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4. Pediatrics MCQs

Practice Set 214 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 4261

Topic: 4. Pediatrics

A 4-year-old child with Neurofibromatosis Type 1 (NF1) presents with congenital pseudarthrosis of the tibia (Crawford Type IV). The patient is scheduled for surgical reconstruction with an intramedullary rod and a vascularized fibular graft. Achieving bony union relies critically on the complete radical resection of which of the following abnormal tissues at the pseudarthrosis site?

. Dysplastic bone marrow
. Avascular cartilage
. Hamartomatous periosteum
. Hypertrophic synovium
. Thickened endosteum

Correct Answer & Explanation

. Hamartomatous periosteum

Explanation

Congenital pseudarthrosis of the tibia (CPT) is frequently associated with NF1. The primary pathognomonic lesion is a thickened, highly cellular, hamartomatous periosteum that chokes the underlying bone, leading to osteoclastic resorption and impaired blood supply. Radical excision of this abnormal periosteal tissue is a prerequisite for achieving successful bony union.

Question 4262

Topic: 4. Pediatrics

In a 6-year-old child diagnosed with spastic diplegic cerebral palsy, which of the following factors serves as the strongest independent predictor for the development of lateral hip displacement (subluxation)?

. Age at diagnosis
. Tone (Ashworth scale)
. Prior heel cord lengthening
. Gross Motor Function Classification System (GMFCS) level
. Presence of equinovarus deformity

Correct Answer & Explanation

. Gross Motor Function Classification System (GMFCS) level

Explanation

The risk of hip displacement in children with cerebral palsy is directly and strongly correlated with their Gross Motor Function Classification System (GMFCS) level. Children who are non-ambulatory (GMFCS levels IV and V) have the highest incidence of hip displacement (up to 90%), necessitating strict radiographic surveillance protocols. The GMFCS is the most critical prognostic indicator.

Question 4263

Topic: 4. Pediatrics

A newborn is diagnosed with Proximal Focal Femoral Deficiency (PFFD). Upon further physical examination and imaging of the affected extremity, which of the following concurrent musculoskeletal anomalies is almost universally present?

. Radial clubhand
. Sprengel deformity
. Congenital vertical talus
. Absent anterior cruciate ligament
. Tibial hemimelia

Correct Answer & Explanation

. Absent anterior cruciate ligament

Explanation

Proximal focal femoral deficiency (PFFD) is heavily associated with fibular hemimelia, shortening of the extremity, and knee instability. Approximately 70-100% of patients with PFFD will have an absent anterior cruciate ligament (ACL). Other common associations include fibular hemimelia and coxa vara, but absent ACL is a classic, universally-tested association.

Question 4264

Topic: 4. Pediatrics

A newborn presents with short limbs, severe rigid clubfeet, 'hitchhiker' thumbs, and cystic swelling of the ear pinnae (cauliflower ears). This skeletal dysplasia is caused by a genetic mutation affecting which of the following?

. Fibroblast growth factor receptor 3 (FGFR3)
. Type I collagen (COL1A1)
. Core binding factor alpha 1 (CBFA1)
. Sulfate transporter (SLC26A2)
. Cartilage oligomeric matrix protein (COMP)

Correct Answer & Explanation

. Sulfate transporter (SLC26A2)

Explanation

The clinical presentation is classic for Diastrophic Dysplasia. It is an autosomal recessive disorder caused by a mutation in the SLC26A2 gene, which encodes a sulfate transporter (also known as DTDST). This results in under-sulfation of cartilage proteoglycans. Key features include hitchhiker thumbs, cauliflower ears, severe clubfeet, and cervical kyphosis.

Question 4265

Topic: 4. Pediatrics

Congenital pseudarthrosis of the clavicle occurs almost exclusively on the right side. If a newborn presents with isolated congenital pseudarthrosis of the LEFT clavicle, what is the most important clinical entity to rule out?

. Echocardiogram and chest radiograph for situs inversus
. Screen for Neurofibromatosis Type 1
. Renal ultrasound
. Genetic testing for Cleidocranial dysplasia
. No further workup needed

Correct Answer & Explanation

. Echocardiogram and chest radiograph for situs inversus

Explanation

Congenital pseudarthrosis of the clavicle is virtually always right-sided, believed to be due to normal right subclavian artery pulsations interfering with the fusion of the medial and lateral primary ossification centers. If it presents on the left side, it implies reversed vascular anatomy, meaning the clinician must urgently rule out dextrocardia or situs inversus.

