Skin, Fat, Cartilage and Bone Grafts Flashcards
A 22-year-old woman is evaluated in the emergency department because of necrotizing fasciitis of the right upper extremity. BMI is 35 kg/m2. After adequate debridement, the entire extensor and flexor compartments are open with exposed tendon. A photograph is shown. Which of the following is the most appropriate initial method of reconstruction?
A) Anterolateral thigh free flap
B) Bilaminate neodermis
C) Full-thickness skin grafts
D) Pedicled abdominal flap
E) Split-thickness skin grafts
The correct response is Option B.
Although a bilaminate neodermis (Integra) artificial skin substitute has been traditionally used in the acute management of burns, there have been many successful reports incorporating its use in general reconstructive plastic surgery. Integra is a bioengineered dermal substitute consisting of a bilayer membrane system. The dermal replacement layer is composed of a cross-linked bovine tendon collagen-glycosaminoglycan (chondroitin-6-sulfate) matrix coated on one side with a synthetic polysiloxane polymer (silicone) layer. This layer functions as an epidermis to control moisture loss from the wound. The collagen matrix serves as a scaffold for ingrowth of fibroblasts, macrophages, lymphocytes, and capillaries and is ultimately replaced by host tissue. Integra “take” mirrors skin graft “take” and follows the sequence of 1) imbibition, 2) fibroblast migration, 3) neovascularization, and 4) maturation.
As the host tissue infiltrates the dermal layer, the collagen layer is biointegrated with the wound to form a vascular neodermis capable of accepting a split-thickness skin graft after a period of approximately 4 weeks. Proper patient selection and careful monitoring for infection or hematoma accumulation are crucial in this time period. After approximately 4 weeks, the silicone layer is removed and a thin (0.008- to 0.010-inch) skin graft can be applied.
Advantages of Integra use include improved cosmesis, diminished scar contracture or development of hypertrophic scar, off-the-shelf availability in large quantities, increased elasticity, and the ability to use thinner skin grafts with subsequent improvement in donor-site morbidity, scar, and time to heal. Other cited advantages include commensurate growth of the grafted tissue in children, potential avoidance of a microsurgical procedure, and placement over tendons with no significant reduction in tendon mobility. The disadvantages of Integra include its high cost, steep learning curve, need for at least two stages with subsequent increased time to final closure, potential for infection under the silicone layer, and lack of adnexal structures with patient concerns of skin dryness.
In this patient, use of Integra with delayed thin split-thickness skin grafts at 4 weeks will give the best outcome in terms of cosmesis and function. A photograph is shown. Split-thickness skin grafts are not a good option in this location because of the risk of graft loss with tendon exposure due to lack of viable paratenon and the risk of secondary contracture at the wrist and elbow. Full-thickness skin grafts would diminish the risk of secondary contracture but harvesting enough tissue to cover the entire arm would be impossible using the inguinal region as a donor site. Full-thickness grafts also require a healthier wound bed for optimal graft “take” and are not likely to heal over exposed tendons.
Free tissue transfer is an excellent technique for resurfacing the forearm, but in this patient, the thigh donor site would be difficult secondary to tissue thickness and the need for an extremely large flap. A better choice could be the scapular or parascapular donor site, perhaps in combination with a preliminary tissue expansion of that location. Obtaining enough tissue would be difficult. Banking the forearm in the abdomen would be less desirable as well, given her obesity and the need for a large surface area.
A 45-year-old man undergoes excision of a basal cell carcinoma of the mid cheek. A 3.6 × 4.7-cm oval skin defect with exposed subcutaneous fat is present. Skin grafting is planned. Which of the following is most likely to minimize long-term scar contracture?
A) Choosing a donor site with appropriate color match
B) Defatting of the skin graft
C) Harvesting with a mechanical dermatome
D) Immobilizing with negative pressure wound therapy
E) Including the entire dermis
The correct response is Option E.
The defect is a full-thickness skin defect with exposed subcutaneous fat. Coverage with a local flap and skin graft are possible reconstructive options. If skin grafting were to be performed, then a full-thickness skin graft would minimize the amount of long-term contracture (secondary contracture). A skin graft can be either split- or full-thickness. Split-thickness grafts can be harvested with a mechanical dermatome, or free hand with a scalpel. Split-thickness skin grafts do not include the entire thickness of the dermis and have less initial contracture at the time of harvest (primary contracture). Full-thickness skin grafts contain both the epidermis and the dermis and would have less long-term contracture.
Harvesting with a mechanical dermatome is useful for obtaining split-thickness skin grafts. Typical thicknesses may range from 8/1000th of an inch to 14/1000th of an inch.
Adequate immobilization of a skin graft is critical for “take” of the graft. Negative pressure wound therapy can be employed to promote adherence of the graft to the wound bed.
Defatting of the skin graft in the case of a full-thickness graft is important to optimize graft “take” in the early postoperative period.
Obtaining skin from a donor site with a close color match to the recipient site is an important aesthetic consideration, but does not affect long-term contracture.
Which of the following processes involves the transformation of recipient mesenchymal cells into osteoprogenitor cells resulting from the stimulation of bone morphogenetic protein?
(A) Endochondral ossification
(B) Membranous ossification
(C) Osteochondrosis
(D) Osteoconduction
(E) Osteoinduction
The correct response is Option E.
Osteoinduction describes the process by which tissue types induce cellular differentiation through their actions on each other. Bone morphogenetic protein is stimulated to induce the transformation of perivascular mesenchyme-like cells, known as pericytes, into osteoprogenitor cells.
Endochondral ossification involves the formation of new bone within a hyaline cartilage framework in the epiphysis of the long bones. The process of membranous ossification is primarily responsible for bone formation in the cranial vault and face; this process involves condensation of mesenchymal tissue. Osteochondrosis describes a group of ossification disorders in children. These disorders, which may affect solitary or multiple sites of ossification, are characterized by degeneration of aseptic necrosis of bone followed by reossification. Osteoconduction is the process of tissue ingrowth from the host recipient bed into the grafted material; the bone-producing osteoprogenitor cells play a crucial role in this process.
A 25-year-old woman is scheduled for correction of a deformity of the nasal dorsum caused by previous nasal trauma as a child. Autologous rib cartilage grafting of the dorsum is planned to correct the deformity. Which of the following complications is most likely in this patient?
A) Extrusion
B) Necrosis
C) Ossification
D) Resorption
E) Warping
The correct response is Option E.
The most consistent complication of cartilage grafting is the propensity to change shape or warp over time. This may be due to the presence of perichondrium or the nonuniform composition of the matrix that can affect the shape when it is placed.
Pure cartilage grafts tend to maintain shape, but grafts with an intact perichondrial layer can curl significantly and lead to unpredictable results. During septal graft harvest, care must be taken to elevate mucoperichondrial flaps in the proper plane. Likewise, auricular or costal cartilage grafts must be harvested in a subperichondrial plane. Removal of the perichondrium and softer outer cartilage layer leaves the more rigid cartilage core, which maintains shape more predictably.
