AIM EXAM ARENA
3rd YEAR MBBS
20 A-TYPE SBA MCQs
3rd YEAR MBBS
20 A-TYPE SBA MCQs
KMU Past Paper Practice
Fractures, Bone Healing, Osteonecrosis and Open-Fracture Assessment
Context-rich Single Best Answer questions designed for integrated KMU annual professional examination practice.
MCQ 1
Question:
A 52-year-old woman develops a vertebral fracture after lifting a light household object. Imaging shows generalized reduction in bone density without a destructive focal lesion. Which classification best describes this injury?
A 52-year-old woman develops a vertebral fracture after lifting a light household object. Imaging shows generalized reduction in bone density without a destructive focal lesion. Which classification best describes this injury?
Traumatic fracture
Stress fracture
Insufficiency fracture
Avulsion fracture
Depressed fracture
Correct Answer: Insufficiency fracture
Explanation: Normal physiological loading acting on structurally weakened bone produces an insufficiency fracture.
MCQ 2
Question:
A 19-year-old runner develops gradually increasing tibial pain without a single traumatic event. Initial examination shows localized tenderness, and later imaging demonstrates a small cortical fracture line. Which mechanism best explains this injury?
A 19-year-old runner develops gradually increasing tibial pain without a single traumatic event. Initial examination shows localized tenderness, and later imaging demonstrates a small cortical fracture line. Which mechanism best explains this injury?
Acute bending of normal bone
Repetitive loading with accumulated microdamage
Traction by a contracting tendon
Collapse of trabecular bone after ischemia
External contamination of the fracture site
Correct Answer: Repetitive loading with accumulated microdamage
Explanation: A stress fracture develops when repeated submaximal loading exceeds the ability of normal bone to repair microdamage.
MCQ 3
Question:
A football player suddenly feels pain near the base of the fifth metatarsal after forceful inversion of the foot. X-ray shows a small bone fragment separated at a tendon attachment. Which pattern is most likely?
A football player suddenly feels pain near the base of the fifth metatarsal after forceful inversion of the foot. X-ray shows a small bone fragment separated at a tendon attachment. Which pattern is most likely?
Compression fracture
Depressed fracture
Impacted fracture
Avulsion fracture
Segmental fracture
Correct Answer: Avulsion fracture
Explanation: Forceful traction by a tendon or ligament may detach a small fragment from its bony attachment.
MCQ 4
Question:
A 64-year-old man falls from standing height and sustains a distal radial injury. X-ray shows one fragment driven into the other, with shortening but limited separation. Which description is most appropriate?
A 64-year-old man falls from standing height and sustains a distal radial injury. X-ray shows one fragment driven into the other, with shortening but limited separation. Which description is most appropriate?
Impacted fracture
Spiral fracture
Open fracture
Avulsion fracture
Segmental fracture
Correct Answer: Impacted fracture
Explanation: Impaction occurs when one fracture fragment is driven into another, producing shortening and relative stability.
MCQ 5
Question:
A child presents after direct trauma to the forearm. X-ray demonstrates localized bulging of the cortex without a visible fracture extending across the bone. Which feature of pediatric bone accounts for this pattern?
A child presents after direct trauma to the forearm. X-ray demonstrates localized bulging of the cortex without a visible fracture extending across the bone. Which feature of pediatric bone accounts for this pattern?
Reduced periosteal activity
Increased cortical brittleness
Greater elasticity of immature bone
Complete closure of the physis
Reduced trabecular content
Correct Answer: Greater elasticity of immature bone
Explanation: Flexible pediatric cortex can buckle under compression without producing a complete break.
MCQ 6
Question:
A forearm X-ray shows the distal fragment translated posteriorly, with overlap of the fracture ends. Which additional deformity is represented by the overlapping fragments?
A forearm X-ray shows the distal fragment translated posteriorly, with overlap of the fracture ends. Which additional deformity is represented by the overlapping fragments?
Distraction
Rotation
Impaction
Shortening
Subluxation
Correct Answer: Shortening
Explanation: Overlap of the fragments reduces the effective length of the bone and is described as shortening.
MCQ 7
Question:
A patient with wrist trauma has marked tenderness, but the first radiographic projection appears normal. What is the best next radiological principle to apply?
