Skin Grafts — MCQs
Delayed wound healing is seen in all except-
First cell to migrate into a wound due to chemotaxis to start the process of wound healing is -
What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
A 43-year-old window cleaner fell off a scaffold. He sustained an open wound on the right leg. Debridement was carried out in the emergency department, and the edges of the wound were left open. Which factor is least likely to inhibit wound contraction?
What type of graft or dressing is used to cover the post-burn wound shown in the image?
What is the eponymous term for a full-thickness skin graft?
The best skin graft for open wounds is -
Wound contraction can be most effectively minimized by:
Which of the following statements about mesh skin grafts is not correct?
Deep skin burns are treated with:
Skin Grafts Indian Medical PG Practice Questions and MCQs
Question 1: Delayed wound healing is seen in all except-
- A. Hypertension (Correct Answer)
- B. Malignancy
- C. Infection
- D. Diabetes
Explanation: ***Hypertension*** - While **severe or uncontrolled hypertension** with microvascular complications may theoretically affect tissue perfusion, hypertension **alone is not classically listed** among the primary independent causes of delayed wound healing in standard surgical teaching. - Unlike the other options, hypertension is **not a direct metabolic or local tissue factor** that impairs the wound healing cascade. - The major recognized factors causing delayed wound healing are infection, metabolic disorders (diabetes, malnutrition), malignancy, and immunosuppression—hypertension does not fall into these classical categories. *Diabetes* - **Hyperglycemia** impairs neutrophil function, reduces collagen synthesis, and causes **microvascular disease** that reduces oxygen and nutrient delivery to wounds. - **Diabetic neuropathy** prevents early wound detection, and peripheral vascular disease further compromises healing. - Diabetes is one of the **most important systemic causes** of chronic non-healing wounds. *Infection* - **Bacterial colonization** prolongs the inflammatory phase and prevents progression to proliferation and remodeling. - Pathogens produce **proteases and toxins** that destroy granulation tissue, consume oxygen, and create a hostile wound environment. - Infection is a **local factor** that directly impairs all phases of wound healing. *Malignancy* - **Cancer-associated cachexia** and malnutrition deprive the body of resources needed for tissue repair. - Tumors can **directly invade** wound sites, and cancer treatments (chemotherapy, radiation) impair cellular proliferation and angiogenesis. - Malignancy creates a **systemic catabolic state** unfavorable for healing.
Question 2: First cell to migrate into a wound due to chemotaxis to start the process of wound healing is -
- A. Lymphocyte
- B. Macrophage
- C. Platelet
- D. Neutrophil (Correct Answer)
Explanation: ***Neutrophil*** - Neutrophils are the **first responders** in the wound healing process, rapidly migrating to the site due to **chemotactic signals** [1,2]. - Their primary role includes **phagocytosing pathogens** and debris, facilitating the subsequent healing phases. *Lymphocyte* - Lymphocytes typically arrive later in the healing process and are mainly involved in **immune response** rather than initial wound healing. - They play a significant role in **adaptive immunity** but do not participate in the **early inflammatory phase**. *Platelet* - While platelets aggregate at the wound site and are crucial for **clot formation**, they do not migrate into the wound through chemotaxis like neutrophils [1]. - Their primary function is to initiate the **hemostatic response** rather than directly phagocytosing debris. *Macrophage* - Macrophages are important for **later stages** of wound healing, clearing debris and coordinating tissue repair, but they arrive after neutrophils. - They are involved in the **remodeling phase** and are not the first cells to respond to the wound. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 188-189. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.
Question 3: What is the primary mechanism responsible for skin graft survival within the first 48 hours after transplantation?
- A. Amount of saline in graft
- B. Plasma imbibition (Correct Answer)
- C. New vessels growing from the donor tissue
- D. Connection between donor and recipient capillaries
Explanation: ***Correct: Plasma imbibition*** - **Plasma imbibition** is the initial process where the transplanted graft absorbs nutrients and oxygen from the recipient bed through diffusion. - This fluid uptake is crucial for the survival of the graft cells before revascularization occurs, typically within the first **24-48 hours**. - The graft acts like a sponge, absorbing serum and plasma from the vascular bed through capillary action and osmosis. *Incorrect: Amount of saline in graft* - While sterile saline is often used to keep donor tissue moist during harvesting and transport, its presence in the graft itself is not the primary mechanism for survival post-transplantation. - Excessive saline could even lead to **edema** and compromise graft take if not properly drained or if it prevents good contact with the recipient bed. *Incorrect: New vessels growing from the donor tissue* - Grafts themselves do not spontaneously grow new vessels; new blood vessels are formed by **angiogenesis** from the recipient bed into the graft over several days. - This process, called **inosculation** and subsequent neovascularization, provides long-term blood supply but is not the primary mechanism of survival within the *first 48 hours*. *Incorrect: Connection between donor and recipient capillaries* - The direct connection of donor and recipient capillaries (inosculation) is a later stage of graft vascularization, typically beginning after **3-5 days**, not within the first 48 hours. - Within the initial 48 hours, the graft relies on diffusion because a complete vascular connection has not yet been established.
