Wound Healing / Keloids Flashcards
1
Q
A 17-year-old boy undergoes excision of a congenital nevus of the scalp. Prior to excision, he underwent placement of a subgaleal tissue expander. Which of the followinggrowth factors is most likely to be upregulated during ischemia in this patient?
A) Epidermal B) Keratinocyte C) Platelet-derived D) Transforming E) Vascular endothelial
A
E) Vascular endothelial
2
Q
Vascular endothelial growth factor
A
Vascular endothelial growth factor (VEGF) is an important mediator of wound healing and is necessary for angiogenesis. It was originally discovered as a protein secreted by tumor cells to increase the permeability of local blood vessels to circulating macromolecules. It has been shown to increase endothelial growth and migration and enhance glucose transport in the endothelial cell, which is needed to match the increased energy required during angiogenesis. Hypoxia has been shown to be a potent stimulus for the expression of VEGF, and current research has been directed at utilizing VEGF to augment healing and viability in situations of tissue ischemia.
3
Q
A 10-year-old girl is referred to the office because of a large, full-thickness cranial defect after sustaining a traumatic injury. Reconstruction with a split cranial bone graft is performed. Which of the following is the most likely mechanism by which the bone graft heals? A) Dural ossification B) Osteoconduction C) Osteogenesis D) Osteoinduction E) Vasculogenesis
A
B) Osteoconduction
4
Q
Method of healing after split cranial bone grafting
A
The most likely mechanism of split cranial bone graft healing is osteoconduction. The split cranial bone graft is primarily cortical. After it isseparated from its blood supply, it serves as a nonviable scaffold for the ingrowth of blood vessels and osteoprogenitor cells from the recipient site. This process of osteoconduction, or creeping substitution, eventually leads to resorption and replacement of most of the graft with new bone. The graft becomes fully osseointegrated with the recipient site
5
Q
Osteoconduction
A
The process of osteoconduction, or creeping substitution, eventually leads to resorption and replacement of most of the graft with new bone, after a graft is infiltrated as a scaffold with vessels and osteoprogenitor cells. The graft becomes fully osseointegrated with the recipient site
6
Q
Spontaneous dural ossification
A
Spontaneous dural ossification can heal full-thickness cranial defects in infancy. After 12 to 18 months of age, the dura will not spontaneously ossify
7
Q
Osteogenesis
A
Osteogenesis is the primary mechanism of bone graft healing for cancellous or vascularized bone grafts. Because these grafts are revascularized rapidly, osteoblasts survive the transplantation and produce new bone at the recipient site.
8
Q
Osteoinduction
A
Osteoinduction involves the stimulation of mesenchymal cells at the recipient site to differentiate into bone-producing cells. Demineralized bone and bone morphogenetic protein produce new bone primarily by osteoinduction.
9
Q
Vasculogenesis
A
Vasculogenesis, the de novo formation of blood vessels from precursor cells, occurs during embryogenesis.
10
Q
Angiogenesis
A
Angiogenesis: the production of new vessels from preexisting vasculature.
11
Q
A 24-year-old woman comes to the office because of painful nodules in both buttocks. She underwent buttock augmentation with injections of liquid silicone by an unlicensed practitioner 4 years ago. Excision of the affected area is performed. Histology of a specimen obtained from the excised tissue is most likely to show which of the following? A) Acellularity B) Calcification C) Granuloma D) Necrosis E) Thrombosis
A
C) Granuloma
12
Q
Potential adverse sequelae after silicone injection
A
Potential adverse sequelae following silicone injection include migration, chronic induration and pigmentary changes, painful subcutaneous nodules, chronic infection, and ulceration. Many of the treated areas require radical resection and reconstruction.
13
Q
Histologic study of postsilicone injection nodules
A
Histologic study of postsilicone injection nodules typically shows granulomas which develop after initial inflammation and fibrosis.
14
Q
A 15-year-old boy undergoes negative pressure wound therapy (NPWT) of a traumatic abdominal wound. Which of the following is the most likely mechanism by which NPWT expedites the healing of this wound?
A) Decrease in bacterial burden
B) Deformation of the wound
C) Desiccation of the wound
D) Increase in matrix metalloproteinase activity
E) Maintenance of exudate from the wound
A
B) Deformation of the wound
15
Q
NPWT Macrodeformation
A
Macrodeformation maintains approximation of the tissues, preventing loss of domain and facilitating earlier closure by delayed primary or secondary intention.
16
Q
NPWT Microdeformation
A
Microdeformation at the interface of the sponge and wound bed changes cell shape, which then affects gene transcription via the cytoskeleton (mechanotransduction). These microdeformational forces, for example, stimulate cellular proliferation and angiogenesis in the wound.
17
Q
NPWT and bacterial burden
A
The effect of NPWT on bacterial burden is unclear. Some studies have suggested that NPWT reduces bacterial counts in the wound, possibly by direct removal or by increasing blood flow. Other studies have found that NPWT may increase certain bacterial levels.
18
Q
NPWT and desiccation
A
NPWT prevents desiccation of the wound. The semiocclusive polyurethane drape limits permeability to gases and water vapor and thus maintains a favorable, moist wound environment.
19
Q
NPWT and matrix metalloproteinase activity
A
NPWT decreases matrix metalloproteinase activity in the wound. Elevated matrix metalloproteinases inhibit wound healing as well as neovascularization.
20
Q
NPWT and exudate
A
NPWT decreases exudate of the wound by removing excess fluid through suction. The reduction in exudate may facilitate wound healing by removing toxic inflammatory mediators and proteinases. Minimizing wound edema also may improve the diffusion of oxygen and nutrients to the wound.
21
Q
A 63-year-old man comes for evaluation of a dehisced surgical incision 3 weeks after undergoing open reduction of the right ankle. He has a history of coronary artery disease, hypertension, hypercholesterolemia, and poorly controlled type 2 diabetes mellitus. He had a myocardial infarction 2 years ago. Physical examination shows a dehisced surgical incision with exposed tibialis anterior tendon without paratenon. A photograph is shown. The patient refuses free tissue transfer. Which of the following is the most appropriate skin substitute for the wound?
A) Biodegradable bilaminate neodermal matrix (Integra)
B) Biosynthetic wound dressing (Biobrane)
C) Cryopreserved neonatal fibroblast-derived dermal substitute (Dermagraft)
D) Human fibroblast-derived composite skin substitute (TransCyte)
E) Living bilayered skin substitute (Apligraf)
A
A) Biodegradable bilaminate neodermal matrix (Integra)
22
Q
Integra
A
Integra is a bilaminate neodermal replacement product that is composed of a biodegradable bovine collagen-glycosaminoglycan (collagen-GAG) matrix underlayer with a silicone outer layer. Although its on-label indication is for burn reconstruction, it also has utility in reconstruction of wounds of exposed bone without periosteum, exposed cartilage without perichondrium, and exposed tendon without paratenon, such as in the scenario described. The collagen-GAG matrix serves as scaffolding for the ingrowth of cells and neovascularization. After regeneration, which takes between 2 to 4 weeks, the silicone outer later is removed and a thin split-thickness skin graft completes the reconstruction by providing epithelial cells over the neovascularized dermal replacement.