A patient with wrist trauma has marked tenderness, but the first radiographic projection appears normal. What is the best next radiological principle to apply?
Exclude fracture based on one normal view
Repeat the same projection only
Obtain an orthogonal second view
Assess only the surrounding soft tissues
Delay all further imaging until swelling resolves
Correct Answer: Obtain an orthogonal second view
Explanation: Fractures and dislocations may be hidden on one projection; perpendicular views improve assessment of cortical continuity and alignment.
MCQ 8
Question:
A radiograph of an injured elbow shows partial loss of articular alignment, but some contact between the joint surfaces is preserved. Which term best describes this abnormality?
A radiograph of an injured elbow shows partial loss of articular alignment, but some contact between the joint surfaces is preserved. Which term best describes this abnormality?
Subluxation
Complete dislocation
Impaction
Malunion
Plastic deformation
Correct Answer: Subluxation
Explanation: Subluxation is incomplete loss of joint congruity, whereas complete dislocation eliminates normal articular contact.
MCQ 9
Question:
A child sustains a fracture close to an active growth plate. The deformity lies in the plane of movement of the adjacent joint. Which feature makes correction during growth more likely?
A child sustains a fracture close to an active growth plate. The deformity lies in the plane of movement of the adjacent joint. Which feature makes correction during growth more likely?
Complete physeal closure
High remodeling potential near the physis
Absence of periosteal cells
Persistence of rotational deformity
Reduced osteoblastic activity in childhood
Correct Answer: High remodeling potential near the physis
Explanation: Young bone remodels most effectively near active growth plates, particularly when deformity lies in the plane of joint motion.
MCQ 10
Question:
A child’s fracture heals with persistent rotational malalignment despite acceptable angular alignment. Why is this deformity particularly important?
A child’s fracture heals with persistent rotational malalignment despite acceptable angular alignment. Why is this deformity particularly important?
Rotation remodels more reliably than angulation
Rotation may persist and impair limb function
Rotation produces direct fracture healing
Rotation prevents formation of a hematoma
Rotation converts the injury into a buckle fracture
Correct Answer: Rotation may persist and impair limb function
Explanation: Rotational deformity has limited remodeling potential and can produce lasting functional malalignment.
MCQ 11
Question:
Four days after a closed fracture, histology shows proliferating capillaries, fibroblasts and early osteogenic cells entering the fracture gap. Which process is occurring?
Four days after a closed fracture, histology shows proliferating capillaries, fibroblasts and early osteogenic cells entering the fracture gap. Which process is occurring?
Final lamellar remodeling
Development of granulation tissue
Complete cortical restoration
Formation of mature articular cartilage
Subchondral collapse
Correct Answer: Development of granulation tissue
Explanation: Early repair replaces the hematoma with vascular granulation tissue containing fibroblasts and osteoprogenitor cells.
MCQ 12
Question:
During fracture healing, cartilage within the temporary bridge is gradually replaced by bone. Which process is mainly responsible for this transition?
During fracture healing, cartilage within the temporary bridge is gradually replaced by bone. Which process is mainly responsible for this transition?
Endochondral ossification
Fat necrosis
Fibrous encapsulation
Suppurative inflammation
Articular cartilage regeneration
Correct Answer: Endochondral ossification
Explanation: The cartilaginous component of the soft callus is replaced by woven bone through endochondral ossification.
MCQ 13
Question:
A healed long-bone fracture gradually regains its normal contour and medullary cavity over several months. Which paired cellular activity produces this change?
A healed long-bone fracture gradually regains its normal contour and medullary cavity over several months. Which paired cellular activity produces this change?
Neutrophil migration and macrophage activation
Chondrocyte proliferation and cartilage expansion
Osteoclastic resorption and osteoblastic formation
Fibroblast contraction and scar maturation
Marrow necrosis and vascular occlusion
Correct Answer: Osteoclastic resorption and osteoblastic formation
Explanation: Remodeling restores normal architecture through coordinated removal of excess bone and deposition of mechanically organized lamellar bone.
MCQ 14
Question:
A tibial fracture shows persistent union failure. Imaging reveals a wide fracture gap with soft tissue interposed between the fragments. Which factor is most directly preventing healing?
A tibial fracture shows persistent union failure. Imaging reveals a wide fracture gap with soft tissue interposed between the fragments. Which factor is most directly preventing healing?