Question 4: A 43-year-old window cleaner fell off a scaffold. He sustained an open wound on the right leg. Debridement was carried out in the emergency department, and the edges of the wound were left open. Which factor is least likely to inhibit wound contraction?
- A. Radiation
- B. Transforming growth factor β (Correct Answer)
- C. Full-thickness skin graft
- D. Cytolytic drug
Explanation: ***Transforming growth factor β*** - **TGF-β** is a potent **pro-fibrotic cytokine** that plays a crucial role in promoting wound contraction and fibrosis by stimulating **fibroblast proliferation**, **myofibroblast differentiation**, and **collagen synthesis**. - Its presence and activity would *enhance* rather than inhibit wound contraction, making it the **least likely factor to inhibit** this process. - In wound healing, TGF-β is essential for the contraction phase and tissue remodeling. *Radiation* - **Ionizing radiation** can damage cells, including **fibroblasts** and **myofibroblasts**, which are essential for wound contraction. - This cellular damage and reduction in viable cells can significantly **impair** the contractile forces within the wound. - Radiation therapy is a known factor that inhibits wound healing and contraction. *Full-thickness skin graft* - A **full-thickness skin graft** introduces a complete layer of skin, including the dermis, into the wound. - The presence of the **dermis** within the graft provides a structural barrier and helps to **anchor the wound edges**, thereby reducing the tendency for contraction. - In contrast, **split-thickness grafts** allow more wound contraction due to less dermal tissue. *Cytolytic drug* - **Cytolytic drugs** are designed to kill cells, and if applied to a wound, they would destroy **fibroblasts** and **myofibroblasts**. - The destruction of these critical cells would directly **inhibit** the cellular machinery responsible for pulling the wound edges together, hence preventing contraction. - These drugs impair the proliferative phase of wound healing.
Question 5: What type of graft or dressing is used to cover the post-burn wound shown in the image?
- A. Split thickness skin graft (Correct Answer)
- B. Full thickness skin graft
- C. VAC dressing
- D. Normal saline dressing
Explanation: ***Split thickness skin graft*** - The image shows a **meshed pattern** on the skin graft, which is characteristic of a **split-thickness skin graft** that has been expanded to cover a larger area. - This type of graft consists of the epidermis and a portion of the dermis, making it more flexible and able to **"take" more reliably** on various wound beds, commonly used for burn wounds. *Full thickness skin graft* - A **full-thickness skin graft** includes the entire epidermis and dermis and typically does not have a meshed appearance. - They are used for smaller defects where cosmesis is a priority, but have a **lower take rate** than split-thickness grafts, making them less suitable for large burn wounds. *VAC dressing* - A **VAC (Vacuum-Assisted Closure) dressing** is a system that applies negative pressure to a wound to promote healing and is not a skin graft itself. - It involves a foam or gauze dressing sealed with an adhesive film, connected to a vacuum pump, which is not what is depicted in the image. *Normal saline dressing* - A **normal saline dressing** is a simple wet-to-dry or wet-to-wet dressing for wound care, involving gauze soaked in normal saline. - This is a basic wound management technique and does not involve grafting or have the characteristic meshed appearance seen in the image.
Question 6: What is the eponymous term for a full-thickness skin graft?
- A. Wolfe's graft (Correct Answer)
- B. Thiersch graft
- C. Fernandez graft
- D. Reverdin graft
Explanation: ***Wolfe's graft*** - A **Wolfe's graft** is the eponymous term for a **full-thickness skin graft**, which includes the epidermis and entire dermis. - This type of graft provides superior cosmetic results and contracts less than split-thickness grafts, making it ideal for facial reconstruction. *Thiersch graft* - A **Thiersch graft** refers to a **split-thickness skin graft**, which only includes the epidermis and a portion of the dermis. - These grafts are easier to harvest and take better in less vascularized beds but are prone to greater contraction and can have a less aesthetic outcome. *Fernandez graft* - **Fernandez graft** is not a recognized eponymous term for a type of skin graft in common medical literature. - This term does not correspond to a standard full-thickness or split-thickness skin grafting technique. *Reverdin graft* - A **Reverdin graft** refers to very small, partial-thickness pieces of skin, essentially tiny bits of epithelium transplanted to promote epithelialization. - This is a **split-thickness** technique, not a full-thickness graft, and is used primarily for small granulating wounds.
