Pediatric Orthopaedics Practice Questions

Q: What is the most common cause of genu valgum (knock knee)?

Idiopathic. **Explanation:** **Genu Valgum**, commonly known as "knock knees," is a condition where the knees angle inward and touch each other while the feet remain apart. 1. **Why Idiopathic is correct:** In the pediatric population, the most common cause of genu valgum is **idiopathic (physiological)**. It is a normal part of the lower limb's rotational and angular development. Children typically transition from physiological genu varum (bow legs) at birth to a neutral alignment at 18–24 months, followed by a peak of **physiological genu valgum between ages 3 and 4**. This usually resolves spontaneously by age 7. 2. **Why other options are incorrect:** * **Osteoarthritis:** While it can cause knee deformities, it more commonly results in genu varum (medial compartment wear) and is a disease of the elderly, not the primary cause in the general population. * **Rheumatoid Arthritis:** This can lead to genu valgum due to lateral compartment erosion and ligamentous laxity, but it is an inflammatory pathology and far less common than idiopathic causes. * **Trauma:** Injuries to the lateral proximal tibial growth plate (e.g., Cozen’s fracture) can cause asymmetric genu valgum, but these are specific, localized incidents rather than the most common cause. **High-Yield Clinical Pearls for NEET-PG:** * **The "3-4 Rule":** Peak physiological genu valgum occurs at **3–4 years** of age. * **Measurement:** It is clinically assessed by the **Intermalleolar Distance (IMD)**. An IMD >8 cm is generally considered pathological if it persists beyond age 8. * **Pathological Causes:** If not idiopathic, consider **Rickets** (most common metabolic cause), skeletal dysplasias, or post-traumatic physeal arrest. * **Surgery:** If correction is needed in a growing child, **Guided Growth (Hemi-epiphysiodesis)** using tension band plates (e.g., 8-plates) is the preferred intervention.

Q: Which of the following is NOT a cause of pseudoarthrosis?

Osteomyelitis. **Explanation:** The term **Pseudoarthrosis** (false joint) refers to a specific pathological condition where there is a failure of bone union, resulting in a fibrocartilaginous interface between bone ends. In pediatric orthopaedics, this is most commonly seen in the tibia. **Why Osteomyelitis is the correct answer:** Osteomyelitis typically leads to **Non-union** or **Infected Non-union**, but not "Pseudoarthrosis" in the clinical sense. In chronic osteomyelitis, the hallmark is the formation of a *Sequestrum* (dead bone) and *Involucrum* (new bone sheath). While the bone may fail to unite due to infection, the underlying pathophysiology involves necrosis and suppuration rather than the specific dysplastic fibrovascular tissue characteristic of Congenital Pseudoarthrosis of the Tibia (CPT). **Analysis of other options:** * **Neurofibromatosis (Type 1):** This is the most common association. Approximately 50% of patients with CPT have NF-1. It is caused by a defect in the periosteum which leads to hamartomatous fibrous tissue formation. * **Idiopathic:** Many cases of pseudoarthrosis occur spontaneously without an identifiable systemic syndrome, though they share the same clinical presentation of bowing and subsequent fracture. * **Multiple Compound Fractures:** Severe trauma with extensive soft tissue loss and bone loss can lead to an acquired pseudoarthrosis, where the bone ends become sclerotic and the medullary canal closes, preventing union. **NEET-PG High-Yield Pearls:** * **Most common site:** Distal third of the Tibia. * **NF-1 Association:** CPT is a "diagnostic criteria" for NF-1 if present with other signs like Café-au-lait spots. * **Radiological sign:** "Pre-pseudarthrosis" shows anterolateral bowing of the tibia. * **Treatment:** Very difficult; often requires the **Ilizarov technique** or **Vascularized Fibular Graft**. Avoid simple casting as it rarely leads to union.

Q: Which of the following is NOT a feature of cleidocranial dysostosis?

