Pediatric Orthopaedics — MCQs

Pediatric Orthopaedics Indian Medical PG Practice Questions and MCQs

Question 151: Which part of the bone is most commonly affected in Tom-Smith arthritis?

A. Upper end tibia
B. Lower end femur
C. Head of femur (Correct Answer)
D. Greater trochanter

Explanation: **Explanation:** **Tom-Smith Arthritis** (also known as Septic Arthritis of Infancy) is a specific type of pyogenic arthritis occurring in infants, typically under the age of one. **Why the Head of Femur is the correct answer:** The hip joint is the most common site for this condition. In infants, the **metaphyseal blood vessels** (trans-physeal vessels) cross the growth plate (epiphysis) to reach the cartilaginous epiphysis. Because the metaphysis of the femur is **intracapsular**, an infection in the bone (osteomyelitis) easily spreads into the joint space. The resulting pus increases intra-articular pressure, compromising the blood supply and leading to the rapid destruction and "disappearance" of the **unossified head of the femur**. **Why other options are incorrect:** * **Upper end tibia & Lower end femur:** While these are common sites for pediatric osteomyelitis, they are mostly extracapsular. Infection here is less likely to result in the catastrophic joint destruction and femoral head dissolution characteristic of Tom-Smith arthritis. * **Greater trochanter:** This is an apophysis that ossifies later in childhood. It is not the primary weight-bearing articular surface and is not the target of destruction in this specific clinical entity. **Clinical Pearls for NEET-PG:** * **Pathogenesis:** Usually follows umbilical sepsis or skin infections (Staphylococcus aureus is the most common organism). * **Radiological Hallmark:** "Empty Acetabulum" or apparent dislocation due to the destruction of the femoral head. * **Clinical Presentation:** The infant holds the limb in "Flexion, Abduction, and External Rotation" (position of maximum joint capacity). * **Sequelae:** Shortening of the limb, Trendelenburg gait, and unstable hip joint in later life.

Question 152: Trident hand is seen in which of the following conditions?

A. Achondroplasia (Correct Answer)
B. Mucopolysaccharidosis
C. Diphyseal achlasia
D. Cleidocranial dystosis

Explanation: **Explanation:** **Achondroplasia** is the most common cause of disproportionate short-limb dwarfism. It is an autosomal dominant condition caused by a mutation in the **FGFR3 gene**, which leads to abnormal endochondral ossification. **Why Achondroplasia is correct:** The **Trident Hand** is a classic clinical sign of Achondroplasia. It occurs because the fingers (digits) are short and nearly equal in length (brachydactyly), with a characteristic **persistent gap between the third (middle) and fourth (ring) fingers**. This separation gives the hand an appearance resembling a "trident" or a three-pronged fork. **Analysis of Incorrect Options:** * **B. Mucopolysaccharidosis (e.g., Hurler’s):** Characterized by a **"Claw hand"** deformity due to joint contractures and "bullet-shaped" phalanges on X-ray, rather than a trident appearance. * **C. Diaphyseal Achlasia (Hereditary Multiple Exostoses):** Involves multiple osteochondromas near the growth plates of long bones. It may cause limb shortening or bowing but does not present with a trident hand. * **D. Cleidocranial Dysostosis:** Primarily affects intramembranous ossification. Key features include absent/hypoplastic clavicles, delayed closure of fontanelles, and supernumerary teeth. **High-Yield Clinical Pearls for NEET-PG:** * **Radiological signs of Achondroplasia:** "Champagne glass" pelvis, "Square" iliac wings, "Bullet-nosed" vertebrae, and narrowing of the interpedicular distance (caudally). * **Inheritance:** Most cases (80%) are due to **de novo mutations** associated with advanced paternal age. * **Intelligence:** Patients with Achondroplasia typically have **normal intelligence** and a normal lifespan, though they are at risk for spinal stenosis and foramen magnum compression.