Question 4266

Topic: Pediatric Lower Extremity

A 3-month-old presents with severe, atypical (complex) clubfoot characterized by a short, chubby foot, a deep transverse plantar crease, and severe equinus. Treatment via the modified Ponseti method should strictly emphasize which of the following?

. Maximum abduction of the foot to 70 degrees
. Immediate posteromedial release
. Serial casting with the knee in extension
. Application of an Ilizarov frame
. Early Achilles tenotomy and limiting abduction to 30-40 degrees

Correct Answer & Explanation

. Early Achilles tenotomy and limiting abduction to 30-40 degrees

Explanation

Atypical or complex clubfeet respond poorly to standard Ponseti casting and are prone to severe complications like iatrogenic midfoot break. The modified Ponseti technique involves recognizing the complex nature early, avoiding hyperabduction (limiting abduction to 30-40 degrees instead of the usual 60-70 degrees), and performing an early percutaneous Achilles tenotomy to correct the severe equinus.

Question 4267

Topic: 4. Pediatrics

A 2.5-year-old child presents with bilateral progressive tibia vara. Radiographs reveal fragmentation of the medial tibial metaphysis with a metaphyseal-diaphyseal angle (Drennan's angle) of 18 degrees. What is the most appropriate next step in management?

. Observation alone
. Proximal tibial valgus osteotomy
. Eight-plate epiphysiodesis of the medial proximal tibia
. Bisphosphonate infusion
. KAFO bracing during weight-bearing

Correct Answer & Explanation

. KAFO bracing during weight-bearing

Explanation

The child has Infantile Blount disease. A metaphyseal-diaphyseal angle (Drennan's angle) greater than 16 degrees strongly predicts true Blount disease rather than physiologic bowing. For children under 3 years of age with an angle > 16 degrees (Langenskiold Stage I or II), the standard initial treatment is KAFO (knee-ankle-foot orthosis) bracing. Surgery is indicated if bracing fails or if the child presents after age 3-4 with advanced stages.

Question 4268

Topic: 4. Pediatrics
A 14-year-old male sustains an isolated Salter-Harris III fracture of the anterolateral distal tibia. Which of the following is the predominant mechanism of injury for this specific fracture pattern?
. Inversion and plantarflexion
. External rotation of the foot on the leg
. Axial loading
. Direct blow to the lateral malleolus
. Hyperdorsiflexion

Correct Answer & Explanation

. External rotation of the foot on the leg

Explanation

The scenario describes a Tillaux fracture (Salter-Harris III of the anterolateral distal tibia). It occurs due to an external rotation force of the foot relative to the leg, leading to an avulsion by the anterior inferior tibiofibular ligament (AITFL). This happens in adolescents because the distal tibial physis closes in a predictable pattern: central, then medial, and finally lateral, leaving the anterolateral portion vulnerable.

Question 4269

Topic: Pediatric Hip

A 12-year-old overweight boy presents with sudden severe left hip pain and is completely unable to bear weight, even with crutches (Loder unstable SCFE). The exceptionally high risk of avascular necrosis (AVN) in this condition is primarily due to disruption of which of the following vessels?

. Artery of the ligamentum teres
. Medial femoral circumflex artery (lateral epiphyseal branches)
. Lateral femoral circumflex artery
. Inferior gluteal artery
. First perforating artery

Correct Answer & Explanation

. Medial femoral circumflex artery (lateral epiphyseal branches)

Explanation

An unstable Slipped Capital Femoral Epiphysis (SCFE) carries an AVN risk of up to 47%. The blood supply to the femoral head in this age group relies almost entirely on the posterosuperior and posteroinferior retinacular vessels, which are terminal lateral epiphyseal branches of the Medial Femoral Circumflex Artery (MFCA). These vessels are uniquely stretched or torn during the acute slip.

Question 4270

Topic: 4. Pediatrics

A 13-year-old elite baseball pitcher presents with insidious onset shoulder pain that occurs primarily during the late cocking and early acceleration phases of throwing. Radiographs show widening and sclerosis of the proximal humeral physis. What is the primary pathophysiology of this specific condition?