Extrusion, necrosis, ossification, and resorption are not known to be affected by the presence or absence of the perichondrial layer. Fresh autologous grafts easily survive transplantation procedures and do not appear to resorb over time.
Autologous cartilage from septum, concha, or rib is considered the ideal graft material. These grafts have very low risk for infection or extrusion compared with an allograft. Cartilage grafts are tolerated well by nasal tissue.
A 25-year-old man is scheduled to undergo reconstruction of a 5 × 5-cm, full-thickness calvarial defect. A titanium/hydroxyapatite cement cranioplasty reconstruction is planned. Which of the following mechanisms best describes the healing process involved?
A) Endochondral ossification
B) Osteochondrosis
C) Osteoconduction
D) Osteogenesis
E) Osteoinduction
The correct response is Option C.
Restoration of craniofacial contour after infection, tumor resection, or trauma can be quite challenging. Autologous bone grafts have long been considered the gold standard due to their high likelihood of osseointegration/healing and low risk of rejection or infection. Autologous bone grafts, however, have several drawbacks, including unpredictable resorption, donor site morbidity, limited availability, prolonged operative times, and difficulty in contouring. As a result, there has been an ongoing search for alternative means of reconstruction with alloplastic material.
The ideal bone substitute should be chemically inert, easily contoured, retain a stable shape over time, strong, resistant to infection or foreign body reaction, inexpensive, and capable of osseointegration and tissue ingrowth. Methylmethacrylate has been used frequently for calvarial reconstruction but suffers several drawbacks, including infection requiring removal of implant, plate fracture, lack of osseointegration, difficulty shaping after polymerization, and necrosis of surrounding tissue due to the exothermic nature of the curing process.
Some of the most promising and well-tolerated alloplastic materials for craniofacial skeletal reconstruction are the calcium phosphate-based compounds. Hydroxyapatite [Ca(PO4)6(OH)2] forms the principal mineral component of bone and constitutes 60% of the calcified human skeleton. Calcium phosphate compounds are bioactive and capable of osteoconduction and osseointegration.
Osseointegration refers to the direct chemical bonding of an alloplast to the bony surface without an intervening fibrous tissue layer. During osteoconduction (creeping substitution), the alloplast acts as a nonviable scaffold for ingrowth of blood vessels and osteoprogenitor cells from the recipient site. Subsequently, the graft/alloplast is resorbed and replaced with new bone. This mechanism is also associated with the healing of cortical bone grafts.
Hydroxyapatite cement is a mixture of tetracalcium phosphate and dicalcium phosphate anhydrous which reacts in an aqueous environment to form a paste that can be easily applied and sculpted to fit the surgical defect. Hydroxyapatite cement sets isothermically, so there is no risk of thermal damage to the surrounding tissues. Additional benefits of hydroxyapatite include “off the shelf” ease of use, maintenance of volume over time, lack of radiologic scatter, and low incidence of infection.
Osteoinduction refers to the direct stimulation of mesenchymal cells at the recipient site by bone morphogenetic protein to differentiate into osteoprogenitor cells. This mechanism of action is associated with the healing of cancellous bone grafts and demineralized bone matrix.
Endochondral ossification is the process by which the cartilaginous soft callus covering a fracture is transformed into bone. Osteogenesis is the process by which vascularized bone grafts heal. Viable osteocytes survive the transplantation process and produce new bone at the recipient site. Osteochondrosis refers to a family of ossification disorders in children.
Which of the following bone grafts does NOT rely on creeping substitution as a mode of remodeling?
(A) Allogenic
(B) Autologous cancellous
(C) Autologous cortical
(D) Free vascularized
(E) Xenogenic
The correct response is Option D.
Free vascularized bone grafts do not rely on creeping substitution (replacement of necrotic bone with osteoblasts and new vascular ingrowth) for remodeling. They do not need to stimulate new bone formation because they are used when little or no bone has been lost.
All nonvascularized bone grafts undergo a degree of resorption and remodeling, including creeping substitution, and have some degree of inductive capacity (ability to stimulate new bone formation). Cancellous bone grafts contain bone morphogenic proteins that stimulate the formation of new bone. Cortical bone grafts and allogenic and xenogenic grafts have less of this inductive capacity.
A 35-year-old Asian woman desires dorsal augmentation to achieve a more “Western” nose. Autologous rib cartilage grafting is planned. Which of the following complications is most common with this procedure?
A) Extrusion
B) Infection
C) Pneumothorax
D) Resorption
E) Warping
The correct response is Option E.
The most consistent complication of costal cartilage grafting is the propensity to warp or change shape over time. This may be due to the presence of perichondrium or the nonuniform composition of the matrix that can affect the shape when it is placed.
Although there is a risk of pleural violation and pneumothorax, these complications are uncommon and can be recognized intraoperatively with the Valsalva maneuver. Through the same exposure for harvesting the rib graft, a red rubber catheter is placed in the chest to evacuate intrathoracic air. As long as the visceral pleura remain intact, a thoracostomy tube is unnecessary.
Fresh autologous grafts easily survive transplantation procedures and do not appear to resorb over time.
Autologous cartilage from septum, concha, or rib is considered the ideal graft material. These grafts have very low risk of infection or extrusion compared with an alloplast. Cartilage grafts are tolerated well by nasal tissue.
A 47-year-old man undergoes split-thickness autografting for the treatment of a forearm burn. Which of the following donor site dressings is most appropriate to optimize wound healing?
A) Alginate covered with occlusive dressing for 7 days
B) Moist gauze covered with occlusive dressing for 7 days
C) Petrolatum gauze covered with occlusive dressing for 2 days, then left open to air
D) Petrolatum gauze left open to air
E) Xenograft left open to air
The correct response is Option A.
To optimize wound healing, a moist wound-healing environment has been shown to be superior to a dry wound-healing environment. Studies on split-thickness skin graft donor sites have not been very well designed, but many studies suggest that a moist dressing is better than a dry dressing, and several review papers support this concept. Although leaving petrolatum gauze open to air is very common and may be the most practical option in certain circumstances, it does not optimize wound healing compared with a moist dressing. The only options listed that provide a moist environment for the duration required for early reepithelialization are gauze covered with occlusive dressing and alginate dressings. Gauze covered with occlusive dressing would not work well, because conventional gauze would stick to the wound and be very difficult to remove without causing significant tissue injury. Alginate dressings are emerging as an excellent option for split-thickness skin graft donor site wounds. They are adaptable, absorptive, nonadhesive, antibacterial, and provide a moist environment for wound healing.
Which of the following soft-tissue fillers is derived from hyaluronic acid?
(A) Dermalogen
(B) Fascian
(C) Isolagen
(D) Restylane
(E) Zyderm
The correct response is Option D.
Restylane is a cross-linked, stabilized, third-generation hyaluronic acid gel that is a byproduct of processed bacteria. Hyalform gel is also comprised of hyaluronic acid, but is culled instead from an animal-based compound. When used as soft-tissue filler, these substances provide low antigenicity, soft texture, and durability. However, they have not yet been approved for use in the United States.
