SUMMARY. Tissue expansion is an important and valuable addition to the reconstructive armamentarium of plastic and reconstructive surgeons. It is a safe technique and can be used successfully for the rehabilitation of selected burn victims. It allows the creation of skin that maintains all the skin characteristics in the area (sensation, texture, colour, and hair follicles) with minimal or no donor site sequelae. It can be accomplished on an out-patient basis under local or general anaesthesia, depending on the area involved and the patient’s condition.
Tissue expansion is an important technique in reconstructive and plastic surgery. It is a mechanical process that increases the surface area of local tissue, representing a new alternative in plastic surgery.
Tissue expansion dates back in time to antiquity when our ancestors began to expand earlobes or lips by inserting objects of larger diameter. In the current century, Charles Neumann described the use of an air-filled subcutaneously placed implant used in an attempt to reconstruct an external ear deformity. This work was published in 1957 and is now forgotten.
In 1975 Chedomir Radovan and Austad, working independently, developed the concept of tissue expansion with a silicone implant. Three years later, after considerable laboratory and clinical experience and subsequent presentations at local meetings by Radovan, Argenta, and other surgeons, tissue expansion gained wide clinical acceptance.
Tissue expansion is based on the observation that living tissues respond dynamically to mechanical stresses placed upon them. Examples of physiological tissue expansion occur during pregnancy, when the abdomen and later the breasts increase in size, and during puberty, when a young woman develops breast tissue; pathological tissue expansion is observed in large tumours, cystic lesions, and morbid obesity.
Tissue expansion is the slow expanding of healthy tissue adjacent to a defect through the use of a silicone envelope endowed with self-sealing injection ports, i.e., expanders.
Progressive inflation increases the overlying tissue by inducing an increase in mitosis and recruiting adjoining tissue. “We are not just expanding, but creating new tissue” (Agris).
Patient selection is important, since this process implies a temporary but significant cosmetic deformity and may interfere with social life and other activities. Only well-motivated persons should be considered as candidates for the procedure, following extensive pre-surgery discussion.
After taking the decision to use tissue expansion, the surgeon must choose the type of flap to be used, and the shape, volume, and location of the expander(s). Depending on the location and amount of tissue needed for reconstruction, the size and number of expanding devices are decided upon, and these are positioned during the first surgical procedure.
At the time of tissue expander placement, a moderate volume of saline is introduced, but only enough, at this time, to fill the dissection space without placing any undue tension on the suture line. Inflation schedules must be individualized according to the nature and anatomical location of the deformity. Filling is generally performed at weekly intervals, and each inflation proceeds to a point of patient discomfort or blanching of the skin overlying the implant.
When the desired expansion has been achieved, the expander is removed and the flap is moved to the recipient site.
The use of tissue expansion in the treatment of burn patients is popular, and several series have been published supporting its use in selected cases.4-7 Tissue expansion is a good approach for the correction of burn deformity in many anatomical sites, including the scalp, face, neck, trunk, and upper and lower extremities.
Tissue expanders may be used to construct large full-thickness skin grafts or local advancement flaps of tissue immediately adjacent to a tissue defect or deformity.8 Previously expanded full-thickness skin grafts represent a good solution in many situations, including the dorsal surface of the hand, face, and neck and retracted scars;9 it will allow large skin grafts to be taken with primary closure of the donor site.
No other tissue in the body has the hair-bearing qualities of the scalp. Traumatic alopecia, burns (Figs. 1a,b), and male pattern baldness can be corrected by expanding and rearranging the remaining hair-bearing tissue.10 New follicles are not created in the process, but individual follicles can be widened by a factor of two, doubling the size of the scalp without obvious alopecia.
| <% immagine "Fig. 1a","gr0000018.jpg","21-yr-old male with burn alopecia; a 1000 cc tissue expander was used.",230 %> | <% immagine "Fig. 1b","gr0000019.jpg","Final apparence demostrating improvement of area of apolecia.",230 %> |
The expanders are best placed in a subgaleal plane, through small incisions that ideally will be used in the second reconstructive procedure. Serial expansion of the scalp may be necessary in young patients, or when large areas of the scalp have been lost.
Tissue expansion has proved to be valuable in neck and facial defect reconstruction, providing skin colour, thickness, and texture similar to those of surrounding tissue.
Different types of skin exist in the face: the forehead and nose are covered by thick skin containing a large number of sebaceous glands and little hair; the neck, upper lip, and cheek have fewer sebaceous glands and thinner skin; and the peri-orbital areas have extremely thin and pliable skin containing a minimal number of sebaceous glands.
