Fracture Healing — MCQs
Nonunion is most common in fracture of the:
Scaphoid fracture which area has maximum chances of AVN/Non-union/Malunion:-
Granulation tissue is replaced by connective tissue in what stage of wound healing?
During resuscitation, fractured ribs most commonly involve:
Marble bone disease is:
Osteogenesis imperfecta is due to a defect in what?
Bone mass is reduced in all of the following conditions EXCEPT:
Ewing's sarcoma arises from which of the following tissues?
Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)
Which of the following statements is true regarding femoral shaft fractures in infants?
Fracture Healing Indian Medical PG Practice Questions and MCQs
Question 1: Nonunion is most common in fracture of the:
- A. Talus
- B. Neck femur (Correct Answer)
- C. Scapula
- D. None of the options
Explanation: ***Neck femur*** - Fractures of the **femoral neck** are highly prone to **nonunion** due to the precarious and often-disrupted blood supply to the femoral head, particularly the **retinacular arteries**. - The high biomechanical stress and difficulty in achieving stable fixation in this region further contribute to the increased risk of nonunion. *Talus* - While talar fractures, especially those of the **talar neck**, can have a high incidence of complications like **avascular necrosis** due to limited blood supply, nonunion is less common than in femoral neck fractures. - The talus has a complex vascular network that, while vulnerable, often allows for healing. *Scapula* - **Scapular fractures** are generally uncommon and, when they occur, typically heal well without surgical intervention. - Due to the surrounding musculature and rich vascular supply, nonunion of the scapula is extremely rare. *None of the options* - This option is incorrect because **nonunion is indeed a significant problem** in specific fractures, particularly those of the femoral neck, making it a viable answer.
Question 2: Scaphoid fracture which area has maximum chances of AVN/Non-union/Malunion:-
- A. Distal 1/3
- B. Proximal 1/3 (Correct Answer)
- C. Scaphoid Tubercle fracture
- D. Middle 1/3
Explanation: ***Proximal 1/3*** - The **proximal pole of the scaphoid** has a precarious blood supply, primarily from retrograde extraosseous vessels entering distally. A fracture in this region can compromise this supply, leading to **avascular necrosis (AVN)**. - Due to the limited blood flow to the proximal fragment, healing is often impaired, increasing the risk of **non-union** and **malunion**. *Distal 1/3* - Fractures in the **distal 1/3 (distal pole)** of the scaphoid typically have a better prognosis. - This area has a more robust blood supply, reducing the risk of AVN and promoting faster healing. *Scaphoid Tubercle fracture* - Fractures of the **scaphoid tubercle** are usually considered stable and intra-articular, with a good blood supply. - These fractures generally heal well with conservative treatment and have a very low incidence of AVN or non-union. *Middle 1/3* - Fractures in the **middle 1/3 (waist)** of the scaphoid are the most common but still pose a significant risk of non-union. - While the risk of AVN is lower than for proximal pole fractures, it is still higher than for distal fractures, due to the critical vascular supply to both fragments.
Question 3: Granulation tissue is replaced by connective tissue in what stage of wound healing?
- A. 7 days (Correct Answer)
- B. 14 days
- C. 21 days
- D. 1 month
Explanation: ***21 days*** - Granulation tissue formation is prominent until about **21 days**, after which it starts to reorganize into fibrous connective tissue [1][2]. - In this stage, collagen deposition increases, contributing to **wound strength** and integrity [2]. *1 month* - By this time, connective tissue maturation continues but the primary transition from granulation tissue typically completes by **21 days** [2]. - It may lead to overestimation of healing progression as remodeling may still be ongoing. *14 days* - At **14 days**, granulation tissue is still present and not yet fully replaced by connective tissue [1]. - This stage primarily involves **vascularization** and **inflammatory responses**, not complete fibrous change [1]. *7 days* - This early phase is characterized by **hemostasis** and **inflammation**, with granulation tissue just beginning to form [1]. - Significant connective tissue replacement has not yet occurred, as the wound healing process is still at the initial stages. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 117-119. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 119-121.
