Tissue expansion

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Tissue expansion
MeSH D015626

Tissue expansion is a technique used by plastic, maxillofacial and reconstructive surgeons to cause the body to grow additional skin, bone, or other tissues. Other biological phenomena such as tissue inflammation can also be considered expansion (see tissue inflammation below).


Skin expansion

Skin expansion is a common surgical procedure to grow extra skin through controlled mechanical overstretch. It creates skin that matches the color, texture, and thickness of the surrounding tissue, while minimizing scars and risk of rejection. [1]

When skin is stretched beyond its physiological limit, mechanotransduction pathways are activated. This leads to cell growth as well as to the formation of new cells. In some cases, this may be accomplished by the implantation of inflatable balloons under the skin. By far the most common method, the surgeon inserts the inflatable expander beneath the skin and periodically, over weeks or months, injects a saline solution to slowly stretch the overlaying skin. The growth of tissue is permanent, but will retract to some degree when the expander is removed. [2] Topically applied tissue expansion devices also exist. These have the benefit of being inexpensive and do not require a surgical procedure to implant them under the skin. [3]

Breast reconstruction surgery, for example, can use this technique when the mammary gland is removed by surgery (mastectomy). Later, a more permanent breast implant filled with saline or silicone gel is inserted under the expanded skin pocket.[ citation needed ]

In other applications, excess skin is grown purposely by expansion on the back or the buttocks, so that it can be harvested later for transplantation to another site where skin was lost due to trauma, extensive wounds, surgery, burns, etc.

Mechanics of skin expansion

Stretching the skin beyond normal expansion invokes several mechanotransduction pathways which increase mitotic activity and promote collagen synthesis. As a result, the skin surface area increases. Continuum mechanics approaches can be used to model skin growth during tissue expansion and non-linear finite element methods can be used to computationally simulate different tissue growth scenarios. [4]

Tissue growth due to skin expansion can be modeled as anisotropic surface area growth as described by the following equations:[ citation needed ]

where is elastic area stretch that is reversible and is irreversible area growth described by:[ citation needed ]

where is a vector in the direction of skin thickness. We assume that the skin does not grow in the thickness direction for area growth is equal to volume growth or . [4] We also assume that the newly created skin will have the same density, stiffness, and microstructure as the original, non-expanded skin. [5]

Radial forearm free flaps

Recent studies have demonstrated that using topical tissue expansion can reduce the need for a split thickness skin graft after harvesting a forearm free flap. [6] The authors noted that this results in less pain as well as reduced healing time. This method has also been shown to be cost effective [3] as well as improve cosmetics.[ citation needed ]

In scalp reconstruction

Tissue expansion has been used on the scalp for treating scalp scarring and baldness, in lieu of hair transplantation when there is insufficient donor hair to transplant on the scar or the scar tissue is not vascularized to support hair growth. [7] [8] For instance, in a patient who had melanomas removed from the scalp resulting in alopecia defects (hair loss), tissue expansion can be used to allow for the removal of scars and complete hair coverage. The two main indications for choosing tissue expansion over hair grafting are the size and shape of the defect relative to potential supply of donor hair, and the quality and thickness of the scar tissue. Areas of significant scarring and/or tissue atrophy, which is likely to make hair grafting unsuccessful, are best excised and replaced by normal expanded scalp skin. According to research from Dr Jeffrey Stuart Epstein while he was a professor at University of Miami, theoretically there is no limit to the amount of tissue that can be created with tissue expansion, provided the process is conducted gradually. [9] [ unreliable medical source? ]

Foreskin restoration

Tissue expansion has also been used for the technique of foreskin restoration, which is usually non-surgical and applies tension externally using specialized devices to replace circumcised tissues with new cells. [10]

Non-surgical tissue expansion techniques can expand one's surviving penile skin, making it a longer tube so it can function like a foreskin. [11]

Men who have been circumcised stretch and apply tension to their shaft and foreskin remnants to expand and elongate tissue in efforts to produce a functional foreskin. This form of tissue expansion can take years, as the amount of skin growth required is typically around 15 in². [12]

