Vascularised Fibular Transfer

The fibula derives its blood supply from branches of the anterior tibial and the peroneal vessels, but when it is transferred as a vascularised bone graft, the peroneal vessels are the sole perfusion source. The peroneal artery is described as a branch of the posterior tibial artery, arising just below the divi-sion of the popliteal into the anterior and posterior tibial branches, but different arterial patterns exist, and when a fibular transfer is being considered it is essential to carry out preoperative arteriograms, anomalies and arteriosclerosis providing the two main contraindications to its use.

The peroneal vessels run distally alongside the fibula, behind the interosseous membrane. In the upper half of the bone they are separated from the interosseous membrane by tibialis posterior, which there is tak-ing origin from it, but in its lower half they lie directly behind the membrane. They provide the nutrient artery which enters the fibula a little above its mid-point, and also have branches which reach the surface of the bone.

Septocutan-eous perforators from the peroneal vessels also pass laterally behind the fibula in the intermuscu-lar septum between the peroneal muscles and soleus, and perfuse the overlying skin. These allow the fibula to be transferred as an osteocutaneous free flap, as well as a vascularised bone graft.

The length of bone which can be harvested
extends from just below the head to above the lower tibiofibular joint, approximately 30 cm, and its segmental pattern of blood supply allows osteotomy to be carried out. The perforating branches are capable of supporting a skin island up to 10cm x 20cm.
Despite the loss of the shaft of the bone, the leg functions remarkably normally in the adult.

In children and adolescents, where long bone growth is not complete, greater circumspection is required in its use, because of the risk of tibial bowing. Raising the flap
The procedure is carried out under tourniquet, and the line joining the head of the fibula and the lateral malleolus is marked out on the skin.

When the transfer is of bone alone, a proximodis-
tal skin incision is made along the fibular skin marking, over a length to match that of the bone to be harvested, and the skin flaps are raised on each side to allow the septum which separates the posterior and peroneal muscle compartments to be identified. As a first step, the common peroneal nerve is identified, and care is taken to protect it.

It represents the proximal limit of har-vesting the bone, the ankle joint being the distal limit. The muscles on each side of the septum are separated from one another, and the lateral sur-face of the fibula reached.
When a skin island is being transferred with the

bone as a composite, it is outlined on the skin as an oval placed symmetrically over the septum between soleus and peroneus longus, centred over the middle or the middle and lower third of the fibula. The skin incision is made, and extended
proximally and distally as necessary, and the flap is elevated from its anterior and posterior borders, deep to the investing layer of fascia, as far as the intermuscular septum.

The septum contains perforating vessels, branches of the per-oneal vessels, which provide the perfusion source for the skin island, but some of the vessels pass into the muscles on each side, and emerge from them near the septum. These should be looked for when the flap is being raised, and a cuff of muscle may have to be elevated with the flap to ensure that they are included in the pedi-cle.

In the initial muscle dissection, separating them from the intermuscular septum, the perfo-rating vessels have to be seen and preserved.
With the muscles on each side of the septum
separated, the dissection proceeds in the same manner with both types of transfer. In mobilising the muscles scalpel dissection is used, the plane being extraperiosteal.

The proximal and distal extent of the mobilisation depends on the length of fibula which is being transferred, but over that length they are mobilised completely.
Mobilisation is begun in the direction of the
anterior surface of the bone, with division of the septum which separates the peroneal from the extensor compartment, and mobilisation of the extensor muscles, taking care to avoid
damage to the anterior tibial vessels.

Vascularised Fibular Transfer

Completion of the mobilisation of the extensors exposes the interosseous membrane from in front.
At this point, the fibula is sectioned proximally and distally at the levels required by the recon-struction, and the interosseous membrane is divided to expose the peroneal vessels which lie behind it.

Section of the bone and division of the membrane, carried out in this order, allows trac-tion to be applied to the membrane while it is being divided, and reduces the risk of injury to the peroneal vessels, in particular the venae comitantes, which are thin walled and easily damaged. It also allows traction to be applied to the bone, once the membrane has been divided, more effectively displaying the structures involved, and making dissection easier and safer.