. Avulsion of the greater tuberosity
. Salter-Harris I fracture (epiphysiolysis) of the proximal humerus
. Osteochondritis dissecans of the humeral head
. Tear of the superior labrum
. Coracoid apophysitis

Correct Answer & Explanation

. Salter-Harris I fracture (epiphysiolysis) of the proximal humerus

Explanation

The scenario describes 'Little League Shoulder', which is essentially a stress fracture or repetitive microtrauma leading to epiphysiolysis (a chronic Salter-Harris Type I fracture) of the proximal humeral physis. It is caused by the repetitive high-torque rotational forces generated during throwing.

Question 4271

Topic: 4. Pediatrics

A 6-year-old boy presents with bilateral hearing loss, mild midface hypoplasia, and rigid flatfeet. Radiographs reveal bilateral calcaneocuboid and carpal coalitions. Genetic testing reveals a Pro250Arg mutation in the FGFR3 gene. What is the most likely diagnosis?

. Apert syndrome
. Crouzon syndrome
. Muenke syndrome
. Pfeiffer syndrome
. Jackson-Weiss syndrome

Correct Answer & Explanation

. Muenke syndrome

Explanation

Muenke syndrome is an autosomal dominant disorder caused by a specific mutation (Pro250Arg) in the FGFR3 gene. It is characterized by coronal craniosynostosis, sensorineural hearing loss, and notably, carpal and tarsal coalitions (especially calcaneocuboid coalitions). Apert, Crouzon, and Pfeiffer syndromes are primarily associated with FGFR2 mutations (though Pfeiffer can be FGFR1/2).

Question 4272

Topic: 4. Pediatrics

Which of the following intramedullary implants is widely considered the modern gold standard for long bone stabilization in a growing child with severe osteogenesis imperfecta, as it accommodates longitudinal growth while minimizing the need for repetitive surgeries?

. Rush pins
. Titanium elastic nails (TENs)
. Fassier-Duval telescoping nails
. Rigid locked intramedullary nails
. Ender nails

Correct Answer & Explanation

. Fassier-Duval telescoping nails

Explanation

In severe osteogenesis imperfecta, long bones frequently fracture and become deformed. Stabilization typically involves multi-level corrective osteotomies (so-called 'shish kebab' technique) followed by intramedullary fixation. The Fassier-Duval telescoping nail is a single-incision telescopic rod designed to elongate as the child grows, preventing the implant from migrating or the bone from 'growing off' the rod, which is a common failure mode for non-telescoping pins (e.g., Rush or TENs).

Question 4273

Topic: Pediatric Hip

A 4-year-old girl is brought to clinic due to a limping gait. Physical examination reveals a positive Trendelenburg sign on the left, leg length discrepancy (left shorter), and limited abduction of the left hip. Radiographs show significant dysplasia and a superolateral dislocation of the left hip. The most appropriate initial surgical management for this patient would be:

. Pavlik harness application.
. Closed reduction and spica cast application.
. Open reduction, femoral shortening osteotomy, and pelvic osteotomy.
. Traction followed by closed reduction.
. Arthroscopic reduction with capsular plication.

Correct Answer & Explanation

. Open reduction, femoral shortening osteotomy, and pelvic osteotomy.

Explanation

For developmental dysplasia of the hip (DDH) presenting in a 4-year-old child with a dislocated hip, the likelihood of successful closed reduction is very low due to soft tissue contractures and acetabular dysplasia. A Pavlik harness (Option A) is ineffective beyond 6-12 months of age. Closed reduction (Option B) or traction followed by closed reduction (Option D) are generally not successful in this age group without significant risk of avascular necrosis (AVN). Open reduction is required to release contractures (e.g., psoas, adductors) and reduce the femoral head. A femoral shortening osteotomy is crucial to reduce pressure on the femoral head after reduction, thereby minimizing the risk of AVN. A pelvic osteotomy (e.g., Dega, Salter, Pemberton) is necessary to provide adequate acetabular coverage for the femoral head (Option C). Arthroscopic reduction (Option E) is typically for much younger children or specific soft tissue interposition issues, not for a chronic dislocation with significant bony changes.