Question 4: During resuscitation, fractured ribs most commonly involve:
- A. 3rd -5th ribs
- B. 2nd -4th ribs
- C. 5th -7th ribs
- D. 4th -6th ribs (Correct Answer)
Explanation: ***4th -6th ribs*** - During **cardiopulmonary resuscitation (CPR)**, compressions are typically applied to the **sternum**, leading to direct pressure on the adjacent ribs. - The **middle ribs**, particularly the 4th, 5th, and 6th, are most susceptible to fracture due to their anatomical position and lever arm during compressions. *3rd -5th ribs* - While these ribs can be fractured during CPR, the **3rd rib** is less commonly affected than the 4th-6th due to its more superior position and attachment. - The range does not fully encompass the ribs most consistently subjected to maximum stress during typical chest compressions. *2nd -4th ribs* - Fractures of the **2nd rib** are relatively uncommon during CPR, as it is more protected by the clavicle and shoulder girdle. - This range largely excludes the **5th and 6th ribs**, which are frequently implicated in CPR-related fractures. *5th -7th ribs* - The **7th rib** is less commonly fractured than the 4th-6th ribs because compressions are generally focused higher on the sternum. - This range includes the 7th rib, which is often below the primary point of maximum force during CPR.
Question 5: Marble bone disease is:
- A. Osteosclerosis
- B. Histiocytosis X
- C. Osteopetrosis (Correct Answer)
- D. Osteomalacia
Explanation: ***Osteopetrosis*** - **Osteopetrosis**, also known as **marble bone disease**, is a rare genetic disorder characterized by abnormally dense bones due to a defect in **osteoclast function** [1]. - Impaired bone resorption leads to an accumulation of woven bone, causing bones to be fragile despite their density [1]. *Osteosclerosis* - **Osteosclerosis** is a general term for increased bone density and can be a feature of various conditions, including osteopetrosis. - However, it is a descriptive term rather than a specific disease diagnosis equivalent to marble bone disease. *Histiocytosis X* - **Histiocytosis X**, also known as **Langerhans cell histiocytosis**, is a rare disorder involving the proliferation of Langerhans cells. - It primarily affects bone but can also involve other organs, presenting with lytic lesions rather than increased bone density. *Osteomalacia* - **Osteomalacia** is a condition characterized by inadequate mineralization of bone tissue, leading to soft and weakened bones. - It is typically caused by **vitamin D deficiency** and is the opposite of increased bone density. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1188-1189.
Question 6: Osteogenesis imperfecta is due to a defect in what?
- A. Type II collagen
- B. Type IV collagen
- C. Type I collagen (Correct Answer)
- D. Type III collagen
Explanation: ***Collagen 1*** - Osteogenesis imperfecta is primarily caused by a defect in **type I collagen** [2], which is crucial for bone strength and structure. - This defect leads to **brittle bones**, resulting in frequent fractures and skeletal deformities . *Collagen 2* - Type II collagen is mainly found in **cartilage** and is critical for **hyaline cartilage formation**, not directly involved in bone integrity. - Defects in type II collagen are associated with conditions like **chondrodysplasia**, rather than osteogenesis imperfecta. *Collagen 4* - Type IV collagen is primarily found in **basement membranes** and plays a role in filtration and structural integrity of tissues. - While important for kidney and eye function, it is not related to the bone fragility seen in osteogenesis imperfecta. *Collagen 3* - Type III collagen is involved in the structure of **reticular fibers** and is crucial for skin and blood vessel integrity. - It is not the primary collagen affected in osteogenesis imperfecta, which is associated specifically with type I collagen defects. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1182. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Question 7: Bone mass is reduced in all of the following conditions EXCEPT:
- A. Osteoporosis
- B. Osteopetrosis (Correct Answer)
- C. Hyperparathyroidism
- D. Osteomalacia
Explanation: **Osteopetrosis** - **Osteopetrosis**, also known as **marble bone disease**, is a rare genetic disorder characterized by **increased bone density** due to defective osteoclast function. - In this condition, osteoclasts are unable to resorb bone, leading to an excessive accumulation of bone tissue, resulting in **densified but brittle bones**. *Osteoporosis* - **Osteoporosis** is characterized by significantly **reduced bone mass** and microarchitectural deterioration of bone tissue [1]. - This leads to increased bone fragility and a higher risk of fractures, as the bone becomes porous and weak [2]. *Hyperparathyroidism* - **Hyperparathyroidism** causes **increased bone resorption** due to excessive parathyroid hormone (PTH) secretion. - PTH mobilizes calcium from the bones, leading to a **decrease in bone density** and potential bone cysts (**osteitis fibrosa cystica**) [3]. *Osteomalacia* - **Osteomalacia** is a condition where there is **defective mineralization of bone osteoid**, leading to softer bones [4]. - While the bone mass might appear structurally normal, the **mineral content is reduced**, making the bone weak and susceptible to bowing and fractures. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1189-1191. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 665-666. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1194. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1194-1195.