Dermalogen (dermis) and Fascian (fascia lata) are homologous sources of injectable filler derived from human tissue. Isolagen is an autologous agent derived from human skin cells that consists of cultured fibroblast media with an extracellular matrix. Zyderm is an injectable filling agent derived from bovine collagen.
A 27-year-old man is scheduled to undergo excision and skin grafting after sustaining a full-thickness burn to the dorsum of the hand. To optimize graft take in this patient, which of the following is the most important aspect of management?
A ) Meshing of the skin graft
B ) Meticulous hemostasis
C ) Negative pressure wound therapy
D ) Use of fibrin glue
E ) Use of a thin split-thickness skin graft
The correct response is Option B.
The most important aspect of recipient site management to optimize graft survival and outcome in this patient undergoing dorsal hand skin grafting is meticulous hemostasis. This is because hematoma is the leading cause of skin graft loss. Meshing a skin graft may promote graft survival by providing a mode of egress for blood and seroma that might form below the graft. However, it is associated with an increased rate of secondary contraction and unfavorable cosmetic results. Both of these factors make meshing undesirable when grafting the dorsum of the hand.
Use of a negative pressure wound therapy dressing can result in improved graft survival, especially in recipient sites with irregular contours. However, it is not critical for the hand. A good dressing and proper immobilization should achieve the same result. Use of this type of dressing is not as important as meticulous hemostasis for ensuring graft survival and outcome.
Fibrin glue has been used to promote graft survival by improving hemostasis and graft adherence. There is also some evidence that fibrin glue may inhibit wound contraction. Nevertheless, it is no substitute for meticulous hemostasis and should only be used as an adjunct to the fundamental techniques of skin graft placement.
Use of a thin split-thickness skin graft is associated with improved graft survival when compared with a thick split-thickness or full-thickness skin graft, but it is also associated with an increased rate of secondary contraction that is not desirable on the dorsum of the hand. Balancing the need for graft survival versus the need to avoid secondary contraction is an important consideration in burn surgery. Using thinner grafts will optimize graft survival, but this is not as critical as ensuring good hemostasis.
A 34-year-old woman is referred for evaluation because of a 9 × 7-cm lateral soft-tissue deformity of the right thigh with skin thickening. She has a history of oncologic resection and external beam radiation of 50 Gy. Which of the following is the most appropriate step in management?
A ) Acellular dermis
B ) Dermal-fat grafting
C ) Full-thickness skin grafting
D ) Lipoaspirate injection
The correct response is Option D.
Radiation has deleterious effects on local vascularity, fibroblast activity, growth factor levels, and mesenchymal stem cell populations. Microscopic examination of irradiated tissue shows microvascular thrombosis and abnormal vasculature. Clinically, irradiated wounds are associated with slower epithelialization, decreased tensile strength, and higher infection and dehiscence rates. Although data are still limited, marked improvements in irradiated tissues have been reported with autologous fat injection. Lipoaspirate injected in areas of chronic radiation wounds improved the wound quality by either promoting a more vascular wound amenable to reconstruction or spontaneous closure. Adipocytes contain stem cells which improve wound vascularity.
Acellular allogeneic dermis is produced from human cadaveric allograft skin. During the skin processing, immunogenic components that include all viable cells are extracted, leaving acellular dermis and extracellular matrix intact. The entire epidermis and all of the dermal cells are removed during a freeze-drying process. The resultant matrix has undamaged collagen types IV and VII, elastin, and laminin. The acellular and porous dermal matrix allows ingrowth and colonization by host fibroblasts and endothelial cells. Acellular allogeneic dermis provides a template for fibrous ingrowth, resulting in an integrated graft that is not rejected. It can be used for almost any area as long as there is adequate blood supply to support the graft. Acellular allogeneic dermis survival in less vascular areas is unknown. Dermal-fat grafts are usually harvested from the same areas as full-thickness skin grafts are. These include the lower abdomen, the suprapubic or periumbilical regions, the gluteal or inframammary folds, the subiliac crest, and even the forearm for hand surgery purposes. An ellipse of skin with dimensions appropriate to fill the recipient defect is outlined. The epithelium can be removed by sharp excision with a scalpel or dermabrasion. Previous radiation, excessive cicatrization, deficiency of circulation, and poor healing qualities caused by poor nutrition and systemic diseases all militate against a satisfactory result.
Skin grafts are used in a variety of clinical situations. The essential indication for the application of a skin graft is wound closure. In general, full-thickness skin grafts are applied to the regions of the face, ears, and hands. Split-thickness skin grafts are usually placed on the trunk and genitalia. Skin grafts are usually the initial treatment of choice for many open wounds that cannot be closed primarily. Grafting offers the simplest method of wound closure in the reconstructive ladder, assuming that primary closure is not possible or would lead to undue tension. Skin grafts are generally avoided in management of more complex wounds. Conditions with deep spaces and exposed bones, such as open sternal wounds, pressure sores, and open fractures, normally require the use of skin flaps or muscle flaps for stable wound coverage. Skin grafts have limited success in wounds with a compromised blood supply, such as irradiated wounds and ischemic ulcers.
A 24-year-old Chinese-American, right-hand-dominant man undergoes cadaveric hand transplantation after traumatic amputation at the right wrist from a machinery accident. The donor is a Hispanic man. Which of the following terms best describes the antigenicity of the transplant?
A) Allograft
B) Autograft
C) Isograft
D) Xenograft
The correct response is Option A.
Any tissue transplantation from another genetically nonidentical human is termed allograft, previously referred to as homograft. As these transplanted tissues are immunologically different from the recipient, they will eventually undergo rejection from the host immune system without immunosuppressive medications. There are many distinct antigens responsible for the rejection process, the most important of which are the major histocompatability complex (MHC) antigens, known as HLA-1 and HLA-2, which reside on the surface of cells.
Autograft implies that the donor tissues come from the same patient – such as the common autologous skin graft.
Isograft comes from a genetically identical donor, namely an identical twin. While such donations are very rare, it is of important historical note that the first human kidney transplantation was performed by Dr. Joseph Murray between identical twin donor and recipient. In this clinical scenario, as one patient is Asian and the other Hispanic, it is clear that the transplant is not an isograft.
Xenograft is a cross-species graft. Porcine skin grafts are commonly used as temporary skin substitutes to promote granulation formation in difficult wound beds.
A 20-year-old man undergoes decompressive craniectomy after a traumatic brain injury. He is now recovered from the injury. The soft tissue overlying the cranial defect is healthy and there is no communication with the paranasal sinuses. Cranioplasty with an alloplastic material is planned. A material with good osteoconductive properties is desired. Which of the following is the most appropriate choice?
A) Hydroxyapatite
B) Polyetheretherketone
C) Polymethylmethacrylate
D) Porous polyethylene
E) Titanium
The correct response is Option A.
The ideal material for cranioplasty is biocompatible, radiolucent, heat resistant, inexpensive, and has low risk for infection and extrusion. A healthy and well-perfused soft-tissue envelope is a prerequisite for alloplastic cranioplasty. Moreover, alloplasts in contact with sinuses have a high risk for infection.