23
Q
Biobrane
A
Biobrane is a temporary, rather than permanent, bilaminar skin substitute that is constructed of an inner layer, composed of nylon and collagen, which is covered by an outer silicone film. Biobrane serves as a temporary wound dressing, usually in burn patients, where it helps prevent evaporative loss (due to the silicone outer layer) and subsequent wound desiccation. It decreases wound pain and provides a barrier to bacterial infection. Biobrane is removed either before permanent grafting or after epithelialization of the wound has occurred.
24
Q
Dermagraft
A
Dermagraft is a dermal substitute composed of neonatal foreskin fibroblasts cultured on a polyglactin mesh, and it is generally used in the treatment of diabetic foot ulcers, where it often is combined with meshed skin grafts
25
TransCyte
TransCyte is a temporary wound dressing. It is a emporary, rather than permanent, bilaminar skin substitute plus an added biologic layer derived from neonatal fibroblasts that are seeded onto the nylon matrix to produce type I collagen, fibronectin, and glycosaminoglycans. TransCyte is removed either before skin grafting or after epithelialization of the wound. It has been shown to significantly decrease pain and time to epithelialization
26
Apligraf
Apligraf, another permanent replacement product, is constructed of type I bovine collagen and cultured neonatal human fibroblasts and keratinocytes. After construction of the dermal matrix equivalent, cultured keratinocytes are applied. It is generally used in the treatment of venous ulcers and diabetic foot ulcers (may take more than one application). Its long-term durability, however, makes it an inappropriate choice in situations with a full-thickness defect with exposed vital structures
27
```
A 67-year-old woman comes to the office for follow-up examination 6 months after debridement of a chronic nondiabetic wound to the lower leg. Following the procedure, the patient was treated with moist dressings. Physical examination shows that the wound is healing less than 15% weekly. Persistent bacteria are suspected. Application of which of the following is the most appropriate nonsurgical management at this time?
A) Alginate dressings
B) Collagenase
C) Film or transparent dressings
D) Hydrogel dressings
E) Silver ion-impregnated dressing
```
E) Silver ion-impregnated dressing
28
Silver ion-impregnated dressing
Silver ions kill a broad spectrum of bacteria. No resistant organisms have been identified, and it is nontoxic to human cells.
29
Alginate dressings
Alginates absorb up to 20 times their weight ad are used to exudate wounds
30
Epithelial cell migration across an acute skin laceration is initiated by which of the following mechanisms?
A ) Contraction of myofibroblasts
B ) Deposition of collagen into the wound
C ) Formation of a fibrin-fibronectin plug
D ) Loss of contact inhibition
E ) Secretion of anti-inflammatory products
D ) Loss of contact inhibition
31
Epithelial cell migration in wounds
Epithelial cell migration is initiated by loss of contact inhibition and occurs from the periphery of the wound and adnexal structures. Cell division occurs in 48 to 72 hours, resulting in a thin epithelial cell bridge across the wound
32
```
A 65-year-old woman is evaluated because of nonhealing sores on her lower extremities. She has a history of alcoholism and is homeless. She appears cachectic, pale, and severely malnourished. She has lost most of her teeth; the gums are purplish and spongy in appearance. Skin examination shows numerous petechiae. Large, superficial, nongranular sores are noted on the legs. Scurvy is suspected. Which of the following processes is most likely to be adversely affected by this patient's nutritional deficiency?
A ) Collagen cross-linking
B ) DNA synthesis
C ) Epithelialization
D ) Fibroblast proliferation
E ) Immune modulation
```
A ) Collagen cross-linking
33
Vitamin C deficiency in wounds
The patient described most likely has a vitamin C deficiency. Vitamin C is an essential nutrient for collagen cross-linking via the hydroxylation of proline and lysine to hydroxyproline andhydroxylysine, respectively. The lack of cross-linking results in impaired collagen synthesis and a decrease in collagen tensile strength. Collagen-containing tissues, such as skin, dentition, bone, and blood vessels, are therefore affected, leading to the development of scurvy. The hallmark signs of scurvy are hemorrhaging in any organ (ie, petechiae, swollen gums), loss of dentition, and a lack of osteoid formation. Deficiency of vitamin C is rare in the United States; however, it can be seen in patientswho are severely malnourished; have a history of alcoholism; or have restrictive diets for medical, social, or economic reasons.
34
Nutrients integral to DNA synthesis and cellular proliferation
Folate and vitamin B6 (pyridoxine) are integral in DNA synthesis and cellular proliferation.
35
Vitamin A in wound healing
Vitamin A is an essential factor in epithelialization and fibroblast proliferation.
Can improve impaired wound healing caused by corticosteroids.
36
Vitamin E in wound healing
Vitamin E is a strong antioxidant and immune modulator.
37
Zinc in wound healing
Zinc is one of the most important micronutrients, as it acts as a cofactor for numerous metalloenzymes and proteins. It is essential for proper protein (like collagen) and nucleic acid synthesis
38
```
During which of the following phases of wound healing is the net rate of collagen synthesis greatest?
A ) Contraction
B ) Fibroblastic
C ) Hemostasis
D ) Inflammatory
E ) Remodeling
```
B ) Fibroblastic
39
Fibroblastic stage of wound healing
During the fibroblastic (proliferative) phase, three to five days after injury, fibroblasts migrate into the wound and lay new collagen. Type 3 collagen predominates early in normal wound healing but is later replaced by Type 1 collagen. It is during this time that the greatest rate of collagen synthesis occurs in the wound.
40
Days 3-5 after injury
During the fibroblastic phase, three to five days after injury, fibroblasts migrate into the wound and lay new collagen. Type 3 collagen predominates early in normal wound healing but is later replaced by Type 1 collagen. It is during this time that the greatest rate of collagen synthesis occurs in the wound.
41
Contraction during wound healing
Contraction begins during the fibroblastic stage (proliferative) and continues well into the remodeling phase.
42
Hemostasis and wound healing
Hemostasis is the brief period before healing starts.This allows for vasoconstriction and clotting to be activated.
43
Maximum tensile strength and wound healing
Maximum tensile strength is achieved after approximately 12 weeks
44
```
A 62-year-old man is scheduled to undergo repair of an abdominal wall hernia. A preoperative photograph is shown. He has a 15-year history of chronic lung disease and receives daily corticosteroids to control his symptoms. Supplementation with which of the following is most likely to decrease impairment of wound healing in this patient?
A ) Vitamin A
B ) Vitamin B1 (thiamine)
C ) Vitamin B2 (riboflavin)
D ) Vitamin B6 (pyridoxine)
E ) Vitamin C
```
A ) Vitamin A
45
Impairment of wound healing by corticosteroids and be treated by:
Animal studies have shown that impairment of wound healing caused by use of corticosteroids can be reversed by the oral administration of vitamin A (retinoic acid), 15,000 IU daily for seven days.
46
```
An 11-year-old girl has full-thickness dermal necrosis in the infusion zone of an antebrachial intravenous catheter which was used for treatment of a metastatic lower extremity sarcoma. Localized swelling was noted five days earlier after approximately 100 mL of the medication extravasated into the subcutaneous tissues. Total parenteral nutrition and intravenous doxorubicin had been administered as well as intravenous cefazolin and vancomycin. CT of the leg with intravenous contrast medium had also been performed in the past week. Which of the following is the most likely causative agent of the dermal necrosis from extravasation injury?
