MCQs – Congenital 2

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High-Yield Summary

This topic is a staple of the Royal College exam, focusing heavily on congenital bone disorders, metabolic skeletal diseases, and pediatric orthopaedic deformities. The single most important clinical trade-off often tested is the timing and choice of surgical intervention versus conservative management in congenital deformities such as radial clubhand and patellar dislocation. While classic exam answers emphasize definitive surgical correction, modern practice increasingly incorporates early splinting and staged procedures to optimize functional outcomes. Understanding biochemical markers and inheritance patterns is critical for diagnosis and genetic counseling.

High-Yield Decision Matrix

Active Recall Q&A

Congenital Bone Disorders

Q: What radiographic appearance is characteristic of melorheostosis?
A: Melorheostosis gives bones a “candle-dripping” appearance.
Related Pearl: This hyperostotic pattern helps differentiate melorheostosis from other sclerosing bone dysplasias.

Q: Where are metachromatic granules found and what is their diagnostic significance?
A: Metachromatic granules are found in lymphocytes and aid in diagnosing Hurler’s syndrome and other mucopolysaccharidoses.
Related Pearl: Metachromatic granules reflect lysosomal storage defects, critical for early diagnosis of these metabolic disorders.

Q: Which syndrome is homocystinuria most commonly confused with, and what are shared features?
A: Homocystinuria is most likely confused with Marfan’s syndrome; both have tall stature, long limbs, arachnodactyly, and scoliosis.
Related Pearl: Unlike Marfan’s, homocystinuria carries a higher risk of thromboembolism, influencing management.

Q: What collagen abnormality is seen in osteogenesis imperfecta?
A: Defective collagen cross-linking is most likely seen in osteogenesis imperfecta.
Related Pearl: This defect leads to bone fragility and abnormal dentition, distinguishing it from other connective tissue disorders.

Q: What conditions are associated with Sprengel’s deformity?
A: Sprengel’s deformity is associated with normal bone, cardiovascular abnormalities, Klippel-Feil syndrome, and metatarsus adductus; it is not associated with developmental dysplasia of the hip (DDH).
Related Pearl: Recognizing these associations guides comprehensive screening for systemic anomalies.

Q: What biomarker is elevated in Duchenne muscular dystrophy detectable at birth?
A: Duchenne muscular dystrophy shows elevated creatine phosphokinase (CPK) in cord blood.
Related Pearl: Early CPK elevation allows for newborn screening and early intervention planning.

Q: What is the typical age and presentation of Caffey’s disease?
A: Caffey’s disease occurs most prominently in the first 6 months, usually before 9 weeks, with febrile illness, hyperirritability, soft tissue swelling, and cortical bone thickening.
Related Pearl: Early onset and systemic symptoms help differentiate it from osteomyelitis.

Q: What are the key features of Larsen’s syndrome?
A: Larsen’s syndrome presents with multiple congenital dislocations, clubfoot, and congenital heart disease.
Related Pearl: Early diagnosis is critical to address joint instability and cardiac anomalies.

Q: Where is the pathological site in achondroplasia growth plates?
A: The pathology is in the hypertrophic and proliferative zones of the growth plate, including the provisional zone of calcification; iliac crest histology is normal.
Related Pearl: This explains why iliac crest bone grafts are unaffected in achondroplasia patients.

Q: What neurological and spinal features are seen in achondroplasia?
A: Narrowing of the foramen magnum and kyphosis, which tends to improve after walking.
Related Pearl: Foramen magnum stenosis is a major cause of morbidity and requires monitoring.

Q: What biochemical abnormality characterizes ochronosis?
A: Increased urine homogentisic acid, which causes urine to turn black when exposed to air.
Related Pearl: This metabolic defect leads to pigment deposition in connective tissues, causing arthritis.

Q: What clinical features are associated with ochronosis?
A: Radiodense liver, chondrocalcinosis, and diffuse arthritis.
Related Pearl: These features help differentiate ochronosis from other causes of arthritis in young adults.

Q: What is the inheritance pattern of vitamin D resistant rickets?
A: It is an X-linked dominant disorder.
Related Pearl: This inheritance pattern explains the variable severity in males and females.

Q: Which type of radial clubhand is most common and what is its laterality?
A: Type 4 (complete absence of radius) is most common; bilaterality is more common than unilateral.
Related Pearl: Bilateral involvement often indicates a more severe phenotype requiring early intervention.

Q: What is the initial management for congenital absence of the radius (type 4 radial clubhand)?
A: Initial splinting like clubfoot, followed by centralization surgery at 6-12 months.
Related Pearl: Early splinting prevents soft tissue contractures and facilitates surgical correction.

Q: Which structure is most at risk during radial clubhand surgery?
A: The median nerve, often just below the fascia and bowstrung across the radial bow.
Related Pearl: Careful dissection is required to avoid nerve injury and preserve hand function.