Hydroxyapatite (HA) is a calcium phosphate compound with chemical structure similar to that of bone. Of the current alloplastic materials used for cranioplasty, it has the highest capacity for osteoconduction. It is available as a powder that is mixed with liquid to turn it into a malleable form that can be molded to the shape of the defect. Custom made HA ceramic implants can also be produced based on specifications of the defect. The major disadvantage of this material is that it is brittle and may fracture when stressed. It is sometimes used with a titanium mesh underlay to provide more structural stability.
Polymethylmethacrylate (PMMA) is a polymerized ester of acrylic acid. It is the most commonly used alloplastic material for cranioplasty. It is prepared in the operating room via an exothermic reaction; therefore, care has to be taken to protect the dura from thermal injury. Custom implants can also be produced. It can be easily contoured to the shape of the defect and has good mechanical strength. It does not have osteoconductive properties.
Porous polyethylene (PPE) is composed of high-density polyethylene microspheres with an interconnected porous structure. This allows tissue ingrowth in the implant. PPE is radiolucent and has been found to have an excellent safety profile. It does not have osteoconductive properties.
Polyetheretherketone (PEEK) is a semi-crystalline organic thermoplastic polymer. It is lightweight, strong, radiolucent, and heat resistant. Because of these properties, it is becoming a popular material for cranioplasty as a customized implant. It does not have osteoconductive properties.
Titanium is used as an alloy with aluminum and vanadium. It is biocompatible, non-corrosive, radiopaque, and heat resistant. Titanium mesh can be cut to the shape of the defect. It can also be used as a customized implant. The major advantages are its strength, ease of use, and low infection rate. The major disadvantage is its cost. It does not have osteoconductive properties
A 58-year-old man is referred by an orthopedic surgeon after undergoing open reduction and internal fixation of a fracture of the ankle after falling down stairs. The repair is complicated by wound dehiscence with 2 × 2 cm of exposed tibialis anterior tendon without paratenon. A photograph is shown. After debridement of healthy tissue, reconstruction is performed using bilaminate neodermis with placement of a standard bolster dressing. At which of the following times relative to placement of the bilaminate neodermis should split-thickness skin grafting be performed?
A) At the same time
B) 1 week after
C) 2 weeks after
D) 4 weeks after
E) 6 weeks after
The correct response is Option D.
Integra is a bilaminate neodermal material that consists of an outer silicone sheet and an inner layer of bovine collagen and glycosaminoglycan (derived from shark cartilage), which acts as a scaffold for regeneration. Specifically, there is migration of host fibroblasts into the matrix, which subsequently proliferate and form collagen. Additionally, there is migration of endothelial cells that form a vascular network within the neodermis, which can subsequently act as a foundation to support staged split-thickness skin grafting, at which time the silicone outer layer is removed and a thin (usually 6–8/1000”) split-thickness autograft is applied. The success, or “take,” of the skin graft depends on whether the neodermis is vascularized sufficiently to maintain graft viability. A 2001 study by Moiemen et al. demonstrated clinically and histologically that this process takes 4 weeks on average, without the use of topical negative pressure.
A follow-up article from 2004 suggests this process can be accelerated from 4 weeks to an average of 7.25 days if topical negative pressure is used. Further follow-up studies based on the clinical appearance of the bilaminate neodermal matrix have suggested reduction in complication rates, improved patient tolerance, and enhanced and accelerated neovascularization with the use of topical negative pressure wound therapy. However, a study published in 2010 looking histologically at various time points could not demonstrate that topical negative pressure wound therapy accelerates neovascularization as verified by the presence of histologically patent vascular channels. The authors found that the median percentage of the template depth that demonstrated canalized channels was 0%, 20%, 61%, and 80% for days 7, 14, 21, and 28, respectively.
Because this question pertains to the use of bilaminate neodermal matrix with the use of a standard bolster dressing and not negative pressure wound therapy, most existing evidence indicates that the most appropriate timing is 4 weeks after placement of the bilaminate neodermis.
A 68-year-old man is diagnosed with squamous cell carcinoma of the floor of the mouth with invasion into the tongue and mandible. A radical resection with immediate reconstruction using a vascularized free fibula bone flap is planned. A vascularized bone flap is an ideal choice in this setting due to its ability to promote bony healing through which of the following pathways?
A) Endochondral ossification
B) Osteoblastic rimming
C) Osteoconduction
D) Osteogenesis
E) Osteoinduction
The correct response is Option D.
Free vascularized fibula grafts are the mainstay for mandibular reconstruction in a variety of settings, from traumatic to oncologic. Like most vascularized bone grafts, they primarily heal by osteogenesis, which involves the formation of new bone by osteoblasts from both the flap and recipient site.
In contrast, non-vascularized cortical bone grafts primarily heal by osteoconduction, or creeping substitution. In this process, the bone graft acts as a template for the ingrowth of cells and blood vessels from the recipient bed and ultimately resorbs.
Cancellous bone grafts and demineralized bone matrix heal primarily by osteoinduction. In this process, bone morphogenetic protein directly stimulates mesenchymal cells at the recipient site to differentiate into osteoprogenitor cells.
Bone fractures heal, in part, by endochondral ossification. When a bone is broken, inflammation triggers chondrocytes to form a soft callus consisting of collagen and proteoglycans at the fracture site. Through endochondral ossification, disorganized woven bone replaces the soft callus to form a hard callus which is remodeled over time into highly organized cortical bone.
Osteoblastic rimming is a histologic finding indicating the presence of bony trabeculae rimmed with osteoblasts. It is seen in a variety of bone disorders.
What is the most effective technique to minimize costal cartilage warping during graft harvesting?
A. Removing the perichondrium to balance interlocking stresses.
B. Scoring the cartilage to release interlocking stresses.
C. Harvesting the central portion of the costal cartilage.
D. Irradiating the cartilage before grafting.
Correct Answer: C. Harvesting the central portion of the costal cartilage.
Warping of cartilage grafts is a phenomenon that occurs
unpredictably in costal cartilage grafts. The theory behind it is that
there are interlocking stresses in a cartilage graft that when
disrupted lead to warping. To date, the most effective technique to
minimize costal cartilage warping is harvesting the central portion of
the costal cartilage. This concept was introduced by Gibson in 1958.
Although these decreases warping, it does not totally eliminate it.
Gillies advocated for the removal of perichondrium to balance the
intrinsic interlocking stresses of the graft; there is no conclusive
evidence that perichondrial stripping or preservation decreases
warping. Warping is also not affected by the level of cartilage graft
harvest. Scoring of cartilage leads to breakage of interlocking
stresses, resulting in bending of cartilage to the opposite side. This
property of cartilage is used for correction of prominent ears.
Irradiation does not result in decreased warping. Recently,
oppositional suturing techniques and oblique split techniques have
been proposed as methods to decrease cartilage warping.
- Gillies HD. Plastic Surgery of the Face. Oxford
University Press;1920. - Davis WB, Gibson T. Absorption of autogenous
cartilage grafts in man. Br J Plast Surg.