Short metacarpals. **Cleidocranial Dysostosis (CCD)** is an autosomal dominant skeletal dysplasia caused by a mutation in the **RUNX2 gene**, which is essential for osteoblast differentiation and intramembranous ossification. ### Why "Short Metacarpals" is the Correct Answer: In CCD, the hands typically show **long second metacarpals** and the presence of **pseudo-epiphyses** at the base of the metacarpals. Short metacarpals (specifically the 4th and 5th) are characteristic of conditions like *Pseudohypoparathyroidism* (Albright's Hereditary Osteodystrophy) or *Turner Syndrome*, but not CCD. ### Analysis of Other Options: * **Short Stature (A):** This is a common feature of CCD. Patients are generally shorter than their peers due to generalized skeletal dysplasia. * **Wide Foramen Magnum (B):** CCD involves delayed ossification of the skull. This leads to wide sutures, late closure of fontanelles (sometimes remaining open for life), and a characteristically **wide foramen magnum**. * **Absent Clavicle (D):** This is the hallmark of the condition. There is partial or complete aplasia of the clavicles (usually the lateral part). This allows the patient to abnormally approximate their shoulders in the midline. ### High-Yield Clinical Pearls for NEET-PG: * **Genetics:** RUNX2 gene (Chromosome 6p21). * **Skull:** Presence of **Wormian bones**, frontal bossing, and hypertelorism. * **Dental:** Highly characteristic **supernumerary teeth** (extra teeth) and delayed eruption of permanent teeth. * **Pelvis:** Delayed ossification of the pubic symphysis (appears wide/absent on X-ray). * **Clinical Sign:** Ability to touch shoulders together in front of the chest.

Q: All of the following conditions can lead to genu recurvatum, except?

Perthes disease. **Explanation:** **Genu recurvatum** is a deformity of the knee joint characterized by excessive hyperextension (beyond 10–15 degrees). It typically results from ligamentous laxity, muscular imbalance, or malunion of fractures around the knee. **Why Perthes Disease is the Correct Answer:** Perthes disease (Legg-Calvé-Perthes) is an idiopathic avascular necrosis of the **femoral head** in children. It primarily affects the **hip joint**, leading to a limp, pain, and restricted abduction and internal rotation. It does not involve the knee joint or the mechanical axis of the tibia/femur in a way that causes hyperextension; therefore, it is not a cause of genu recurvatum. **Analysis of Other Options:** * **Poliomyelitis:** This is a classic cause. Weakness of the quadriceps leads the patient to lock their knee in hyperextension to maintain stability during the stance phase of gait. Over time, this stretches the posterior capsule, resulting in recurvatum. * **Rheumatoid Arthritis:** Chronic inflammation leads to ligamentous laxity and joint destruction. If the posterior cruciate ligament (PCL) or posterior capsule becomes incompetent, the knee can drift into hyperextension. * **Rickets:** Nutritional deficiencies lead to softened bones. Weight-bearing on weak physes can cause anterior bowing of the femur or tibia, or a "tilting" of the tibial plateau, resulting in a recurvatum deformity. **Clinical Pearls for NEET-PG:** * **Most common cause worldwide:** Historically, Poliomyelitis (due to muscle imbalance). * **Congenital Genu Recurvatum:** Often associated with developmental dysplasia of the hip (DDH). * **Hand-to-knee gait:** Seen in Polio patients with quadriceps weakness to prevent the knee from buckling by forcing it into recurvatum. * **Osseous vs. Postural:** Rickets causes *osseous* recurvatum, while Polio causes *postural/ligamentous* recurvatum.

Q: The primary defects in Congenital Talipes Equinovarus (CTEV) are the following EXCEPT:

Calcaneus. **Explanation:** Congenital Talipes Equinovarus (CTEV), also known as Clubfoot, is a complex congenital deformity characterized by a specific sequence of malalignments. The standard mnemonic to remember the primary components of CTEV is **CAVE**. 1. **C – Cavus:** Excessive longitudinal arch of the foot (due to tight intrinsic muscles). 2. **A – Adduction:** Forefoot adduction at the Tarsometatarsal joints. 3. **V – Varus:** Inversion and adduction of the hindfoot at the Subtalar joint. 4. **E – Equinus:** Plantarflexion at the Ankle joint (due to tight Achilles tendon). **Why Calcaneus is the Correct Answer:** "Calcaneus" refers to a deformity where the foot is dorsiflexed at the ankle (the opposite of Equinus). In CTEV, the heel is in **Equinus** (pointed downwards). Therefore, Calcaneus is not a component of CTEV; rather, it is the hallmark of a different condition called *Talipes Calcaneovalgus*. **Analysis of Incorrect Options:** * **Equinus:** A primary defect caused by the contracture of the Tendo-Achilles, leading to the inability to dorsiflex the foot. * **Adduction:** Occurs primarily at the midtarsal joints where the forefoot moves medially in relation to the hindfoot. * **Varus:** A key hindfoot deformity where the heel tilts inward, primarily involving the subtalar and talocalcaneonavicular joints. **Clinical Pearls for NEET-PG:** * **Order of Correction (Ponseti Method):** Corrected in the order of **C-A-V-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 long axis of the talus and calcaneus is **decreased** in CTEV (normal is 20–40°).