Division of the interosseous membrane is best
begun distally where the peroneal vessels lie directly behind the septum, and can be immedi-ately identified, mobilised, and distally ligated. The vessels are traced upwards under direct vision, mobilising them and dividing branches directed away from the fibula, making sure at the same time that their attachments to the fibula are preserved.

Proximally, where tibialis posterior is taking origin from the fibula, the vessels run between it and flexor hallucis longus, sometimes through the substance of the latter, from which they then have to be mobilised. Dissection and clearance of the vessels is continued up to their point of origin from the parent posterior tibial vessels, any residual muscle attachments being divided, and leaving the proximal vascular pedicle as the sole attachment.

The length of pedicle which is available for anastomosis is often less than ideal and, particu-larly when the transfer is as an osteocutaneous flap, lies in an awkward position. As a con-sequence vein grafts may be required. When the transfer is osteocutaneous, osteotomies can only be carried out with safety on the anterior or anterolateral aspect of the bone.

Transferred purely as bone, any of the surfaces can be used, other than the one from which the branches of the peroneal vessels are entering.
When bone alone has been transferred, skin
suture with suction drainage is sufficient. When the flap is osteocutaneous the secondary defect is split skin grafted, preferably delayed.

A splint is used for several weeks to support the lower leg and foot, and prevent the development of an equi• nus deformity, until the muscles heal and function normally. An ultimately normal gait is the rule. Clinical usage

This transfer can be made either as one of bone alone, or as a composite with a flap of skin, its
dimensions up to 20 cm x 10 cm. The characteris• tics of the bone, which determine its clinical role, are the length available, up to 30 cm, and its strength. Initially the bone is not strong enough to bear the body weight, but it can undergo hypertrophy to the extent of weightbearing successfully.

It can safely be osteotomised, and should be able to accept osseo-integrated implants.

These flaps are perfused by branches of the circumflex scapular artery and its associ-ated veins. The artery is formed by division of its parent vessel, the subscapular, itself a branch of the axillary artery.

The subscapular artery passes down on the posterior wall of the axilla for approximately 4 cm, where it divides into the thoracodorsal artery which continues down to reach the latissimus dorsi muscle, and the circumflex scapular artery, the latter the larger branch of the two. Almost immediately the artery passes into the triangular intermuscular space.

This space is bounded above by subscapularis and teres minor, below by teres major, laterally by the long head of triceps, and the artery, while curving round the lateral border of the scapula inside the space, gives off musculoskeletal branches. Emerging from between teres major and minor into the subcutaneous tissues overlying the scapula, it divides into a horizontal branch which runs towards the midline approximately 2 cm below the spine of the scapula, and a des-cending branch which runs obliquely down-wards, parallel to the lateral border of the scapula.

These terminal cutaneous branches have each been used as the basis of a fasciocutaneous free flap, one the horizontal flap, the other the parascapular flap. The main musculoskeletal branch of the circumflex scapular artery is given off in the trian-gular space, and passes deep to infraspinatus into the infraspinous fossa.

Before doing so, it gives off a branch which runs down parallel to the lateral border of the scapula as far as its inferior angle, where it anastomoses with the deep branch of the transverse cervical artery. In its course it gives off a series of small branches which provide a periosteal supply to the scapula along its lateral border, through its muscle attachments.

These provide the perfusion source which allows a strip of the lateral border of the scapula to be trans-ferred, usually as a vascularised composite along with one of the fasciocutaneous flaps. The horizontal flap is designed approximately midway between the spine of the scapula and its inferior angle; the parascapular flap runs parallel to the lateral border of the scapula, both as ellipses.

Scapular Flaps

The two flaps share a common centre, the site where the cutaneous branch of the parent artery emerges from the intermuscular space, between the teres muscles. Identification of the space provides the point from which the central line of the ellipse is drawn on the skin, parallel to the spine of the scapula in the case of the horizon-tal flap, parallel to its lateral border in the case of the parascapular flap.

The width of each flap is limited in practice by the need to be able to close the secondary defect directly, 24cm x 12cm being considered an absolute maximum.

Raising the flap

 

Both flaps are raised from their distant ends towards the point of entry of the vessels, the plane of elevation baring the underlying muscles to ensure that the flaps contain their axial ves-sels. As the vascular pedicle is approached the vessels become visible on the deep surface of the flap. It is a short pedicle, but it can be lengthened if the vessels are traced back to their subscapular origin in the axilla.