1956;9(3):177-185. doi:10.1016/s0007-
1226(56)80032-5 - Farkas JP, Lee MR, Lakianhi C, Rohrich RJ. Effects
of carving plane, level of harvest, and oppositional
suturing techniques on costal cartilage warping.
Plast Reconstr Surg. 2013;132(2):319-325.
doi:10.1097/PRS.0b013e3182958aef - Akkina SR, Most SP. The effect of perichondrium
on cartilage graft properties. Curr Opin Otolaryngol
Head Neck Surg. 2022;30(4):215-218.
doi:10.1097/MOO.0000000000000812 - Adams WP Jr, Rohrich RJ, Gunter JP, Clark CP,
Robinson JB Jr. The rate of warping in irradiated
and nonirradiated homograft rib cartilage: a
controlled comparison and clinical implications.
Plast Reconstr Surg. 1999;103(1):265-270.
doi:10.1097/00006534-199901000-00042 - Farkas JP, Lee MR, Rohrich RJ. Technical
maneuvers to decrease warping of peripheral
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A 67-year-old woman comes to the office for evaluation of abscesses on her face 5 weeks after undergoing autologous fat grafting for augmentation of the cheek. Physical examination shows multiple erythematous nodules, areas of induration, and microabscesses on both cheeks. Temperature is 99.5°F (37.5°C). Liposuction donor sites show no abnormalities. A 1-week course of ciprofloxacin prescribed by the patient’s family doctor failed to resolve the problem. Results of Gram stain and routine culture and sensitivity are negative. Which of the following is the most likely diagnosis?
A) Atypical mycobacterial infection
B) Herpes zoster infection
C) MRSA infection
D) Mucocutaneous candidiasis
E) Staphylococcus epidermidis infection
The correct response is Option A.
Mycobacteria are ubiquitous in soil and water, and infections caused by these organisms can complicate aesthetic liposuction and autologous fat-grafting procedures. The postoperative symptoms include cellulitis, abscess formation, draining sinuses, and postoperative wound infection. Patients often do not have fever, chills, or other signs of systemic infection. While patients on immunosuppressive medications seem to be at higher risk, the problem also occurs in patients with healthy immune systems. More than 50% of patients will test negative for acid-fast bacilli, in addition to negative routine culture results. Polymerase chain reaction assay testing is now available for the most common species of nontuberculous mycobacterium, and is a useful rapid screening test for patients suspected of having this diagnosis.
Bacterial infections (MRSA) would tend to show symptoms earlier, have systemic signs, and are usually easily cultured. Herpetic infections usually present with fluid-filled vesicles earlier in the postoperative course, and often have pain as a primary complaint. There is no history of previous injectable fillers, or implants, to suggest a biofilm-related infection in this patient. Mucocutaneous candidiasis is a chronic disease of the skin, nails, and mucosal surfaces.
A 63-year-old woman is scheduled to undergo autologous fat injection to improve the contour and increase the size of the right breast. She underwent reconstruction of the right breast with a latissimus dorsi flap 10 months ago because of mastectomy. The patient does not have or desire a breast prosthesis. Which of the following is the most likely sequela of autologous fat injection in this patient?
A) Calcification
B) Donor site irregularity
C) Fat resorption
D) Hypertrophic scarring
E) Skin necrosis
The correct response is Option C.
Although controversial, autologous fat injection (lipo-modeling) to the breast and the reconstructed breast has gained popularity in recent years. This can be attributed to several factors, including the publication of large numbers of patient series’ demonstrating the safety, efficacy, and improvements in the harvest and preparation of fat. However, the most common complication of fat injection remains to be the resorption of the grafted fat, ranging from 30 to 70%.
Fat and skin necrosis, calcification, hypertrophic scarring, and contour irregularity of both the recipient and donor sites can occur, but to a lesser extent. The rate of skin necrosis is low. Hypertrophic scarring is more common in patients with a history of poor scarring. In the case of calcifications, pre- and postoperative examination by a radiologist specialized in breast imaging is necessary to limit the risk of breast cancer, which may occur coincidentally with lipo-modeling.
Which of the following strategies is most effective in improving long-term viability of fat grafts?
A) Harvest fat from an abdominal donor site
B) Harvest fat with a syringe rather than a suction pump
C) Inject fat with a low-shear device
D) Process fat with telfa gauze rolling technique
E) Use tumescent solution without lidocaine
The correct response is Option C.
One of the biggest shortcomings of fat grafting is unpredictable graft survival. Fat grafting can be divided into three major steps: harvest, processing, and injection. Each step has the potential to influence the viability of transplanted fat. Fat donor site does not make a difference in fat graft viability. Lidocaine has been shown to inhibit the growth and metabolism of adipocytes. However, these effects disappear once the lidocaine is removed from the harvested fat and therefore does not affect long-term graft viability. Harvest technique, either with handheld syringe or a suction device, has not been shown to influence graft viability. Although some surgeons avoid centrifugation in an attempt to decrease trauma to fat cells, there is no objective evidence that centrifugation decreases fat cell viability. Trauma to fat cells, during processing or injection, affects fat graft survival. Injection of fat with low-shear devices has been shown to improve fat viability. Similarly, injection with larger cannulas has been shown in a few studies to increase fat survival. Strategies that hold promise in the future to increase fat cell viability include platelet-rich plasma, stem cell enrichment, and scaffolds.
A 30-year-old man comes to the emergency department after falling on his outstretched left hand 6 hours ago. He injured the same hand 3 years ago and underwent open reduction and internal fixation and distal radius bone grafting to repair a metacarpal fracture of the index finger. Physical examination and x-ray study obtained today show an exposed, fractured plate. He undergoes hardware removal and multiple washouts, resulting in a 1-cm bone defect. Reconstruction of the defect is planned using bone graft from Gerdy’s tubercle of the tibia. The cortical window should be made just proximal and medial to which of the following muscles?
A) Extensor digitorum longus
B) Extensor hallucis longus
C) Peroneus longus
D) Popliteus
E) Tibialis anterior
The correct response is Option E.
The lateral tibial tubercle (Gerdy’s tubercle), on the proximal lateral tibia, is an excellent source of cancellous bone graft and would provide ample graft for use in this patient. In the patient described, the ipsilateral distal radius was harvested in the original surgery and is not available. Patient factors including obesity may make other bone graft donor sites such as the iliac crest less appealing.
Gerdy’s tubercle is located between the tibial tubercle and patellar tendon insertion to the medial side and the head of the fibula to the lateral side. Bone can be harvested through a 3- to 4-cm oblique incision, and the cortical window is made just proximal and medial to the tibialis anterior origin.
The popliteus muscle is posterior to the knee. The extensor hallucis longus and extensor digitorum longus muscles originate more distally on the tibia. The peroneus longus originates from the fibula, not the tibia.
Following split-thickness skin grafting, which of the following dressings can be used at the donor site to minimize discomfort, reduce the risk for infection, and decrease healing time?
(A) Bismuth tribromophenate-impregnated gauze (Xeroform)
(B) Heterograft
(C) Hydrocolloid polymer complex (DuoDerm)
(D) Silicone membrane-nylon fabric composite (Biobrane)
(E) o-Tolylazo-_-naphthol- (Scarlet Red-) impregnated gauze
The correct response is Option C.