A ) Cefazolin
B ) Doxorubicin hydrochloride
C ) Radiographic contrast medium
D ) Total parenteral nutrition
E ) Vancomycin
```
B ) Doxorubicin hydrochloride
While any of the agents listed could be harmful in sufficient volume, doxorubicin hydrochloride (Adriamycin) is the one agent that should raise particular alarm. Adriamycin is associated with severe soft-tissue necrosis and warrants close follow-up for early surgical debridement,
47
Treatment of doxorubicin hydrochloride extravasation
Adriamycin is associated with severe soft-tissue necrosis and warrants close follow-up for early surgical debridement, if needed. Dilution of the agent with saline or hyaluronidase may be helpful. Other early interventions, which are standard to all extravasation injuries, include splinting, elevation, local dressings, and close serial examination
48
Treatment of extravasation injuries
Early interventions, which are standard to all extravasation injuries, include splinting, elevation, local dressings, and close serial examination.
49
```
An 80-year-old woman has been receiving papain-ureaointment for management of a pressure necrosis wound over the lateral aspect of the right calf. A 4 * 10-cm diameter zone of black, dry, insensate eschar is noted on the right calf. A 1-cm zone of mild erythema and slight liquefaction of the eschar edges are noted. No tenderness to palpation is noted. Pedal pulses are present. Which of the following is the main disadvantage of using a papain-urea ointment in this patient?
A ) Elevation of compartment pressures
B ) Inadequate debridement
C ) Painful dressing changes
D ) Renal toxicity
E ) Resistant organism infection
```
B ) Inadequate debridement
The patient described has a full-thickness dermal injury with ensuing liquefactive necrosis that requires sharp debridement to healthy tissue. Enzymatic ointments are not sufficient for this level of necrotic tissue burden.
These are slow-acting agents that allow separation of superficial eschar over days to weeks.
50
Papain
Papain is a potent digestant of nonviable protein material but does not affect healthy tissues.
51
Urea
Urea increases the digestive potency of papain, which is a potent digestant of nonviable protein material but does not affect healthy tissues.
52
Papain is inactivated by:
Dressings containing silver ions inactivate papain and they should not be used together.
53
A 52-year-old woman (shown) is evaluated six years after bilateralmastectomies and radiation therapy for cancer of the left breast because of a new, small open area near the left axillary fold which she first noted three weeks ago. She has been compliant with postoperative oncologic surveillance. Temperature is 98.9°F (37.2°C), pulse is 80 bpm, respirations are 16/min, and blood pressure is 140/75 mmHg. Physical examination shows a 2 * 2-cm open ulcer on the left chest wall with exposed rib. Which of the following is the most likely cause of the ulcer?
A ) Abscess
B ) Loss of skin integrity from intertriginous shearing forces
C ) Lymphedema drainage tract
D ) Osteoradionecrosis of the underlying ribs
E ) Recurrent breast cance
D ) Osteoradionecrosis of the underlying ribs
54
Mechanism of injury from ionizing radiation
The mechanism of injury from this radiation is through free radical production which, in turn, directly damages the DNA.
55
Acute effects of radiation -> over time
In the acute period, the effects of radiation may manifest themselves as erythema and edema of the skin, vasodilation with endothelial edema, and lymphatic obliteration. This eventually leads to capillarythrombosis and subsequent inadequate tissue oxygenation. Over time, nonhealing ulcers can spontaneously develop, sometimes years later.
56
When do most recurrences of breast cancer occur
Most recurrent breast cancer occurs within the first five year
57
Intertriginous shearing presentation
Intertriginous shearing would most often present as superficial epidermal loss with possible superinfection with yeast due to moisture
58
Recurrence rate of keloid scars after surgical excision
Keloid scars are associated with an extremely high recurrence rate. Surgical excision alone is associated with a recurrence rate of up to 80%.
59
Methods investigated to improve success in treatment of keloids and success rate
Methods investigated to improve success in treatment of these lesions include intralesional injection of corticosteroids, interferon, retinoic acid, and 5-fluorouracil. Even with these interventions, the rate of recurrence is approximately 50%.
60
Pressure therapy for keloid recurrence
Pressure therapy has been found to be helpful in decreasing keloid recurrence but requires ongoing treatment for three to ten months, which may not be acceptable
61
Radiation therapy for keloid recurrence
Radiation therapy has emerged as an effective method to prevent keloid scarring. External beam irradiation has been shown to decrease recurrence rates to 12%–27%, but it may be associated with pigmentary changes.
62
```
A 42-year-old man develops a dehiscence of the abdominal incision six weeks after undergoing a lower body lift. Medical history includes a 100-lb (45-kg) weight loss during the past three years. Which of the following is the most likely cause of the wound-healing problem?
A ) Hematoma
B ) Patient movement
C ) Seroma
D ) Skin necrosis
E ) Wound infection
```
C ) Seroma
63
Body lift procedures after massive weight loss: overall rate, and most common complication and rate
Body lift procedures after massive weight loss have a complication rate of approximately 50%. The most common complication is wound dehiscence, which occurs in greater than 30% of patients.
Although infection and skin necrosis can occur in the postoperative period and result in wound dehiscence, seroma is much more common.
64
Early wound dehiscence after body lift after massive weight loss
Wound dehiscence can be characterized as either early (in the immediate postoperative period) or late. Early wound dehiscence may be caused by patient movement.
65
Late wound dehiscence after body lift after massive weight loss
Wound dehiscence can be characterized as either early (in the immediate postoperative period) or late. Late wound dehiscence is often due to underlying seroma.
66
```
A 76-year-old woman with type 1 diabetes mellitus is scheduled to undergo surgical intervention for chronic ulceration of the lower extremities. Which of the following factors is NOT likely to impair wound healing in this patient?
A ) Advanced age
B ) Chronic anemia
C ) Chronic use of corticosteroids
D ) Malnutrition
E ) Poor control of diabetes
```
B ) Chronic anemia
67
Increased age vs healing
Aging is associated with reduced production of collagen and angiogenesis and a diminished response to environmental stresses.
68
Steroid impairment of healing
By reducing inflammation, steroids impair angiogenesis, fibrogenesis, wound contraction, reduced wound strength, and delay healing. O
69
Anemia vs healing
Does not impair healing
70
Malnutrition vs healing
Malnutrition, including caloric, protein, vitamin, and mineral insufficiency, impairs the immune system, prevents tissue repair, and may lead to progression or recurrence of a wound. A
71
Diabetes vs healing
Diabetes mellitus adversely affects healing by altering circulation, attenuating inflammation, reducing tissue oxygenation, and adversely affecting glucose metabolism resulting in stress hyperglycemia.
72
Factors which impair wound healing
```
Diabetes mellitus
Malnutrition
Aging
Steroids
Infection
Smoking
Poor tissue oxygenation
Radiation
Chemotherapy
Presence of foreign bodies
Cancer
```
73
```
A 26-year-old man comes to the emergency department because he has a laceration of the anterior aspect of the right lower leg. Physical examination shows a superficial 2-cm full-thickness skin laceration. Sutures are placed. If the wound heals normally, which of the following is the earliest time that the epidermis is likely to be restored?
