Tissue expansion: Concepts, techniques and unfavourable results

Abstract

The phenomenon of tissue expansion is observed in nature all the time. The same properties of the human skin to stretch and expand and yield extra skin if placed under continuous stress over a prolonged period of time has been utilised for reconstructive purposes with the help of a silicon balloon inserted under the skin and progressively filled with saline. The technique of tissue expansion is now more than three decades old and has been a value addition to our armamentarium in reconstructive surgery in all parts of the body. However, it still requires careful patient selection, meticulous planning and faultless execution to successfully carry out the process, which usually lasts for more than 8-12 weeks and involves two sittings of surgery. Any compromise in this process can lead to unfavourable results and complications, some minor, which allow continuance of the process to attain the expected goal and others major, which force abandonment of the process without reaching the expected goal. This article seeks to highlight the intricacies of the concept of tissue expansion, the technique related to flawless execution of the process and likely complications with emphasis on their management. We also present our results from a personal series of 138 patients operated over a period of 18 years between 1994 and 2012.

INTRODUCTION

The ability of our tissues to stretch and expand gradually over time has been observed and documented, both in physiological and pathological situations, throughout medical history.

Laxity of the abdominal wall following 9 months of pregnancy or laxity of the skin and soft-tissues all over the body following massive weight loss is so commonly observed in every day practice. Stretching of the chest skin to form a ptotic breast mound following puberty, under the influence of hormonal factors is also a form of physiological tissue expansion. Even skeletal tissues expand under certain circumstances as evidenced by stretching of the calvaria at the level of the cranial sutures when an infant's brain enlarges rapidly with growth in the first couple of years after birth.

In pathological situations, the skin and soft-tissues over benign tumours such as lipomas and malignant tumours such as soft-tissue sarcomas also show stretching and expansion.

We have all seen photographs of specific ethnic examples of tissue expansion done for aesthetic purposes unique to those cultures, such as using progressively larger plates in the lower lips of Chadian African women and metallic rings to stretch the neck in Burmese women.

The use of silastic tissue expanders extends this natural principle by utilising the property of human skin to stretch and expand over a period of time under constant stress with actual increase in the amount of skin available, along with increased vascularity in the expanded skin.

HISTORY OF TISSUE EXPANSION

Strangely the first few attempts at “tissue” expansion were directed not at soft-tissue, but at bone. Codvilla[1] reported femoral elongation using bony traction in 1905 followed by Magnuson (USA) in 1908 who reported the use of an external traction device to surgically lengthen shortened bones in the leg.[2] He also reported that this could be used to successfully and concomitantly stretch the soft-tissues of the leg as well. Thereafter Putti in Italy in 1921[3] showed that sustained traction on bone over a month's period could result in 8-10 cm of lengthening not only in the bone, but also in the vital soft-tissue structures such as the muscles, nerves and blood vessels, surely a precursor to the Illizarov method.

Dr. Charles Neumann of New York published the first clinical report of reconstruction of part of the external ear using a latex balloon in 1957 after presenting it at a meeting of the ASPRS in 1956. Credit for pioneering tissue expansion as we perform it today is given to two individuals in the USA who conceived it separately, both of them apparently oblivious of the other's work. These were Dr. Chedomir Radovan at Georgetown University who used it clinically for the 1^st time in January 1976 to resurface an arm defect[4] and Dr. Eric Austad who did his first cases with an osmotically driven self-inflating expander manufactured by Dow Corning Medical Products at the University of Michigan in 1977.[5] Both presented the findings of their initial few cases at a meeting in Toronto in 1979. This meeting finally generated sufficient interest in this revolutionary and innovative technique, which added a new exciting weapon to the armamentarium of reconstructive surgery.

All early discussion on tissue expansion focused on the tremendous importance of proper patient selection and meticulous attention to technique. In their early cases, the pioneers in this technique honestly reported a high incidence of major and minor complications related especially to certain anatomical areas such as the lower extremities, to paediatric patients and in compromised tissues. This incidence of unfavourable results due to poor patient selection, compromise in technical issues, specific patient populations and specific areas of the body continues to this day, more than three decades and thousands of cases later, even in the most experienced hands.

TYPES OF TISSUE EXPANDERS

Tissue expanders are balloons made of silicon and filler ingredients, moulded into a pre-shaped prosthesis, which can be filled with saline through a valve system, which is either incorporated on the expander's surface (early expanders had this structure which is not seen nowadays) or is remote and connected by a flexible silastic filling tube to the expander (nearly all expanders nowadays have a remote valve). The greatest advantage of the remote valve and filling tube is to keep the injection point well away from the balloon thereby avoiding any risks of balloon puncture while inflating the expander. Remote placement allows positioning at a place under the skin where it can be easily palpated.

The standard tissue expanders available from the manufacturing companies are usually circular, rectangular or crescentic (croissant) in shape and are usually made in commonly required volumes/capacities from 50 cc to 1000 cc in increments of 50 cc-100 cc [Figure 1]. Most defects can be quite satisfactorily reconstructed using standard expanders available off the shelf from the manufacturer.

Figure 1.