Question 8: Ewing's sarcoma arises from which of the following tissues?
- A. Mesenchymal stem cells (Correct Answer)
- B. Endothelial cells
- C. Osteocytes
- D. Primitive neuroectodermal cells
Explanation: ***Mesenchymal stem cells*** - **Ewing's sarcoma** arises from **mesenchymal stem cells (MSCs)**, which are multipotent stromal cells of mesodermal origin. - The characteristic **t(11;22)(q24;q12) translocation** results in the **EWS-FLI1 fusion gene**, which transforms mesenchymal stem cells into the malignant small round blue cells characteristic of Ewing's sarcoma. - This mesodermal/mesenchymal origin explains its predominant occurrence in **bone and soft tissues**. *Endothelial cells* - Tumors arising from **endothelial cells** are **vascular tumors** such as hemangiomas or angiosarcomas. - These have distinct histological features with vascular channel formation, unlike the solid sheets of small round blue cells seen in Ewing's sarcoma. *Osteocytes* - Tumors derived from **osteocytes** or osteoblastic cells are **bone-forming tumors**, such as osteosarcoma. - **Osteosarcoma** produces osteoid and has a distinct histology and genetic profile from Ewing's sarcoma. *Primitive neuroectodermal cells* - Historically, Ewing's sarcoma was thought to arise from **primitive neuroectodermal cells (PNETs)** due to occasional neural marker expression. - However, modern molecular studies have established that Ewing's sarcoma originates from **mesenchymal stem cells**, not neuroectodermal cells. - The term "PNET" in this context is now considered **outdated**.
Question 9: Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)
- A. Osteogenesis imperfecta (Correct Answer)
- B. Osteopetrosis
- C. Osteomalacia
- D. Osteitis fibrosa cystica
Explanation: ***Osteogenesis imperfecta*** - This condition is primarily caused by **genetic defects** in the production of **type I collagen**, leading to fragile bones. - Due to these defects, bones are prone to **fractures** with minimal trauma. *Osteopetrosis* - Characterized by abnormally **dense bones** due to a defect in **osteoclast function**, not collagen structure [1]. - This leads to bones that are brittle and prone to fracture, but the underlying cause is different from collagen abnormalities [1]. *Osteomalacia* - This refers to the **softening of bones** due to impaired **mineralization**, most commonly from **vitamin D deficiency** or phosphate imbalance. - It does not involve a primary defect in the genetic structure or processing of type I collagen. *Osteitis fibrosa cystica* - This is a bone lesion caused by **severe hyperparathyroidism**, leading to excessive bone resorption and replacement by fibrous tissue and cysts. - It is an endocrine disorder affecting **calcium metabolism**, not a primary collagenopathy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Question 10: Which of the following statements is true regarding femoral shaft fractures in infants?
- A. Femoral shaft fractures in infants heal rapidly.
- B. Traction is usually sufficient for treatment.
- C. Child abuse is a common cause of femoral shaft fractures in infants. (Correct Answer)
- D. Non-accidental trauma should be considered in the differential diagnosis of femoral shaft fractures in infants.
Explanation: ***Child abuse is a common cause of femoral shaft fractures in infants.*** - **Non-accidental trauma** is a significant cause of femoral shaft fractures in infants, necessitating a high index of suspicion. - The forces required to fracture a healthy infant's femur are substantial, making **accidental trauma** less common than in older children. *Femoral shaft fractures in infants heal rapidly.* - While pediatric fractures generally heal faster than adult fractures, the statement is too broad and doesn't capture the critical context of infant femur fractures. - The primary concern in infant femoral fractures is the etiology (i.e., ruling out child abuse), not solely the healing time. *Traction is usually sufficient for treatment.* - **Pavlik harness** or **spica casting** are common treatment modalities for femoral shaft fractures in infants. - While traction can be part of the initial management, definitive treatment typically involves casting to maintain reduction and allow healing. *Non-accidental trauma should be considered in the differential diagnosis of femoral shaft fractures in infants.* - While true, this statement is less precise than stating that child abuse is a "common cause." - **Child abuse** encompasses non-accidental trauma and highlights the likelihood that such fractures are inflicted.
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