Biology of Bone Grafting — MCQs

10 questions

Which of the following statements are correct about Kiel bone? 1. Xenograft 2. Allograft 3. Treated by detergent, sterilized, and freeze-dried 4. Ox or calf bone denatured with 20% H2O2, acetone, and sterilized

The graft with the maximum osteogenic potential is:

The ideal synthetic material used for femoropopliteal bypass when autologous vein is unavailable is:

What is the primary organic component of bone?

Which of the following is the appropriate treatment for atrophic non-union?

Which of the following is TRUE about bone healing in elderly patients?

Which of the following bone defects offers the best chance for bone fill?

Which of the following is the POOREST recipient bed for a skin graft?

The operative procedure known as "microfracture" is done for the

Q10

Compression osteosynthesis may be used in all these areas except?

Biology of Bone Grafting Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following statements are correct about Kiel bone? 1. Xenograft 2. Allograft 3. Treated by detergent, sterilized, and freeze-dried 4. Ox or calf bone denatured with 20% H2O2, acetone, and sterilized

A. 2 & 4
B. 2 & 3
C. 1 & 3
D. 1 & 4 (Correct Answer)

Explanation: ***1 & 4*** - **Kiel bone** is a type of **xenograft**, meaning it is derived from a different species (usually ox or calf). - It is prepared by **denaturing** ox or calf bone with 20% H2O2 and acetone, followed by sterilization, to reduce antigenicity and ensure safety. *2 & 4* - This option incorrectly states that Kiel bone is an **allograft**, while it is, in fact, a **xenograft**. - The preparation method of denaturing with 20% H2O2 and acetone, and sterilization, correctly describes Kiel bone processing. *2 & 3* - This option incorrectly identifies Kiel bone as an **allograft** and states that it is treated by detergent, sterilized, and freeze-dried. - While some bone grafts are treated this way, it is not the specific processing for Kiel bone, which uses H2O2 and acetone. *1 & 3* - This option correctly identifies Kiel bone as a **xenograft**, but incorrectly states its processing involves detergent, sterilization, and freeze-drying. - The distinguishing feature of Kiel bone preparation is the use of **H2O2 and acetone** for denaturing.

Question 2: The graft with the maximum osteogenic potential is:

A. Allograft
B. xenograft
C. Autocortical
D. autocancellus (Correct Answer)

Explanation: ***autocancellus*** - **Autocancellous** bone grafts are considered the gold standard due to their high osteogenic potential as they contain **viable osteoblasts** and **bone marrow stromal cells**. - The porous structure of cancellous bone also provides a **scaffold** for new bone formation and excellent revascularization. *Allograft* - **Allografts** are grafts transferred between genetically dissimilar individuals of the same species and are **osteoconductive** and **osteoinductive** but lack viable cells and thus have lower osteogenic potential than autografts. - They undergo sterilization processes that can further reduce their osteoinductive properties and may elicit an **immune response** from the recipient. *xenograft* - **Xenografts** are grafts transferred between different species and primarily serve as an **osteoconductive scaffold**. - They lack live osteogenic cells and have the **lowest osteogenic potential** due to significant immunological barriers and species-specific biochemical differences. *Autocortical* - **Autocortical** grafts are structural and provide mechanical support, but their **osteogenic potential is lower** than cancellous bone. - Cortical bone has a denser structure with fewer viable cells and a slower revascularization rate compared to cancellous bone.

Question 3: The ideal synthetic material used for femoropopliteal bypass when autologous vein is unavailable is:

A. Dacron
B. Xenograft
C. Saphenous vein
D. PTFE (non-expanded)
E. Cryopreserved vein graft
F. ePTFE (Correct Answer)
. Polyethylene terephthalate (PET)
. Allograft

Explanation: ***ePTFE (Expanded Polytetrafluoroethylene)*** - **ePTFE** is the preferred synthetic graft for femoropopliteal bypass when autologous vein is unavailable - Offers good **biocompatibility** and relative resistance to **thrombosis** - Provides superior patency rates in above-knee femoropopliteal bypasses compared to other synthetic materials (5-year patency ~50-60%) - The expanded structure allows tissue ingrowth and better integration *Dacron (Polyethylene terephthalate)* - Generally used for **larger diameter vessels** (e.g., aortoiliac grafts) - Has **inferior patency rates** in smaller diameter femoropopliteal position compared to ePTFE - More prone to kinking and associated with higher rates of intimal hyperplasia in peripheral circulation *Saphenous vein* - The autologous saphenous vein is the **gold standard** for femoropopliteal bypass with superior long-term patency (5-year patency ~70-80%) - However, this question specifically asks for synthetic material when vein is unavailable or unsuitable - Not always available or of adequate quality in all patients *PTFE (non-expanded)* - **Non-expanded PTFE** lacks the porous structure of ePTFE - Not used for vascular grafts due to absence of tissue ingrowth capability - The **expanded** form is specifically engineered for vascular applications

Question 4: What is the primary organic component of bone?

