Metabolic Bone Diseases Practice Questions

Q: A 60-year-old person suffering from myositis ossificans progressive, what is the usual cause of death?

Lung disease. **Explanation:** **Myositis Ossificans Progressiva**, also known as **Fibrodysplasia Ossificans Progressiva (FOP)**, is a rare genetic disorder characterized by the progressive transformation of soft tissues (muscles, tendons, and ligaments) into heterotopic bone. **Why Lung Disease is the Correct Answer:** The primary cause of mortality in FOP is **Thoracic Insufficiency Syndrome**. As the disease progresses, heterotopic ossification involves the intercostal muscles, paravertebral soft tissues, and the joints of the thoracic cage. This leads to: 1. **Chest Wall Restriction:** The rib cage becomes "frozen" or fused, severely limiting expansion during inspiration. 2. **Respiratory Failure:** Chronic restrictive lung disease develops, leading to pneumonia and eventually right-sided heart failure (Cor Pulmonale). Most patients succumb to respiratory complications by their 40s or 50s. **Analysis of Incorrect Options:** * **A. Nutritional deficiency:** While jaw involvement (ankylosis of the temporomandibular joint) can make eating difficult, it is rarely the primary cause of death due to modern nutritional support. * **B & D. Bed sore and Septicemia:** While immobility increases the risk of pressure sores and subsequent sepsis, these are secondary complications. The physiological hallmark that limits lifespan in FOP is the mechanical failure of the respiratory system. **Clinical Pearls for NEET-PG:** * **Genetic Mutation:** Caused by a mutation in the **ACVR1 gene** (encoding the ALK2 receptor). * **Classic Sign:** Congenital **malformation of the great toe** (short, hallux valgus) is a pathognomonic early diagnostic clue. * **Management Caution:** Avoid intramuscular injections, biopsies, or surgeries, as **trauma triggers "flare-ups"** and rapid new bone formation.

Q: Which of the following are characteristic features of childhood osteopetrosis?

Multiple fractures and hepatosplenomegaly. **Explanation:** **Osteopetrosis (Albers-Schönberg disease)**, also known as "Marble Bone Disease," is a genetic disorder characterized by **defective osteoclast function**. Because osteoclasts fail to resorb bone, the bone becomes excessively dense but structurally weak and brittle. 1. **Why Option A is Correct:** * **Multiple Fractures:** Despite the increased bone density (radiopacity), the lack of normal remodeling leads to poor bone quality, making them prone to "chalk-stick" fractures. * **Hepatosplenomegaly:** The excessive bone formation obliterates the medullary (bone marrow) cavity. To compensate for the loss of hematopoietic space, the body resorts to **extramedullary hematopoiesis** in the liver and spleen, leading to their enlargement. 2. **Why Other Options are Incorrect:** * **Option B:** While hepatosplenomegaly is present, it is an incomplete description. The hallmark clinical paradox of osteopetrosis is "dense but fragile" bones. * **Option C & D:** **Frontal bossing** is more characteristic of Rickets or Thalassemia. **Cataracts** are not a feature of osteopetrosis; however, patients may suffer from **optic atrophy** or blindness due to the narrowing of cranial nerve foramina (bone overgrowth compressing the nerves). **NEET-PG High-Yield Pearls:** * **Radiology:** Look for the "Bone within a bone" appearance (Endobone) and "Erlenmeyer flask deformity" of the distal femur. * **Rugger-Jersey Spine:** Characterized by dense bands at the superior and inferior endplates (also seen in Renal Osteodystrophy). * **Complications:** Pancytopenia (due to marrow space loss) and cranial nerve palsies (most commonly CN II, VII, and VIII). * **Treatment:** Bone marrow transplant is the definitive treatment for the infantile (malignant) form to provide functional osteoclasts.