(A)12 Hours
(B)24 Hours
(C)2 to 3 Days
(D)4 to 5 Days
(E)6 to 7 Days
```
(B)24 Hours
74
When is it safe to get a surgical incision wet?
After closing a surgical incision, epithelialization usually occurs within24 hours, at which point it is no longer necessary to keep the wound dry. Washing to remove dried blood can reduce bacterial proliferation and improve wound healing. This process may take longer in patients in whom wound healing may be compromised, such as elderly patients or patients with diabetes.
75
Reaction after destroying basement membrane
If the basement membrane has been destroyed, epithelial cells and keratinocytes located on wound edges proliferate and send out projections to reestablish a protective barrier against fluid loss and bacterial invasion. The stimuli for epithelial proliferation and chemotaxis are epidermal growth factor and transforming growth factor (TGF)-α produced by activated platelets and macrophages.
76
```
In an acute wound, which of the following structures initiate coagulation, hemostasis, and the inflammatory cascade?
(A)Endothelial cells
(B)Eosinophils
(C)Macrophages
(D)Neutrophils
(E)Platelet
```
(E)Platelet
77
Initial changes in a wound after injury are _______ in nature:
Initial changes in a wound after injury are vascular in nature. Blood vessels are disrupted and hemorrhage ensues, damaging the epidermal barrier. After vasoconstriction occurs, the coagulation cascade is activated to reduce blood loss.
78
Platelet initiation of hemostasis/normal inflammatory response
Platelets release:
- adenosine diphosphate (ADP), which, in the presence of calcium, stimulates further platelet aggregation.
Alpha granules in the platelets release
- cytokines such as platelet-derived growth factor (PDGF), transforming growth factor (TGF)-β, TGF-α, basic fibroblast growth factor (bFGF), platelet factor IV, and β-thromboglobulin. These proteins initiate the wound healing cascade by attracting and activating fibroblasts, endothelial cells, and macrophages.
Platelets also contain lysosomes, which include proteases
Platelet dense bodies:
- store vasoactive amines, such as serotonin, which increase microvascular permeability.
79
Result of extrinsic and intrinsic coagulation pathway activation:
The extrinsic and intrinsic coagulation pathways are activated, resulting in a fibrin mesh with aggregated platelets embedded in it.
80
The early inflammatory phase following coagulation activates _________, and initiates the __________, which leads to ____________.
The early inflammatory phase following coagulation activates complement and initiates the classic molecular cascade, which leads to infiltration of the wound with neutrophils within 24 to 48 hours of injury.
81
Neutrophils reach a wound within __________ (time) of injury
Neutrophils reach a wound within 24 to 48 hours of injury
82
Role of neutrophils in a wound
Neutrophils act as defensive units, phagocytosing bacteria and foreign debris from the wound to prevent infection.
83
Fate of neutrophils in a wound
Neutrophils are phagocytosed by macrophages and destroyed
84
When are macrophages the dominant cell type in a wound?
Between 48 and 72 hours after injury, macrophages are the dominant cells in the wound.
85
Where to macrophages come from (in a wound)?
When circulating monocytes migrate through the blood vessel wall and into the wound, they transform into macrophages.
86
Function of macrophages in a wound
Macrophages are key regulatory cells for repair.
They function in phagocytosis of bacteria and dead tissue. Macrophages also secrete collagenases and cytokines responsible for proliferation of fibroblasts, resulting in collagen production, and for proliferation of endothelial cells, resulting in angiogenesis
87
A 55-year-old woman is admitted to the hospital for treatment of chronic pancreatitis. She has a 10-year history of severe rheumatoid arthritis managed with corticosteroids. Physical examination performed on admission shows an ulcer of the right ischium with purulent drainage. Results of culture show a polymicrobial infection. Serum albumin level is 1.8 g/dl. Necrotic soft tissue is debrided, resulting ina 6 × 4-cm defect and exposure of the underlying ischium. Which of the following is the most appropriate next step in management?
(A)Enzymatic debridement
(B)Vacuum-assisted closure (VAC) therapy
(C)Skin graft(D)Gluteus fasciocutaneous flap
(E)V-Y hamstring advancement flap
(B)Vacuum-assisted closure (VAC) therapy
88
Under optimal conditions, the peak tensile strength of a skin incision is achieved at approximately how many days after injury and reaches what percentage of the tensile strength of unwounded skin?
Days-Percentage
```
(A)30d, 75%
(B)60d, 80%
(C)90d, 85%
(D)120d, 90%
(E)150d, 95%
```
(B)60d, 80%
89
Peak tensile strength after injury: time, and amount vs baseline
The peak tensile strength of skin is achieved at approximately 60 days after injury and reaches approximately 80% of the original unwounded tensile strength.
90
Hyperbaric oxygen therapy has the greatest utility in the treatment of which of the following wounds?
(A)Diabetic foot ulcer with osteomyelitis
(B)Extravasation injuries
(C)Grade 4 pressure sore of the ischium
(D)Pyoderma gangrenosum
(E)Superficial partial-thickness burn
(A)Diabetic foot ulcer with osteomyelitis
91
Hyperbaric oxygen therapy has been proven to improve wound healing in which conditions?
The effect of hyperbaric oxygen (HBO) therapy on wound healing has been shown in several clinical trials. There is proven utility in conditions such as osteomyelitis, necrotizing infections, and ischemia reperfusion injury.
The use of HBO in the treatment of diabetic lower extremity wounds has shown improved healing rates and decreased amputations.
92
A poorly nourished 70-year-old woman is brought to the emergency department after sustaining burns in a house fire. Examination shows partial-thickness burns on 10% of the total body surface area. Nutritional supplementation is planned. Which of the following best describes the role of vitamin C in wound healing?
(A)Acts as a cofactor in the hydroxylation of proline and lysine for pro collagen formation
(B)Alters prostaglandin production by inhibiting phospholipase A2 activity
(C)Inhibits leukocyte migration into the wound
(D)Promotes epithelialization and fibroblast proliferation through its effect on metalloenzymes
(E)Promotes formation of oxygen free radicals
(A)Acts as a cofactor in the hydroxylation of proline and lysine for pro collagen formation
93
Specific role of Vitamin C in collagen synthesis
Vitamin C plays a pivotal role in collagen synthesis, being an essential cofactor in the hydroxylation of proline and lysine for procollagen formation. Procollagen residues are then altered intracellularly to form collagen. Vitamin C deficiency therefore results in scars of poorer tensile strength and abnormal capillary formation
94
Functions of vitamin C in wound healing
Vitamin C plays a role in collagen synthesis, as an essential cofactor in the hydroxylation of proline and lysine for pro collagen formation
Vitamin C has an antioxidant function, neutralizing the effects of oxygen free radicals
Vitamin C an increase resistance to infection by facilitating leukocyte migration into the wound.
95
```
A 21-year-old man sustains a flame burn to the distal aspect of the left forearm, resulting in a hypertrophic scar. Silicone gel sheeting is applied to the scar. Which of the following is the most likely mechanism of action that the silicone gel sheeting will have on the scar?