Different types of tissue expanders

Differential expanders are those which are designed to produce more expansion in one part than in the other around the surface area of the same expander. This is done by altered the stiffness or thickness of the silicon envelope differentially in different areas of the expander. Custom-built expanders are those, which are specially ordered with specifications related to volume, width, length and projection related to a specific defect.

Anatomical expanders are those, which were used specifically in the field of breast reconstructions to produce a ptotic expanded envelope mimicking the breast shape and proportions. Once the expansion of the skin envelope is completed, they would be replaced by implants. A variation of the same is the Becker expander-implant double lumen two chamber system (inner chamber filled with saline during the expansion and outer chamber prefilled with gel to provide the feel of an implant), which can function as an expander to create the skin expansion necessary and then function as a permanent breast implant once the expansion is completed. The Becker system also has a remote valve with a filling tube, the difference being that this part of the apparatus can be detached by traction at the end of expansion. This allows automatic sealing of the saline-filled chamber and functioning of the system as a permanent implant thereafter.

PLANNING FOR TISSUE EXPANSION

It is important that the patient be psychologically stable because he/she has to accept the temporary aesthetic disfigurement due to the expanded balloon. They must be clear about this aspect in advance and be willing to go through the entire process. Good quality well-vascularised tissue at the donor site free of any bacterial infection or contamination is a prerequisite since the balloon causes continuously dynamic expansion forces on the tissues over the period of its use. As a foreign body placed under the skin, the presence of any bacterial contamination predisposes to risks of infection and extrusion of the expander.

Selecting the size, shape and volume: There are various methods advocated to select the right size, shape and volume of the tissue expander to be used in any particular case. This is related to the (1) size of the defect, (2) size and location of the available donor site and (3) expected advancement of a hemispherical domed flap.

Radovan[6] as well as Morgan and Edgerton[7] have suggested that the expander base must be the same size as the defect to be closed. So a doubling of the dome surface would theoretically allow coverage of both defect and donor site. Gibney[8] recommends that the expander base must be at least 2.5-3 times the defect's width. van Rappard et al.[9] studied surface area increases of a number of expanders of different size and shape. They recommended that when using a rectangular or crescentic expander the appropriate size expander would be one in which the surface area of the expander base is 2.5 times as large as the defect to be closed. In the case of round expanders, the diameter of the expander base rather than the area of the base should be 2.5 times as large as the defect. Another method of selecting an expander is based on the circumference of the balloon portion of the expander. The expander must be of sufficient volume so that the apical circumference of the dome of skin overlying the fully inflated expander is two to 3 times the width of the defect.

Manders et al.[10] left it simple-he recommends that the largest possible expander that will fit at the donor site should be used. That way, even if the chosen expander creates excessive skin, suturing the expanded flap of tissue without tension will keep widening of the post-operative scar to a minimum. This logic has its roots in the phenomenon of ‘tissue stretch-back’ which is the ability of expanded tissue/tissue stretched over a long period to contract back immediately after the tension is relieved or to shorten slowly over time. This can result in a wide stretched scar, secondary distortion of an adjacent mobile structure or hypertrophicity of the scar.

Whatever be the shape of the expander, circular/rectangular/crescentic, the yield is finally a more or less domed hemispherical flap. van Rappard et al.[9] estimated that use of a rectangular expander provides the most effective surface area gained when compared to the round or crescent. Rectangular expanders gain 38% in tissue area of the calculated surface increase of the expander, whereas round expanders gain 25% and crescent expanders gain 32% of calculated surface increase.

Another approach to maximising expansion benefits is to use more than one expander adjacent to the defect, possibly on both sides of it. This allows division of the amount of expansion required for a particular defect between the two expanders ensures enough tissue for coverage IF one donor site is inadequate and also decreases the duration of expansion. If on the other hand, more than one expander cannot be accommodated around the defect, then one must plan to do as much as possible in the first expansion, tackle as much as possible of the defect in that episode and then do re-expansion at the same site once again 6 months later to complete the task.

GUIDELINES FOR INSERTION OF EXPANDER

Following measurements of the defect/lesion to be tackled and selection of the expander size/shape/volume based on the same, it is good practice to outline the dimensions of the expander on the skin at the donor site along with the planned remote site for placement of the injection valve.

The incision for insertion of the expander must also be planned taking into account the planned direction of future advancement of the expanded flap and safe dissection of pocket for the balloon. Hence, the incision should usually either be adjacent to the lesion where it would be the leading edge of the advancement flap or it could even be within the lesion taking care that the closure would be safe and secure and that there would be minimal or no expansion of the lesion itself.[10] The incision can also be remote from the defect if the tissue characteristics adjacent to the defect require this safety, e.g. skin grafted area, unstable skin over the lesion etc.

There is a school of thought that the incision should be radial or perpendicular to the expander to lessen the risk of wound dehiscence during the process of expansion, but this is not always possible and indeed may be impractical from the point of view of creating additional scars and disturbing relaxed skin tension lines.

The length of the incision need not be as long as the base diameter of the expander to be used. Usually, an incision of 3-5 cm is adequate for careful and meticulous dissection of a reasonably large pocket to comfortably fit the chosen expander.

A practical consideration at the beginning of surgery is to ensure that all surgical and assisting personnel wear powder-free gloves. If they are not available, the powdered gloves worn by all personnel must be thoroughly washed with a solution of normal saline before any instruments or drapes to be part of the procedure are touched or used.

