Pediatric Orthopaedics Practice Questions

Q: Which age group does Perthes disease primarily affect?

4 - 8 years. **Explanation:** **Legg-Calvé-Perthes Disease (LCPD)** is an idiopathic avascular necrosis of the femoral head occurring in children. The underlying pathology involves a temporary disruption of the blood supply to the capital femoral epiphysis, leading to bone infarction, collapse, and subsequent remodeling. **Why 4–8 years is correct:** Perthes disease characteristically affects children between the ages of **4 and 8 years** (with a broader range of 3–12 years). It is significantly more common in boys (4:1 ratio). During this age window, the blood supply to the femoral head is in a transitional state, making it particularly vulnerable to ischemia. **Analysis of Incorrect Options:** * **Less than 4 years:** While it can occur, it is rare. Children diagnosed under age 5 generally have a much better prognosis due to the greater remodeling potential of the immature skeleton. * **10–25 years:** This age group is more characteristic of **Slipped Capital Femoral Epiphysis (SCFE)**, which typically affects adolescents (10–15 years) during their growth spurt. * **Greater than 25 years:** Avascular necrosis in adults is usually secondary to specific risk factors like trauma, steroid use, or alcohol abuse, rather than the idiopathic pediatric process of Perthes. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Painless limping or mild hip/knee pain with restricted **abduction and internal rotation**. * **Radiology:** Look for the **"Crescent sign"** (subchondral fracture) and increased radiodensity of the femoral head. * **Prognosis:** The most important prognostic factor is the **age at onset** (older children have a worse prognosis). * **Classification:** Catterall, Herring (Lateral Pillar), and Salter-Thompson classifications are used to grade severity.

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

Head of femur. **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.

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

Achondroplasia. **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.

Q: A short-statured boy with rhizomelic limbs and brachydactyly is a feature of which condition?

Achondroplasia. ### Explanation **Achondroplasia** is the most common cause of disproportionate short stature [1]. It is an autosomal dominant condition caused by a gain-of-function mutation in the **FGFR3 gene**, which inhibits chondrocyte proliferation at the epiphyseal growth plate [1]. 1. **Why Achondroplasia is correct:** * **Rhizomelic shortening:** This refers to the disproportionate shortening of the proximal segments of limbs (humerus and femur), a hallmark of achondroplasia [1]. * **Brachydactyly:** Shortening of the fingers and toes is characteristic, often presenting as a **"Trident hand"** (increased space between the 3rd and 4th digits). * Other features include macrocephaly, frontal bossing, and midface hypoplasia [1]. 2. **Why other options are incorrect:** * **Laron dwarfism:** Caused by growth hormone (GH) receptor insensitivity. It results in **proportionate** short stature with high GH levels and low IGF-1 levels. * **Hypothyroidism:** Congenital hypothyroidism (Cretinism) causes stunted growth and delayed bone age, but it is typically associated with intellectual disability, coarse facies, and a protuberant abdomen rather than specific rhizomelic limb shortening. * **Morquio disease (MPS IV):** A mucopolysaccharidosis characterized by short-trunk dwarfism (spondyloepiphyseal dysplasia), corneal clouding, and odontoid hypoplasia, rather than isolated rhizomelic limb shortening. **Clinical Pearls for NEET-PG:** * **Inheritance:** 80% of cases are due to **de novo mutations** associated with advanced paternal age [1]. * **Radiology:** Look for "squaring" of iliac wings (Champagne glass pelvis) and narrowing of the interpedicular distance in the lumbar spine. * **Intelligence:** Individuals with achondroplasia typically have **normal intelligence** and a normal lifespan.

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

Shortening of limb. 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) 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 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.

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

Cleidocranial dysplasia. ### 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.

Q: A child presented with a fall on an outstretched hand with the elbow in full extension. On examination there is pain and swelling over his right elbow. What is the probable diagnosis?

