The Posterior Interosseous Flap

The Posterior Interosseous Flap B Youssef1, A Dancey, 1 V P Sumathi2, F C Peart1.

1.Regional Department of Burns and Plastic Surgery, University Hospital Birmingham, Selly Oak Hospital, Birmingham, United Kingdom. 2.Department of Musculoskeletal Pathology, The Royal Orthopaedic Hospital, Birmingham, United Kingdom.

Case report

A 57 year-old gentleman presented to his General Practitioner with a swelling on the dorsal aspect of his left hand. The swelling had gradually increased in size over the last 12 months. It was not painful, associated with any neurological symptoms or functional loss. There was no history of trauma or infection.

There was no significant past medical history of note and he does not take any regular medication. He works in a slaughterhouse, he does not smoke and drinks socially.

On examination he had a five by seven cm swelling on the dorsal aspect of his left hand. It was soft, smooth, mobile and it did not appear to involve the extensor tendons. The patient was able to make a composite fist, he had full extension at the metacarpal-phalangeal joint and at the proximal and distal inter-phalangeal joints. There was no associated lymphadenopathy or neurovascular deficit.

An MRI (Figure 1 and 2) and incision biopsy were performed. Histology confirmed the presence of a desmoplastic fibroblastoma (collagenous fibroma). This is a rare benign soft tissue tumour of fibroblastic origin. In keeping with the current literature on collagenous fibroma they present as firm, well-circumscribed subcutaneous, or intramuscular, painless masses typically long standing in duration. Complete surgical excision is the recommended course of action (1). And this was the proposed plan with immediate reconstruction of the defect after discussion at the soft tissue tumour multi-disciplinary meeting.

Figure 1: transverse section through the hand revealing the soft tissue tumour above the 4th and 5th metacarpals.

Figure 2: Coronal section through the left hand, demonstrating the soft tissue mass.

Procedure

A doppler examination of the vessel and the perforating branches of the interosseous vessels was performed.

The surface marking of the posterior interosseous artery was drawn along a line joining the lateral epicondyle of the humerus and the ulnar styloid. A point nine cm distal to the lateral epicondyle of the humerus marks the centre of the fasciocutaneous element of the flap (Figure 3).

A tourniquet was inflated to 230mmHg prior to dissection to create a bloodless field. The tumour extended down to the periosteum of the metacarpals, it involved extensor digiti minimi (EDM), extensor digitorum communis (EDC) to the ring finger and the paratenon from EDC to the middle finger. The skin and tumour was excised taking these structures en bloc with the underlying periosteum and the fascia from the interosseous muscles (Figure 4,5).

Extensor indicis proprius was harvested and split into two tails and transferred to EDC at the level of the MCPJ via a 900 weave through the tendon using a 3.0 braided polyester suture (Ticron, Tycon) (Figure 6).

The vessels lie orientated in the sagital plane in the fascial septum between extensor carpi ulnaris and extensor digiti minimi muscles. The artery is superficial in the distal half and in the proximal half it lies underneath extensor digiti minimi. Therefore the flap was raised distal to proximal. The pivot point is 2 cm distal to the radio-carpal joint, it is at this point that the posterior interosseous artery anastomoses with the anterior interosseous artery. The flap was then tunnelled to the dorsum of the hand from its pivot point. The superficial veins were preserved and haemostasis was achieved (Figure 7,8,9).

The flap was inset and the donor site covered with meshed SSG. The skin bridge was divided and a split skin graft was placed over the pedicle. One 10 French suction drain was placed under the flap (Figure 10). The tourniquet was released and excellent blood flow was observed to the flap.

Figure 3: pre-operative marking. Flap designed according to the size of the tumour. Length and position of the pedicle marked.

Figure 4: Initial dissection of the soft tissue tumour on the dorsum of left hand.

Figure 5: The excised soft tissue tumour. excised

Figure 6: Extensor Digitorum Communis (EDC) to the small and ring finger was excised en bloc with the tumour and an Extensor Indicis Proprius transfer to EDC performed.

Figure 7: Elevation of the flap the posterior interosseous artery and its venae commitantes are displayed.

Figure 8 & 9: Fascio-cutaneous flap and pedicle completely elevated.

Figure 10:Image of the flap in its final position and the donor site covered with a split skin graft.

Figure 11:Two weeks post operatively, the flap and skin graft have taken well.

Pathology

The results of the histo-pathological examination of the specimen were discussed at the multi-disciplinary meeting, which confirmed that this was a desmoplastic fibroblastoma.

Figure 12: Macroscopic picture: cut surface shows a well circumscribed, greyish white tumour measuring 5x4x2.7 cm.