The plane of dissection/insertion is usually the natural relatively avascular plane over the muscle fascia in most parts of the body. In the scalp and forehead, it may be in the subgaleal plane to minimise bleeding. The characteristics of the overlying skin also play a role in determining this plane. If the overlying skin is scarred and unstable, a deeper plane is chosen to ensure sufficient skin vascularity and integrity to withstand the stresses of the expansion. If the skin is thick and relatively more resistant to soft-tissue stretch, the plane could be more superficial. In general, a natural tissue plane, an avascular plane or a plane which minimises bleeding during pocket dissection is infinitely preferable in the overall scheme of things. Dissection is a combination of sharp and blunt methods with haemostasis achieved as required along the way. A practical consideration is to avoid the use of gauze pieces during the creation of the dissection pocket, using only commercially available surgical mops. This is to completely obviate the risk of inadvertently leaving any gauze pieces or gauze threads within the pocket.

A separate reasonably tight tunnel and space remote from the area of expander placement is dissected for the injection valve, such as that it is easily palpable from the surface. This may usually be over a bony prominence such as mastoid in the face or over the ribcage/iliac crest in the upper/lower torso. The plane of this dissection should be such that it is superficial enough for easy palpation and yet deep enough to avoid pressure necrosis of the skin from the hard valve surface and edges. The actual site of valve placement must be a snug fit to prevent valve displacement. An absorbable suture of 4-0 Vicryl may be used to retain the tubing in the place where it exits from the tunnel created for the valve so as to ensure that it stays in place. This is a matter of personal choice and experience.

Sometimes the valve and connector tubing may be kept externally outside the skin for ease of injection, particularly in the paediatric age-group. However, care of such an external system needs to be extremely meticulous because the chances of complications are quite high. It should be used only in the most extenuating circumstances or where constant monitoring of the system is possible.

Once a pocket of adequate dimensions in the selected tissue plane is dissected, such that the expander will sit comfortably and away from the incision site, meticulous haemostasis is done. Undue excessive charring of tissue during haemostasis should be avoided. The pocket may then be irrigated with a solution of povidone iodine or an antibiotic. The pocket is carefully examined to make sure that there are no gauze threads or any other foreign material within.

The expander is removed out of its sterile packaging only at the appropriate time once all the preliminary steps have been completed. It is carefully examined for integrity of the envelope, any folds are stretched out gently and the joint of the balloon with the tubing and the tubing with the valve is carefully inspected. One method to ensure the integrity is to fully immerse the expander, tubing and valve in a bowl of normal saline and gently squeeze it to examine for any escaping air bubbles. Once it is confirmed that there is no leakage, the excess air within the expander is removed by using a No. 24 scalp vein needle inserted into the valve dome. A practical consideration is to make sure that there are no sharp instruments, cautery pencils etc., anywhere in the operative area when the expander is being inspected to avoid inadvertent puncture of the balloon. A change of gloves (with the attendant procedure to thoroughly wash powdered gloves once again if such are being used) may be considered at this point before the expander is directly touched. It is also prudent to ensure that only the operating surgeon (one person only) should actually directly handle the expander unit throughout the procedure.

The manufactured packaging usually includes a metal connector, which may be used to join a transected tubing (only in expanders which are being re-used) or to adjust the length of the tubing between the expander and the valve.

Depending upon the relation of the valve placement area (distal or proximal to expander placement site) to balloon, the former is slipped gently into place first or later. This should be a snug fit as mentioned above so that it is not displaced due to the patient's movements later. A retaining suture to the adjacent soft-tissue can also be considered. The expander balloon is then gently inserted and smoothened into place in the pocket taking care that (1) the entire base sits comfortably on the pocket bed without any impingement onto the sides/walls of the pocket and (2) any folds or sharp edges are smoothened out as much as possible. The connecting tubing must lie under the expander or to the sides, but definitely not over it to avoid any skin erosion. Care must be taken to ensure that the tubing is taut or smoothly coiled and does not kink or curl sharply so as to avoid flow obstruction.

The system is then tested once again by injecting 10-20 cc of normal saline through the remote valve using a No. 24 scalp vein to ensure smooth and safe structural continuity from the valve through the tubing to the balloon.

The balloon is checked for a final time with regard to placement and envelope folds and edges. Closure is then meticulously done in 2-3 layers with interrupted buried 3-0 PDS sutures in deep (and superficial layers if necessary) and 4-0 ethilon interrupted or continuous sutures on the skin. Skin sutures will be removed at 10-14 days once good primary healing has occurred.

Once closure is completed, the balloon is further inflated with saline to a capacity enough to (a) obliterate any dead space in the pocket, (b) maintain the pocket size and (c) smoothen out any wrinkles and folds in the expander envelope. The amount of this intraoperative filling of the balloon must be carefully balanced with maintenance of acute tissue vascularity, patient stretch pain and stress on the suture line. Under-filling is preferable to overfilling and risk to tissue vascularity and good stress-free primary healing of the suture line.

