Musculoskeletal Radiology — MCQs

Musculoskeletal Radiology Indian Medical PG Practice Questions and MCQs

Question 11: What is the best radiographic view for the temporomandibular joint (TMJ)?

A. Lateral oblique view
B. PA view
C. Waters view
D. Orthopantomogram (OPG) (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Orthopantomogram (OPG)** **Why OPG is the best view:** The Orthopantomogram (OPG) is the primary screening modality and the most commonly used radiographic view for the Temporomandibular Joint (TMJ). Its superiority lies in its ability to provide a **panoramic, bilateral, and comparative view** of both TMJs, the mandibular condyles, and the ascending rami on a single film. It is particularly effective for detecting gross bony changes, fractures of the condylar neck, and developmental anomalies. While MRI is the gold standard for soft tissue (disc) evaluation, OPG remains the best initial radiographic choice for osseous assessment. **Analysis of Incorrect Options:** * **A. Lateral Oblique View:** While it can visualize the condyle, it often suffers from superimposition of the contralateral side and base of the skull, making it less diagnostic than a panoramic view. * **B. PA View:** This view is primarily used to assess mediolateral displacement of fractures or gross asymmetry but provides poor visualization of the joint space and condylar morphology due to the density of the petrous temporal bone. * **C. Waters View (Occipitomental):** This is the gold standard for **Paranasal Sinuses (specifically the Maxillary sinus)**. It does not provide a clear view of the TMJ anatomy. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for TMJ Disc/Soft Tissue:** MRI (T1 for anatomy, T2 for effusion). * **Best for Bony Erosion/Ankylosis:** Non-contrast CT (NCCT). * **Trans-cranial View (Schuller’s):** Historically used to see the lateral aspect of the joint, but largely replaced by OPG/CT. * **Reverse Towne’s View:** Excellent for visualizing high condylar fractures and the condylar neck.

Question 12: Champagne glass pelvis is seen in which of the following conditions?

A. Congenital Dislocation of Hip (CDH)
B. Down's syndrome
C. Cretinism
D. Achondroplasia (Correct Answer)

Explanation: **Explanation:** **Achondroplasia** is the most common cause of disproportionate short-limbed dwarfism. It is an autosomal dominant condition caused by a mutation in the **FGFR3 gene**, which leads to abnormal endochondral ossification. The characteristic **"Champagne Glass Pelvis"** occurs due to specific bony deformities: * **Short, squat iliac wings:** The ilia are reduced in vertical height. * **Horizontal acetabular roofs:** This creates a flat appearance. * **Narrow sacrosciatic notch:** This combination results in a pelvic inlet that is wide and shallow, resembling the bowl of a champagne glass. **Analysis of Incorrect Options:** * **Congenital Dislocation of Hip (CDH/DDH):** Characterized by Putti’s Triad (superolateral displacement of the femoral head, increased acetabular angle, and delayed ossification of the femoral epiphysis), not a champagne glass shape. * **Down’s Syndrome:** Associated with an **"Elephant Ear Pelvis"** (large, flared iliac wings) and a decreased acetabular and iliac angle. * **Cretinism (Hypothyroidism):** Radiologically presents with delayed skeletal maturation, epiphyseal dysgenesis (fragmented "stippled" epiphysis), and increased bone density, but not the specific champagne glass morphology. **High-Yield Clinical Pearls for NEET-PG:** * **Spine:** Posterior scalloping of vertebrae and narrowing of the interpedicular distance (caudally). * **Hands:** **Trident Hand** (persistent space between the 3rd and 4th digits). * **Long Bones:** Rhizomelic shortening (proximal segments like femur/humerus are shortest) and "Chevrons" (V-shaped) physeal growth plates. * **Skull:** Frontal bossing with midface hypoplasia and a narrowed foramen magnum.

Question 13: What is the best radiological view for the diagnosis of a scaphoid fracture?