(A)Alteration of cytokine levels
(B)Direct chemical effect
(C)Hydration
(D)Increased oxygen tension
(E)Pressure
```
(C)Hydration
96
Most likely mechanism of action of silicone gel sheeting
Although the exact mechanism of action of silicone gel sheeting is unknown, the most widely accepted hypothesis is that there is an increase in hydration resulting from occlusion, which is supported by in vitro data.
97
To be effective, silicone gel sheeting must be worn in this manner:
It is generally thought that for silicone gel sheeting to be effective it must be worn for at least 12 hours a day for three months or longer
98
A 3-year-old girl is brought to the office by her parents two months after sustaining an injury to the right ankle for evaluation of the scar shown. Which of the following is the most appropriate management?
(A)Excision
(B)Oral administration of a corticosteroid
(C)Radiation therapy
(D)Topical administration of vitamin E
(E)Observation
(E)Observation
99
Time course of hypertrophic scars
Hypertrophic scars develop soon after the injury (within six to eight weeks). They can worsen up to six months but subside with time.
100
The extent of hypertrophic scarring is related to:
The extent of scarring relates to the initial depth of injury.
101
Contractures are related to which type of scar?
Contractors are related to hypertrophic scars, especially over joints.
Hypertrophic scars have a predilection to occur over the flexor surface of joints.
102
```
Which of the following laboratory results of fluid analysis is increased in chronic wounds relative to acute wounds?
(A)Growth factor level
(B)Matrix deposition
(C)Metalloproteinase level
(D)Protease inhibitor level
(E)Tissue oxygen tension
```
(C)Metalloproteinase level
103
Which of the following is the mechanism of action of pressure garments in management of fibroproliferative scars?
(A)Alteration in cell shape
(B)Hypoxia of local tissue
(C)Increase in synthesis of tissue proteinases
(D)Increase in temperature of the scar
(E)Induction of matrix-specific autoantibodies
(B)Hypoxia of local tissue
104
```
Two months after undergoing reduction mammaplasty, a 28-year-old woman has scars that are softening but maintaining strength. The mechanism by which this process occurs is an increase in which of the following?
(A) Chondroitin-4 sulfate
(B) Hyaluronic acid
(C) Integrin
(D) Type I collagen
(E) Water content
```
(D) Type I collagen
105
Normal skin ratio of collagen types
4x Type I collagen : 1x Type III collagen
106
```
A 3-year-old girl is brought to the office by her parents two months after sustaining an injury to the right ankle for evaluation of the scar shown. Which of the following is the most critical consideration in determining the next step in treatment?
(A) Age of the patient
(B) Anatomic location
(C) Histologic findings
(D) Mechanism of injury
(E) Natural history
```
(E) Natural history
This patient has a hypertrophic scar. Correct diagnosis of the abnormal scar will directly influence treatment options for this patient.
107
```
During the inflammatory phase of wound healing, which of the following cellular components is most likely to appear first?
(A) Fibroblasts
(B) Lymphocytes
(C) Macrophages
(D) Myofibroblasts
(E) Neutrophils
```
(E) Neutrophils
108
Chronological appearance of cels in a wound
Platelets
Neutrophils
Macrophages / lymphocytes
Fibroblasts / epithelial cells / endothelial cells
109
```
In creation of a normal collagen molecule, the amino and carboxy terminal peptides must be removed from which of the following molecules?
(A) Collagen fiber
(B) Collagen fibril
(C) Hydroxylated lysine
(D) Procollagen
(E) Proline
```
(D) Procollagen
110
Evolution of collagen
Procollagen - recreated from cells ; has its amino and carboy terminal ends cleaved off to form.. ->
Collagen molecule, which crosslinks with other collagen molecules to form...->
A collagen fiber.
111
```
One year after ear piercing, a 21-year-old woman has the slow-growing posterior auricular lesion shown. Pathologic examination of this lesion is most likely to show excess of which of the following?
(A) Basal cells
(B) Collagen
(C) Fat
(D) Melanin
(E) Myofibroblasts
```
(B) Collagen
112
Characteristic histologic finding of keloids
The characteristic histologic finding of keloids reveals extensive random collagen fibrils in densely packed bundles.
113
A 62-year-old man with type 2 diabetes mellitus has a nonhealing wound on the right foot six months after he sustained a degloving injury of the dorsal surface of the right foot. Radiographs obtained at the time of injury showed no abnormalities. Physical examination shows a 6 _ 8-cm wound on the dorsal aspect of the foot with minimal granulation tissue, exposed tendons, and intact sensation to the sole. Which of the following is the most appropriate diagnostic study?
(A) Semmes-Weinstein monofilament test
(B) MRI of the foot
(C) Bone scan
(D) Determination of ankle-brachial index
(E) Measurement of transcutaneous oxygen
(E) Measurement of transcutaneous oxygen
114
Foot/ankle pressures for spontaneous healing
For a wound to heal spontaneously, the ankle pressure should exceed 40 mmHg, the great toe pressure should be greater than 40 mmHg, the great toe pressure should be greater than 40 mmHg, and the patient should have pulsatile plethysmography and a transcutaneous oxygen higher than 30 torr. If one of these criteria is not met, the patient can be expected to have difficulty healing and further vascular assessment with angiography.
115
```
A 32-year-old man undergoes surgical repair of a deep, contaminated laceration of the dorsum of the left hand with general anesthesia and an upper arm tourniquet. Exploration shows laceration of the extensor tendons. Thirty minutes into the procedure, the anesthesiologist reports that prophylactic antibiotics have not been administered. To decrease risk of infection without adversely affecting the healing of the tendons, the most appropriate intervention is initiation of intravenous administration of antibiotics, debridement, and cleansing/irrigation of the wound with a 1:1000 dilution of which of the following solutions?
(A) 0.25% Acetic acid
(B) Normal saline
(C) 3% Hydrogen peroxide
(D) 1% Povidone-iodine
(E) 0.05% Sodium hypochlorite
```
(D) 1% Povidone-iodine
In the choices listed, only irrigation with a 1:1000 solution of 1% povidone-iodine (0.001% povidone-iodine) will provide full bactericidal activity without significant fibroblast toxicity.
116
Special consideration of antibiotics and limb operations
Prophylactic antibiotics should be administered before inflation of a tourniquet for obvious reasons.
117
Irrigation solutions: desired vs undesired activities
Irrigation of wounds with topical antimicrobials has shown efficacy over irrigation with saline alone. However, the concentration of the topical antimicrobial impacts fibroblast toxicity (undesired) and bactericidal activity (desired).
118
Ideal irrigation solution
Many wound solutions are used; only 0.001% povidone-iodine and 0.005% sodium hypochlorite are toxic to common gram-negative and -positive bacteria and nontoxic to fibroblasts
119
```
Which of the following processes of healing provides maximal tensile strength of a wound?
(A) Accumulation of collagen
(B) Addition of sugar moieties
(C) Hydroxylation of lysine
(D) Hydroxylation of proline
(E) Molecular cross-linking
```
(E) Molecular cross-linking
120
Peak increase in tensile strength occurs when? When is ACTUAL maximal peak strength?
Peak increase in tensile strength occurs three to six weeks after injury but approaches maximal after about three months when it achieves up to 80% of the normal skin strength.
121
```
Which of the following types of cells has been shown to mediate wound contraction?