Patient and/or relatives must be clearly advised about the vital importance of taking care of the donor site with avoidance of any kind of trauma. If the expander is placed in the flanks or sides of the torso or limbs or head where it is likely to come under compression by body position especially during sleep, avoidance of such a position is explained to the patient with judicious use of soft pillows to avoid pressure/weight of the body on the expander. This is particularly true and mandatory in paediatric cases where the child is not aware and cannot be held responsible for such care.

A meticulous chart is maintained, which mentions the expander size/volume and shape inserted, the location of the placement on the body, amount of saline filled intraoperatively and any special features encountered during placement/precautions and care to be taken thereafter. Printed sticky labels containing information about the manufacturing batch details and shape/volume of the expander are usually part of the packaging and should be added to the patient's discharge sheet, OT notes and hospital records for ready future reference. It is wise to retain the original or a copy of the expansion chart with the surgeon's office while the original or copy is given to the patient with instructions to bring it at the time of each expansion session.

THE EXPANSION PROCESS

A time of 2-3 weeks is given for uneventful good primary healing of the incision suture line. No expansion is done during this period. The body tissue reaction forms a smooth sterile film around the expander balloon in this time. A course of broad spectrum antibiotic coverage is provided for the first few days (5-7 days) as in any clean surgical procedure. Any special circumstances may warrant more prolonged medication at the discretion of the surgeon. Suture removal is at 10-14 days.

Patient is then called back weekly on an out-patient basis for the serial expansion process. This is usually done as an office procedure without any anaesthesia. In the paediatric age group, the pain of the needle prick onto the valve at the time of injection may be obviated by the use of topical local anaesthetic gel (prilox) an hour prior to the scheduled procedure. The specific area dabbed with anaesthetic gel should be covered with a gauze piece or a piece of clean plastic wrap for increased efficacy of action of the topical anaesthetic agent.

The skin and tissues are examined for any signs of inflammation and local tenderness. The healed suture line is examined for strength and presence of any stretching/thinning out. The expander is palpated to assess for any folds. The valve is also palpated to assure easy accessibility and placement well away from the expander.

After meticulous cleaning and prepping of the entire area (expander placement area plus valve placement area and around) as for any sterile/aseptic procedure, the valve area is carefully palpated once again and a No. 24 scalp vein is pierced through the skin perpendicularly into the dome of the injection valve. Using a 10 cc/20 cc luer-lock syringe, gentle aspiration is first done to ensure continuity of the system and smooth return of saline from the expander. Then taking care not to introduce any air into the tubing and the balloon, further expansion of the balloon is done with normal saline. The amount of expansion at any particular session is decided by (1) palpating the expanded dome and assessing if it is still soft and pliable (add some more saline) or tight and tense (end of expansion for that session), (2) assessing the skin for signs of continued blanching on pressure at multiple points and good capillary return on release of the pressure (tissue tolerance) and (3) patient tolerance (pain and discomfort with feeling of too much tightness signals end of expansion for that session).[11] All these factors are balanced and fluid added or withdrawn towards the end of expansion in each session.

The scalp vein needle is removed and the prick point is kept under pressure for a minute until any point bleeding stops. The point is dabbed with antiseptic ointment and may be covered with a sterile gauze piece or a Band-Aid for 24 h.

The appropriate entry of additional expansion done and the total volume achieved at each session is meticulously made in the expansion chart. Remarks must be made promptly about any problems seen or symptoms/local signs encountered at each session both for ready reference and medicolegal purposes. Specific fresh instructions related to use of analgesics to get over the discomfort encountered for 24 h or so due to tightness at the end of each session, use of antibiotics if required for any signs of inflammation/potential infection etc., encountered at that session. The importance of observation of this protocol during the expansion process which typically lasts for 6-12 weeks in order to ensure a smooth and complication free treatment process cannot be over-emphasized. The process of weekly or biweekly expansion continues until clinical impressions and actual measurements show that an adequate amount of skin has been expanded.

Although the manufacturer guidelines caution about limiting the amount of expansion to the capacity of the expander, a good quality expander can definitely be safely over-expanded to double the capacity and more, depending on the requirements of the procedure [Figures 2 and 3]. However two factors do affect the actual process in practice - (1) the thinness of the skin envelope as the overexpansion continues and (2) the increased risk of back-pressure leakage through the one-way valve.

Figure 2.

A 50 cc rectangular expander overinflated to 125 cc

Figure 3.

A 500 cc rectangular expander overinflated to 1200 cc, before removal from scalp

REMOVAL OF EXPANDER AND FLAP ADVANCEMENT

When it is deemed that the amount of expansion necessary to serve the purpose of covering the expected defect is completed, expansion is stopped. A period of approximately 2 weeks is then given to allow the expanded skin to stay stretched to that level. The property of stress relaxation of the skin is taken advantage of during this time.

At the time of the second surgery, once the patient is anaesthetised, one final intraoperative expansion can be done to obtain 1-2 cm of additional tissue. Since the pain tolerance factor is removed under anaesthesia, the limits of this intraoperative expansion depends upon tissue factors such as blanching and skin pallor. About 20% of the expander capacity can be easily inflated in one final session to obtain a little additional expansion. The 15-30 min that this process acts for usually will not create any irreversible ischaemic changes because rapid relaxation of the stretch/stress takes place as soon as the skin is incised and the expander taken out.

