Orthopedic Manifestations of Genetic Disorders — MCQs

10 questions

In which condition is the presence of an extra pair of ribs sometimes observed?

Which of the following is least commonly associated with Down's syndrome?

A 10-year-old boy presents with frequent fractures and blue sclerae. This patient most likely carries a mutation in a gene that encodes which of the following proteins?

A 10-year-old girl presents with severe joint laxity, scoliosis, and a history of easy bruising. Which of the following conditions is most likely?

Mutations in type I collagen fibres results in:

An intrauterine scan at the 13th week of pregnancy showed a fetus with multiple long bone fractures. What is commonly associated with this finding?

The most commonly involved nerve in lunate dislocation is -

Identify the true statement regarding the clinical examination given in the image:

False about fracture of vertebrae

Q10Easy

Slipped capital femoral epiphysis is seen most commonly in which age group?

Orthopedic Manifestations of Genetic Disorders Indian Medical PG Practice Questions and MCQs

Question 1: In which condition is the presence of an extra pair of ribs sometimes observed?

A. Down syndrome
B. Turner syndrome (Correct Answer)
C. Holt-Oram syndrome
D. Fibrous dysplasia
E. Klinefelter syndrome

Explanation: ***Turner syndrome*** - **Turner syndrome** (45,X) is often associated with skeletal abnormalities, including an extra pair of ribs (cervical ribs) in some cases. - Other common skeletal features include **short stature**, a **shield chest**, and **cubitus valgus**. *Down syndrome* - **Down syndrome** (trisomy 21) is characterized by specific facial features, intellectual disability, and congenital heart defects. - While it can manifest with various skeletal anomalies, an extra pair of ribs is not a characteristic feature. *Klinefelter syndrome* - **Klinefelter syndrome** (47,XXY) is characterized by hypogonadism, tall stature, gynecomastia, and learning difficulties. - Skeletal features may include long limbs and decreased bone density, but cervical ribs are not typically associated with this condition. *Holt-Oram syndrome* - **Holt-Oram syndrome** is a genetic disorder affecting heart and limb development, specifically the upper limbs (thumb abnormalities, phocomelia). - It does not typically involve the presence of an extra pair of ribs. *Fibrous dysplasia* - **Fibrous dysplasia** is a bone disorder where normal bone is replaced by fibrous tissue, leading to weakened bone and fractures. - It is a localized bone condition and does not involve the presence of supernumerary ribs.

Question 2: Which of the following is least commonly associated with Down's syndrome?

A. Periodontal disease
B. Delayed eruption of deciduous teeth
C. Premature loss of deciduous teeth (Correct Answer)
D. Retrognathia

Explanation: ***Premature loss of deciduous teeth*** - **Premature loss of deciduous teeth** is the **least commonly associated** feature with Down syndrome among the given options. - While individuals with Down syndrome have increased periodontal disease that can lead to tooth loss, **premature exfoliation of deciduous teeth as a primary developmental feature is uncommon**. - Tooth loss, when it occurs, is typically a **secondary consequence** of severe periodontal destruction rather than an intrinsic developmental anomaly causing premature shedding. - Unlike the delayed eruption pattern which is a consistent finding, premature loss is not a characteristic feature of Down syndrome itself. *Delayed eruption of deciduous teeth* - This is a **common characteristic** of Down syndrome, not the least common. - Infants with Down syndrome frequently experience **delayed eruption of both deciduous and permanent teeth**, reflecting the generalized slower maturation seen in this condition. - Dental developmental delay is well-documented and consistently observed. *Periodontal disease* - This is **very common** in Down syndrome, with prevalence rates of 58-96%. - Individuals have significantly **increased prevalence and severity of periodontal disease** due to compromised immune function, poor oral hygiene, and specific anatomical factors. - One of the most consistent oral manifestations of Down syndrome. *Retrognathia* - **Retrognathia** (recessed lower jaw) is a **common craniofacial feature** in Down syndrome. - Contributes to difficulties in feeding, speech, and can impact airway patency. - Part of the characteristic facial phenotype.