(A) Epithelial cells
(B) Lymphocytes
(C) Macrophages
(D) Myofibroblasts
(E) Polymorphonuclear cells
```
(D) Myofibroblasts
122
Myofibroblasts are developed from?
Myofibroblasts are derived from fibroblasts in the wound, which under conditions of stress elongate and show features of a myocyte.
123
When are myofibroblasts in a wound?
Myofibroblasts first appear in the wound by the third day after injury and persist for approximately 21 days, after which time they slowly disappear. They persist longer in open contracting wounds
124
```
Which of the following types of collagen is most abundant in a healed scar?
(A) I
(B) II
(C) III
(D) IV
(E) V
```
(A) I
125
Most common collagen in the body
The most abundant type of collagen in a healed scar is Type I.
126
Type II collagen
Type II collagen is found predominantly in cartilage and vitreous.
127
Type III collagen
Type III collagen is the second most abundant collagen in a healed scar. It also exists in elastic tissues, such as blood vessels.
128
Type IV collagen
Type IV collagen is located mainly in the basement membranes.
129
Type V collagen
Type V collagen is widespread.
130
Type I collagen
The most abundant type of collagen in a healed scar is Type I. This type is the most abundant collagen in the body, including the skin.
131
```
Which of the following is the predominant cell responsible for the intermediate phase of wound healing and collagen synthesis (days 3 through 21)?
(A) Erythrocyte
(B) Fibroblast
(C) Myoepithelial cell
(D) Neutrophil
(E) Platelet
```
(B) Fibroblast
132
Intermediate phase of wound healing
The intermediate phase of wound healing begins on the second or third day after injury and continues until approximately 21 days after injury. This phase begins with chemotaxis and proliferation of mesenchymal cells, angiogenesis, and epithelialization. Ultimately, collagen synthesis, wound contraction, and proteoglycan synthesis predominate in this phase; fibroblasts and macrophages are the primary cells involved.
133
Which of the following interventions is LEAST likely to improve the appearance of a hypertrophic scar?
(A) Application of silicone gel sheeting
(B) Application of vitamin E gel
(C) Intralesional injection of a corticosteroid
(D) Pressure therapy
(E) Prolonged application of paper tape
(B) Application of vitamin E gel
Application of vitamin E products is popular in the skin-care industry despite the paucity of scientific evidence about its effectiveness. Some animal models have demonstrated improvement in healing of radiation-induced wounds with vitamin E. However, no studies have shown clear-cut improvement in hypertrophic or normal scars. In fact, the only controlled study showed no benefit. Localized dermatitis may occur with application of vitamin E products
134
Vitamin E products and scars
Application of vitamin E products is popular in the skin-care industry despite the paucity of scientific evidence about its effectiveness. Some animal models have demonstrated improvement in healing of radiation-induced wounds with vitamin E. However, no studies have shown clear-cut improvement in hypertrophic or normal scars. In fact, the only controlled study showed no benefit. Localized dermatitis may occur with application of vitamin E products
135
Steroid injections and hypertrophic scars
Intralesional injection of triamcinolone and other corticosteroids typically have a response rate greater than 50% but can cause skin atrophy, depigmentation, telangiectasis, and pain.
136
Pressure therapy and hypertrophic scars
Pressure therapy has been used to manage keloids and hypertrophic scars since the early 1970s. The use of pressure garments (specially fitted elastic garments often with silicone inserts) to treat postburn scarring and contractures is a standard of care.
137
Adhesive microporous tape and hypertrophic scars
Application of adhesive microporous tape to fresh surgical wounds has been endorsed by an international panel on scar management. Uncontrolled clinical trials have shown its efficacy. The mechanism is unknown but may be similar to the action of silicone gel sheeting.
138
Which of the following is the most likely mechanism of action of silicone sheeting/gel pads in enhancing scar maturation?
(A) Decreasing wound tension
(B) Deregulating cellular integrins
(C) Enhancing epidermal contact inhibition
(D) Increasing the static electronegative field
(E) Maintaining regulated wound temperature
(D) Increasing the static electronegative field
139
Mechanism of silicone sheeting / gel pads
Silicone sheeting and silicone gel pads are used to treat hypertrophic or immature scars and keloids. Although their exact mechanism of action is unknown, some surgeons postulate that their positive effect is associated with the generation of an increased static electronegative field by the silicone. This mechanism of action results in favorable wound effects. Other theories propose that the wound-healing mechanism is related to the decreased oxygenation, sustained pressure, or hydrating effects of silicone oil resulting from the use of these products
140
```
Which of the following is an absolute contraindication to performing vacuum-assisted closure (VAC) therapy for wound management?
(A) Bacterial colonization of the wound
(B) Open fracture of a long bone
(C) Presence of an enteric fistula
(D) Presence of exposed blood vessels
(E) Presence of osteomyelitis
```
(D) Presence of exposed blood vessels
141
Presence of exposed vessels and Wound VAC
The presence of exposed arteries or veins is an absolute contraindication to VAC therapy because the vessel may burst and subsequently hemorrhage into the VAC device; this can be potentially fatal
142
Presence of open fractures and Wound VAC
VAC therapy is an option for management of open fractures until definitive flap reconstruction can be performed
143
Presence of osteomyelitis and Wound VAC
The presence of osteomyelitis in the wound bed is not a contraindication to VAC therapy
144
Presence of bacteria and Wound VAC
Although VAC therapy is not contraindicated in open wounds, which by their nature are colonized by bacteria, the presence of gross bacterial infection precludes the use of the VAC device.
145
Presence of enteric fistula and Wound VAC
The presence of an enteric fistula within the wound is no longer an absolute contraindication to VAC therapy.
146
Advantages of the VAC in open wounds
Vacuum-assisted closure (VAC) is an effective technique for management of open wounds. Advantages include promoting the ingrowth of healthy granulation tissue, decreasing the duration of the wound healing process, simplifying dressing changes, and increasing the intervals between dressing changes.
147
```
Which of the following is the ratio of type I collagen to type III collagen in hypertrophic or immature scars?
(A) 1:4
(B) 1:2
(C) 2:1
(D) 4:1
```
(C) 2:1
148
Normal skin type I to type III collagen ratio
4:1
149
Hypertrophic scar type I to type III collagen ratio
2:1
150
Immature scar type I to type III collagen ratio
2:1
151
Deep mechanical massage has been shown to result in which of the following?
(A) Accumulation of collagen bands
(B) Accumulation of mast cell aggregates
(C) Retention of adipocyte cell architecture
(D) Thickening of the epidermis
(A) Accumulation of collagen bands
152
Deep mechanical message or therapeutic massage units can be used for:
Deep mechanical massage, using therapeutic massage units (ie, Endermologie), can be performed for reduction or correction of moderate amounts of cellulite and is often used postoperatively in patients who have undergone body contouring procedures.
153
Histological results after deep mechanical message / therapeutic massage units
According to the results of an experimental animal study, there is an accumulation of dense longitudinal collagen bands in the middle and deep subcutaneous regions that increases proportionately with the number of treatments administered. Distortion and disruption of adipocytes were also demonstrated in this study.
Deep mechanical massage has not been shown to have any effect on epidermal thickness or accumulation of mast cell aggregates
154
```
Which of the following is the primary disadvantage of autologous cartilage grafting?
