the front wheel of the engine (Fig. 1, 2). He was admitted to our department 30 minutes after the injury. Considering the extent of the injury and the fact that there was no other associate injury, we performed urgent primary revision. During revision we realized debridement of all necrotic tissues (Fig. 3). The thumb was intact. The index finger was almost completely degloved from the level of the proximal third of the proximal phalanx. Its flexor and extensor tendon was intact, and inside there was open proximal interphalangeal joint dislocation. Complete loss of arteries and veins from the level of degloving and digital nerves was pulled out to the more proximal level.

The third and fourth digits were mutilated with no possibility of reconstruction; simultaneously there were skin defects on both digits, dorsal and volar from the level of the metacarpophalangeal joint. The little finger was also crushed, with an unreconstructible middle and distal phalanx.

Open shaft fracture of the fifth metacarpal was stabilised with a screw. The stump of the proximal phalanx of the little finger was covered with local skin flap without tension.

The extent of injury to the third and the fourth finger was assessed, and subsequently wound debridement was performed; finally only the stumps of the proximal phalanges remained. The residual skin defect, covering the degloving index finger and the stumps of the third and fourth finger, could not be covered with one flap. We decided on a flap combination.

First we created a posterior interosseous artery flap from the ipsilateral forearm; we took a fasciocutaneous flap 12 x 6 cm in size on an arterial pedicle, and we utilized this flap to cover the stumps of the third and fourth fingers (Fig. 4). The length of the pedicle was 12 cm. From the place of anastomosis a. interossea anterior and posterior we made an incision directly to the skin defect. We prefer not to place an arterial pedicle of the flap in a previously made subcutaneous tunnel, due to the increased risk of flap necrosis (Fig. 5). The defect on the fingers was fully covered. The donor defect was covered with split thickness skin graft from left thigh.

The open dislocation of the proximal interphalangeal joint of the index finger was reduced and stabilized with Kirschner wire.

The best solution for covering the index finger seemed to be a hypogastric (superficial epigastric) flap. A flap 12 cm long was used. The donor site was first closed by mobilizing the skin margins. The flap was tubularised, and the index finger was inserted into the tubularised flap, fixed with sparse sutures (Fig. 6). The upper extremity was fixed with orthesis. Both flaps were vital and healed primarily (Fig. 7).

From the time of operation we noticed weak bleeding from the wound on the left thigh after taking the split thickness graft. Bleeding continued despite the application of local haemostyptics and the patient’s normal coagulation status. We supposed that the patient suffered from an undiagnosed coagulation disorder, but this was not confirmed. Finally we had to stop the bleeding with coagulation. No bleeding was later registered, and the wound healed without further complications. The patient was discharged after 10 days and treated on an outpatient basis. After 3 weeks we separated the hypogastric flap from the abdominal wall. The donor defect was closed with suture and healed spontaneously. The wound on the tip of the index finger healed more slowly, after repeated revision. The Kirschner wire was removed from stab incision after 6 weeks. Subsequently the patient began to rehabilitate. After 4 weeks of rehabilitation he could grasp an object between the index finger and thumb. He was capable of basic functional use of the hand (including grasping large and small objects, though the power of grasp was decreased). The extent of movement in the PIP joint of index finger is limited to 70 degrees of flexion, while there is virtually no active movement in the DIP joint. After rehabilitation the patient underwent defatting procedure twice; despite this, he is not satisfied with the cosmetic appearance of the hand (Fig. 8, 9). He has repeatedly refused any further operations.

DISCUSSION AND CONCLUSION

The first mention of Posterior Interosseous Artery (PIA) Flap was made by Zancolli in 1985, but he only published this almost 3 years later, in 1988 (15).

Penteado and Masquelet were the first authors who published their experience with PIA flaps, in 1986 and 1987 (8, 10).

The flap affords a very durable and aesthetic option for soft-tissue coverage of the dorsum of the hand. The flap donor site can usually be closed primarily with little to no morbidity. In comparison to other local and distally based flaps, such as the radial forearm flap, major blood vessels are spared. The PIA flap should be considered a reliable and judicious alternative to free microvascular transfer procedures for soft-tissue defects of the hand proximal to the level of the PIP joint (16).

PIA flaps are also a good option for palmar defects or to wrap around neurolyzed nerves (12).

The flap may be easily and safely employed in the coverage of soft tissue defects of the hand and the wrist due to such advantages as minimal donor area morbidity, an acceptable cosmetic appearance, and a more simple dissection than that required for other surgical flaps (5, 6, 9).

It is possible to apply a PIA flap urgently in emergencies without increased risk of complication, and this method of application shortens hospitalisation time in clinical practice (4).

Several cutaneous branches of the posterior interosseous artery supply the skin of the dorsal aspect of the forearm. This vascular anatomy allows the surgeon to obtain an island flap of the dorsal forearm based on the distal anastomosis between the two interosseous arteries at the distal part of the interosseous space (15).