Question 4274

Topic: Pediatric Upper Extremity & Spine
A 6-year-old boy presents to the emergency department after falling off a swing. He has a visibly deformed right elbow. Examination reveals an obviously swollen, cool, and pale hand with diminished radial pulse. Capillary refill is >3 seconds. Radiographs confirm a displaced, comminuted supracondylar humerus fracture (Gartland Type III extension type). What is the immediate priority after initial assessment and analgesia?
. Emergent CT angiography to assess vascular injury.
. Closed reduction and percutaneous pinning.
. Exploration of the brachial artery and repair.
. Immediate traction in the emergency department.
. Application of a long arm splint and observation.

Correct Answer & Explanation

. Closed reduction and percutaneous pinning.

Explanation

This is a critical scenario indicating a displaced supracondylar humerus fracture with signs of vascular compromise (cool, pale hand, diminished radial pulse, poor capillary refill). The first and most critical orthopedic intervention is an attempt at gentle closed reduction and percutaneous pinning (Option 1). Often, the vascular compromise is due to kinking or spasm of the brachial artery over the displaced fracture fragments. Reduction of the fracture can restore blood flow by decompressing the artery. If the pulse does not return after successful reduction and pinning, then an emergent vascular exploration (Option 2) is warranted. CT angiography (Option 0) is not the immediate priority; the clinical signs are sufficient for urgent action. Traction (Option 3) alone is not the definitive management. Splinting and observation (Option 4) is contraindicated with vascular compromise.

Question 4275

Topic: Pediatric Hip

An obese 13-year-old male presents with acute onset of severe left hip and knee pain and an inability to bear weight after stumbling. On examination, the left leg is externally rotated and shortened. He resists all attempts at passive hip motion. Radiographs reveal a significantly displaced left Slipped Capital Femoral Epiphysis (SCFE). Which of the following is the most appropriate urgent management step?

. Gentle closed reduction and spica casting.
. Percutaneous in situ pinning without reduction.
. Open reduction and internal fixation.
. Traction followed by percutaneous pinning.
. Non-weight-bearing and observation for stability.

Correct Answer & Explanation

. Percutaneous in situ pinning without reduction.

Explanation

This presentation describes an unstable Slipped Capital Femoral Epiphysis (SCFE), defined by the inability to bear weight. Unstable SCFE is an orthopedic emergency due to the high risk of avascular necrosis (AVN) of the femoral head. The most appropriate urgent management is percutaneous in situ pinning without reduction (Option B). The goal is to stabilize the physis and prevent further slip. Attempts at forceful closed reduction (Option A) carry a significantly increased risk of AVN due to disruption of the retinacular vessels, and are generally contraindicated. Open reduction and internal fixation (Option C) is typically reserved for severe chronic slips or failed in situ pinning. Traction (Option D) is not the primary intervention. Non-weight-bearing and observation (Option E) is insufficient and dangerous for an unstable slip.

Question 4276

Topic: Pediatric Upper Extremity & Spine

A 14-year-old girl is diagnosed with Adolescent Idiopathic Scoliosis. Her current Cobb angle is 48 degrees, and she has a Risser sign of 3. She experiences mild back pain after prolonged standing but denies any neurological symptoms. Her skeletal maturity is nearing completion. What is the most appropriate management recommendation?

. Observation with serial radiographs every 6-12 months.
. Bracing with a thoracolumbosacral orthosis (TLSO).
. Surgical correction with posterior spinal fusion.
. Referral for chiropractic manipulation.
. Physical therapy focused on core strengthening and flexibility.

Correct Answer & Explanation

. Surgical correction with posterior spinal fusion.

Explanation

The standard indication for surgical correction of Adolescent Idiopathic Scoliosis (AIS) is a Cobb angle greater than 45-50 degrees. This patient has a 48-degree curve and a Risser sign of 3, indicating some remaining growth potential, which means the curve could still progress. Given the magnitude of the curve and the patient's age and Risser sign, surgical correction with posterior spinal fusion (Option C) is the most appropriate management to prevent further progression and improve alignment. Observation (Option A) is for smaller curves (<20-25 degrees). Bracing (Option B) is typically recommended for progressive curves between 25-45 degrees in skeletally immature patients to prevent progression, but it is less effective for curves already >45 degrees or nearing skeletal maturity. Chiropractic manipulation (Option D) and physical therapy (Option E) are not proven to correct or halt the progression of AIS curves of this magnitude.