Excessive lamellar remodeling
Loss of physical continuity for bony bridging
Premature closure of the growth plate
Increased articular congruity
Excessive osteocyte survival
Correct Answer: Loss of physical continuity for bony bridging
Explanation: A persistent gap and interposed tissue prevent effective callus bridging and contribute to nonunion.
MCQ 15
Question:
A patient with an open tibial injury arrives with mud embedded in the wound. Which immediate local measure best limits additional contamination before definitive surgery?
A patient with an open tibial injury arrives with mud embedded in the wound. Which immediate local measure best limits additional contamination before definitive surgery?
Repeated bedside probing of the wound
Immediate tight closure of the skin
Sterile covering and limb immobilization
Forceful movement to test fracture stability
Delayed protection until operative assessment
Correct Answer: Sterile covering and limb immobilization
Explanation: Prompt sterile coverage limits further contamination, while immobilization reduces tissue injury before definitive debridement.
MCQ 16
Question:
During debridement of an open fracture, a bone fragment is completely stripped of soft-tissue attachment and appears nonviable. Why is preservation of this fragment undesirable?
During debridement of an open fracture, a bone fragment is completely stripped of soft-tissue attachment and appears nonviable. Why is preservation of this fragment undesirable?
It will produce excessive joint cartilage
It may act as a devitalized focus for infection
It will immediately remodel into lamellar bone
It prevents all inflammatory-cell recruitment
It converts the wound into a closed fracture
Correct Answer: It may act as a devitalized focus for infection
Explanation: Completely devascularized bone has poor host defense and can support persistent contamination and infection.
MCQ 17
Question:
A patient develops osteonecrosis after a displaced fracture around a joint. Which anatomical event most directly initiated the lesion?
A patient develops osteonecrosis after a displaced fracture around a joint. Which anatomical event most directly initiated the lesion?
Disruption of critical intraosseous vessels
Excessive formation of fracture callus
Increased osteocyte oxygen delivery
Expansion of normal articular cartilage
Premature lamellar remodeling
Correct Answer: Disruption of critical intraosseous vessels
Explanation: Traumatic interruption of the blood supply causes ischemic death of marrow and osteocytes.
MCQ 18
Question:
Histological examination of an ischemic bone lesion shows necrotic marrow fat and trabeculae with absent osteocyte nuclei. Which finding confirms death of the bone cells?
Histological examination of an ischemic bone lesion shows necrotic marrow fat and trabeculae with absent osteocyte nuclei. Which finding confirms death of the bone cells?
Increased chondrocyte columns
Empty lacunae within the trabeculae
Dense neutrophilic microabscesses
Diffuse osteoid mineralization
Uniform marrow hyperplasia
Correct Answer: Empty lacunae within the trabeculae
Explanation: Loss of osteocyte nuclei leaves empty lacunae, a characteristic microscopic feature of osteonecrosis.
MCQ 19
Question:
A patient with osteonecrosis has sclerosis surrounding a necrotic segment on imaging. Which process most likely contributes to this increased density?
A patient with osteonecrosis has sclerosis surrounding a necrotic segment on imaging. Which process most likely contributes to this increased density?
Complete restoration of normal marrow
New bone deposition on dead trabeculae
Loss of all mineralized tissue
Formation of a fibrocartilaginous callus
Diffuse bacterial calcification
Correct Answer: New bone deposition on dead trabeculae
Explanation: Repair from viable margins deposits new bone on necrotic trabecular scaffolds, producing relative sclerosis.
MCQ 20
Question:
A patient with a displaced long-bone fracture initially has normal distal pulses. After splint application, the limb becomes increasingly painful and numb. Which action is most appropriate?
A patient with a displaced long-bone fracture initially has normal distal pulses. After splint application, the limb becomes increasingly painful and numb. Which action is most appropriate?
Assume perfusion remains adequate because pulses were initially present
Wait for routine follow-up radiography
Reassess and document the neurovascular status immediately
Encourage active exercise of the injured limb
Ignore sensory symptoms if alignment is improved
Correct Answer: Reassess and document the neurovascular status immediately
Explanation: New pain or neurological symptoms after immobilization may indicate evolving compression or vascular compromise and require urgent reassessment.