Bone expansion

Bone is another tissue that can be expanded relatively easily, by using external devices which are slowly separated using mechanical contraptions, so that bone grows in response to elongation (bone distractor). Other techniques and external devices have been studied and have shown some success, such as in the fitbone surgery. [13] This technique was pioneered in 1951 by the Russian physician Ilizarov, and is called the Ilizarov apparatus. It is capable of lengthening limbs in cases of pathological loss of bone, asymmetry of limbs, dwarfism, short stature, etc. In reconstructive and cosmetic surgery, bone expanders have been used to elongate the mandibula in cases of congenital disorders, trauma, tumors, etc. Other newer devices such as the orthofix and intramedullary skeletal kinetic distractor (ISKD) are also used for limb lengthening. It can add over 6 inches per bone, but is expensive, painful, and time-consuming (each procedure lasts around 8–12 months).[ citation needed ]

Muscle expansion

Muscle tissue may also expand and grow, in a process known as stretch-induced myofibrillogenesis. [14] [15]

Tissue inflammation

Inflammation, in the biological sense, refers to the cellular response of the body to disturbances, be they internal or external. In the case of asthma or chronic bronchitis the human body responds to allergens or pollutants by flooding the bronchial tree and airway walls with mononuclear cells. The layers of the airway wall, including the inner epithelial tissue lining thickens and expands anywhere from 10% to 300% of healthy individuals, and obstructs air flow. [16] Enduring the disease long term coupled with airway hyperresponsiveness (smooth muscle contraction or Bronchial hyperresponsiveness) leads to chronic continuous inflammation and thickening, and noticeable airway remodeling consisting of stiffer airways and lost elasticity. [17] Inflammation in a constricted cylinder, as with an airway, eventually folds over on itself, leading to mechanically studied buckling patterns and growth relationships within tissue linings. [18] [19]

Breast tissue expansion

Tissue expansion is a common technique used for breast reconstruction. [20] This essentially involves expansion of the breast skin and muscle using a temporary tissue expander. [21] Three to four weeks after the mastectomy, a saline solution will be injected into the expander to gradually fill it. This process is supported by a tiny valve mechanism located inside the expander and it will continue until its size is slightly larger than the other breast. Typically it can take several weeks to months to complete the process. This tissue expander is removed after a few months and microvascular flap reconstruction or the insertion of a permanent breast implant is done at the time. Chemotherapy or radiation is sometimes recommended by the medical/radiation oncologist following mastectomy. These treatments delay the tissue expansion process by approximately four to eight weeks. Tissue expanders have silicone outer shells and either an internal valve or external port to allow for saline fluid injections.[ citation needed ]

Alternatives to skin expansion

Research dedicated to alternative skin grafts is currently within the purview of tissue engineering. Multiple engineered tissue-derived and tissue-like substances have made it through the FDA and into the market, though financial success has been moderate. [22] Limitations of this strategy include long incubation times, as well as difficulty in mimicking that exact mechanical and biological properties of functional skin. [23] However, benefits range from decreased donor site morbidity (as a result of no longer needing to harvest from skin expansion) as well as a ready-available source of materials for emergency medicine in the case of traumatic burn or injury. There remains much clinical interest today in developing inexpensive engineered skin grafts that possess the mechanical and biological properties of skin.[ citation needed ]

See also

Related Research Articles

Breast reconstruction Surgical rebuilding of a breast

Breast reconstruction is the surgical process of rebuilding the shape and look of a breast, most commonly in women who have had surgery to treat breast cancer. It involves using autologous tissue, prosthetic implants, or a combination of both with the goal of reconstructing a natural-looking breast. This process often also includes the rebuilding of the nipple and areola, known as nipple-areola complex (NAC) reconstruction, as one of the final stages.

Plastic surgery Medical surgical specialty

Plastic surgery is a surgical specialty involving the restoration, reconstruction, or alteration of the human body. It can be divided into two main categories: reconstructive surgery and cosmetic surgery. Reconstructive surgery includes craniofacial surgery, hand surgery, microsurgery, and the treatment of burns. While reconstructive surgery aims to reconstruct a part of the body or improve its functioning, cosmetic surgery aims at improving the appearance of it.