Question 3: A 10-year-old boy presents with frequent fractures and blue sclerae. This patient most likely carries a mutation in a gene that encodes which of the following proteins?

A. Collagen (Correct Answer)
B. Fibrillin
C. Keratin
D. Myosin

Explanation: ***Collagen*** - Collagen mutations commonly result in various **connective tissue disorders** and defects in structural integrity [1]. - It plays a critical role in **skin, bones, and cartilage**, making it a significant candidate for mutations affecting these areas [1]. *Keratin* - Keratin is a protein primarily found in **skin, hair, and nails**, and mutations typically cause **epidermal dysplasia or disorders** like keratoderma. - While important for structural integrity, keratin is less associated with broader connective tissue disorders. *Fibrillin* - Fibrillin is essential for maintaining the **elasticity and structure of connective tissues**, predominantly in **Marfan syndrome** [2]. - Mutations lead to issues with connective tissue but are not as broadly relevant as collagen in this context [2]. *Myosin* - Myosin is primarily involved in **muscle contraction** and is not typically associated with **connective tissue** disorders. - Mutations in myosin often relate to **muscle diseases**, which are not relevant to the context of connective tissue mutations. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 154-155. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Genetic Disorders, pp. 153-154.

Question 4: A 10-year-old girl presents with severe joint laxity, scoliosis, and a history of easy bruising. Which of the following conditions is most likely?

A. Ehlers-Danlos syndrome (Correct Answer)
B. Marfan's syndrome
C. Rheumatoid arthritis
D. Osteogenesis imperfecta

Explanation: ***Ehlers-Danlos syndrome*** - This syndrome is characterized by defects in **collagen synthesis** and structure, leading to **joint hypermobility** (laxity) [1], skin hyperextensibility, and fragility, which explains the easy bruising [1]. - **Scoliosis** is a common musculoskeletal manifestation due to weakened connective tissue support [1]. *Marfan's syndrome* - While Marfan's syndrome also presents with **joint laxity** and **scoliosis**, its defining features include distinct skeletal abnormalities (e.g., **arachnodactyly**, sternal deformities) and **cardiovascular abnormalities** (e.g., aortic root dilatation), which are not mentioned here. - **Easy bruising** is not a prominent feature of Marfan's syndrome. *Rheumatoid arthritis* - This is an **autoimmune inflammatory arthritis** primarily affecting synovial joints, causing pain, swelling, and stiffness, often symmetrically. - It does not typically present with severe **joint laxity** throughout the body, **scoliosis**, or **easy bruising** as primary features in a 10-year-old. *Osteogenesis imperfecta* - This condition is characterized by **brittle bones** due to defective collagen, leading to recurrent **fractures** with minimal trauma. - While patients can have some **joint laxity** and **scoliosis**, the most prominent symptom is bone fragility, often accompanied by **blue sclerae**, which is not mentioned, and easy bruising is less indicative than in EDS.

Question 5: Mutations in type I collagen fibres results in:

A. Osteogenesis imperfecta (Correct Answer)
B. Osteosclerosis
C. Osteopetrosis
D. Marfan's syndrome

Explanation: ***Osteogenesis imperfecta*** - This condition is primarily caused by **genetic defects** in the genes encoding **Type I collagen**, particularly *COL1A1* and *COL1A2*. - It leads to **fragile bones** that fracture easily, **blue sclera**, **hearing loss**, and **dentinogenesis imperfecta**, due to the impaired formation of collagen, a major component of bone and connective tissues. *Osteosclerosis* - This refers to a general term for **increased bone density** and hardening of bone, which can be a symptom of various conditions. - It is not caused by a specific mutation in Type I collagen but rather points to an **imbalance in bone remodeling** where bone formation outpaces resorption. *Osteopetrosis* - Also known as **Albers-Schönberg disease** or **marble bone disease**, this condition is characterized by **abnormally dense bones** due to a defect in **osteoclast function**, which impairs bone resorption [1]. - It is primarily caused by mutations in genes involved in osteoclast development and acidification, such as *CLCN7*, not Type I collagen genes [1]. *Marfan's syndrome* - This is a **connective tissue disorder** caused by a mutation in the *FBN1 gene* encoding **fibrillin-1**, a protein essential for the formation of elastic fibers. - It affects the **skeleton, eyes, heart, and blood vessels**, leading to features like tall stature, long limbs, and cardiovascular abnormalities, distinct from collagen defects causing bone fragility. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.