Expansion prostheses in the face and neck are placed in the subcutaneous space. Placing the prosthesis beneath the platysma muscle is useful to provide an extra layer of coverage.
Defects of the chest and abdomen (Figs. 2a-d) are best approached with multiple expanders placed around the defect. The placing of large rectangular or round prostheses above the fascia allows expansion of skin soft tissues to close defects of almost any size.13 A large portion of the abdominal wall can be reconstructed by expanding the full thickness of the remaining abdominal wall.
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<% immagine "Fig. 2a","gr0000020.jpg","22-yr-old male presenting burn scar on thorax and abdomen. ",230 %> | <% immagine "Fig. 2b","gr0000021.jpg","Two tissue expanders, each 500 cc, implanted in subcutaneous pockets on either side of defect.",230 %> |
| <% immagine "Fig. 2c","gr0000022.jpg","Immediate post-operative result.",230 %> | <% immagine "Fig. 2d","gr0000023.jpg","Post-operative view six months after reconstruction.",230 %> |
The skin and soft tissue of the extremities adapt well to tissue expansion.15 Defects of the extremities (Fig. 3) are best corrected by the placement of multiple expanders in a subcutaneous plane. The use of multiple expanders has the advantages of rapid skin creation and greater comfort because of the distribution of the expansion forces.
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| <% immagine "","gr0000027.jpg","",150 %> | <% immagine "","gr0000028.jpg","",150 %> | <% immagine "","gr0000029.jpg","",150 %> |
Fig. 3 - 28-yr-old female presenting burn scars in lower extremity. (Top left) Anterior thigh defect. (Top centre) 400 cc expander with remote valve used for reconstruction and expanded over a period of 8 weeks. (Top right) Post-operative view after expanded flap advancement, demonstrating aesthetic improvement. (Bottom left) Burn scar in popliteal region. (Bottom centre) Tissue expander implanted in subcutaneous pocket. (Bottom right) When expansion had been achieved, the expander was removed, the skin graft was excised, and the expanded skin was tailored to cover the defect completely.
Anatomical distortion of the underlying musculature occurs, but function and strength are maintained.
Expansion in the distal lower extremity usually proceeds at a slower pace because concomitant oedema and circulatory embarrassment may complicate the procedure.
Neuropraxia has been reported in the lower extremity, particularly in the distribution of the sural nerve. When this occurs it is best to deflate the prosthesis and reinflate more slowly.
The advantages of tissue expansion include the superior quality of the reconstruction since skin expansion takes advantage of the adjacent tissue and provides the same colour, texture, skin characteristics as regards thickness and appendages (hair growth), no or minimal donor site scar, and cost effectiveness (compared with other reconstructive procedures).
Tissue expansion provides reconstruction tissue that is very similar to the lost tissue and the contour is usually superior to that achieved with other techniques.
However, despite these advantages, tissue expansion is not a perfect technique without certain problems, disadvantages, and limitations;16 the disadvantages of the technique include the need for two stages, the multiple visits for serial injections, the objectionable temporary appearance, and the interference with everyday activities and clothing habits.
Also, whatever the methodology, the expected or calculated increase in surface area often falls short of clinical requirements.17,18
All silicone elastomer envelopes currently available have an intrinsic safety factor that probably allows hyperinflation up to 15 or more times the stated maximum installation volume.19,20 Following his study of the efficacy of overexpansion using tissue expanders, Hallock19 expressed the opinion that the anxiety during the initial selection process for the appropriate expander should not be a matter of great concern.
Most of the complications in tissue expansion are relatively minor and do not usually interfere with the procedure’s successful completion.
Although the complication rate during skin expansion and the degree of severity have decreased as more experience has been gained, complications still occur. These include infection, product failure, implant exposure, trauma, lost port, leaking, and the compromise of adjacent structures. Long-term complications essentially consist of persistent oedema, widening of scars, loss of sensitivity, and occasionally bone deformities induced by compression.
Standardizing peri-operative care and the technique of placement, expansion, and reconstruction may help to further decrease complication rates.
RESUME. L’expansion tissulaire enrichit notamment les armes reconstructives des chirurgiens plastiques et reconstructives. La technique est sûre et peut être utilisée avec succès dans la rééducation de certains patients brûlés. Elle permet la création d’une peau qui maintient toutes les caractéristiques cutanées de la zone (sensibilité, contexture, couleur, follicules pileux) sans séquelles dans les sites donneurs ou avec des séquelles minimales. La technique peut être effectuée en régime de consultation externe sous anesthésie locale ou générale, selon la zone intéressée et les conditions du patient.