A. Anteroposterior
B. Lateral
C. Oblique (Correct Answer)
D. Any of the above

Explanation: **Explanation:** The scaphoid is the most commonly fractured carpal bone. Due to its unique anatomy—it is tilted anteriorly and lies at an angle to the long axis of the forearm—standard views often result in the bone appearing foreshortened or obscured by overlapping carpal bones. **Why Oblique is the Correct Answer:** The **Oblique view (specifically the PA Oblique with ulnar deviation)** is considered the best for diagnosing scaphoid fractures. Ulnar deviation moves the scaphoid away from the radius and "stretches" it out, while the oblique angle (usually 45 degrees) brings the long axis of the scaphoid parallel to the film. This profile view minimizes bony overlap and clearly demonstrates the waist of the scaphoid, where most fractures occur. **Why Other Options are Incorrect:** * **Anteroposterior (AP):** In a neutral AP view, the scaphoid is tilted, causing it to appear "foreshortened" (the signet ring sign). This overlap makes it difficult to detect non-displaced hairline fractures. * **Lateral:** This view is excellent for assessing carpal alignment (e.g., DISI/VISI) and lunate dislocations, but the scaphoid is superimposed over other carpal bones, making it poor for primary fracture detection. **Clinical Pearls for NEET-PG:** * **Scaphoid Series:** A standard "Scaphoid Series" typically includes four views: PA, Lateral, Oblique, and PA with Ulnar Deviation (Navicular view). * **Occult Fractures:** If clinical suspicion is high (tenderness in the **Anatomical Snuffbox**) but X-rays are negative, the management is a thumb spica cast and a repeat X-ray in 10–14 days. * **Gold Standard:** **MRI** is the most sensitive imaging modality for detecting occult scaphoid fractures within the first 24 hours. * **Complication:** The most dreaded complication is **Avascular Necrosis (AVN)**, specifically of the proximal pole, due to its retrograde blood supply.

Question 14: A dense zone of calcification at the growing metaphysis seen in scurvy is described by which sign?

A. Wimberger's ring sign
B. Pelkan spur
C. Frankel's line (Correct Answer)
D. Trummerfeld zone

Explanation: **Explanation:** Scurvy (Vitamin C deficiency) leads to defective collagen synthesis, which impairs osteoid formation. However, mineralized cartilage continues to be produced, leading to a buildup of calcified matrix at the metaphysis. **1. Why Frankel’s Line is correct:** **Frankel’s line** (also known as the "white line of Frankel") represents a dense, radiopaque zone of provisional calcification at the growing metaphysis. Because the body cannot form new bone (osteoid) to replace the calcified cartilage, this zone thickens and appears abnormally white on X-ray. **2. Analysis of Incorrect Options:** * **Wimberger’s ring sign:** This refers to a thin, sclerotic rim surrounding a lucent center in the epiphysis (the ossification center). It is characteristic of scurvy but occurs in the epiphysis, not the metaphysis. * **Pelkan spur:** These are lateral bony projections (marginal spurring) at the metaphysis caused by the outward extension of the white line of Frankel and healing of subperiosteal hemorrhages. * **Trummerfeld zone:** Also known as the "scurvy zone," this is a radiolucent (dark) transverse band located just proximal to Frankel’s line. It represents a zone of rarefaction where bone trabeculae are sparse and weak. **3. NEET-PG High-Yield Pearls for Scurvy:** * **Corner Sign:** A small marginal metaphyseal fracture (early sign). * **Subperiosteal Hemorrhage:** Leads to lifting of the periosteum; though not visible initially, it becomes apparent as "cloaking" during healing when it calcifies. * **Clinical Triad:** Anemia, Bone pain (pseudoparalysis), and Skin/Gum bleeding. * **Key Radiographic Sequence (Distal to Proximal):** Wimberger Ring (Epiphysis) → Frankel’s Line (Dense Metaphysis) → Trummerfeld Zone (Lucent Metaphysis).

Question 15: What is the investigation of choice for spinal metastasis?