(A) Immunogenicity
(B) Resorption
(C) Rigidity
(D) Warping
```
(D) Warping
155
Advantages of autologous cartilage grafts
Autologous cartilage grafts are versatile and can be used for joint reconstruction and soft-tissue fill. The grafts can be carved easily; they retain form with minimal resorption. Because autologous cartilage grafts are biocompatible, there is no risk for rejection.
156
Types of cartilage used for grafting
hyaline, elastic, fibrocartilage
157
Hyaline cartilage used for grafting
Hyaline cartilage functions as a covering for the articular surface of bones. The nasal alae and septum, costal cartilage, and trachea are composed of hyaline cartilage.
158
Elastic cartilage used for grafting
Elastic cartilage is found in the external ear, epiglottis, and portions of the larynx.
159
Fibrocartilage
fibrocartilage is firm and comprises intervertebral disks, ligaments, and tendons.
160
Disadvantages of cartilage grafting
The primary disadvantage of autologous cartilage grafting is the potential for warping. There is an inherent tension within the subperichondrial layer that is released when the cartilage is not carved in a balanced cross section.
161
Which of the following factors has been shown to stimulate fibroblasts to produce collagen?
(A) Platelet-derived growth factor (PDGF)
(B) Transforming growth factor-beta (TGF-B)
(C) Tumor necrosis factor-alpha (TNF-B)
(D) Vascular endothelial growth factor (VEGF)
(B) Transforming growth factor-beta (TGF-B)
162
Epineural scarring that occurs after injury to peripheral nerves leads to:
he epineurial scarring that occurs following injury to peripheral nerves leads to deposition of type I collagen within fibroblasts, subsequently resulting in inhibition of axonal regeneration. Studies have shown that antibody blockage of TGF-B is clinically beneficial in facilitating optimal axonal regeneration after injury.
163
TGF-B has stimulates fibroblasts to:
Transforming growth factor-beta (TGF-B) has been shown to stimulate fibroblasts to produce collagen. This factor is one of several signaling molecules and is produced by mesenchymal cells.
164
A 26-year-old man sustains circumferential abrasions and lacerations to the right arm in a roll-over motor vehicle collision. On examination, the arm is covered in dirt and debris. In addition to irrigation of the wound site, which of the following is the most appropriate initial management?
(A) Immediate closure
(B) Operative closure
(C) Immediate split-thickness skin grafting
(D) Daily whirlpool hydrotherapy
(E) Mechanical debridement
(E) Mechanical debridement
The most appropriate management of this patient is irrigation and mechanical debridement of the wound site. Patients with soft-tissue lacerations covered with debris often have foreign particles embedded within the dermis or subcutaneous tissue. If this material is not removed promptly, a traumatic tattoo will ultimately develop; treatment of this complication is difficult and frequently unsuccessful. Therefore, mechanical devices, such as scrub brushes or pulse irrigation devices, should be used with physical retrieval to ensure that all debris is removed.
165
Depth of effectiveness of hydrotherapy
Hydrotherapy may be useful inremoving surface debris but not subcutaneous debris.
166
```
Administration of which of the following vitamins to a surgical wound has been shown to reverse the adverse effects associated with corticosteroid use?
(A) Vitamin A
(B) Vitamin B6
(C) Vitamin B12
(D) Vitamin C
(E) Vitamin E
```
(A) Vitamin A
167
Vitamin A vs steroids on a cellular level
The negative effects on wound healing resulting from corticosteroid use occur secondary to an arrested inflammatory phase. Corticosteroids inhibit wound macrophages and disrupt the mechanisms of fibrogenesis, endogenesis, and wound contraction.
168
Corticosteroids on a cellular level vs wound healing
Corticosteroids inhibit wound macrophages and disrupt the mechanisms of fibrogenesis, endogenesis, and wound contraction.
169
```
Which of the following substances has been shown to occur in higher levels in keloids and red hypertrophic scars than in pink or white hypertrophic scars?
(A) Adenosine triphosphate
(B) Creatine kinase
(C) Fibronectin
(D) Guanosine triphosphate
```
(A) Adenosine triphosphate
170
Types of scars with high ATP
When compared with more mature pink and white scars, keloids and red hypertrophic scars have been shown to have higher levels of adenosine triphosphate.
171
Activity of glycolytic enzymes in keloids and hypertrophic scars
Both keloids and hypertrophic scars actively synthesize collagen fibers and have been shown to have increased activityof glycolytic enzymes in vivo.
172
```
In patients with vitamin C deficiency, which of the following physiologic findings is most likely to be decreased?
(A) Amino acid hydroxylation
(B) Fibronectin production
(C) Helical integrity
(D) Monocyte activation
(E) Prothrombin production
```
(A) Amino acid hydroxylation
na patient who has a vitamin C (ascorbic acid) deficiency, hydroxylation of amino acids such as lysine and proline is likely to be decreased
173
Primarily responsible for covalent crosslinks of collagen
Hydroxylysine and hydroxyproline are the primary components of collagen, with hydroxylysine being responsible for the formation of covalent crosslinks.
174
Primary components of collagen
Hydroxylysine and hydroxyproline are the primary components of collagen, with hydroxylysine being responsible for the formation of covalent crosslinks.
175
Animals unable to manufacture vitamin C naturally
Both humans and guinea pigs are unable to manufacture vitaminC naturally.
176
Cellular hallmarks of vitamin A deficiency
Decreases in fibronectin production and monocyte activation are the hallmarks of vitamin A deficiency.
177
Inhibited production in vitamin K deficiency
Prothrombin production is inhibited in patients with vitamin K deficiency.
178
First phase of wound healing and primary cells
Inflammation is the initial phase of wound healing; polymorphonuclear leukocytes (PMNs) and macrophages are primarily involved in this process. This interval typically lasts from four to six days; during this time, clots, foreign bodies, and bacteria are removed, and the wound surface closes.
179
Second phase of wound healing and primary cells
The proliferative phase, also known as the collagen and regenerative phase, is characterized by collagen production and increased strength within the wound. Fibroblasts are primarily responsible for the collagen production. This process begins approximately seven days after injury; its duration is approximately five weeks.
180
Third/final phase of wound healing and overall concept
Maturation, or remodeling, is the final phase and can last for more than two years. Maturation and cross linking of collagen occur during this phase.
181
Which of the following is the most likely result following the intralesional injection of corticosteroids for treatment of keloids?
(A) Absence of adverse effects on the surrounding tissues
(B) Decreased risk for malignant degeneration
(C) Decreased risk for recurrence
(D) Lack of effectiveness on the connective tissue composition of the keloid
(E) Symptomatic relief of itching and burning
(E) Symptomatic relief of itching and burning
182
Corticosteroids have been proven to do what to keloids?
Corticosteroids have been shown to relieve the itching and burning symptoms associated with the keloids, as well as to decrease the collagen content of the keloids and subsequently decrease their size.
183
```
Which of the following impairs the process of epithelialization during wound healing?