Figure 13: Microscopic image (x40): shows a paucicellular lesion composed of spindled and stellate shaped fibroblasts set in a collagenous stroma.

The excision margins were clear of tumour and no further treatment is required at this stage. He will be followed up at regular intervals as an outpatient.

Anatomy of the posterior interosseous flap

The posterior interosseous flap is a type B fascio-cutaneous flap. The flap is developed in a plane between the fascia and muscle. Here exists a layer of loose connective tissue and fat containing cutaneous veins, nerves and a rich network of arteries.

The perforating vessels of the posterior interosseous artery penetrate the fascia to run longitudinally with numerous transverse anastomoses in the subcutaneous tissue. The fascia envelops the muscle tissue and thickens to form a septum between individual muscle bellies. The posterior interosseous artery arises from the common interosseous artery, passes posteriorly above the interosseous membrane and then runs between supinator superficially and abductor polllicis longus deeply with the posterior interosseous nerve to descend and supply the extensors muscles of the forearm. It forms an anastomosis with the distal branches of the anterior interosseous artery and the dorsal carpal arch. The artery gives of perforators along its entire length. The septocutaneous perforators anastomose in the superficial layer of the deep fascia and form rich vascular arcades. Near the wrist joint, three types of anastomoses have been identified. The first one with the anterior interosseous artery is located just proximal to the distal radio-ulnar joint. The second one with the dorsal carpal arch, and the third includes several branches that surround the ulnar head on both sides and anastomoses with the ulnar artery. This rich vascular supply means that the flap can be raised even when one of the anastomoses is injured. .

Course and distribution of the posterior interosseous artery

Cross section through the middle third of the forearm.

Venous drainage is from both the superficial and the deep systems, and there are multiple anastomoses between these venous channels. There is venous drainage through the superficial veins and the venae commitantes within pedicle to ensure flap survival (2).

Discussion

Reconstruction of the soft tissue on the dorsum of the hand can be a challenging problem. Free flaps can be time consuming, require specialised equipment and labour intensive post-operative care. Distant flaps may require multiple stage reconstruction and prolonged periods of immobilisation.

Local fascio-cutaneous flaps, although limited in mobility and quantity, offer simple and effective wound coverage. The donor sites do not often require reconstruction and can be closed directly or using a split skin graft.

Fasciocutaneous flaps Fasciocutaneous flaps are tissue flaps that include skin, subcutaneous tissue, and the underlying fascia.

When moving skin alone, the distance it can travel is limited by its length to breadth ratio. Including the deep fascia with its prefascial and subfascial plexuses enhances the circulation of these flaps, but also frees these limb flaps from the length and breadth limitations they were previously subjected to. They are simple to elevate, quick, and fairly reliable in healthy patients. They provide ideal resurfacing where a thin flap of tissue is required. No functional loss results from the area they are raised as no muscle is taken.

Fasciocutaneous flaps can be used to provide cover over areas of bare tendon and bone. The procedure can be pre-planned, as described in our case report, based on the direction and orientation of the fascial plexus or fasciocutaneous perforators. These flaps provide a donor sites in areas where random axial flaps are not feasable. There are disadvantages; they are not as resistant to infection as muscle flaps and predicting failure can be difficult (2,3).

Cormack and Lamberty classification of fasciocutaneous flaps (4,5). 

Type A has multiple fascio-cutaneous perforators. They enter at the base of the flap and extend through the full length of the flap. The flap can be based proximally, distally, or as an island.



Type B has a single moderately sized fasciocutaneous perforator. This can be used as a free flap or as an island.



Type C has multiple small perforators running along the fascial septum. The supplying artery is included with the flap. It can be based proximally, distally, or as a free flap.



Type D is an osteomyocutaneous flap. It has multiple small perforators running along the fascial septum, the supplying artery is included in the flap. It can be based proximally or distally on a pedicle or used as a free flap.

Forearm flaps Flaps originating from the volar aspect of the forearm

The axial pattern reverse forearm flap: the axial-pattern reverse radial forearm fasciocutaneous flap has become one of the primary flaps for reconstruction of softtissue defects of the hand. This pedicled flap provides a good amount of malleable and relatively hairless tissue with a durable blood supply. Its diadvantages include sacrificing a major artery, this may jeopardize the hand’s viability and affect the morbidity and appearance of the donor site (6).

The axial pattern reverse forearm fascial flap: involves a fascial flap and split skin grafting to cover the wound. Only the fascia is taken with this flap and therefore there is less donor site morbidity. As with the previous flap this does involve sacrificing a major vessel (7).