Extension of the dissection in this way increases the length of the pedicle and the calibre of the vessels, both making for ease in transfer as a free flap. The degree of technical dif-ficulty involved in the dissection is largely dependent on the amount of fat which sur-rounds the vessels, and in the obese patient this can be considerable.

When the transfer is as a fasciocutaneous flap, the musculoskeletal branches of the circumflex scapular vessels are divided to allow the vessels to be mobilised, but when the transfer includes bone these vessels have to be carefully pre-served. The segment of bone transferred, approximately 1.5 cm in width, is cut from the lateral border of the scapula from just below the origin of the long head of triceps, a length of up to 14cm.

This part of the scapula is perfused through its muscle attachments, and these must be preserved intact when the bone is being cut.

Scapular Flaps

Clinical usage

 

The skin which both flaps transfer has the thick-ness and lack of flexibility typical of dorsal skin generally, and this may be a factor of importance when the method is being considered for use. The thickness of the subcutaneous fat is variable but can be substantial.

The shortness of the pedi-cle and the small calibre of the vessels involved, unless extended to the origin of the circumflex scapular vessels, make for a degree of technical difficulty in the transfer, and the extension adds considerably to the difficulty of dissection. A fur-ther adverse factor is that both flaps involve turning the patient, unless the surgeon is willing to carry out the entire procedure, creation of the defect and elevation of the flap, in the lateral position, a position which for most surgeons lacks the virtue of familiarity.

In its osteofasciocu-taneous version a serious question mark concer-ning its use relates to the considerable disruption of the musculature of the shoulder girdle which it leaves in the scapular area. The potential it cre-ates for frozen shoulder must be a major deter-rent to its use, particularly in the older patient.

NON-PARAPLEGIC PRESSURE SORES The usual sites of pressure sores in the non-para-plegic are the sacral area and heel, occasionally the iliac crest, and the background to their occur-rence is immobility of the patient. Although immobility is ultimately responsible for the local pressure being prolonged for sufficiently long to produce the local ischaemia which leads to the sores, other factors are usually present which predispose to their occurrence.

Sores occur most often as a complication of an emaciating illness. Loss of subcutaneous fat reduces the cushion it provides and, coupled with the reluctance of the patient to move as a consequence of the lassitude typical of such an illness, combines to create the conditions for their occurrence. When a pressure sore arises in a relatively young patient, a neurological factor, such as multiple sclerosis, is virtually always present.

Management of such a sore depends on the
sites involved, how extensive each sore is and, most of all, to what extent the progress of the debilitating illness can be halted and, hopefully, reversed. In this respect the most important assessment of the plastic surgeon is whether the sore is extending in extent or depth, is static, or is showing signs of healing with marginal epithelialisation.
While the sore is extending the plastic sur-
geon has no active role to play.

The problem is essentially one of nursing and medical care. Once the sore has become static and, even more, shows signs of healing, the question becomes one of deciding whether meeting the conditions needed for successful reconstruction of the ulcer,
whether by graft or flap, might halt or even re-verse the improvement in the patient’s medical state.

A most important element in making the decision is to appreciate that the change from the bedridden to an ambulant state is likely to allow the healing process to progress, even though healing may be by marginal epithelialisation, and will be a slow process.
The patient at very least must be able to keep pressure off the site of the sore before active sur-gery can even be contemplated.

This aspect of the problem has to be emphasised very strongly, and the need to observe it is paramount, even if it pre-cludes surgery in the majority of patients. If this is not strictly observed, it is virtually certain there will be a failure to achieve healing in the short term or to maintain healing in the long term.
In practice, the number of patients suitable for an aggressive surgical approach to the problem is very small. The solution lies more often in get-ting the patient ambulant.

Ambulation immedi-ately relieves pressure on the typical ulcer sites, allowing spontaneous healing to begin. A strik-ing example of this is seen in the pressure sore of the heel, typically sited posteriorly over the tendo Achillis and the adjoining os calcis, which begins to heal as soon as the patient begins to walk and pressure is transferred to the normally weightbearing part of the heel. Certainly one should not rush into surgical treatment of such sores.