Foreskin restoration

Foreskin restoration is the process of expanding the skin on the penis to reconstruct an organ similar to the foreskin, which has been removed by circumcision or injury. Foreskin restoration is primarily accomplished by stretching the residual skin of the penis, but surgical methods also exist. Restoration creates a facsimile of the foreskin, but specialized tissues removed during circumcision cannot be reclaimed. Actual regeneration of the foreskin is experimental at this time. Some forms of restoration involve only partial regeneration in instances of a high-cut wherein the circumcisee feels that the circumciser removed too much skin and that there is not enough skin for erections to be comfortable.

Rhinoplasty Surgical procedure to enhance or reconstruct a human nose

Rhinoplasty, commonly called nose job, medically called nasal reconstruction is a plastic surgery procedure for altering and reconstructing the nose. There are two types of plastic surgery used – reconstructive surgery that restores the form and functions of the nose and cosmetic surgery that changes the appearance of the nose. Reconstructive surgery seeks to resolve nasal injuries caused by various traumas including blunt, and penetrating trauma and trauma caused by blast injury. Reconstructive surgery can also treat birth defects, breathing problems, and failed primary rhinoplasties. Rhinoplasty may remove a bump, narrow nostril width, change the angle between the nose and the mouth, or address injuries, birth defects, or other problems that affect breathing, such as a deviated nasal septum or a sinus condition. Surgery only on the septum is called a septoplasty.

Sex reassignment surgery for female-to-male transgender people includes a variety of surgical procedures that alter anatomical traits to provide physical traits more comfortable to the trans man's male identity and functioning.

Male-to-female sex reassignment surgery involves reshaping the male genitals into a form with the appearance of, and as far as possible, the function of female genitalia. Before any surgery, patients usually undergo feminizing hormone therapy, though this is not a requirement. There are associated surgeries patients may elect to undergo, including vaginoplasty, facial hair removal, facial feminization surgery, breast augmentation and various other procedures.

Breast augmentation Surgical procedure

Breast augmentation and augmentation mammoplasty is a cosmetic surgery technique using breast-implants and fat-graft mammoplasty techniques to increase the size, change the shape, and alter the texture of the breasts. Augmentation mammoplasty is applied to correct congenital defects of the breasts and the chest wall. As an elective cosmetic surgery, primary augmentation changes the aesthetics – of size, shape, and texture – of healthy breasts.

Breast reduction Plastic surgery procedure

Reduction mammoplasty is the plastic surgery procedure for reducing the size of large breasts. In a breast reduction surgery for re-establishing a functional bust that is proportionate to the woman's body, the critical corrective consideration is the tissue viability of the nipple–areola complex (NAC), to ensure the functional sensitivity and lactational capability of the breasts. The indications for breast reduction surgery are three-fold – physical, aesthetic, and psychological – the restoration of the bust, of the woman's self-image, and of her mental health.

Skin grafting

Skin grafting, a type of graft surgery, involves the transplantation of skin. The transplanted tissue is called a skin graft.

Grafting refers to a surgical procedure to move tissue from one site to another on the body, or from another creature, without bringing its own blood supply with it. Instead, a new blood supply grows in after it is placed. A similar technique where tissue is transferred with the blood supply intact is called a flap. In some instances a graft can be an artificially manufactured device. Examples of this are a tube to carry blood flow across a defect or from an artery to a vein for use in hemodialysis.

Hair transplantation Surgical operation to relocate hair follicles

Hair transplantation is a surgical technique that removes hair follicles from one part of the body, called the 'donor site', to a bald or balding part of the body known as the 'recipient site'. The technique is primarily used to treat male pattern baldness. In this minimally invasive procedure, grafts containing hair follicles that are genetically resistant to balding are transplanted to the bald scalp. Hair transplantation can also be used to restore eyelashes, eyebrows, beard hair, chest hair, pubic hair and to fill in scars caused by accidents or surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.