A. MRI (Correct Answer)
B. Bone Scan
C. X-ray Spine
D. CT Scan

Explanation: **Explanation:** **MRI (Magnetic Resonance Imaging)** is the investigation of choice for spinal metastasis because of its superior soft-tissue contrast and high sensitivity for detecting bone marrow replacement. Metastatic cells typically replace the fatty marrow, a change that MRI can detect long before cortical bone destruction occurs. Furthermore, MRI is the gold standard for evaluating the spinal cord, nerve roots, and the extent of epidural involvement (the "thecal sac" compression), which is critical for surgical and radiation planning. **Why other options are incorrect:** * **Bone Scan (Technetium-99m MDP):** While highly sensitive for detecting osteoblastic activity across the entire skeleton, it has lower specificity. It can yield false negatives in purely lytic lesions (e.g., Multiple Myeloma) and cannot assess spinal cord compression. * **X-ray Spine:** This is the least sensitive modality. A "winking owl sign" (pedicle destruction) only becomes visible after **30-50% of bone mineral content** is lost. * **CT Scan:** Excellent for assessing cortical bone integrity and fracture risk (mechanical stability), but it is less sensitive than MRI for early marrow infiltration and soft tissue detail. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest sign on X-ray:** Destruction of the pedicle (Winking Owl Sign). * **Most common site of spinal metastasis:** Thoracic spine. * **Red Flag:** Any patient with a known primary malignancy presenting with new-onset back pain must undergo an MRI to rule out **Spinal Cord Compression**, which is a neurosurgical emergency. * **PET-CT:** Useful for whole-body staging but MRI remains superior for localized spinal evaluation.

Question 16: Which imaging modality best visualizes soft tissues like cartilage and tendons?

A. CT scan
B. MRI (Correct Answer)
C. Radionuclide scan
D. Ultrasound

Explanation: **Explanation:** **MRI (Magnetic Resonance Imaging)** is the gold standard for visualizing soft tissues, including cartilage, tendons, ligaments, and muscles. This is due to its superior **soft tissue contrast resolution**. MRI utilizes the behavior of hydrogen protons in different tissue environments; since soft tissues have varying water and fat content, they produce distinct signals, allowing for precise anatomical detail of non-bony structures. **Why other options are incorrect:** * **CT Scan:** While excellent for cortical bone detail and acute hemorrhage, CT has poor soft tissue contrast. It is generally used in MSK radiology for complex fractures or when MRI is contraindicated. * **Radionuclide Scan (Bone Scan):** This is a functional/metabolic imaging tool. It is highly sensitive for detecting increased bone turnover (e.g., metastasis, osteomyelitis) but lacks the anatomical resolution to visualize soft tissue structures like tendons. * **Ultrasound:** Although useful for superficial tendons (like the Achilles) and dynamic studies, it is operator-dependent and cannot visualize structures deep to bone or intra-articular cartilage (like the meniscus) effectively. **High-Yield Clinical Pearls for NEET-PG:** * **Investigation of Choice (IOC)** for Meniscal and Cruciate ligament tears: **MRI**. * **IOC** for early Osteomyelitis: **MRI** (most sensitive); Bone scan is an alternative if MRI is unavailable. * **IOC** for Avascular Necrosis (AVN) of the femoral head: **MRI**. * **T1-weighted images** are best for anatomy; **T2-weighted images** are best for pathology (fluid/edema appears bright).

Question 17: The "hair on end" appearance on skeletal radiographs is characteristically seen in which of the following conditions?