Q: What defines a complete terminal paraxial radial hemimelia?
A: Total absence of the radius with corresponding absent fingers.
Related Pearl: This severe deficiency impacts both bone and soft tissue development, complicating reconstruction.

Q: What deformities are associated with congenital absence of the fibula?
A: Anteromedial bowing of the tibia, lateral displacement of the foot, ankle and hindfoot valgus, and usually some degree of hindfoot equinus.
Related Pearl: These deformities often require staged orthopedic correction to restore alignment.

Q: What are the clinical features of congenital patellar dislocation?
A: Irreducible patellar dislocation at birth, flexion contracture, genu valgum, and external tibial torsion.
Related Pearl: Early surgical intervention is necessary to prevent secondary joint damage.

Q: What surgical procedures are involved in correcting congenital patellar dislocation?
A: Complete lateral quadriceps release, iliotibial band release, medial quadriceps stabilization, and patellar tendon centralization.
Related Pearl: Multiplanar soft tissue balancing is essential for stable patellar tracking.

Q: Name a few disorders transmitted by X-linked dominant inheritance.
A: Vitamin D resistant rickets (hypophosphatemic rickets) is one example.
Related Pearl: X-linked dominant disorders often show variable expressivity and may affect females less severely.

Q: How can bilateral radioulnar synostosis with fixed pronation be managed?
A: Osteotomy of the nondominant hand to place it in supination may improve function.
Related Pearl: Functional positioning is prioritized over anatomical correction in synostosis management.

Classic Clinical Notes

• Melorheostosis gives bones the “candle-dripping” appearance.

• Metachromatic granules are found in lymphocytes and aid in the diagnosis of Hurler’s syndrome (and other mucopolysaccharidoses).

• Homocystinuria is most likely confused with Marfan’s syndrome. Patients are tall, with long limbs, and may show arachnodactyly and scoliosis.

• Defective collagen cross-linking is most likely seen in osteogenesis imperfecta ??? homocystinuria? Marfans?

• Sprengels deformity is associated with normal bone, cardiovascular abnormalities, Klippel Feil, and metatarsus adductus – it is not been shown to be associated with DDH.

• Duchennes will have an elevated CPK in cord blood.

• Caffey’s disease (infantile cortical hyperostosis) is found most prominently during the first 6 months. It usually begins earlier than 9 weeks of age. It is characterized by a febrile illness with hyperirritability, swelling of soft tissues, and cortical thickening of bone.

• Larsen’s syndrome is seen with multiple congenital dislocations, clubfoot, congenital heart disease.

• In achondroplasia, the iliac crest histology is normal – the iliac crest growth is appositional, not endochondral. The area of pathology is in the hypertrophic and proliferative zones, which includes the provisional zone of calcification. Miller feels that the area of pathology is mainly in the proliferative zone, which does not include the zone of provisional calcification. There is narrowing of the foramen magnum and kyphosis which tends to improve once walking.

• In ochronosis, there is an increase in urine homogentisic acid. They get big radiodense livers, chondrocalcinosis, and diffuse arthritis. Ochronosis is a rare hereditary disorder of tyrosine and phenylalanine degradation resulting from the absence of homogentisic acid oxidase – leads to the accumulation of homogentisic acid in urine – causes urine to turn black when exposed to air.

• Vitamin D resistant rickets is an x-linked dominant disorder.

• In radial clubhand, type 4 is most common (complete absence); bilaterality is more common than unilateral.

• In congenital absence of the radius (type 4 radial clubhand), they should be splinted initially (like a clubfoot) then undergo centralization of the hand at 6-12 months.

• The structure most at risk in the radial clubhand surgery is the median nerve. It is often just below the fascia, and bowstrung across the radial bow.

• A totally absent radius with corresponding fingers is a complete terminal paraxial radial hemimelia.

• Congenital absence of the fibula is associated with anteromedial bowing of the tibia. The foot is laterally displaced relative to the tibia and there is ankle and hindfoot valgus that may be mild or severe. There is usually some degree of hindfoot equinus.

• In congenital patellar dislocation, the patellar dislocation is irreducible at birth. Flexion contracture, genu valgum, and external tibial torsion are present. Surgical correction includes a complete lateral quadriceps release, iliotibial band release, medial stabilization of the quads, and patellar tendon centralization.

• Few things are transmitted x-linked dominant – vitamin D resistant rickets (hypophosphatemic rickets) is one.

• Osteogenesis imperfecta is associated with abnormal dentition, deafness, normal urinary hydroxyproline levels, and abnormal synthesis of collagen – this probably affects their ability to crosslink.

• In the patient with bilateral radioulnar synostosis with fixed pronation in both, it may be helpful to osteotomize the nondominant hand and put it into supination.

Last Updated on January 25, 2026 by Christian Veillette