A. 10% collagen
B. 10% noncollagenous protein
C. 20% noncollagenous protein
D. 90% collagen protein (Correct Answer)

Explanation: ***90% collagen protein*** - **Type I collagen** constitutes around 90% of the organic matrix of bone, providing its tensile strength and flexibility [1]. - This extensive collagen network forms the framework upon which **mineral crystals** (hydroxyapatite) are deposited [1]. *10% collagen* - This percentage is significantly lower than the actual proportion of collagen in the organic matrix of bone. - If collagen only represented 10%, bone would lack its characteristic **tensile strength** and elasticity [2]. *10% noncollagenous protein* - While noncollagenous proteins like **osteocalcin** and **osteonectin** are important for bone mineralization and cell signaling, they only constitute about 10% of the *organic matrix*, not the entire bone, and are not the *primary organic component* [1]. - The dominant organic component is collagen, which provides the structural scaffold [1]. *20% noncollagenous protein* - This percentage is inaccurate; **noncollagenous proteins** typically make up about 10% of the bone's organic matrix [1]. - A higher proportion of noncollagenous proteins would alter the bone's mechanical properties, potentially making it more brittle.

Question 5: Which of the following is the appropriate treatment for atrophic non-union?

A. External fixation
B. Application of cast
C. Stabilization and bone grafting (Correct Answer)
D. Internal fixation

Explanation: ***Stabilization and bone grafting*** - Atrophic non-union is characterized by a **lack of biological activity** and an **absence of callus formation**, requiring both **biological stimulation** (bone graft) and **mechanical stability** (stabilization). - Bone grafting provides **osteogenic cells**, **osteoconductive scaffold**, and **osteoinductive growth factors** to promote healing, while stabilization ensures the fracture fragments remain in apposition. *External fixation* - While providing stability, external fixation alone does not address the **biological deficiency** inherent in atrophic non-union. - It's mainly used for **open fractures**, **comminuted fractures**, or when internal fixation is not feasible, often as a temporary measure. *Application of cast* - A cast provides some immobilization but is generally insufficient for non-union, especially atrophic types, due to its **limited stability** and inability to compress the fracture site effectively. - It also does not contribute to the **biological stimulation** needed for healing in atrophic non-unions. *Internal fixation* - Internal fixation provides stability, but in atrophic non-union, the primary issue is a **lack of healing potential**, not just instability. - Without a concomitant **bone graft**, internal fixation alone is unlikely to achieve union in atrophic non-unions.

Question 6: Which of the following is TRUE about bone healing in elderly patients?

A. Enhanced Angiogenesis
B. Better Callus Formation
C. Faster Healing Rate
D. Delayed Union is More Common (Correct Answer)

Explanation: ***Delayed Union is More Common*** - **Aging** is associated with a decrease in the number and activity of **osteoblasts** and stem cells, leading to a slower bone remodeling process. - Reduced **blood supply** to the fracture site and the presence of comorbidities in elderly patients contribute to delayed healing and an increased risk of complications like non-union. *Enhanced Angiogenesis* - **Angiogenesis**, the formation of new blood vessels, tends to be reduced in elderly patients due to age-related changes in growth factor production and endothelial cell function. - A compromised blood supply to the fracture site negatively impacts the delivery of essential nutrients and cells required for bone repair. *Better Callus Formation* - **Callus formation**, a crucial step in secondary bone healing, is often impaired in elderly individuals. - This impairment is due to decreased cellular activity, reduced growth factor production, and a less robust inflammatory response. *Faster Healing Rate* - Bone healing is generally **slower** in elderly patients compared to younger individuals. - This diminished healing rate is attributed to a decline in osteogenic potential, reduced vascularity, and frequently, poorer overall health status.

Question 7: Which of the following bone defects offers the best chance for bone fill?