A. Thalassemia (Correct Answer)
B. Scurvy
C. Rickets
D. Hemochromatosis

Explanation: The **"hair-on-end" appearance** (also known as the "crew-cut" sign) is a classic radiological finding seen on a lateral skull X-ray. It occurs due to **compensatory extramedullary hematopoiesis**. In chronic hemolytic anemias like **Thalassemia major** and Sickle Cell Anemia, the bone marrow undergoes massive hyperplasia to compensate for the shortened lifespan of red blood cells. This expands the marrow space (diploic space), thinning the outer table of the skull. New bone is laid down in vertical striations perpendicular to the inner table, creating the appearance of hair standing on end. ### Why the other options are incorrect: * **Scurvy (Vitamin C deficiency):** Characterized by findings around the growth plates of long bones, such as the **White line of Frankel**, **Wimberger’s ring sign** (sclerotic rim around epiphysis), and **Pelkan spurs**. * **Rickets (Vitamin D deficiency):** Primarily affects the metaphysis of long bones, leading to **cupping, fraying, and splaying**. It does not cause diploic space expansion. * **Hemochromatosis:** Typically presents with "hook-like" osteophytes at the metacarpophalangeal (MCP) joints and chondrocalcinosis, rather than skull vault changes. ### NEET-PG High-Yield Pearls: * **Thalassemia Skull:** Aside from the "hair-on-end" sign, look for **obliteration of the maxillary sinuses** and malocclusion of teeth (Chipmunk facies). * **Sickle Cell Anemia:** Also shows the "hair-on-end" sign, but is more uniquely associated with **H-shaped vertebrae** (Reynold’s sign) due to central endplate infarction. * **Differential Diagnosis:** This sign can also be seen in Hereditary Spherocytosis and Iron Deficiency Anemia (rarely, in severe cases).

Question 18: Rugger Jersey Spine is seen in:

A. Fluorosis
B. Achondroplasia
C. Renal osteodystrophy (Correct Answer)
D. Marfan's syndrome

Explanation: **Explanation:** **Rugger Jersey Spine** is a classic radiological sign characterized by prominent horizontal bands of increased bone density (sclerosis) at the superior and inferior endplates of the vertebral bodies, with a relatively radiolucent center. This appearance mimics the horizontal stripes on a traditional rugby jersey. 1. **Why Renal Osteodystrophy is Correct:** In chronic kidney disease, secondary hyperparathyroidism leads to **Renal Osteodystrophy**. The pathophysiology involves a paradoxical combination of bone resorption and osteosclerosis. While PTH increases bone resorption, it also stimulates osteoblastic activity. In the spine, this results in excessive osteoid deposition and mineralization specifically at the vertebral endplates, creating the characteristic striped appearance. 2. **Why Other Options are Incorrect:** * **Fluorosis:** Typically presents with **diffuse, uniform osteosclerosis** (chalky white bones) and ligamentous calcification (e.g., sacrospinous ligament), rather than a banded pattern. * **Achondroplasia:** Characterized by a **decrease in interpedicular distance** (caudally), posterior vertebral scalloping, and "bullet-nosed" vertebrae. * **Marfan’s Syndrome:** Associated with skeletal abnormalities like arachnodactyly, pectus excavatum, and **scoliosis**, but not specific sclerotic banding. **High-Yield Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Rugger Jersey Spine:** Osteopetrosis (though it more commonly presents as "Sandwich vertebrae" or "Bone-within-bone" appearance). * **Other signs of Renal Osteodystrophy:** Subperiosteal bone resorption (most common in radial aspect of middle phalanges), "Salt and pepper" skull, and Brown tumors. * **Key distinction:** Rugger Jersey Spine = Renal Osteodystrophy; Sandwich Vertebrae = Osteopetrosis.

Question 19: The 'Molten Wax' appearance of bones on X-ray is characteristic of which condition?