(A) Basic fibroblast growth factor
(B) Epidermal growth factor
(C) Isotretinoin
(D) Keratinocyte growth factor
(E) Tretinoin
```
(C) Isotretinoin
184
What is isotretinoin
Isotretinoin (13-cis retinoic acid, or Accutane) is a retinoid, one of a family of vitamin A-related agents. Because of its antikeratinization effect, which results in thinning of the stratum corneum and decreased activity of skin appendages such as sebaceous glands, as well as its effect on wound epithelialization, it is used in the treatment of cystic acne. In addition, patients who have been taking isotretinoin experience delayed or poor wound healing following chemical peeling or laser skin resurfacing because of the effect on wound epithelialization.
185
What does isotretinoin do to epithelialization?
Isotretinoin (13-cis retinoic acid, or Accutane) is a retinoid, one of a family of vitamin A-related agents. Because of its antikeratinization effect, which results in thinning of the stratum corneum and decreased activity of skin appendages such as sebaceous glands, as well as its effect on wound epithelialization, it is used in the treatment of cystic acne.
186
How long should a patient have discontinued isotretinoin before chemical peel or laser skin resurfacing?
Patients who have been taking isotretinoin experience delayed or poor wound healing following chemical peeling or laser skin resurfacing because of the effect on wound epithelialization. Therefore, it is recommended that isotretinoin be discontinued a minimum of one year before chemical peeling or laser peeling is performed.
187
Actions of fibroblast growth factor
Basic fibroblast growth factor is a polypeptide and a member of the family of fibroblast growth factors (FGF). This agent stimulates important aspects of wound healing, including angiogenesis, collagen and collagen matrix syntheses, wound contraction, and epithelialization.
188
Actions of keratinocyte growth factor
Epidermal growth factor is a polypeptide FGF that affects endothelial cells, fibroblasts, and smooth muscle cells. Because epithelial cells have been shown to have the greatest number of receptors for epidermal growth factor, the primary effect of epidermal growth factor is believed to be promotion of epithelialization
189
Keratinocyte growth factor
Keratinocyte growth factor is produced by fibroblasts and also primarily affects epithelialization; only epithelial cells have keratinocyte growth factor receptors. Delayed wound healing has been reported in transgenic animals that lack this signaling receptor
190
Actions of tertian and clinical use
Although tretinoin is also classified as a retinoid, its effects are far different than isotretinoin. Tretinoin (all-trans-retinoic acid, Retin-A) promotes epithelialization by stimulating mitotic activity and decreasing the turnover of follicularepithelial cells. As a result, tretinoin is often used as a pretreatment in patients undergoing chemical peeling and laser skin resurfacing to accelerate wound healing. Other conditions for which tretinoin has proved beneficial include skin aging, acne vulgaris, and dysplastic nevus syndrome, as well premalignant and malignant tumors such as actinic keratosis, carcinoma in situ, and superficial basal cell carcinoma.
191
```
Which of the following is the predominant type of collagen found in basement membrane?
(A) Type I
(B) Type II
(C) Type III
(D) Type IV
(E) Type V
```
(D) Type IV
192
Predominant collagen in basement membrane.
Type IV collagen is the predominant collagen in basement membrane.
Type V collagen is also found within the basement membrane in lesser amounts than type IV collagen.
193
```
Which of the following sites is most susceptible to the development of a keloid following injury?
(A) Eyelid
(B) Genitalia
(C) Upper arm
(D) Palm
(E) Sole
```
(C) Upper arm
194
Where are keloids located (and not located)
Keloids are most likely to develop on theface, cheek, earlobe, shoulder, upper arm, and anterior chest; in contrast, they are rarely seen on the eyelid, cornea, umbilical cord region, palm, genitalia, or sole.
195
```
In patients who exhibit allergic sensitivity to bovine collagen, which of the following types of immunologic response is most common?
(A) IgA antibodies
(B) IgD antibodies
(C) IgE antibodies
(D) IgG antibodies
(E) IgM antibodies
```
(D) IgG antibodies
196
Zyderm - composition and form
Zyderm is a purified form of bovine collagen that consists of 95% type I collagen with 5% type II collagen. It is available in two concentrations, 35 mg/mL and 65 mg/mL, as well as in a glutaraldehyde cross-linked form known as Zyplast, which in theory degrades more slowly. Enzymatic processing is used to remove the nonhelical portion of the collagen molecule, thus reducing most of its associated antigenicity.
197
Zyderm use
These various forms of injectable collagen are used for correction of depressed scars, shallow or soft acne scars, and fine facial rhytids associated with aging. Ice pick acne scars cannot be treated with collagen injections. In patients undergoing treatment, the collagen is injected intradermally in excess amounts, which are necessary to compensate for absorption of the saline component of the solution.
Some of the injected collagen is lost over the next six to nine months as collagen breakdown occurs.
198
Adverse effects of Zyderm
Because approximately 3% of all treated patients will have an allergic reaction to injectable bovine collagen, skin testing should be performed prior to any treatment. Following intradermal injection of a test dose into the volar forearm, the patient should be assessed 72 hours after injection and again at four weeks after injection, as any adverse changes noted at the test site may indicate an allergic reaction. This is defined as the onset of erythema, induration, tenderness, or swelling to any degree, with or without pruritus, that appears more than 24 hours after injection and/or persists longer than six hours.
199
Ability/effectiveness in preventing adverse effects of Zyderm
Approximately 66% of those patients who are allergic to injectable collagen will have a positive reaction within 72 hours, while 33% will develop positive findings within four weeks. An additional 1% willhave negative findings on skin testing but will subsequently develop an allergic reaction following injection. One study of those patients who had negative skin tests and subsequent allergic reactions showed that 56% developed a reaction following the first treatment, while 28% experienced the reaction after two treatments.
All of the patients who exhibited allergic sensitivity developed IgG antibodies against bovine collagen. In contrast, 50% developed IgA antibodies; IgD, IgE, and IgM antibodies were not identified
200
```
In normal wound healing, collagen synthesis and collagen breakdown typically reach a state of equilibrium approximately how many days after injury?
(A) 7
(B) 14
(C) 21
(D) 60
(E) 90
```
(C) 21
201
In normal wound healing, collagen synthesis vs breakdown reaches equilibrium when?
In normal wound healing, collagen synthesis and collagen breakdown typically reach a state of equilibrium approximately 21 days after initial injury.
202
Collagen synthesis depends primarily on?
Collagen synthesis depends primarily on production of procollagen by fibroblasts.
his procollagen is inserted into secretory vessels that move toward the cell surface. It then is cleaved into collagen at the level of the cell membrane, and the collagen is then released into the wound. Macrophages help to regulate collagen synthesis by producing growth factors that stimulate fibroblast proliferation and subsequent collagen productio
203
How is collagen degraded?
In collagen degradation, fibroblasts, granulocytes, macrophages, and other cells produce specific matrix metalloproteinases (MMP) at the wound site. The MMP family of zinc-dependent endopeptidases includes collagenase, gelatinase, and stromelysin.
204
MMP's absent in acute wounds
Several members of the MMP family have been linked to chronic wounds; these substances, such as MMP-2 and MMP-9, have been shown to be absent in acute wounds. A higher turnover of extracellular matrix is thought to contribute to the delayed healing or nonhealing seen in association with chronic wounds. Transforming growth factor-beta can be used to combat this; it has beenshown to decrease MMP activity and increase the activity of MMP inhibitors