Question 4277

Topic: Pediatric Hip

An 11-year-old obese male underwent in situ pinning for a stable, mild slipped capital femoral epiphysis (SCFE) of the left hip 6 months ago. He now presents with acute, severe, new onset left hip pain, limited range of motion, and a temperature of 38.5°C. Radiographs show no further slippage but evidence of joint space narrowing and subchondral lucency. What is the MOST likely complication, and what is the definitive diagnostic test?

. Progression of SCFE; repeat MRI.
. Contralateral SCFE; evaluate asymptomatic hip.
. Chondrolysis; hip aspiration and MRI.
. Avascular necrosis of the femoral head; CT scan.
. Osteomyelitis; blood cultures and bone biopsy.

Correct Answer & Explanation

. Chondrolysis; hip aspiration and MRI.

Explanation

This presentation (acute severe pain, limited ROM, fever, joint space narrowing, subchondral lucency) following SCFE treatment, especially in an obese adolescent, is highly suspicious for chondrolysis. Chondrolysis is a severe complication of SCFE, characterized by rapid destruction of articular cartilage, leading to joint space narrowing and stiffness. While AVN can also occur, the fever and rapid onset of severe pain along with joint space narrowing (rather than femoral head collapse seen later in AVN) point more towards chondrolysis.Option A (Progression of SCFE) is unlikely given the 'no further slippage' on radiographs.Option B (Contralateral SCFE) is common in SCFE patients but doesn't explain the acute symptoms and radiographic findings in the affected hip.Option C (Chondrolysis; hip aspiration and MRI) is the most likely diagnosis. Hip aspiration is crucial to rule out septic arthritis (which can mimic chondrolysis symptoms and sometimes coexist). MRI is excellent for evaluating cartilage status, synovitis, and ruling out other pathologies like avascular necrosis.Option D (Avascular necrosis) is a serious complication of SCFE, but the acute fever and the specific radiographic findings (joint space narrowing) make chondrolysis a stronger primary suspicion. CT is good for bone detail, but MRI is superior for cartilage and AVN in early stages.Option E (Osteomyelitis) is less likely to present primarily with joint space narrowing and subchondral lucency, and bone biopsy is more invasive than initially warranted. While septic arthritis should be ruled out (hence aspiration), osteomyelitis of the femoral head is a rarer primary complication here.

Question 4278

Topic: Pediatric Hip

A 3-year-old female is diagnosed with developmental dysplasia of the hip (DDH) after parents notice a limp and asymmetry in gait. Physical examination reveals a positive Trendelenburg sign and limited abduction of the left hip. Radiographs show a dislocated left hip with a shallow acetabulum and underdeveloped femoral head. What is the MOST likely initial treatment strategy?

. Pavlik harness application.
. Open reduction and Dega osteotomy.
. Closed reduction under anesthesia with hip spica cast application.
. Femoral osteotomy and Pemberton acetabuloplasty.
. Observation with serial ultrasounds.

Correct Answer & Explanation

. Open reduction and Dega osteotomy.

Explanation

The treatment for DDH is highly dependent on the patient's age and the severity of the dysplasia. A 3-year-old with a dislocated hip, limp, Trendelenburg sign, and radiographic evidence of a shallow acetabulum and underdeveloped femoral head represents a late presentation of DDH.Option A (Pavlik harness application) is effective for infants up to 6 months of age (and sometimes up to 12 months for reducible hips). It is contraindicated and ineffective for a dislocated hip in a 3-year-old, as the hip is unlikely to be reducible by gentle manipulation and the child is too old for this non-operative approach.Option B (Open reduction and Dega osteotomy) is a common and appropriate treatment for late-presenting DDH (typically 18 months to 8 years) where closed reduction is unlikely or has failed, and there is significant acetabular dysplasia. Open reduction is needed to place the femoral head into the true acetabulum, and an acetabuloplasty (like a Dega or Salter osteotomy) is performed to improve acetabular coverage and provide stability to the joint.Option C (Closed reduction under anesthesia with hip spica cast application) might be attempted in children under 18-24 months for reducible hips. For a 3-year-old with a chronically dislocated hip, closed reduction is often not possible due to soft tissue contractures (e.g., psoas, adductors), and even if achieved, the severe acetabular dysplasia would likely lead to redislocation without additional bony procedures.Option D (Femoral osteotomy and Pemberton acetabuloplasty) is also a valid surgical option for this age group, often combined with open reduction. The Pemberton is another type of acetabuloplasty. However, the Dega osteotomy is well-established for this age group to improve coverage. Both B and D are surgical options, but B is a common, well-described primary approach.Option E (Observation with serial ultrasounds) is appropriate only for mild dysplasia or hip instability in very young infants (e.g., Barlow/Ortolani positive) and is completely inappropriate for a 3-year-old with a dislocated hip and functional deficits.