A. Osteoporosis
B. Osteopoikilosis
C. Melorheostosis (Correct Answer)
D. Osteogenesis imperfecta

Explanation: **Explanation:** **Melorheostosis** (Option C) is a rare, non-hereditary sclerosing bone dysplasia. The characteristic radiographic hallmark is **flowing hyperostosis** along the cortex of long bones, typically involving only one side of the bone (monostotic or polyostotic but usually unilateral). This appearance is classically described as **"dripping molten candle wax"** or the **"Molten Wax" sign**. Pathologically, it represents a mixture of cortical thickening and mesenchymal dysplasia, often following a sclerotome distribution. **Analysis of Incorrect Options:** * **A. Osteoporosis:** Characterized by decreased bone density (osteopenia), thinning of the cortex, and loss of trabeculae, leading to "radiolucent" bones—the opposite of the dense sclerosis seen in melorheostosis. * **B. Osteopoikilosis:** Another sclerosing dysplasia, but it presents as multiple, small, well-defined **"spotted" radiopaque foci** (bone islands) clustered around joints. It does not show the flowing, linear pattern of melorheostosis. * **D. Osteogenesis Imperfecta:** A genetic disorder of collagen synthesis characterized by osteopenia, multiple fractures, "Gracile" bones, and deformities like "Saber shin" or "Codfish vertebrae," rather than focal hyperostosis. **High-Yield Clinical Pearls for NEET-PG:** * **Distribution:** Melorheostosis typically follows a **sclerotome** distribution (areas of bone supplied by a single spinal sensory nerve). * **Clinical Presentation:** While often asymptomatic, it can cause joint stiffness, pain, or limb length discrepancy. * **Associated Sign:** On bone scan, it shows increased uptake (hot spots), which helps differentiate it from other benign sclerotic lesions. * **Mnemonic:** **M**elorheostosis = **M**olten wax.

Question 20: Erlenmeyer flask deformity of the femur is seen in all of the following conditions, except?

A. Osteopetrosis
B. Gaucher's disease
C. Thalassemia
D. Paget's disease (Correct Answer)

Explanation: ### Explanation **Erlenmeyer Flask Deformity** refers to a characteristic radiographic finding where the distal metaphysis of the femur (and sometimes the proximal tibia) fails to undergo normal remodeling. This results in a flared, bulbous appearance with cortical thinning, resembling the laboratory glassware. #### Why Paget’s Disease is the Correct Answer (The "Except") In **Paget's Disease**, the hallmark is a "thickening" of the cortex and coarsening of the trabeculae. While it causes bone expansion, it does not typically present with the specific symmetric, metaphyseal flaring seen in Erlenmeyer flask deformity. Instead, Paget’s is characterized by cortical thickening, bowing of long bones, and a "blade of grass" or "candle flame" lytic lesion. #### Why the Other Options are Incorrect The deformity occurs due to a failure of **metaphyseal remodeling** (osteoclast dysfunction or marrow expansion): * **Osteopetrosis:** The primary defect is osteoclast failure. Bones cannot be remodeled, leading to dense, "marble-like" bones with flared ends. * **Gaucher’s Disease:** This is the **most common cause**. Glucocerebroside-laden macrophages (Gaucher cells) infiltrate the bone marrow, causing mechanical pressure and expansion of the metaphysis. * **Thalassemia:** Chronic severe anemia leads to massive compensatory **extramedullary hematopoiesis**. The expanding erythroid marrow widens the bone from within, preventing normal tapering. #### NEET-PG High-Yield Pearls * **Mnemonic for Causes (LEAD G):** **L**ead poisoning, **E**nchondromatosis (Ollier disease), **A**lbers-Schönberg (Osteopetrosis), **D**ysosteosclerosis, **G**aucher’s disease. * **Gaucher’s Disease:** Look for "Erlenmeyer flask" + "Avascular Necrosis (AVN) of the femoral head" + "Bone crises." * **Osteopetrosis:** Look for "Bone-within-a-bone" appearance and "Sandwich vertebrae." * **Thalassemia:** Look for "Hair-on-end" appearance of the skull and "Salt and pepper" appearance of the spine.

Practice by Chapter

Radiographic Anatomy of Bones and Joints

Practice Questions

Imaging of Fractures and Dislocations

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Arthritides: Inflammatory and Degenerative

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Metabolic Bone Diseases

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Bone and Soft Tissue Tumors

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Congenital Skeletal Anomalies

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Spine Imaging

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Skeletal Infections

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Sports Medicine Imaging

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Imaging of Prostheses and Implants

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Musculoskeletal Ultrasound

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MSK Interventional Procedures

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