Question 6: An intrauterine scan at the 13th week of pregnancy showed a fetus with multiple long bone fractures. What is commonly associated with this finding?

A. Osteogenesis imperfecta (Correct Answer)
B. Marfan syndrome
C. Achondroplasia
D. Cretinism

Explanation: ***Osteogenesis imperfecta*** - **Multiple long bone fractures** detected early in pregnancy are a classic presentation of **osteogenesis imperfecta (OI)**, a genetic disorder characterized by **bone fragility**. - OI is primarily caused by mutations in genes encoding **type I collagen**, leading to defective bone formation. *Achondroplasia* - This condition is a form of **dwarfism** characterized by disproportionately short limbs and a normal-sized trunk, resulting from a mutation in the **FGFR3 gene**. - While it affects bone growth, it typically does not cause **multiple fractures** prenatally. *Marfan syndrome* - This is a connective tissue disorder affecting the skeletal, ocular, and cardiovascular systems, characterized by **tall stature**, **long limbs and fingers**, and **aortic root dilation**. - It results from a mutation in the **fibrillin-1 gene** and is not primarily associated with prenatal long bone fractures. *Cretinism* - This is a historical term for **congenital hypothyroidism**, which results from severely deficient thyroid hormone production in a newborn. - It leads to developmental delays, growth retardation, and intellectual disability, but not to **multiple bone fractures**.

Question 7: The most commonly involved nerve in lunate dislocation is -

A. Ulnar nerve
B. Median nerve (Correct Answer)
C. Posterior interosseous
D. Anterior interosseous

Explanation: ***Median nerve*** - In a **lunate dislocation**, the lunate bone dislocates anteriorly and rotates. This displaced lunate can directly compress the **median nerve** within the carpal tunnel, which lies just anterior to it. - Compression of the median nerve leads to symptoms of **carpal tunnel syndrome**, including numbness and tingling in the thumb, index, middle, and radial half of the ring finger. *Ulnar nerve* - The **ulnar nerve** passes through Guyon's canal, which is located more medially and is generally not directly compressed by an isolated lunate dislocation. - While other wrist injuries can affect the ulnar nerve, it is not the most common nerve involved in lunate dislocation. *Posterior interosseous* - The **posterior interosseous nerve** is a branch of the radial nerve and supplies muscles in the posterior compartment of the forearm; it is located away from the carpal bones and is very rarely affected by lunate dislocation. - Injury to this nerve typically results in wrist drop or issues with finger extension. *Anterior interosseous* - The **anterior interosseous nerve** is a branch of the median nerve that supplies deep flexor muscles in the forearm; it also lies away from the direct path of a dislocated lunate. - Injury to this nerve leads to an inability to make the "ok" sign due to paralysis of the flexor pollicis longus and flexor digitorum profundus to the index finger.

Question 8: Identify the true statement regarding the clinical examination given in the image:

A. Wrist is held in forced flexion for 60 sec eliciting pain (Correct Answer)
B. Wrist is held in forced extension for 60 sec
C. Wrist is held in forced flexion for 45 sec eliciting pain
D. Wrist is held in forced extension for 45 sec