Question 4279

Topic: 4. Pediatrics

A 7-year-old female presents with progressive scoliosis. Radiographs show a right thoracic curve of 35 degrees with a compensatory left lumbar curve. There is no evidence of underlying neurological conditions or congenital vertebral anomalies. She has a positive Adam's forward bend test. What is the MOST appropriate initial management plan?

. Surgical correction with posterior spinal fusion.
. Bracing with a thoracolumbosacral orthosis (TLSO).
. Observation with serial radiographs every 6-12 months.
. Skeletal traction followed by serial casting.
. Physical therapy focusing on core strengthening and stretching.

Correct Answer & Explanation

. Bracing with a thoracolumbosacral orthosis (TLSO).

Explanation

This patient presents with adolescent idiopathic scoliosis (AIS). The management of AIS depends primarily on the curve magnitude, skeletal maturity, and progression.Option A (Surgical correction with posterior spinal fusion) is generally indicated for curves greater than 45-50 degrees in skeletally immature or mature patients, or for progressive curves despite bracing. A 35-degree curve, even if progressive, typically does not meet the surgical threshold at 7 years old unless it's rapidly progressing or is congenital/neuromuscular (which are ruled out).Option B (Bracing with a thoracolumbosacral orthosis (TLSO)) is the MOST appropriate initial management for progressive curves between 25 and 45 degrees in skeletally immature patients. A 35-degree curve in a 7-year-old (who is skeletally immature) falls squarely into this category. The goal of bracing is to prevent curve progression, especially during growth spurts, thereby avoiding surgery.Option C (Observation with serial radiographs) is appropriate for curves less than 20-25 degrees or in skeletally mature patients with non-progressive curves.Option D (Skeletal traction followed by serial casting) is a technique used for severe, rigid curves, often in very young children with early-onset scoliosis (EOS) (e.g., Mehta casting) or for preoperative correction in very severe curves, but not for initial management of a 35-degree AIS curve.Option E (Physical therapy) can be an adjunct for pain management and improving posture but has not been shown to halt or correct curve progression in AIS.

Question 4280

Topic: 4. Pediatrics

A 3-year-old child presents with a congenital short right lower limb, equinus foot, and knee flexion contracture. Radiographs show a shortened, hypoplastic femur with a pseudarthrosis at the proximal metaphyseal-diaphyseal junction and absence of the femoral head and acetabulum. The contralateral limb is normal. This presentation is most consistent with which of the following conditions?

. Congenital coxa vara.
. Proximal Femoral Focal Deficiency (PFFD) Type C.
. Developmental dysplasia of the hip (DDH).
. Fibrous dysplasia of the femur.
. PFFD Type D.

Correct Answer & Explanation

. PFFD Type D.

Explanation

Proximal Femoral Focal Deficiency (PFFD) is a rare congenital anomaly characterized by varying degrees of femoral shortening and proximal femoral underdevelopment. The Aitken classification system is widely used: Type A and B have a proximal femoral segment, while Type C and D have absence of a proximal femur. Type D involves the absence of the femoral head and acetabulum, with an intact shaft but often associated with a pseudarthrosis, as described in the scenario. Type C also lacks the femoral head and acetabulum but often has a shorter, more dysplastic femoral shaft. Given the description of 'absence of the femoral head and acetabulum' and 'pseudarthrosis at the proximal metaphyseal-diaphyseal junction' with a hypoplastic femur, Type D PFFD is the most fitting description. Congenital coxa vara (Option A) involves an abnormal decrease in the neck-shaft angle but typically has a formed femoral head and acetabulum. DDH (Option C) is a maldevelopment of the hip joint but doesn't involve femoral hypoplasia to this extent. Fibrous dysplasia (Option D) is a bone disorder, not a congenital deficiency resulting in such severe limb shortening and joint absence.

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