Management is most difficult when it is appar-
ent that the patient is likely to be permanently bedridden. Considerable judgment is required in managing such a situation, and sympathy for the unfortunate patient must not be allowed to override a realistic assessment of the problem. The decision is usually in the direction of saying that surgery is contraindicated.

The dilemma is seen in its most acute form in the patient, frequently young, who is suffering from multiple sclerosis, and who has developed
a pressure sore. The harsh fact is that the devel-opment of a pressure sore is often the first step in the downward course of the patient with multi-ple sclerosis, and the question the surgeon must ask himself is whether his surgery will not have the effect of accelerating the downward course.

Pressure Sore Management

Such a patient virtually always requires a flap to reconstruct the defect and the position which has to be maintained for a successful result all too often results in a fresh pressure sore elsewhere.
When a decision has been made that the defect should be treated surgically the choice lies between a graft and a flap and the selection depends on the character of the defect.

The defect with little or no undermining is likely to be suitable for grafting; the defect with signifi-cant undermining is rarely suitable for grafting, and requires a flap. The flaps suitable for the various sites are largely similar to those used in the paraplegic patient.
The sore involving the heel is best left to heal
spontaneously no matter how long it takes.

The alternative reconstructions make demands on the patient which are not acceptable in the age group typically involved.

If a keloid is surgically excised, the probability that the resulting scar will develop into a fresh keloid is extremely high, and the more florid the keloid the greater the probability. For this reason surgery of keloids is generally to be avoided.

Management

However, when the scar is hypertrophic
rather than keloid and is bridging a flexure, so that contracture appears to have been a factor in its initiation, correction of the contractural element as part of the excisional treatment seems often to reduce markedly the likelihood of recurrence.
The first line of treatment in the circumscribed
keloid is injection of the highly active steroid, triamcinolone.

This can be dramatically successful with obvious flattening and softening apparent in a matter of days.
Nevertheless, it must be remembered always that triamcinolone is itself an extremely potent drug whose action is not fully understood. Caution in its use is essential. It must be injected into the substance of the keloid, and enough injected to make the whole keloid blanch.

Injection can be repeated weekly. When the keloid has become flat with the surrounding skin, treatment should stop. Further injections will produce local skin and fat, atrophy. Remarkably enough the drug is effective regard-less of whether the keloid is red and ‘fresh’ or white and ‘mature’.
A recent additional form of treatment has come in the form of silicone gel.

The gel is applied to the affected area and held in position by tape. The mode of action is unclear and the rate at which the activity of the keloid subsides varies. The method has the virtue of being non-invasive, which is particularly useful in children, and of having no side-effects.

Although not effective in every case, experience has been that scars which fail to improve with silicone gel tend not to respond to injection of triamcinolone either.
The rate of change in the keloid appears to
depend on the length of time for which the gel is applied. Ideally it should be worn at all times other than when washing or bathing.
Surgical treatment may be justified in managing small, troublesome keloids, especially those arising in the earlobes.

This site is almost impossible to treat with other than steroid injections -even when successful, this can leave an unsightly, pendulous remnant behind. Under these circumstances, excision followed by a small dose of radiation may be effective in removing the keloid and preventing recurrence. Although this technique is by no means successful in every instance, the risk of recurrence is one which many patients are prepared to accept.

In clinical practice, the major problems arise
when the condition complicates burns and degloving injuries, the extent of the keloid change precluding the use of steroids and silicone gel. Quite apart from the appearance of the scarring and the contractural problems so frequently associated with it, the severity of the itch which usually accompanies it causes the patient to scratch the area, often to the extent of producing excoriation and exacerbating the problem generally.

It is in this situation that the application of sustained pressure has had a dramatic effect both in mitigating the itch and in causing the condition to regress, with flattening and softening of the previously raised, indurated areas. The mode of action is not known, but its effectiveness has resulted in the development of garments custom-fitted to the individual patient, so that constant uniform pressure is applied to the areas involved.

These garments are worn continuously until resolution is largely complete, which this may take a year and more. Radiation injury 7 The forms of radiation injury in which the plastic surgeon becomes involved are radiodermatitis and radionecrosis , and the aspects which concern him are the ischaemia of the irradiated
tissues and the association of radiation damage with neoplasia.