The incision for the advancement flap is usually at the border between the expander and the lesion/defect. This incision is carefully deepened to the capsule. A scalp vein is then inserted into the port and adequate quantity of saline is withdrawn so as to create some tissue laxity over the capsule area. This is done so that the incision in the capsule does not inadvertently cut into the balloon and burst it. The expander is then gently removed. The tunnel that leads to the port site is then incised under direct vision (putting the tube under some tension as it emerges from the tunnel) with an electrocautery on coagulating current, along the length of the tunnel up to the area of the port, then blunt dissection is done to expose the port, the port is freed and removed.

A trial advancement of the expanded flap across the lesion/defect is then made to assess the reach of the flap and if the flap appears to fall marginally short or is a tight fit, an incision is carefully made with electrocautery to divide the base of the capsule. If any more release is necessary, then parallel incisions may be carefully made in the capsule in the axis of advancement. It is very rare to need a complete capsulectomy to unfurl the flap fully.

Once it is confirmed that the expander will cover the entire defect/lesion, excision of the lesion or final preparation of the defect is carried out and haemostasis confirmed. The flap is then advanced as required. It is a worthwhile trick to take a few absorbable tacking/quilting sutures between the capsule (proximal to the advancing edge) and the base/floor of the defect to anchor the flap. This will reduce the amount of flap retraction and also help in reduction of any scar stretching by relieving the tension on the actual suture-line. This is particularly important when the flap is “anti-gravity,” such as an advancement flap from the neck or lower jawline to correct a high malar defect/lesion… in such a case, anchorage of the capsule to the periosteum of the infraorbital area as mentioned above will reduce the drag on the flap and avoid not only scar stretching, but also any chances of lower eyelid ectropion.

Use of a suction drain for 24-48 h is a matter of discretion depending on the individual case. Closure is usually done in 2-3 layers, deep suturing with absorbable sutures (3-0 Vicryl, PDS, Monocryl) and skin closure with either subcuticular PDS or Monocryl or a running stitch of 4-0/5-0 ethilon. Suture removal would be at 8-10 days post-operative.

The use of steristrips or micropore paper tapes across the scar for a period of 3 weeks helps in reduction of scar stretching. If on observation over a period of 6 months, any hypertrophic city of the scar is noticed and then the use of silicon sheets, scar modifying creams and/or intralesional steroid injections may be considered as required.

UNFAVOURABLE RESULTS AND COMPLICATIONS⁽¹⁹⁾

Tissue expansion is a long multi-staged process, which requires correct patient selection, careful planning and meticulous execution with great attention paid to detail, sterile techniques and 3 dimensional movement of skin over the course of the treatment.

It is therefore likely that some complications and unfavourable results are par for the course. Complications may be minor, which are related to the implant system itself and inadequacy of completion of the goals OR major, which force one to alter the original surgical plan or temporarily abandon it.

Minor complications include issues related to haematomas and seromas, valve placement or location, exposure of the valve alone and inadequacy of the expansion related to the defect/lesion. Major complications include (1) cellulitis and closed infections, (2) exposure of the expander balloon itself, (3) deflation of the balloon and (4) ischaemic necrosis of the overlying skin.[12]

Area-wise, expansion in the lower extremity appears to have the highest rate of complications. This may be related to less vascularity in the lower limbs and contours of the limbs on which the expander lies. In comparison, expansion in the torso and head/neck appears to have the least complications.[13]

HAEMATOMAS AND SEROMAS

Bleeding into the newly dissected space is an iatrogenic issue.[14] Meticulous haemostasis at the time of expander insertion is important. Some advocate the use of drains for a period of 24-48 h but our view is that one should rather not have any component in the system which has external connectivity to a sterile closed system as this potentially increases the risk of contamination and infection from the outside. If an haematoma is detected as evidenced by excessive pain, bogginess in the pocket and increased tissue tension, it is immediately addressed by opening the pocket, draining the haematoma, irrigating the pocket, confirming haemostasis, replacing the expander and closing securely once again followed by a course of 5-7 days of antibiotic coverage. Expansion can be started after 2-3 weeks once good healing of the incision site is assured.

In spite of the expander being a foreign body, seromas are relatively infrequent. They are usually due to tissue reaction or following absorption of a sterile haematoma. Rarely, they may be due to leakage of the injected saline into the potential tissue space between the expander and the overlying skin. If significant, they may require careful aspiration (with risk of balloon puncture) or drainage. Small seromas usually do not compromise the process of expansion.

CELLULITIS AND CLOSED INFECTIONS

Since the expander system is an implant, it is prone to subclinical or clinically significant infections from extraneous sources as well as from contamination within the system. The usual causes are: (1) Peri-operative iatrogenic contamination, (2) infections from folliculitis or abscesses in the skin or adjacent unstable/infected tissue in the lesion/defect and (3) infections related to the injection valve/port.[15]

Lapses in the meticulous sterile technique, which needs to be observed intra-operatively may cause bacterial contamination of the dissected space in which the expander is inserted. Lapses in a ‘need-to-touch’ basis sterile handling of the unit may also compromise sterility. This is soon evident within the first few days after expander placement in the form of skin erythema, local tenderness and systemic symptoms [Figure 4]. These should be detected and treated with broad spectrum antibiotics and surgical intervention at the earliest. If necessary, the incision may be opened and the expander removed, the cavity washed thoroughly and a decision taken to either replace the expander or temporarily abandon the process until the infection is fully settled. If a decision is taken to put the expander back in and continue the process, then swabs must be sent for culture and antibiotic sensitivity and appropriate course of antibiotics started.