An occlusive dressing consisting of a polyurethane foam and a hydrocolloid polymer complex (DuoDerm), or a semiocclusive dressing consisting of synthetic adhesive moisture vapor permeable films (eg, Op-Site, Tegaderm) will minimize patient discomfort, reduce the risk for infection, and decrease healing time.
Fine mesh gauzes (eg, Scarlet Red, Vaseline, Xeroform) use the semiopen technique of wound healing. Epithelialization and infection rates are favorable, but, when compared with other dressings, pain and discomfort are greater.
Another version of the semiopen wound-healing technique involves the use of a semipermeable silicone membrane and a knitted nylon fabric covalently bonded to porcine collagen (Biobrane). This method is more comfortable for the patient but is associated with a higher rate of infection following skin grafting.
Biologic dressings (eg, cadaveric skin homografts, heterografts, porcine xenografts, amniotic membranes) are frequently associated with marked inflammation of the wound, delayed epithelialization, and prolonged wound healing times.
Acellular dermal matrix (AlloDerm) is used in plastic surgery for each of the following purposes EXCEPT
(A) correcting retraction of the lower eyelid after blepharoplasty
(B) decreasing adhesions after repair of an abdominal hernia
(C) reducing incidence of oronasal fistulas after cleft palate repair
(D) resurfacing thin pockets in mammaplasty
(E) treating osteomyelitis of the tibia
The correct response is Option E.
AlloDerm is cadaveric dermis that is processed to be acellular and nonimmunogenic and is then freeze-dried for preservation. Although AlloDerm seems to be used ubiquitously in plastic surgery; it is not indicated for management of osteomyelitis. One of the principles in management of osteomyelitis is the transfer of healthy vascularized tissue. Although AlloDerm provides a substrate for tissue ingrowth, it does not bring in any blood supply.
Use of AlloDerm matrix has been described in the literature for abdominal wall reconstruction, lower eyelid reconstruction, lining of breast implant capsules, and cleft palate repair.
An otherwise healthy 7-year-old boy is brought to the office because of a 4-year history of progressive soft-tissue atrophy of the left forehead with coup de sabre. Examination shows skin atrophy, discoloration, and alopecia at the hairline in the V1 distribution. Which of the following is the most appropriate method to correct the deformity?
A) Forehead contouring with a calcium phosphate ceramic
B) Free tissue transfer
C) Implantation of a custom silicone prosthesis
D) Injection of hyaluronic dermal filler
E) Serial fat grafting
The correct response is Option E.
Parry-Romberg syndrome can be associated with underlying neurologic disease. The symptoms generally first manifest in the first or second decade of life and can involve bone, cartilage, fat, or skin. Free tissue transfer performed once the disease has stabilized has been shown to be a highly satisfactory correction. However, in recent years, fat grafting has become a more utilized option. Although more procedures are required, it can begin in younger patients even if the disease is still active. It also has demonstrated high patient satisfaction.
Hyaluronic acid dermal fillers are not FDA-approved in children and are unlikely to provide long-term correction. Custom prostheses or calcium phosphate ceramics would not reconstruct with like tissue; one would be less likely to have a stable, soft aesthetically pleasing result.
A deep split-thickness skin graft that has been harvested from the scalp has approximately two thirds of the follicular unit (shaft) within the dermis. The percentage of the follicular unit that can be expected to produce hair growth is closest to
(A) 0%
(B) 30%
(C) 50%
(D) 85%
(E) 100%
The correct response is Option B.
If the upper two thirds of the follicular unit (shaft) are transplanted, approximately 30% of the follicles will produce new hair growth. Although the new hairs will be thinner, normal coloring can be expected. The middle third of the hair follicle is partially responsible for hair growth; in contrast, the hair bulb, which in the past was believed to be responsible for hair growth, is actually not required in order to grow new hairs. The bulb is located in the subcutaneous fat beneath the dermis and does contribute somewhat to the growth and health of the hair but is not a necessary factor for growth.
A 45-year-old woman undergoes placement of a dorsal only cartilage graft during secondary rhinoplasty. Which of the following operative steps is most likely to minimize warping of the cartilage graft?
(A) External stabilization
(B) Maintaining recipient bed vascularity
(C) Precise graft fixation
(D) Preservation of perichondrium
(E) Symmetrical design
The correct response is Option E.
Autogenous rib cartilage grafts have gained more widespread use in rhinoplasty as dorsal onlay grafts and columellar struts. However, the usefulness of rib as a donor site has been limited by difficulties with postoperative cartilage warping.
Symmetrical graft design decreases cartilage warping because it regulates the tendency of the inner mass of cartilage to expand and become distorted during the harvesting process. Studies have shown that the compact outer subperichondrial layer regulated the tendency of a loose inner cartilaginous mass to warp. Symmetric graft design was found to more evenly regulate the stresses that caused warping. When considering donor sites for the nasal dorsum, costal cartilage ribs have been shown to be particularly useful because of the availability of a generous and naturally straight segment requiring minimal trimming and carving.
Internal stabilization of autogenous rib cartilage grafts with Kirschner wires has been found to effectively prevent graft warpage.
Preservation of graft perichondrium influences cartilaginous growth through the preservation of chondrocytes. This concept has been found to be of particular use in the fabrication and reconstruction of ear cartilage framework in children.
Precise graft fixation is important in the avoidance of external distortion due to graft migration or displacement.
Maintaining recipient bed vascularity is important to avoid graft extrusion resulting from tissue compromise.
Which of the following techniques minimizes fat necrosis and increases the viability of fat grafting?
A) Avoidance of pressure on grafted areas postoperatively
B) Avoiding placement of the grafts in irradiated tissue
C) Centrifuging the fat grafts
D) Placing the graft in multiple small volumes in a lattice-like framework
E) Using ultrasound-assisted liposuction to harvest grafts
The correct response is Option D.
The results of fat grafting are dependent upon the surgeon’s experience and technique. Strategies to increase the take of the fat graft and decrease fat necrosis include atraumatic harvest techniques. Placement of the graft in multiple small aliquots increases the availability for vascularity and creating a lattice-like framework when depositing the grafts avoids large-volume deposits. Placement of the grafts in a few large-volume deposits is avoided to minimize fat necrosis and creation of fatty oil cysts. Fat grafting has been refuted for soft tissues that have been affected by radiation.
A 32-year-old woman comes to the office because of capsular contracture of the right breast. She underwent bilateral augmentation mammaplasty with saline implants 9 years ago. Revision surgery using simultaneous implant exchange with fat grafting is planned. Which of the following is the most likely fat retention volume over a 6-month period in this patient?
A) 25%
B) 45%
C) 65%
D) 85%
The correct response is Option C.
Previously published work using radiologic volumetric data analysis with fat grafting for cosmetic augmentation mammaplasty demonstrates volume retention over 6 months of 64 ± 11%. Such loss of breast volume may be attributable to an element of apoptosis, a reduction in adipocyte volume after transplantation and survival, or a reduction in the fluid content of the grafted slurry. In reality, all three of these factors are likely to contribute to volume reduction over time.