Radical mastectomy

Radical mastectomy is a surgical procedure involving the removal of breast, underlying chest muscle, and lymph nodes of the axilla as a treatment for breast cancer. Breast cancer is the most common cancer among women today, and is primarily treated by surgery, particularly during the early twentieth century when the mastectomy was developed with success. However, with the advancement of technology and surgical skills, the extent of mastectomies has been reduced. Less invasive mastectomies are employed today in comparison to those in the past. Nowadays, a combination of radiotherapy and breast conserving mastectomy are employed to optimize treatment.

Male chest reconstruction

Male chest reconstruction refers to any of various surgical procedures to masculinise the chest by removing breast tissue or altering the nipples and areolae. Male chest reconstruction may be performed in cases of gynecomastia and gender dysphoria. Transmasculine people may pursue chest reconstruction, also known as top surgery, as part of transitioning.

Amastia refers to a rare clinical anomaly in which both internal breast tissue and the visible nipple are absent on one or both sides. It affects both men and women. Amastia can be either isolated or comorbid with other syndromes, such as ectodermal dysplasia, syndactaly and lipoatrophic diabetes. This abnormality can be classified into various types, and each could result from different pathologies. Amastia differs from amazia and athelia. Amazia is the absence of one or both mammary glands but the nipples remain present, and athelia is the absence of one or both nipples, but the mammary gland remains.

A DIEP flap is a type of breast reconstruction in which blood vessels called deep inferior epigastric perforators (DIEP), as well as the skin and fat connected to them, are removed from the lower abdomen and transferred to the chest to reconstruct a breast after mastectomy without the sacrifice of any of the abdominal muscles.

MIRA is a multidisciplinary and complementary method for treating many chronic diseases. The MIRA Procedure is a result of combining efforts from different medical fields developed in the University of Chicago in 1992. It basically consists in medically grafting live rejuvenated tissue in the form of autologous adipose adult stem cells to a damaged organ in order to restore it and improve its function. This method is currently approved by the U.S. Food and Drug Administration (FDA).

Flap (surgery) Surgical procedure in which tissue is transferred with intact blood supply

Flap surgery is a technique in plastic and reconstructive surgery where any type of tissue is lifted from a donor site and moved to a recipient site with an intact blood supply. This is distinct from a graft, which does not have an intact blood supply and therefore relies on growth of new blood vessels. This is done to fill a defect such as a wound resulting from injury or surgery when the remaining tissue is unable to support a graft, or to rebuild more complex anatomic structures such as breast or jaw.

Scalp reconstruction is a surgical procedure for people with scalp defects. Scalp defects may be partial or full thickness and can be congenital or acquired. Because not all layers of the scalp are elastic and the scalp has a convex shape, the use of primary closure is limited. Sometimes the easiest way of closing the wound may not be the ideal or best way. The choice for a reconstruction depends on multiple factors, such as the defect itself, the patient characteristics and surgeon preference.

Free-flap breast reconstruction is a type of autologous-tissue breast reconstruction applied after mastectomy for breast cancer, without the emplacement of a breast implant prosthesis. As a type of plastic surgery, the free-flap procedure for breast reconstruction employs tissues, harvested from another part of the woman's body, to create a vascularised flap, which is equipped with its own blood vessels. Breast-reconstruction mammoplasty can sometimes be realised with the application of a pedicled flap of tissue that has been harvested from the latissimus dorsi muscle, which is the broadest muscle of the back, to which the pedicle (“foot”) of the tissue flap remains attached until it successfully grafts to the recipient site, the mastectomy wound. Moreover, if the volume of breast-tissue excised was of relatively small mass, breast augmentation procedures, such as autologous-fat grafting, also can be applied to reconstruct the breast lost to mastectomy.

Scalp reduction is a surgical procedure in which the hairless region of the scalp of a bald man is reduced. This procedure can reduce the area of the scalp in which hair transplantation is needed, or even eliminate the need for hair transplantation.


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