Q: Epiphyseal plate fractures are classified by:

Salter-Harris classification. **Explanation:** The **Salter-Harris classification** is the gold standard system used to categorize fractures involving the epiphyseal plate (growth plate) in children [1]. This classification is crucial because the growth plate is the weakest part of the pediatric skeleton, and injuries here can lead to permanent growth disturbances [1]. * **Type I:** Slipped (Separation through the physis) [1]. * **Type II:** Above (Physis + Metaphysis) – **Most common type.** [1] * **Type III:** Lower (Physis + Epiphysis) – Intra-articular [1]. * **Type IV:** Through (Metaphysis + Physis + Epiphysis) [1]. * **Type V:** Erased/Crush (Compression of the physis) – Worst prognosis [1]. **Analysis of Incorrect Options:** * **Herring’s Classification:** Used for **Legg-Calvé-Perthes disease** (Lateral Pillar classification) to determine prognosis based on the height of the lateral pillar of the femoral head. * **Garden’s Classification:** Used for **Fracture Neck of Femur** in adults, based on the degree of displacement (Stages I-IV). * **Pauwel’s Classification:** Also used for **Fracture Neck of Femur**, but based on the **angle of the fracture line** relative to the horizontal plane (predicts shear force stability). **High-Yield Clinical Pearls for NEET-PG:** * **Thurston-Holland Sign:** A triangular metaphyseal fragment seen in Salter-Harris **Type II** fractures [1]. * **Prognosis:** Types I and II generally have a good prognosis and can often be managed conservatively. Types III and IV require anatomical reduction to prevent growth arrest and joint incongruity [1]. * **Most Common:** Salter-Harris Type II is the most frequently encountered clinical presentation [1].

Question 1

What is the most common cause of genu valgum (knock knee)?

Accepted Answer

Idiopathic

Answer

Osteoarthritis

Answer

Rheumatoid arthritis

Answer

Trauma

Question 2

Which of the following is NOT a cause of pseudoarthrosis?

Accepted Answer

Osteomyelitis

Answer

Idiopathic

Answer

Multiple compound fractures

Answer

Neurofibromatosis

Question 3

Which of the following is NOT a feature of cleidocranial dysostosis?

Accepted Answer

Short metacarpals

Answer

Short stature

Answer

Wide foramen magnum

Answer

Absent clavicle

Question 4

All of the following conditions can lead to genu recurvatum, except?

Accepted Answer

Perthes disease

Answer

Rheumatoid arthritis

Answer

Poliomyelitis

Answer

Rickets

Question 5

Which of the following is the most common complication following surgery after repair of Sprengel deformity?

Accepted Answer

Brachial plexus injury

Answer

Infection

Answer

Mediastinitis

Answer

Dislocation of the shoulder

Question 6

Symptomatic spinal injury without radiological evidence is most commonly found in which patient population?

Accepted Answer

Children

Answer

Elderly

Answer

Teenagers

Answer

Young adults

Question 7

A nine-year-old girl with a simple, undisplaced fracture of the shaft of her right tibia has been treated with an above-knee plaster cast. Four years prior, she was affected by poliomyelitis. What is the best possible advice you can offer her parents regarding the prognosis of the fractured limb's union?

Accepted Answer

Fracture will unite normally.

Answer

Fracture will unite slowly.

Answer

Fracture will not unite.

Answer

Fracture will unite upon attaining puberty.

Question 8

A 3-year-old child presents with a fracture of the femoral shaft, which has been immobilized on traction for two months. What is the next step in management?

Accepted Answer

Hip spica cast and, if necessary, internal fixation

Answer

Callow traction for 2 months

Answer

Open reduction and Kuntscher's intramedullary nailing or plating

Answer

Traction by Thomas splint

Question 9

The primary defects in Congenital Talipes Equinovarus (CTEV) are the following EXCEPT:

Accepted Answer

Calcaneus

Answer

Equinus

Answer

Adduction

Answer

Varus

Question 10

Epiphyseal plate fractures are classified by:

Accepted Answer

Salter-Harris classification

Answer

Herring's classification

Answer

Garden's classification

Answer

Pauwel's classification

Pediatric Orthopaedics — MCQs

Pediatric Orthopaedics — MCQs

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