Figure 4.

Cellulitis over one of the expanders (right side) placed in the abdomen

Cellulitis of the overlying skin seen later in the process is usually due to contamination from folliculitis, stitch abscesses, abscesses under scabs or due to some lapse in strict asepsis during the weekly inflation process. Rarely, it may be due to poor blood supply to the area which pre-disposes to infection, this is most often seen in the lower extremity. Cellulitis is treated on an emergent basis by: (1) Stopping expansion temporarily, (2) deflating the expander by 10% to minimise any ischaemic compromise, (3) instituting immediate antibiotic and anti-inflammatory cover and (4) local treatment with fomentation with glycerine/magnesium sulphate. Quite often, this treatment will tide over the crisis and allow resumption of the process within 7-10 days. If in spite of this treatment, it progresses further to overt infection with attendant systemic signs and symptoms, then a decision about removal of the expander is imminent.

Subclinical infections may sometimes cause thickening of the capsule in the middle of the expansion process with resultant extraordinary resistance to expansion. In such cases, it is observed that it is very difficult to fill the expander by an adequate amount at the weekly session of filling, it causes unusual pain to the patient well before the expected limits of tissue tolerance at that session and there is back-flow from the valve leaking through the skin. A decision may need to be taken to cut losses, abandon the expansion process and remove the expander. Whether a capsulotomy or capsulectomy is necessary at that point is a matter of surgeon discretion. Without the expander/implant within, capsules are known to disappear within 6-month time. The decision on whether to do as much advancement of the flap as possible at that point depends upon the lesion/defect and a joint decision of the patient and treating surgeon. The surgeon can then consider re-insertion of the expander after a minimum of 3-6 months.

EXPOSURE OF THE EXPANDER AND/OR VALVE

The common reasons for this complication are: (1) breakdown of the incision through which the expander was inserted, (2) persistent implant folds causing erosion of the overlying skin and (3) if and when the expander is inserted under unstable thin burnt or scarred skin, under skin grafts or irradiated tissue.[16]

The reason for extrusion of the expander through the incision is usually from an implant pocket created too small so that the implant is placed too close in contact with the suture line. If breakdown of the incision occurs early in the process (during the process of primary healing of the incision after expander insertion) and is detected immediately, there exists a chance to try and salvage the process by immediately taking the patient up for surgery, widening the breakdown area, checking for any implant folds and correcting them (including increasing the size of the dissected pocket if necessary so that the expander can lie comfortably without folding and not in immediate contact with the suture line), cleaning out the pocket with thorough lavage, replacing the expander and resuturing in layers, followed by coverage with appropriate antibiotics.[16] The expansion process is then delayed until such time as the new closure heals fully, usually 2-3 weeks.

If implant exposure occurs later in the process, it is usually due to instability of the overlying skin or abnormal thinning of the skin leading to skin breakdown either due to mechanical pressure from the expander (folds or otherwise) or an ischaemic process [Figures 5a–c]. In most such cases, the exposure will not occur at the site of the incision scar, but over some part of the expander dome. If the exposure is limited and/or there is a potential exposure with the goal of expansion being near, then further gradual expansion may be attempted with extremely close observation and local measures to control any infection [Figure 6]. If however the exposure is large and the goal of expansion is far away, then attempts at salvage are mostly futile and it is time to cut losses and abandon the process. The process may be re-attempted 6 months later after strong healing of the dehisced area.

Figure 5a.

Expander balloon exposure in neck

Figure 5c.

Exposed balloon and port in same patient

Figure 6.

Thinning of skin over expander with potential exposure

Figure 5b.

Expander exposure due to overzealous expansion and thinning of skin in forehead (300 cc rectangular expander)

Sometimes only the valve may be exposed from pressure necrosis [Figure 5c]. This may be due to the fact that often the valve is placed subcutaneously for better palpability and it rests on unyielding underlying bone for the same purpose. In such cases, the edges of the valve may cause pressure necrosis of the overlying skin. One-way of tackling this is to completely exteriorise the valve and look after it with appropriate local antiseptic measures and systemic antibiotics until the rest of the process is completed.[17,18] If there is a potential for infection or there is actual infection in the system and there are systemic signs of overt infection of the expander itself, then salvage may not be possible and the process may need to be abandoned with whatever expansion possible at that stage being done at the discretion of the surgeon and patient.

DEFLATION OF THE BALLOON

The most common cause for this in the past, when implant ports/valve were incorporated on the dome itself, was iatrogenic due to misdirected needle pricks into the expander envelope itself. This would obviously lead to puncture, leakage and finally deflation, which was basically an implant failure.

With the introduction of remote ports, this aetiology for deflation is now rare and almost unheard of, unless the port is placed unusually close to the expander in the first place and then either migrates closer to it due to slippage from its position or as expansion proceeds, the expansion process inflates the expander and brings its edge close to the port.