Question 153: Tom Smith arthritis is:

A. TB arthritis of hip in adults
B. TB arthritis of hip in infancy
C. Septic arthritis of infant (Correct Answer)
D. Infection of congenital dislocation of hip

Explanation: **Explanation:** **Tom Smith’s Arthritis** (also known as Tom Smith’s disease) refers to **acute septic arthritis of the hip in infants** (usually under one year of age). The underlying medical concept involves the unique vascular anatomy of an infant's hip. In infancy, the transphyseal vessels cross the growth plate, allowing an infection in the metaphysis (osteomyelitis) to spread directly into the joint space, leading to rapid destruction of the cartilaginous femoral head. Because the femoral head is largely cartilaginous at this age, it can be completely "dissolved" or absorbed, leading to a pathological dislocation or a "flail hip" later in life. **Analysis of Options:** * **Option A & B:** Tuberculosis (TB) of the hip presents with a more chronic, indolent course. While TB can affect the hip in children (often presenting with the "wandering acetabulum"), the specific eponym "Tom Smith" is reserved for pyogenic/septic infections in infancy. * **Option D:** While a congenital dislocation of the hip (CDH/DDH) results in a displaced hip, it is a developmental structural issue, not a primary infectious process. Tom Smith’s arthritis may *result* in a hip that looks dislocated on X-ray, but the etiology is sepsis. **NEET-PG High-Yield Pearls:** * **Common Organism:** *Staphylococcus aureus* is the most common cause, though *Streptococcus* and *H. influenzae* (in unimmunized) are also seen. * **Clinical Presentation:** The infant typically presents with a high fever, "pseudoparalysis" of the limb, and pain on passive motion. * **Radiological Sign:** In late stages, the "empty acetabulum" sign is seen due to the destruction of the femoral head. * **Sequelae:** Shortening of the limb, Trendelenburg gait, and significant hip instability.

Question 154: An absolute indication for X-ray of the pelvis in cases of congenital dislocation of the hip is all of the following except:

A. Positive family history
B. Breech presentation
C. Unstable hip
D. Shortening of limb (Correct Answer)

Explanation: In the management of Developmental Dysplasia of the Hip (DDH), the primary goal is early detection. However, the timing and modality of imaging are critical. **Why "Shortening of limb" is the correct answer:** Shortening of the limb (Galeazzi sign) is a **clinical finding** suggestive of a dislocated hip, but it is not an absolute indication for an immediate X-ray in a neonate. In newborns, the femoral head is entirely cartilaginous and not visible on X-ray until the ossification center appears (usually between 4–6 months). Therefore, in a neonate with clinical shortening, **Ultrasonography (USG)** is the gold standard investigation, not an X-ray. **Analysis of Incorrect Options:** * **A & B (Positive Family History & Breech Presentation):** These are the two strongest **risk factors** for DDH. Current protocols mandate objective imaging (USG if <4 months, X-ray if >4 months) for all infants with these risk factors, even if the clinical exam is normal. * **C (Unstable Hip):** If a clinical exam (Barlow or Ortolani test) reveals instability, it is a mandatory indication for imaging to confirm the diagnosis and guide treatment. **NEET-PG High-Yield Pearls:** * **Investigation of Choice:** USG (Graf’s method) for infants <4 months; X-ray for infants >4 months. * **X-ray Landmarks:** Look for the femoral head in the lower inner quadrant formed by **Hilgenreiner’s line** (horizontal) and **Perkin’s line** (vertical). * **Acetabular Index:** Usually <30° in newborns; an increased angle suggests dysplasia. * **Shenton’s Line:** An interrupted line indicates subluxation or dislocation.

Question 155: Delayed or failed closure of the fontanelles, open skull sutures, and multiple wormian bones are features of which of the following conditions?