Avascularity is stated to increase in severity up to 6 months postirradiation, plateauing thereafter, but the fact that both conditions manifest themselves clinically very much later than this would suggest that the ischaemic process may progress for a much longer period.
Radiodermatitis is most often seen today in the facial skin and scalp, and in skin sites which were used as portals in the process of irradiating deep structures, such as intra-abdominal tumours, thyroid tumours, or regional lymph nodes, usually in the neck.

Radiotherapy was also at one time a standard method of treating such facial conditions as acne, sycosis barbae, or lupus vulgaris, and ringworm of the scalp. Although it may no longer be used in this way, patients are still seen with the problems which have resulted from its use. The type of radiation used did not penetrate deeply, and it is unusual to find the deeper tissues significantly involved.

As a result, the excision required in treating an area of radiodermatitis does not often need to be carried deeply much beyond the skin and der-mis. When there is doubt about how deeply the condition extends, the degree of mobility of the skin is a good guide, mobility indicating absence of deep involvement. The vascularity of the base left when the area of radiodermatitis has been excised will also give a good guide to the form that reconstruction should take, graft or flap.

A free skin graft can generally be expected to take well, provided excision has been carried out to clinically normal well-vascularised tissue, though the defect left following excision of radiodermatitis of the scalp treated 40-50 years ago for ringworm is not usually successfully managed using a split skin graft.
Where the site has been used as a portal the
situation is quite different. The entire block of tissue between the skin and the target site is involved.

This form of radiodermatitis has much in common with radionecrosis, and in time frequently progresses to it.
Radionecrosis which involves the skin implies ulceration and is indicative of much more deeply extending ischaemia. In managing such an ulcer the first need is to establish whether or not the ulcer has a neoplastic com-ponent. Biopsy should be used as routine, and it should be both generous and representative.

A diagnosis of radionecrosis made in the absence
of pathological confirmation should not be accepted.
The surgical problems set by radionecrosis can be of considerable magnitude, both from the point of view of resection and of reconstruction. The tissues involved are woody hard, and when essential structures such as major vessels and nerves lie in the involved field the technical diffi-culties do not require stressing.

Ideally the entire area of involvement should be excised both mar-ginally and in depth as a preliminary to recon-struction, but this may not always be practicable, particularly in terms of depth clearance, because of the involvement of vital structures. Reconstruction of such a defect virtually always requires a flap with the blood supply which it brings with it.

If it has not been possible to resect the radionecrotic area in its entirety, the pedicle of the flap used to reconstruct the defect, with its content of blood vessels, is best left undivided indefinitely. Division of the pedicle in such cir-cumstances, even after a very prolonged period of time, is liable to be followed by necrosis of the flap, but if the zone of avascularity has been completely resected the problem does not arise.

If a free flap has been used it is essential to use donor vessels outwith the area of radiation damage.
The association with neoplasia takes two forms, the tumour either arising de nouo in the
irradiated field, or occurring as continuing growth in a neoplasm treated by radiotherapy. The de nova tumour can appear as a late develop-ment in the tissues which were irradiated, even though the primary condition was neither malig-nant nor had malignant potential.

Management

The tumour can be a carcinoma or sarcoma, and often presents as an ulcer appearing in the area.
The extent of the resection required depends on the clinical problem for which the radio-therapy was used, and the type of radiation. Because of its effects on the local lymphatics, metastasis to the regional nodes is rare, and the local tumour tends to remain circumscribed both marginally and in depth, developing within the irradiated area.

Unless the tumour has been grossly neglected, resection need be little more extensive than that required for the background of radiodermatitis or radionecrosis. Tumour recurrence following radiotherapy presents either as failure to respond to the radia-tion, or as recurrence after apparent cure. It tends to be clinically atypical, frequently masquerad-ing as radionecrotic ulceration.

Diagnosis is not made any easier when, as often happens, radionecrosis and recurrent tumour coexist in a single ulcer. As already emphasised, biopsy is
essential. Detailed consideration of how post-irradiation recurrent tumour should be managed is beyond the scope of this book, except to com-ment that the pattern of behaviour associated with the particular tumour tends to be lost, and the destruction of lymphatic channels by the radiation may result in bizarre metastatic patterns.