Nowadays, the usual causes of implant deflation and failure are: (1) severe trauma to the area due to poor care of the expander or deliberate injury, (2) massive overexpansion well beyond the capacity of the expander to stretch resulting to bursting and (3) poor quality of the expander itself.

There may be two other rare reasons for implant failure. It may be due to avulsion of the connecting tubing from the expander or from the port and damage to it somewhere between the two. This is more likely if an in-line metal connector has been used to join the expander balloon to the valve after reducing the tube length by trimming it for some reason. This would result in leakage of whatever saline is injected into the port through this damaged area rather than filling the expander. The other reason could be due to backflow leakage from the otherwise self-sealing valve/port itself due to disruption of the one way mechanism following multiple punctures.

Puncture and damage to the expander balloon itself is a disaster and can be tackled only by replacement of the entire system. Damage to the tubing and valve is addressed in the same way if it occurs early in the process. If it occurs later in the process, the only option may be to cut losses as mentioned above.

FLAP ISCHAEMIA AND SKIN NECROSIS

This is a dreaded complication because it directly affects the tissue that is expected to be recruited by tissue expansion. Compromise of the vascularity and ischaemia in the flap is usually due to pressure from the underlying inflating expander. Most commonly, this may be caused by originally creating too thin a skin flap by dissection in too superficial a plane [Figure 7]. This may also be due to poor quality skin such as after irradiation or when the expander is placed under skin grafts or atrophic skin or by too rapid or too much expansion in a short period. Persistent implant folds also predispose to skin necrosis in that area.

Figure 7.

Skin necrosis at edge of flap

Respecting the end point indication of expansion at any one session– local pain, blanching and high tissue tension will help avoid this problem during the process of expansion. Thin skin in elderly patients or children should be expanded more carefully than otherwise. If the skin has been previously expanded or where the skin is compromised by diabetes, irradiation or collagen disorders, the expansion must be judicious.

If impending skin loss is noticed early by the signs of persistent pallor of the flap and poor capillary return on pressure release, then the expander must be immediately deflated to allow for maximum tissue perfusion and the skin flap observed. If the skin is already necrosed and irreversibly damaged when noticed, then early debridement of the necrotic skin is mandatory to avoid infection [Figure 8]. In such cases, the process of expansion is abandoned, the expander removed and the wound closed and allowed to heal.

Figure 8.

Early ischaemic changes over skin flap proceeding to full thickness necrosis

BONE RESORPTION/NEW BONE FORMATION/BONE MOLDING

This is usually seen in cases where expansion is done in the scalp and the balloon is placed over the calvarium. Pressure from the inflating balloon is often noted to cause bone resorption and contour depressions under the balloon with ridges of new bone formation at the margins of the balloon, which are palpable in the capsule when the expander is removed at the end of the process. These are temporary in nature and usually resolve within 3-6 months after the compression from the balloon is relieved. Bone resorption is more commonly seen in children and elderly patients.

NEUROPRAXIAS AND NERVE DYSFUNCTIONS

These are quite rare in spite of expander balloons being placed in the proximity of major nerves in the extremities or in the head/neck. Temporary nerve dysfunctions from tingling and numbness to sensory and motor deficits may be noticed very rarely. They are due to compression from direct mechanical pressure or traction on a nerve due to anatomical restriction. These symptoms resolve completely and rapidly if taken note of and recognised promptly and treated before any focal demyelination occurs. Treatment is in the form of deflating the expander balloon and assessing the relief of symptoms and then proceeding with further expansion in a slower fashion. If recurrence of symptoms occurs and is debilitating and/or involves motor function, a decision about continuing expansion needs to be taken between the patient and surgeon.

NEED FOR SECONDARY PROCEDURES

It must emphasise that certain secondary procedures may be necessary after the primary 2 staged completion of the treatment. This usually pertains to revision of stretched scars and/or hypertrophicity along the scar line. Since expanded flaps are usually quite thin, there is no necessity for defatting procedures in most cases. It is best to primarily tackle dog-ears resulting from movement of the expanded skin flap rather than waiting for them to resolve. This can be done with the usual judicious cutbacks and other methods of dog-ear removal. If the goal of treatment is not completely achieved, a second sitting of tissue expansion or some other modality of reconstruction may be necessary. This is best done at least 6 months after the completion of the first course of treatment. It is vital to understand that although tissue expansion has yielded extra skin, it has also thinned it down, so second sittings of tissue expansion, especially in the paediatric age group must have that factor kept in mind.

Conclusion

In summary, Tissue expansion is a vital and valuable tool in our reconstructive armamentarium but one which requires a careful and correct patient selection, meticulous planning and precise step-wise execution. It is a gratifying answer for many difficult lesions and defects resulting from congenital and post-traumatic causes. Like all modalities of reconstruction, there always lies the possibility of unfavourable results because of the use of a prosthesis, the long duration of the entire process and several ambiguous intrinsic and extrinsic factors related to the same. However as long as one anticipates these sequelae and complications and is able to tackle them satisfactorily, it remains one of the most exciting advancements in our field in the last 50 years.

OUR PERSONAL SERIES

A total of 138 cases of tissue expansion were done by the authors between 1994 and 2012 [Figures 9 to 20]. Of these, 105 patients were operated at a tertiary care municipal hospital between 1994 and 2005 and 33 patients was operated at different private hospitals between 1998 and 2012. The age range of the patients was between 7 and 64 years.