A. Cleidocranial dysplasia (Correct Answer)
B. Crouzon syndrome
C. Treacher Collins syndrome
D. Goldenhar syndrome

Explanation: ### Explanation **Cleidocranial Dysplasia (CCD)** is an autosomal dominant skeletal dysplasia caused by a mutation in the **RUNX2 gene**, which is essential for osteoblast differentiation. The hallmark of this condition is defective intramembranous ossification, which primarily affects the skull and the clavicles. * **Why Option A is correct:** In CCD, the failure of intramembranous bone formation leads to delayed closure of the anterior fontanelle (often remaining open into adulthood) and widened cranial sutures. To compensate for these gaps, the body forms **Wormian bones** (small, irregular ossicles within the sutures). Other classic features include absent or hypoplastic clavicles (allowing the patient to approximate their shoulders) and supernumerary teeth. **Why the other options are incorrect:** * **B. Crouzon Syndrome:** This is a craniosynostosis syndrome characterized by **premature closure** of cranial sutures (brachycephaly), resulting in midface hypoplasia and proptosis. It is the opposite of the "open sutures" seen in CCD. * **C. Treacher Collins Syndrome:** This is a mandibulofacial dysostosis affecting the 1st and 2nd branchial arches. It presents with malar hypoplasia, coloboma of lower eyelids, and ear abnormalities, but does not involve Wormian bones or delayed fontanelle closure. * **D. Goldenhar Syndrome:** Also known as Oculo-Auriculo-Vertebral (OAV) syndrome, it is characterized by hemifacial microsomia, epibulbar dermoids, and vertebral anomalies. **High-Yield Clinical Pearls for NEET-PG:** * **Wormian Bones Mnemonic (PORK CHOPS):** **P**yknodysostosis, **O**steogenesis Imperfecta, **R**ickets, **K**inky Hair Syndrome (Menkes), **C**leidocranial Dysplasia, **H**ypothyroidism/Hypophosphatasia, **O**ne (Down Syndrome), **P**achydermoperiostosis, **S**tilling-Turk-Duane Syndrome. * **CCD Key Features:** Drooping shoulders, "Hot cross bun" appearance of the skull, and short stature.

Question 156: Post poliomyelitis, a patient has grade H power in Gastrocnemius, grade HI in Peroneus, and grade IV in Tibialis Anterior. What is the resulting deformity?

A. Calcaneovalgus
B. Equinovarus
C. Calcaneovarus (Correct Answer)
D. Genu valgus

Explanation: In Post-Polio Residual Paralysis (PPRP), deformities occur due to **muscle imbalance** around a joint. The stronger muscle groups pull the limb toward their side, while the paralyzed or weaker muscles fail to provide counter-traction. ### **Explanation of the Correct Answer** To solve this, analyze the muscle power provided: * **Gastrocnemius (Grade II):** Weak plantarflexion. * **Peroneus (Grade III):** Weak eversion. * **Tibialis Anterior (Grade IV):** Strong dorsiflexion and inversion. **The Mechanism:** 1. **Calcaneus Deformity:** The Tibialis Anterior (Grade IV) is significantly stronger than the Gastrocnemius (Grade II). This results in the foot being pulled into **dorsiflexion**, leading to a Calcaneus deformity. 2. **Varus Deformity:** The Tibialis Anterior is also a powerful inverter. Since the Peroneals (evertors) are weaker (Grade III), the foot is pulled into **inversion**, leading to a Varus deformity. * **Result:** Calcaneus + Varus = **Calcaneovarus**. ### **Analysis of Incorrect Options** * **A. Calcaneovalgus:** This would occur if the Peroneals (evertors) were stronger than the Tibialis muscles (inverters). * **B. Equinovarus:** This occurs when the Gastrocnemius (plantarflexor) is stronger than the Tibialis Anterior (dorsiflexor). This is the most common deformity in CTEV, but not in this specific muscle profile. * **D. Genu Valgus:** This is a knee deformity (knock-knees) usually resulting from lateral compartment growth issues or muscle imbalances at the hip/knee, not the ankle muscles described. ### **High-Yield Clinical Pearls for NEET-PG** * **Rule of Thumb:** In PPRP, the deformity is always caused by the **stronger** muscle group. * **Tendon Transfer:** For Calcaneovarus, a common surgical intervention is the **Steindler Flexor Release** or transferring the Tibialis Anterior to the lateral side of the foot to balance the pull. * **Most common PPRP deformity:** Equinovarus (due to the relative strength of the triceps surae and tibialis posterior).