Which of the following is the most common unfavorable result of lip augmentation with acellular dermal homograft?
(A) Exposure
(B) Hematoma
(C) Infection
(D) Rejection
(E) Resorption
The correct response is Option E.
Graft resorption has been reported as the most common complication of lip augmentation with acellular dermal homograft (Alloderm), a product derived from human cadaveric skin for use in soft-tissue augmentation. During harvest of the graft, the dermal and extracellular matrices are left intact, while the immunogenic components are removed. Alloderm can be used for skin grafting of burn wounds, nasal reconstruction, replacement of gingiva, and facial augmentation. Good results have been reported with the use of Alloderm for lip augmentation. Complications other than resorption, such as graft exposure or rejection, hematoma, and infection, have been reported to be minimal.
Which of the following soft-tissue fillers is derived from hyaluronic acid?
(A) Dermalogen
(B) Fascian
(C) Isolagen
(D) Restylane
(E) Zyderm
The correct response is Option D.
Restylane is a cross-linked, stabilized, third-generation hyaluronic acid gel that is a byproduct of processed bacteria. Hyalform gel is also comprised of hyaluronic acid, but is culled instead from an animal-based compound. When used as soft-tissue filler, these substances provide low antigenicity, soft texture, and durability. However, they have not yet been approved for use in the United States.
Dermalogen (dermis) and Fascian (fascia lata) are homologous sources of injectable filler derived from human tissue. Isolagen is an autologous agent derived from human skin cells that consists of cultured fibroblast media with an extracellular matrix. Zyderm is an injectable filling agent derived from bovine collagen.
A 33-year-old man who sustained burns to 95% of the total body surface area five days ago is scheduled to undergo the initial stages of surgical reconstruction. In preparing this patient, which of the following is the advantage of using cultured epidermal autografts versus split-thickness skin grafts?
A ) Donor site
B ) Durability
C ) Elasticity
D ) Immediate availability
E ) Reduced expense
The correct response is Option A.
With use of cultured epidermal autografts, no donor site limitations exist. The patient’s own keratinocytes are expanded in tissue culture and a small skin specimen may be cultured and expanded within two to three weeks. Unfortunately, there is no dermal matrix tissue and, therefore, the graft lacks the elastic quality of normal skin or even split-thickness skin grafts. This results in wounds that are stiff, and motion is limited in the face and around joints. Likewise, the lack of a dermis results in very slow basement membrane formation; therefore, there are frequent problems with blistering and easy shearing. The use of cultured epidermal autografts is somewhat limited by its high cost and delay in availability as the tissue is cultured.
A 34-year-old woman is referred for evaluation because of a 9 × 7-cm lateral soft-tissue deformity of the right thigh with skin thickening. She has a history of oncologic resection and external beam radiation of 50 Gy. Which of the following is the most appropriate step in management?
A ) Acellular dermis
B ) Dermal-fat grafting
C ) Full-thickness skin grafting
D ) Lipoaspirate injection
The correct response is Option D.
Radiation has deleterious effects on local vascularity, fibroblast activity, growth factor levels, and mesenchymal stem cell populations. Microscopic examination of irradiated tissue shows microvascular thrombosis and abnormal vasculature. Clinically, irradiated wounds are associated with slower epithelialization, decreased tensile strength, and higher infection and dehiscence rates. Although data are still limited, marked improvements in irradiated tissues have been reported with autologous fat injection. Lipoaspirate injected in areas of chronic radiation wounds improved the wound quality by either promoting a more vascular wound amenable to reconstruction or spontaneous closure. Adipocytes contain stem cells which improve wound vascularity.
Acellular allogeneic dermis is produced from human cadaveric allograft skin. During the skin processing, immunogenic components that include all viable cells are extracted, leaving acellular dermis and extracellular matrix intact. The entire epidermis and all of the dermal cells are removed during a freeze-drying process. The resultant matrix has undamaged collagen types IV and VII, elastin, and laminin. The acellular and porous dermal matrix allows ingrowth and colonization by host fibroblasts and endothelial cells. Acellular allogeneic dermis provides a template for fibrous ingrowth, resulting in an integrated graft that is not rejected. It can be used for almost any area as long as there is adequate blood supply to support the graft. Acellular allogeneic dermis survival in less vascular areas is unknown. Dermal-fat grafts are usually harvested from the same areas as full-thickness skin grafts are. These include the lower abdomen, the suprapubic or periumbilical regions, the gluteal or inframammary folds, the subiliac crest, and even the forearm for hand surgery purposes. An ellipse of skin with dimensions appropriate to fill the recipient defect is outlined. The epithelium can be removed by sharp excision with a scalpel or dermabrasion. Previous radiation, excessive cicatrization, deficiency of circulation, and poor healing qualities caused by poor nutrition and systemic diseases all militate against a satisfactory result.
Skin grafts are used in a variety of clinical situations. The essential indication for the application of a skin graft is wound closure. In general, full-thickness skin grafts are applied to the regions of the face, ears, and hands. Split-thickness skin grafts are usually placed on the trunk and genitalia. Skin grafts are usually the initial treatment of choice for many open wounds that cannot be closed primarily. Grafting offers the simplest method of wound closure in the reconstructive ladder, assuming that primary closure is not possible or would lead to undue tension. Skin grafts are generally avoided in management of more complex wounds. Conditions with deep spaces and exposed bones, such as open sternal wounds, pressure sores, and open fractures, normally require the use of skin flaps or muscle flaps for stable wound coverage. Skin grafts have limited success in wounds with a compromised blood supply, such as irradiated wounds and ischemic ulcers.
A 27-year-old woman is scheduled to undergo rhinoplasty using homograft rib cartilage for reconstruction of the dorsum of the nose. Which of the following interventions during this procedure is most effective to reduce long €‘term warping of the graft?
(A) Access to a peripheral segment
(B) Insertion of the graft at least 30 minutes after carving
(C) Scoring of the graft
(D) Suture fixation
(E) Use of nonirradiated material
The correct response is Option B.
To minimize the long €‘term clinical effects of cartilage warping, it is recommended to wait at least 30 minutes after carving the graft to allow initial warping to occur. The observed warping can then be accounted for in the final graft placement. Further warping may continue for some time, but the majority will occur within the first 30 to 60 minutes.
Use of nonirradiated graft material may predispose more warping than irradiated material; however, this may depend on the dose of radiation. Doses of 3 to 4 million rads are less likely to result in graft warping compared with no radiation, but at doses of 1.5 to 2.5 million rads, the warping may be similar to that of nonirradiated grafts.
Central cuts of cartilage grafts are less likely to warp than are peripheral cuts. Scoring of the graft will result in warping of the graft. Suture fixation will not prevent graft warping.
Which of the following grafts has minimal resorption and loss of volume?
(A) Bone
(B) Cartilage
(C) Macro-fat
(D) Micro-fat
(E) Muscle
The correct response is Option B.