The PIA course corresponds to a line drawn from the lateral epicondyle of the humerus to the head of the ulna, i.e. to the septum between the extensor carpi ulnaris and extensor digiti minimi proprius muscles. The artery, which has an average calibre of 1.7 mm, gives off 7 to 14 cutaneous branches in its course. The PIA anastomoses the anterior interosseous artery and the dorsal carpal network in 98.6% of cases. The artery remains closely related to the deep branch of the radial nerve and is crossed by the branches of this nerve to the extensor carpi ulnaris muscle. The cutaneous distribution of the PIA extends from elbow to wrist, centred on the epicondylar-ulnar line, with an average breadth of 5 cm (8, 10).

The PIA flap is based on posterior interosseous artery, which is branch of the common interosseous artery. The existence of distal anastomosis between PIA and Anterior Interosseous Artery (AIA) facilitates the use of this flap as a reversed pedicled flap.

Later it was observed (2) that there is a choke anastomosis between the recurrent dorsal branch of the anterior interosseous artery and the posterior interosseous artery at the level of the middle third of the posterior forearm, but no anastomosis was found in the proximal third of the forearm. In the distal third of the posterior forearm there is a recurrent branch of the anterior interosseous artery (traditionally called the distal anastomosis of the interosseous arteries). It was assumed that the blood flow is not reversed when the so-called posterior interosseous reverse forearm flap is raised. From this point of view, this flap could be renamed the recurrent dorsal anterior interosseous direct flap; however, the classical name is maintained for practical purposes. From the venous standpoint, the cutaneous area included in this flap belongs to an oscillating type of venous territory and is connected to the deep system through an interconnecting venous perforator that accompanies a medial cutaneous arterial branch located at 1 to 2 cm distal to the middle point of the forearm.

To summarize, the flap advantages are as follows: no impairment of main forearm arteries; possibility to close donor site with suture unless the flap size is larger than 4 x 4 cm and use as osteofasciocutaneous flap; opportunity to raise flap as free flap.

The disadvantages are these: in 5% of the population there is no distal anastomosis between PIA and AIA, which may comprise flap usage; visible scar; hair growth in recipient area; no sensitivity and jeopardizing of nervus radialis profundus during dissection.

It is not appropriate to use a flap in cases of previous surgery in dorsal forearm and in cases when the flap required is smaller than 3x3 cm.

Before dissections PIA and its anastomosis should be verified with a Doppler probe, or dissection should begin with verification of distal ramus communicans (7, 12).

Anatomical variant was described in 24 per cent of patients, but not all of them compromise realization of flap dissection (12). Missing PIA in the middle third of forearm has also been recorded, along with course of distal perforator artery in musculus extensor digiti minimi and crossing of ramus superficialis nervus radialis with distal perforator artery.

No significant statistical correlation was found between occurrence of anatomical variants and complications (necrosis of flap). A risk factor for flap necrosis is enlargement of flap more proximal than 4–5 cm above the proximal perforator vessel.

For the reverse posterior interosseous flap to be reliable the flap should include the septocutaneous perforators in the distal third of the forearm. To cover distant defects reliably by a flap with a long pedicle, the flap should extend up to the distal third of the forearm to include a piece of skin with numerous perforators (1).

When distant flaps are indicated for coverage of acute hand wounds, it is advantageous to design the service-able portion of the flap on the distal area of the vascular territory of the groin flap (hypogastric or groin flap). Cautious but “radical” defatting can be performed on the lateral portion of the groin flap territory. When constructed in this way, the long medial base of the groin flap allows freedom of movement at the wrist and metacarpophalangeal and interphalangeal joints, thus decreasing oedema and stiffness. In the management of soft-tissue defects in the hand requiring distant flap coverage, it is possible to utilize the conventional groin flap in preference to the microvascular free flap when both techniques will deliver equal results (3).

The hypogastric flap (Superficial Epigastric) was first described in 1946 by Shaw and Payne (11). This flap has proved suitable for coverage of hand defects.

Advantages of the hypogastric flap include: 1 – its location in an area with little hair; 2 – minimal donor site morbidity; 3 – multiple arteriovenous supply; 4 – potential for incorporating bone with overlying skin flap even when used as a pedicle flap; and 5 – potentially large size. Disadvantages include: 1 – problems with colour matching; 2 – possibility of damage to vessels from previous inguinal surgery; and 3 – thickness of the flap in obese patients (13).

It is possible to find in the literature (14) a reference to combinations of posterior interosseous and lateral arm flap, which are appropriate almost for every hand injury. We suppose that the combination of arterialised pedicle flaps from the forearm and distant axial pattern flaps is also a suitable alternative for use in case of serious hand injury.

Address for correspondence:

Rastislav Burda, MD.

Department of Trauma Surgery

Faculty Hospital of Louis Pasteur

Rastislavova 43

040 01 Košice

Slovakia

E-mail: burda@netkosice.sk