Question 157: The typical deformity in CTEV is:

A. Ankle equinus
B. Subtalar inversion
C. Forefoot adduction
D. All the above (Correct Answer)

Explanation: **Explanation:** Congenital Talipes Equinovarus (CTEV), commonly known as clubfoot, is a complex three-dimensional deformity involving the foot and ankle. The correct answer is **All the above** because CTEV is defined by a specific sequence of four anatomical components, often remembered by the mnemonic **CAVE**. 1. **C – Cavus:** High arch of the foot (due to the first metatarsal being plantarflexed). 2. **A – Adduction:** The forefoot is deviated medially at the tarsometatarsal joints (**Option C**). 3. **V – Varus:** Inversion and adduction of the calcaneum at the subtalar joint (**Option B**). 4. **E – Equinus:** Plantarflexion at the ankle joint due to a tight Achilles tendon (**Option A**). **Why other options are "incorrect" as standalone answers:** While Ankle equinus, Subtalar inversion (Varus), and Forefoot adduction are all present in CTEV, selecting any single one would be incomplete. The pathology is a syndrome of all these malalignments occurring simultaneously. **High-Yield Clinical Pearls for NEET-PG:** * **Order of Correction (Ponseti Method):** Correction must follow the sequence **C $\rightarrow$ A $\rightarrow$ V $\rightarrow$ E**. Cavus is corrected first by supinating the forefoot, followed by adduction and varus. Equinus is always corrected last (often requiring a percutaneous Achilles tenotomy). * **Pirani Score:** Used to assess the severity of CTEV and monitor progress during casting. * **Kite’s Angle:** On X-ray (AP view), the angle between the talus and calcaneus is **decreased** in CTEV (normal is 20–40°). * **Primary Pathology:** The head of the talus is the "pivot" point, and the navicular and calcaneum are displaced medially and around it.

Question 158: Which of the following is most likely to be associated with 'Tom Smith Arthritis'?

A. Pyogenic infection of infancy (Correct Answer)
B. Tuberculosis
C. Rheumatoid arthritis in children
D. Osteoarthritis in middle-aged men

Explanation: **Tom Smith Arthritis** (also known as Acute Epiphysitis of Infancy) refers to a specific type of **septic (pyogenic) arthritis of the hip joint occurring in infants** (usually under one year of age). ### Why Option A is Correct In infants, the **trans-physeal vessels** are still patent, allowing an infection in the metaphysis (osteomyelitis) to cross the growth plate directly into the epiphysis and the joint space. Because the femoral head is largely cartilaginous at this age, the pyogenic infection (commonly *Staphylococcus aureus* or *Streptococcus*) rapidly destroys the capital femoral epiphysis. This leads to a "flail hip" with significant shortening and instability. ### Why Other Options are Incorrect * **B. Tuberculosis:** While TB can affect the hip (Pott’s paraplegia or hip TB), it is a chronic granulomatous infection. Tom Smith Arthritis is specifically defined as an acute, destructive pyogenic process in infancy. * **C. Rheumatoid arthritis in children:** Known as Juvenile Idiopathic Arthritis (JIA), this is an autoimmune inflammatory condition, not an acute infectious destruction of the epiphysis. * **D. Osteoarthritis:** This is a degenerative "wear and tear" disease of the articular cartilage seen in older populations, unrelated to the infantile infectious etiology of Tom Smith Arthritis. ### Clinical Pearls for NEET-PG * **Commonest Site:** Hip joint (due to the intra-articular nature of the metaphysis). * **Clinical Presentation:** An infant presenting with a "pseudoparalysis" of the limb, high fever, and pain on passive movement. * **Radiological Hallmark:** Late stages show a complete disappearance of the femoral head and neck (the "empty acetabulum" appearance). * **Sequelae:** Severe limb length discrepancy, Trendelenburg gait, and early-onset secondary osteoarthritis.

Question 159: The Telescopic test is useful in the diagnosis of which condition?