Explanation: ***Wrist is held in forced flexion for 60 sec eliciting pain*** - The image depicts **Phalen's test**, used to diagnose **carpal tunnel syndrome**. In this test, the patient's wrists are held in maximal sustained **flexion** for 30-60 seconds. - The reproduction of **tingling or pain** in the median nerve distribution (thumb, index, middle, and radial half of the ring finger) within this time frame indicates a positive test. *Wrist is held in forced extension for 60 sec* - Holding the wrist in **forced extension** for 60 seconds describes **reverse Phalen's test**, not the standard Phalen's test shown. - While reverse Phalen's test also assesses for **carpal tunnel syndrome**, it typically involves holding the wrists in **extension**. *Wrist is held in forced flexion for 45 sec eliciting pain* - While **flexion** is correct for Phalen's test, the standard duration is up to **60 seconds**, not specifically 45 seconds to determine a positive result. - Pain should be elicited within this timeframe, but the 45-second duration is not the most accurate statement regarding the full range of the test's timing. *Wrist is held in forced extension for 45 sec* - This option incorrectly states **forced extension** rather than flexion for Phalen's test, and the specific duration of 45 seconds is not universally cited as the definitive endpoint for a positive result. - **Forced extension** is part of the reverse Phalen's maneuver, not the test shown.

Question 9: False about fracture of vertebrae

A. Fracture dislocation is common in flexion rotation injury
B. Chance fracture occurs due to flexion distraction injury
C. Wedge compression causes flexion injury
D. Anterior longitudinal ligament runs along the posterior surface of vertebral bodies (Correct Answer)

Explanation: ***Anterior longitudinal ligament runs along the posterior surface of vertebral bodies*** - The **anterior longitudinal ligament (ALL)** runs along the **anterior aspect** of the vertebral bodies, preventing hyperextension. - The **posterior longitudinal ligament (PLL)** runs along the posterior surface of the vertebral bodies, within the vertebral canal. *Fracture dislocation is common in flexion rotation injury* - **Flexion-rotation injuries** are highly unstable and frequently lead to **fracture-dislocations** of the vertebral column. - The combined forces cause significant disruption of both bony and ligamentous structures, increasing the likelihood of displacement. *Chance fracture occurs due to flexion distraction injury* - A **Chance fracture** (or seatbelt fracture) is caused by a **flexion-distraction injury**, typically seen in individuals wearing lap belts during deceleration. - This mechanism results in a horizontal splitting of the vertebral body and posterior elements. *Wedge compression causes flexion injury* - A **wedge compression fracture** is the most common type of vertebral fracture and results from a **flexion injury** (hyperflexion). - The anterior portion of the vertebral body collapses, creating a wedge shape, while the posterior column remains intact.

Question 10: Slipped capital femoral epiphysis is seen most commonly in which age group?

A. Infants
B. Adolescents (Correct Answer)
C. Old age
D. Childhood

Explanation: **Explanation:** **Slipped Capital Femoral Epiphysis (SCFE)** is a classic hip disorder characterized by the displacement of the capital femoral epiphysis from the femoral neck through the physeal plate. 1. **Why Adolescents is correct:** The condition occurs most commonly during the **adolescent growth spurt** (typically ages 10–16 years). During this period, the growth plate (physis) thickens and weakens under the influence of growth hormones, while the periosteum thins. This mechanical instability, often combined with **obesity**, leads to a "slip" where the epiphysis remains in the acetabulum while the neck moves anteriorly and superiorly. 2. **Why other options are incorrect:** * **Infants:** Hip pathology in this group is usually Developmental Dysplasia of the Hip (DDH) or Septic Arthritis. * **Childhood:** The most common hip pathology in younger children (ages 4–8) is **Legg-Calvé-Perthes disease** (avascular necrosis). * **Old age:** Hip issues in the elderly are typically related to Osteoarthritis or Neck of Femur fractures. **High-Yield Clinical Pearls for NEET-PG:** * **Typical Profile:** An obese adolescent male presenting with a limp and hip or **referred knee pain**. * **Clinical Sign:** **Drehmann Sign** (obligate external rotation of the hip during passive flexion). * **Radiology:** Look for **Trethowan’s Sign** (Klein’s line fails to intersect the femoral head). * **Associated Conditions:** If seen in younger children, suspect endocrine disorders like **Hypothyroidism** or Growth Hormone deficiency. * **Management:** The definitive treatment is **In-situ pinning** (Internal fixation with a single cannulated screw).

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