Tissue Expansion Surgery
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 unfavorable 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.
About Tissue Expansion Treatment
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.
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.
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). 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 [Figures22 and and3].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.
Removal of Expander and flap advancement after surgery
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.