A. Perthes disease
B. Intracapsular fracture neck of femur (Correct Answer)
C. Malunited trochanteric fracture
D. Ankylosis of the hip joint

Explanation: **Explanation:** The **Telescopic Test** (also known as the "Telescoping Sign") is a clinical maneuver used to detect **abnormal mobility** along the long axis of the femur. It is performed by flexing the hip and knee to 90 degrees and applying alternating upward and downward pressure (pushing and pulling) on the thigh. **1. Why Option B is Correct:** In an **Intracapsular fracture of the neck of femur** (specifically unimpacted or non-union cases), the continuity between the femoral head and the shaft is lost. Since the head remains fixed in the acetabulum while the shaft is free to move, the clinician can feel the femur "sliding" up and down. This axial instability is the hallmark of a positive telescopic test. **2. Why Other Options are Incorrect:** * **Perthes Disease:** This is an avascular necrosis of the femoral head. The joint remains intact and stable; the primary clinical findings are a painful limp and restricted internal rotation/abduction, not axial instability. * **Malunited Trochanteric Fracture:** In malunion, the bone has healed, albeit in a deformed position (usually coxa vara). Because the bone is continuous, there is no "telescoping" movement. * **Ankylosis of the Hip:** Ankylosis refers to joint stiffness or fusion. The hip is immobile, making a telescopic test impossible to perform. **Clinical Pearls for NEET-PG:** * **Developmental Dysplasia of the Hip (DDH):** The Telescopic test is also classically positive in DDH (dislocated hip), where the femoral head can be moved in and out of the acetabulum. * **Differential:** If a question mentions "Telescoping" in a pediatric context, think **DDH**; in an adult trauma context, think **Fracture Neck of Femur**. * **Other Hip Tests:** Remember to differentiate this from **Trendelenburg’s sign** (abductor weakness) and **Thomas Test** (fixed flexion deformity).

Question 160: A young child presents with abnormal development of membranous bones, characterized by a broad skull and associated facial and dental anomalies. Which other bones are most likely to be affected?

A. Clavicles (Correct Answer)
B. Femurs
C. Metatarsals
D. Phalanges

Explanation: ### Explanation The clinical presentation described—abnormal development of membranous bones, broad skull (delayed closure of fontanelles), and dental anomalies—is a classic description of **Cleidocranial Dysplasia (CCD)**. **Why Clavicles are the Correct Answer:** Cleidocranial Dysplasia is an autosomal dominant disorder caused by a mutation in the **RUNX2 gene**, which is essential for osteoblast differentiation. It primarily affects bones formed via **intramembranous ossification**. The **clavicle** is the first bone in the body to ossify and does so primarily through intramembranous ossification. In CCD, the clavicles are typically hypoplastic or entirely absent (aplastic), allowing the patient to abnormally approximate their shoulders in the midline. **Why Other Options are Incorrect:** * **B, C, and D (Femurs, Metatarsals, Phalanges):** These are long or short tubular bones that develop primarily through **endochondral ossification** (cartilage template replaced by bone). While CCD can show minor secondary effects in these bones (like pseudoepiphyses in metacarpals), the hallmark of the disease is the failure of membranous bone formation, making the clavicle the most characteristic site of involvement. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Mutation in **RUNX2** (CBFA1) on Chromosome 6p21. * **Skull Findings:** Delayed closure of sutures/fontanelles, presence of multiple **Wormian bones**, and frontal bossing. * **Dental Findings:** Supernumerary (extra) teeth and delayed eruption of permanent teeth. * **Clinical Sign:** Ability to touch shoulders together in front of the chest. * **Stature:** Patients often have moderately short stature but normal intelligence.

Practice by Chapter

Developmental Dysplasia of Hip

Practice Questions

Clubfoot

Practice Questions

Pediatric Fractures

Practice Questions

Growth Plate Injuries

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Legg-Calvé-Perthes Disease

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Slipped Capital Femoral Epiphysis

Practice Questions

Pediatric Spine Deformities

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Cerebral Palsy: Orthopaedic Aspects

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Neuromuscular Disorders in Children

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Pediatric Bone and Joint Infections

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Limb Length Discrepancies

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Orthopedic Manifestations of Genetic Disorders

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