Supracondylar fracture of the humerus. ### Explanation **Correct Option: C. Supracondylar fracture of the humerus** **Mechanism and Concept:** Supracondylar fracture of the humerus is the most common elbow fracture in children (peak age 5–8 years). The classic mechanism is a **fall on an outstretched hand (FOOSH) with the elbow in extension**. In this position, the olecranon process is forced into the olecranon fossa, acting as a fulcrum that causes the thin supracondylar bone to snap. This results in an **extension-type** fracture (95% of cases), where the distal fragment is displaced posteriorly. **Analysis of Incorrect Options:** * **A. Fracture of the olecranon:** Rare in children; usually occurs due to a direct blow to the point of the elbow or a forceful contraction of the triceps. * **B. Posterior dislocation of the elbow:** While the mechanism (FOOSH) is similar, dislocations are much more common in **adults**. In children, the supracondylar area is physiologically weaker than the joint ligaments, making a fracture far more likely than a dislocation. * **D. Fracture of both bones of the forearm:** While FOOSH can cause forearm fractures, the clinical presentation specifically mentions pain and swelling **over the elbow**, pointing toward a periarticular injury. **NEET-PG High-Yield Pearls:** * **Clinical Sign:** On examination, the **three-point bony relationship** (medial epicondyle, lateral epicondyle, and olecranon) is **maintained** in supracondylar fractures but **disturbed** in elbow dislocations. * **Complications:** The most serious acute complication is injury to the **Brachial artery** or **Median nerve** (specifically the Anterior Interosseous Nerve). * **Late Sequel:** **Gunstock deformity** (Cubitus varus) is the most common late complication due to malunion. * **Emergency:** Always check the radial pulse to rule out **Volkmann’s Ischemic Contracture**.

Question 1

Which of the following is NOT part of the Ortolani test?

Accepted Answer

A jerk is given to the knee to dislocate the femur head (jerk of exit).

Answer

Examiner's thumb rests on the medial thigh.

Answer

Examiner's fingers lie on the greater trochanter.

Answer

Hips are flexed to 90 degrees and gently abducted.

Question 2

Which age group does Perthes disease primarily affect?

Accepted Answer

4 - 8 years

Answer

Less than 4 years

Answer

10 - 25 years

Answer

Greater than 25 years

Question 3

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

Accepted Answer

Head of femur

Answer

Upper end tibia

Answer

Lower end femur

Answer

Greater trochanter

Question 4

Trident hand is seen in which of the following conditions?

Accepted Answer

Achondroplasia

Answer

Mucopolysaccharidosis

Answer

Diphyseal achlasia

Answer

Cleidocranial dystosis

Question 5

What is the most commonly dislocated joint in the child's hand?

Accepted Answer

Metacarpophalangeal joint

Answer

Distal interphalangeal joint

Answer

Proximal interphalangeal joint

Answer

Carpometacarpal joint

Question 6

A short-statured boy with rhizomelic limbs and brachydactyly is a feature of which condition?

Accepted Answer

Achondroplasia

Answer

Laron dwarfism

Answer

Hypothyroidism

Answer

Morquio disease

Question 7

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

Accepted Answer

Shortening of limb

Answer

Positive family history

Answer

Breech presentation

Answer

Unstable hip

Question 8

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

Accepted Answer

Cleidocranial dysplasia

Answer

Crouzon syndrome

Answer

Treacher Collins syndrome

Answer

Goldenhar syndrome

Question 9

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?

Accepted Answer

Calcaneovarus

Answer

Calcaneovalgus

Answer

Equinovarus

Answer

Genu valgus

Question 10

A child presented with a fall on an outstretched hand with the elbow in full extension. On examination there is pain and swelling over his right elbow. What is the probable diagnosis?

Accepted Answer

Supracondylar fracture of the humerus

Answer

Fracture of the olecranon

Answer

Posterior dislocation of the elbow

Answer

Fracture of both bones of the forearm

Pediatric Orthopaedics — MCQs

Pediatric Orthopaedics — MCQs

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