Although all of these tissues may be used for grafts, autologous cartilage grafts offer minimal resorption and loss of volume and provide good results in many clinical settings. The metabolic rate of cartilage is 1/100 to 1/500 the rate of other human tissues. It has low glycolytic activity and consumption because of its small cell population and relative isolation by the cartilage matrix. This isolation helps protect cartilagenous tissue from resorption. Readily accessible sites for cartilage grafts are the septum, auricular cartilage, and ribs.
Bone grafts, which depend on the size of the bone, have variable resorption rates based on the clinical circumstance. Macro-fat grafts are usually unreliable. They have high resorption rates and are more effectively used as dermal fat grafts to minimize resorption and fibrosis. Given by lipoinjection, micro-fat grafts may exhibit greater longevity than macro-fat grafts. However, their resorption may be 25% to 50% of the injected volume. Muscle grafts are not routinely used. Rather, vascularized muscle flap grafts are preferred for transferring muscle tissue.
Which of the following is an advantage of using the dermal regeneration template (Integra) instead of a thin split-thickness autograft for reconstruction of the hand?
(A) Elimination of donor site
(B) Improved cosmesis
(C) Increased wound contraction
(D) Reduced risk of hematoma
(E) Shorter healing time
The correct response is Option B.
The advantages of Integra include the availability of large quantities, the simplicity and reliability of the placement technique, and the pliability and cosmetic appearance of the resulting cover.
Integra does not eliminate the use of a donor site. However, the skin graft used at the second stage is typically thinner than that used in single-stage grafting, so Integra does avoid the use of a deep donor site, which decreases the risk of infection, scarring, and permanent pigment changes.
Wound contraction with Integra is typically less than that with single-stage split-thickness skin grafting. Compared with autologous skin, Integra purportedly has no decrease in the hematoma rate. In one study, the incidence of hematoma under Integra was 9 out of 39 cases. Because Integra requires a second surgery after 3 to 4 weeks for coverage with a thin split-thickness skin graft, it has a longer healing time until final wound coverage.
A healthy 20-year-old woman presents with a deep abrasion injury of the left volar forearm that she sustained in a bicycle accident. Physical examination of the forearm shows exposed flexor tendons. The wound is debrided, and no vital nerves or vessels are exposed. The wound is approximately 4 × 4 cm. A bilaminate acellular dermal regenerative matrix is used to reconstruct the defect. The application of negative-pressure therapy is most likely to result in which of the following outcomes in this patient?
A) Increase in matrix take
B) Increase in timing to definitive skin graft
C) Negative-pressure therapy is not indicated
D) No change in matrix take
E) No change in timing to definitive skin graft
The correct response is Option A.
The application of negative-pressure therapy results in an increase in matrix take. Dermal regeneration matrix (DRM) (clinical example is Integra) is a mesh-bilayered acellular matrix composed of a cross-linked bovine tendon collagen and glycosaminoglycan dermal equivalent, and a semipermeable polysiloxane (silicone) epidermal equivalent. It is a biodegradable matrix that acts as a scaffold for fibroblast and endothelial invasion and capillary growth. DRM has been approved by the FDA (Federal Drug Administration) for use in partial- and full-thickness wounds, pressure ulcers, venous leg ulcers, surgical wounds, chronic vascular ulcers, second-degree burns, and draining wounds.
The combination of DRM with fibrin glue and postoperative negative-pressure therapy versus DRM alone in acute and chronic wounds increased the take rate from 78 to 98%. Moreover, the interval between DRM and skin transplantation was decreased from 24 to 10 days, thus decreasing the length of hospital stay (Level II evidence).
The other options are therefore incorrect. Negative-pressure therapy is commonly used in these clinical scenarios.
A 30-year-old man who works as a laborer comes to the emergency department after sustaining avulsion injuries over the dorsum of the index, long, and ring fingers of his right dominant hand after being caught in a press. The wounds measure 3 × 1 cm each. Physical examination shows exposed extensor tendons from the proximal interphalangeal joint to the dorsal fold. Artificial dermis was placed. Which of the following is the most appropriate method of reconstruction?
A) Full-thickness skin graft
B) Radial artery free flap
C) Reverse radial forearm flap
D) Split-thickness skin graft
E) No further treatment
The correct response is Option D.
Split-thickness and full-thickness skin grafting directly over extensor tendons will lead to scarring due to lack of paratenon. Paratenon is necessary for tendon gliding. The use of artificial dermis can allow for tendon gliding. Artificial dermis has been shown to result in favorable aesthetic and functional outcomes. Although a second surgery is required, it results with lower donor site morbidity. Once the dermal template is adherent, it can then be grafted. The correct response is split grafting because the artificial dermis acts as the deep layer. Split-thickness grafts alone would not be useful where padding is required. Split grafts have a higher contracture rate than full grafts. Also, split grafts alone would not be beneficial because of the high potential for adherence. A full-thickness graft with its dermal elements would not be necessary in this case because the artificial skin provides the dermal elements. Full-thickness graft does not contract as much as split-thickness grafts. In this situation, the split graft contracture would result in a smaller, potentially more aesthetic scar.
Re-epithelialization is usually reserved for wounds measuring 1 cm or less; therefore, it would be inappropriate to not give additional treatment. Although the wound would close, the result would be less aesthetic with tendon adherence and potential dysesthesia, and it would require a longer period to heal. The reversed radial forearm flap would not be necessary and would not be long enough to reach the fingertips as well. Similarly, a radial forearm free flap would not be necessary.
- Under average conditions, which of the following percentages represents the expected six-month resorption rate of fat injections?
- (A) 10%
- (B) 30%
- (C) 50%
- (D) 70%
- (E) 90%
Please note: Question 4 has been deleted from the examination.
The key points of the theory of fat survival are as follows: 1) fat is a dynamic tissue; 2) cells that suffer trauma lose more volume; and 3) the recipient site makes an important difference in graft survival based on the vascularity of the bed. Careful handling of the graft is critical. Therefore, given the ideal conditions of minimal traumatic technique, meticulous fat graft size, and recipient bed selection, we should expect approximately 60% to 80% long-term graft survival based on several studies.
Moore and co-workers reported on the effects of mechanical damage to fat cells harvested with syringe suction lipectomy versus excision with local anesthetics. The mechanical damage to tissue aspirated versus tissue that was excised was unchanged. Lidocaine inhibited the glucose metabolism and lipolysis of adipocytes in culture. The effect was maintained only for as long as the lidocaine was present.
Also, as Smahel reported, fat grafts, like other grafts, must be small enough to be revascularized but large enough to maintain structural integrity and some native blood vessels. When part of the graft is not revascularized, the fat becomes necrotic and is not simply resorbed but is broken up and removed by the cellular elements.
Karaoglu and co-workers have studied the recipient site of fat grafts and seen a statistically significant increase in fat graft survival in supramuscular layer (81.95 “ 4.40%) than in subcutaneous (41.62 “ 3.29%) and submuscular layer (37.31 “ 5.77%) (P < 0.05). This study demonstrates that selection of an appropriate recipient site should enhance ultimate survival of the fat graft.