Figure 9.

Case 1 - Three expanders (two 50 cc rectangular in forehead and one 500 cc rectangular in neck) placed for correction of forehead and left cheek and jawline scarring

Figure 20.

Case 12 - Use of two expanders in separate sittings to resurface the left cheek followed by reconstruction of the nose in a case of post-burn scarring in an 8-year-old boy

Figure 10.

Case 2 - Use of two 500 cc rectangular tissue expanders over bilateral deltopectoral flap areas for improving post-burns cheek scarring

Figure 11.

Case 3 - Correction of skin grafted post-burns area in cheek with a 200 cc round neck expander

Figure 12.

Case 4 - Expanded forehead flap for reconstruction of the nose

Figure 13.

Case 5 - Expanded forehead flap used for reconstruction of post-traumatic nasal reconstruction

Figure 14.

Case 6 - 500 cc rectangular expander used for correction of scalp alopecia in two stages

Figure 15.

Case 7 - 300 cc round expander used for reconstruction of nose - forehead defect had to be resurfaced with skin graft

Figure 16.

Case 8 - Expanded parascapular free flap for resurfacing severe scarring on left cheek

Figure 17.

Case 9 - Expansion in neck for resurfacing of giant melanocytic nevus on right cheek (500 cc rectangular expander)

Figure 18.

Case 10 - Forehead expansion used to correct a complex Tessier cleft-the expanded flap was used partially for lining and partially for cover

Figure 19.

Case 11 - Post-burn thigh scarring corrected by expansion in 2 stages - note stretched scar in spite of expansion

A total of 34 patients (24.6%) required insertion of more than one expander. Of these, 26 patients (18.8%) had 2 expanders inserted [Figure 21] and 8 (5.8%) patients had three expanders inserted [Figure 22]. Only 11 patients (8%) required two sittings of expander insertion to complete the goals of defect/lesion coverage. The sites for insertion of 180 expander balloons in 138 patients were as follows: Scalp (37), forehead (32), face (19), neck (32), upper extremities (10), trunk (26) and lower extremities (24).

Figure 21.

Examples of two expanders in one patient

Figure 22.

Examples of three expanders in one patient

Of the 138 patients operated, expansion was successfully carried out to the planned limit of the procedure in 126 patients (91.3%). In the remaining 12 patients (8.7%), expansion had to be abandoned due to major complications. Of these 12 patients, only one patient followed-up for a re-expansion after a period of 6 months.

Of the 12 patients with major complications in whom expansion had to be abandoned, the first nine were patients operated between 1994 and 1999, possibly part of our learning curve. The other three patients were operated between 1999 and 2007. We have had no major complications in any patient operated after 2007-2012.

We did not have a single patient with a haematoma or seroma that required re-exploration and drainage or aspiration.

Closed infection or cellulitis was noticed in three patients (2.2%) out of the 138 [Figure 4]. One was in the trunk and the other two in the thigh. In all three cases, the cause was probably peri-operative contamination. Both cases were identified early (in the first 2 weeks before expansion was started) and managed by conservative measures (a course of antibiotics and local fomentation). All three cases resolved only at the cost of delayed expansion, which could proceed without any further problems after two more weeks. In our series, therefore, since these infections did not affect the final outcomes, they were not counted in the major complications that forced abandonment of the procedure.

We had only one case of valve exposure in our series - this patient also had a simultaneous balloon exposure [Figure 5c]. We had a total of nine cases of balloon exposure (6.5%) in our series of 138 patients. The highest rate of exposure was in the face and neck (five cases), thighs (three cases) and forehead (one case). The exposure occurred due to dehiscence at the incision site in four cases, over the flap due to undetected implant folds and skin erosion in three cases and due to unstable skin (post-burn scarred skin) in two cases. In all but one case, the patient requested removal of the balloon and refused any further expansion. In only one case with exposure of the balloon in the neck, the patient came back for re-expansion after 6 months and the subsequent expansion was completed successfully without any problems.

There was one case with potential exposure of the balloon in the neck due to thinning of skin in an 8-year-old boy almost at the end of expansion. However, the procedure could be successfully completed without any problems [Figure 6].

We had two cases of implant failure/deflation (1.4%). In one case, the expander was in the scalp to correct post-burns alopecia in a young child and the history given was of a violent blow to the head of our patient by another child resulting in bursting of the balloon. This took place in the 5^th week of expansion. In the second case, the expander had been placed in the thigh in a young adult woman, there was no obvious history of trauma or violence, but the patient came with clear-cut implant deflation in the 3^rd week of expansion.

We had only one case of flap necrosis (0.7%) which occurred in a patient with an expander placed in the neck. This occurred over the centre of the flap in the 3^rd week of inflation. There were no warning signs such as erythema or blister formation or absence of blanching at the time of the previous session of expansion. Patient followed up 5 days later with a clear-cut ischaemic area of dimensions 6 cm × 4 cm. All conservative measures failed and the ischaemia progressed to a full thickness eschar, which had to be debrided, the expander removed and the process abandoned [Figure 8]. Wound healing was then pursued by secondary intention as the patient refused any other modality of treatment. Patient was lost to further follow-up before the wounds had completely healed.