Question 7: The best skin graft for open wounds is -
- A. Isograft (tissue from a genetically identical individual)
- B. Allograft (tissue from a donor of the same species)
- C. Autograft (tissue from the patient's own body) (Correct Answer)
- D. Xenograft (tissue from a different species)
Explanation: ***Autograft (tissue from the patient's own body)*** - **Autografts are the gold standard** for permanent wound closure because they are derived from the patient's own body, eliminating the risk of immunologic rejection - They provide the **best cosmetic and functional results**, as the transplanted tissue is genetically identical to the recipient's unaffected skin - Permanent solution with optimal healing and integration *Isograft (tissue from a genetically identical individual)* - While an isograft (from an identical twin) would also avoid immune rejection due to genetic identity, it is rarely a practical option as most patients do not have an identical twin - Isografts are essentially a specialized form of autograft but with a donor other than the patient themselves - Not the "best" choice since it requires an identical twin donor *Allograft (tissue from a donor of the same species)* - Allografts (from another human donor) are used as **temporary biological dressing** for large burns or wounds when autograft sites are limited, but they are eventually rejected by the recipient's immune system - Helpful for providing temporary wound coverage, reducing fluid loss, and preventing infection, but they **do not provide permanent closure** - Used as a bridge until autograft is available *Xenograft (tissue from a different species)* - Xenografts (from a different species, e.g., pig skin) are used as **temporary biological dressing**, primarily for burn wounds, to close the wound and provide a barrier against infection and fluid loss - Always rejected by the immune system within a few weeks and cannot provide permanent coverage due to significant antigenic differences - Only a temporary measure for wound protection
Question 8: Wound contraction can be most effectively minimized by:
- A. Allowing secondary granulation
- B. Full thickness grafting (Correct Answer)
- C. Split skin graft
- D. Dressing with placenta
Explanation: ***Full thickness grafting*** - **Full-thickness skin grafts** include the epidermis and full dermis, which contains **fewer myofibroblasts** than split-thickness grafts, thus minimizing contraction. - The greater amount of dermal tissue acts as a **mechanical barrier** to prevent excessive wound contraction, providing a more stable and aesthetically pleasing result. *Allowing secondary granulation* - Healing by **secondary intention** involves substantial granulation tissue formation, which is rich in **myofibroblasts** and leads to significant wound contraction. - This method of healing is often used for infected or contaminated wounds but results in the **most contraction**. *Split skin graft* - **Split-thickness skin grafts** contain only a portion of the dermis, making them prone to **moderate to significant wound contraction**. - While better than secondary intention, the thin dermal layer provides less resistance to the contractile forces of the **myofibroblasts**. *Dressing with placenta* - **Placental tissue dressings** can promote wound healing by providing growth factors and a scaffold for regeneration. - However, they do not inherently prevent or minimize **wound contraction** in the same way that a full-thickness graft mechanically does, as they do not replace the entire dermal layer.
Question 9: Which of the following statements about mesh skin grafts is not correct?
- A. They allow egress of fluid collections under the graft.
- B. They permit coverage of large areas.
- C. They “take” satisfactorily on granulating bed.
- D. They contract to the same degree as a grafted sheet of skin. (Correct Answer)
Explanation: ***They contract to the same degree as a grafted sheet of skin.*** - This statement is incorrect because **meshed skin grafts** undergo **greater primary and secondary contraction** compared to unmeshed, full-thickness sheet grafts. - The fenestrations in the meshed graft allow for stretching and expansion, but this also contributes to increased contraction as the graft heals and remodels. *They allow egress of fluid collections under the graft.* - The **fenestrations** created by the meshing process provide small openings that facilitate the **drainage of seroma or hematoma** from beneath the graft. - This feature is crucial for graft survival as fluid accumulation can lift the graft, impairing nutrient diffusion and leading to graft failure. *They permit coverage of large areas.* - Meshing a skin graft allows it to be **expanded to cover an area up to 1.5 to 9 times larger** than the original harvested skin. - This is particularly useful in managing **large burn wounds** or extensive skin defects where donor sites are limited. *They “take” satisfactorily on granulating bed.* - Meshed grafts tend to tolerate **less ideal recipient beds**, such as those with some granulation tissue or minor contamination, better than sheet grafts. - The fenestrations allow for drainage and better adherence, which can compensate for a suboptimal underlying bed.
Question 10: Deep skin burns are treated with:
- A. Amniotic membrane
- B. Split thickness graft (Correct Answer)
- C. Full thickness graft
- D. Synthetic skin derivatives
Explanation: ***Split thickness graft*** - A **split-thickness skin graft (STSG)** involves transferring the epidermis and a portion of the dermis from a donor site to the burned area. - This type of graft is commonly used for deep partial-thickness or full-thickness burns because it provides good coverage with minimal donor site morbidity and has a high take rate. *Amniotic membrane* - **Amniotic membrane** is primarily used as a biological dressing for superficial burns or chronic wounds, promoting healing and reducing pain. - It does not provide permanent skin coverage for deep burns, which require viable skin for closure. *Full thickness graft* - A **full-thickness skin graft (FTSG)** includes the entire epidermis and dermis, resulting in better cosmetic and functional outcomes. - However, FTSGs are typically used for smaller, deeper defects or areas requiring maximum durability, rather than extensive deep burns, and their take rate is lower compared to STSGs. *Synthetic skin derivatives* - **Synthetic skin derivatives** (e.g., Integra, Biobrane) can be used as temporary dressings or matrices to facilitate wound healing in deep burns, but they typically require subsequent grafting. - They do not provide permanent, living tissue for definitive closure of large, deep burn wounds.
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