A. 3 Walled defect (Correct Answer)
B. Hemisepta
C. Osseous crater
D. 2 Walled defect

Explanation: ***3 Walled defect*** - A **3-walled defect** provides the best prognosis for bone fill because it retains the most natural bone structure, enhancing the ability to contain bone graft material effectively. - The presence of three bony walls offers **excellent support and blood supply** for graft survival and successful bone regeneration. *Hemisepta* - A **hemisepta** refers to a one-walled defect, which offers very limited containment for graft materials. - It has a **poor prognosis** for bone fill due to insufficient support and rapid loss of grafting material. *Osseous crater* - An **osseous crater** is a two-walled defect where the buccal and lingual walls are present, but the interproximal walls are missing. - While better than a one-walled defect, it still presents challenges in graft containment and has a **less predictable outcome** compared to a 3-walled defect. *2 Walled defect* - A **2-walled defect** offers less containment and support for bone graft materials compared to a 3-walled defect. - The reduced number of walls means there is a **higher chance of graft material displacement** and a slower healing process.

Question 8: Which of the following is the POOREST recipient bed for a skin graft?

A. Fat (Correct Answer)
B. Muscle
C. Deep fascia
D. Skull bone

Explanation: ***Fat*** - **Fat** is a poor recipient for a skin graft due to its **limited vascularity**, which hinders the necessary process of revascularization for graft survival. - The high metabolic demand of a graft cannot be adequately met by the relatively avascular subcutaneous fat, leading to graft failure. *Muscle* - **Muscle tissue** is an excellent recipient bed for skin grafts due to its **rich blood supply**. - Its robust vascularity effectively supports the revascularization and survival of the grafted tissue. *Deep fascia* - **Deep fascia** provides a good vascularized bed for skin grafts, as it has a reasonable blood supply from underlying muscles and surrounding tissues. - This vascularization is sufficient to nourish and ensure the take of a skin graft. *Skull bone* - **Skull bone** (specifically the periosteum covering it) can serve as an adequate graft bed due to its vascular supply. - If the **periosteum** is intact and healthy, it offers sufficient blood flow for graft survival.

Question 9: The operative procedure known as "microfracture" is done for the

A. Delayed union of femur
B. Osteochondral defect of femur (Correct Answer)
C. Non union of tibia
D. Loose bodies of ankle joint

Explanation: ***Osteochondral defect of femur*** - **Microfracture** is a surgical technique used to stimulate the growth of **fibrocartilage** in areas of damaged articular cartilage, such as an **osteochondral defect**. - It involves creating small holes in the **subchondral bone** to allow stem cells and growth factors from the bone marrow to form a new reparative tissue. *Delayed union of femur* - **Delayed union** typically involves an extended time for fracture healing, which is often managed through prolonged immobilization, **bone grafting**, or sometimes revision surgery. - Microfracture specifically targets cartilage repair, not the process of **bony union** after a fracture. *Non union of tibia* - **Non-union** refers to the failure of a fractured bone to heal within a reasonable timeframe, often requiring surgical intervention with **bone grafts** or **internal fixation**. - This condition involves bone healing problems, distinct from cartilage defects that microfracture addresses. *Loose bodies of ankle joint* - **Loose bodies** in a joint are typically removed surgically, often arthroscopically, to relieve pain and prevent joint damage. - This procedure does not involve the repair of cartilage defects, which is the primary goal of microfracture.

Question 10: Compression osteosynthesis may be used in all these areas except?

A. Comminuted fractures of the mandible (Correct Answer)
B. FZ suture (provides anatomical support)
C. Bone graft fixation (promotes healing)
D. Root of zygomatic arch (maintains structural integrity)

Explanation: ***Comminuted fractures of the mandible*** - **Compression osteosynthesis** is generally **contraindicated** in comminuted fractures because the application of compression can further **displace or fragment** the multiple bone pieces. - Such fractures often require **tension band plating** or **reconstruction plates** to stabilize the fragments without causing additional compression or displacement. *FZ suture (provides anatomical support)* - The **frontozygomatic (FZ) suture** is an area where compression osteosynthesis can be effectively used to achieve **stable fixation** and **anatomical reduction**. - Compression helps to **stabilize the bone segments** at the suture line, leading to better healing and restoration of orbital rim integrity. *Bone graft fixation (promotes healing)* - Compression osteosynthesis is often employed in **bone graft fixation** to promote **intimate contact** between the graft and the host bone, which is crucial for successful **graft incorporation and healing**. - This compression enhances **vascularization** and reduces movement, creating a more favorable environment for **osteogenesis**. *Root of zygomatic arch (maintains structural integrity)* - Compression osteosynthesis can be effectively used at the **root of the zygomatic arch** to maintain **structural integrity** and achieve stable fixation of fractures in this region. - Applying compression helps to **reduce fracture gaps** and provides stability, which is essential for restoring the contour and function of the midface.

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free