The distally based radial forearm fascio-cutaneous flap: This type of flap was proposed to avoid the disadvantages caused by axial-pattern reverse radial forearm fasciocutaneous flaps. It is based on the septocutaneous perforators of the distal radial artery and therefore does not involve sacrificing a major artery (8).

Flaps originating from the dorsal aspect of the forearm

The de-epithelialized turnover flap: This is a reversed dermis flap. The pedicle of the flap remains intact. The mobile upper part of the flap is turned over the defect and the pedicle itself. A mesh graft covers both, the flap and the donor site.

Local adipo-fascial turnover flap: This flap is reliant on the amount of soft tissue that is available this limits the extent to which this flap can be raised. This is, however, a reliable and straightforward way to resurface a defect on the dorsal aspect of the hand (9).

Radial forearm flap: The radial forearm flap was described in China in 1978. It is supplied by the septocutaneous perforating branches of the radial artery in the forearm. Generally, the skin is thin, pliable, and usually hairless while the vascular pedicle may be up to 18 cm in length and the vessel diameters are usually large (2 - 4 mm). The superficial radial nerve and the medial and lateral antebrachial cutaneous nerves can also be made part of this flap to add sensation to the tissue. Patency of the ulnar artery and superficial palmar arch should be confirmed prior to elevating this flap. It does leave a conspicuous donor site. An osteofasciocutaneous version of this flap has been described with a segment of radius to create a vascularized bone graft.

Ulnar artery forearm flap: The ulnar artery forearm flap, located on the ulnar aspect of the forearm, is based on the septocutaneous perforators of the ulnar artery, which has a diameter of 2.5-3.0 cm. It is similar to the radial forearm flap and can be dissected to include bone, nerve, or a musculotendinous unit. This flap is used as free flap or as a pedicled flap for coverage of the upper extremity. In addition, it may be used as a vascular conduit or fascia-only flap.

The posterior interosseous artery flap: Type B fasciocutaneous flap based over the dorsal aspect of the forearm between the radius and ulna. It is based on the posterior interosseous artery branch of the common interosseous artery. Its main advantage is that it avoids sacrificing the two main arteries of the forearm. Dissection of the pedicle can be difficult and complicated. It can also be raised as an osteofasciocutaneous falp, creating a vascularised piece of ulna. It is used to reconstruct defects on the dorsum of the hand, wrist and first web space (10).

Conclusion The case report has demonstrated that the posterior interosseous artery flap offers excellent tissue for reconstruction of the dorsum of the hand. In addition it does not compromise any major vessels and avoids the dissection of lymphatic and venous systems on the volar aspect of the forearm. This gentleman has had a good functional and cosmetic result following resection of the tumour on the dorsum of the hand.

References 1. Ogose A, Hotta T, Emura I, Higuchi T, Kusano, Saito H. Collagenous fibroma of the arm: a report of two cases. Skeletal Radiol. 2000 Jul;29(7):417-20. 2. Kim S.K. Distally based dorsal forearm fasciosubcutaneous flap. Plast Reconstr Surg. 2004 Aug;114(2):389-96; discussion 397-9. 3. McGregor AD, McGregor IA. Fundemental Techniques of Plastic Surgery. Churchill Livingstone, Edinburgh 2000. 4. Lamberty BG, Cormack GC. Fasciocutaneous flaps.Clin Plast Surg. 1990 Oct;17(4):713-26. 5. Woodberry KM, Robertson K. Flaps, Fasciocutaeous flaps. http://www.emedicine.com/plastic/topic243.htm.

6. Weinzweig N, Chen L, Chen ZW. The distally based radial forearm fasciosubcutaneous flap with preservation of the radial artery: an anatomic and clinical approach. Plast Reconstr Surg. 1994 Oct;94(5):675-84. 7. Reyes, F. A., and Burkhalter, W. E. The fascial radial arm flap. J. Hand Surg. (Am.) 13: 432, 1988. 8. Tiengo C, Macchi V, Porzionato A, Bassetto F, Mazzoleni F, De Caro R. Anatomical study of perforator arteries in the distally based radial forearm fasciosubcutaneous flap Clin Anat. 2004 Nov;17(8):636-42.

9. Lin SD, Chou CK, Lau CS. Clinical application of the adipofascial turnover flap in the leg and ankle. Ann Plast Surg. 1992 Jul;29(1):70-5. 10. Angrigiani, C, Grilli, D, Dominikow, D, and Zancolli E. A. Posterior interosseous reverse forearm flap: Experience with 80 consecutive cases. Plast Reconstr Surg. 1993 Aug;92(2):285-93.