Q: In a rural posting, a 35-year-old farmer comes to the OPD. Identify the condition shown:

Skeletal fluorosis. ***Skeletal fluorosis*** - The image on the left shows a person with **bowing of legs** and **joint deformities**, consistent with the chronic bone and joint pain, and stiffness characteristic of skeletal fluorosis. - The accompanying X-ray on the right, showing increased bone density and periosteal new bone formation (indicated by the arrow), is a classic radiographic finding in **skeletal fluorosis** caused by *excess fluoride intake*, often from contaminated drinking water in rural areas. *Neurolathyrism* - This condition is caused by the neurotoxin **ODAP** found in *Lathyrus sativus* (grass pea) and primarily manifests as **spastic paraplegia** and weakness of the lower limbs, typically without significant bone deformities or characteristic X-ray changes seen here. - While it affects locomotion and is prevalent in rural farming communities due to dietary habits, the visual and radiological findings presented do not align with its typical presentation. *Tropical spastic paraparesis* - This is a chronic progressive **myelopathy** often associated with **HTLV-1 infection**, characterized by **spasticity** and weakness primarily in the lower limbs, bladder dysfunction, and sensory disturbances. - It does not present with the specific bone deformities or the radiographic findings of increased bone density and periosteal new bone formation observed in the image. *Guillian-Barre syndrome* - This is an **acute post-infectious demyelinating polyneuropathy** characterized by *rapidly progressive ascending paralysis* and areflexia, which is a medical emergency. - It has an acute onset and lacks the chronic bony changes and deformities depicted in the image.

Q: A 72-year-old woman presents with bone pain and tenderness in her lower extremities and left clavicle. Laboratory studies reveal elevated calcium, decreased phosphate, and elevated serum alkaline phosphatase. X-ray spine shows?

Osteitis fibrosa cystica. ***Osteitis fibrosa cystica*** - The combination of **elevated calcium**, **decreased phosphate**, and **elevated alkaline phosphatase** is classic for **primary hyperparathyroidism**, which leads to osteitis fibrosa cystica. - The X-ray image shows evidence of **bone resorption**, particularly **subperiosteal resorption** in the distal phalanges, which is highly characteristic of this condition. *Paget's disease of the bone* - Characterized by **disordered bone remodeling**, leading to localized areas of **bone enlargement** and **sclerosis**, often with a normal calcium and phosphate level. - The elevated alkaline phosphatase is consistent, but normal calcium and phosphate would be expected, and the X-ray findings for Paget's usually show pronounced **cortical thickening** or a **"cotton wool" appearance**. *Osteomalacia* - Results from **defective mineralization of bone due to vitamin D deficiency**, leading to low calcium or phosphate, and elevated alkaline phosphatase. - While laboratory findings can be similar, osteomalacia often presents with characteristic **pseudofractures (Looser zones)** on X-ray, which are not depicted here. *Osteoporosis* - Involves **decreased bone density** and increased fracture risk, typically with normal calcium, phosphate, and alkaline phosphatase levels. - The X-ray would show generalized **osteopenia**, but the specific findings of subperiosteal resorption and the given lab values (elevated calcium, decreased phosphate) point away from uncomplicated osteoporosis.

Q: Identify the deformity seen in this child with rickets:

Genu varum (Bow legs). ***Genu varum (Bow legs)*** - The image shows the knees bowed outwards resulting in a **bow-legged appearance**, which is characteristic of **genu varum**. - **Rickets** is a common cause of genu varum, as the softened bones are unable to bear weight and bend outwards. *Genu valgum (knock knees)* - **Genu valgum** presents as the knees bending inwards, appearing to "knock" against each other, which is the opposite of what is seen in the image. - While rickets can also cause genu valgum, the depicted deformity clearly shows outward bowing. *Windswept deformity* - A **windswept deformity** involves one knee being in **valgus** (knock-kneed) and the other in **varus** (bow-legged). - The image does not show this combination; both knees appear to be bowed outwards. *Gunstock deformity* - **Gunstock deformity** is an angular deformity of the elbow, typically related to a **supracondylar humerus fracture**. - This deformity affects the upper limb and is not related to the lower limb presentation in the image.

Q: The appearance shown in the image is called as Simian Posturing. Notice the bent trunk, flexed legs and loss of spine normal axis. It occurs due to disordered bone turnover involving pelvis and vertebra. Which condition is most associated with this presentation?

Paget's disease. ***Paget's disease*** - **Paget's disease** is characterized by disordered bone turnover, leading to bone enlargement, deformity, and weakness. This can result in changes in posture, such as **simian posturing** due to involvement of the pelvis and vertebrae, as described. - The abnormal bone remodeling in Paget's disease can cause **bowing of long bones**, skull enlargement, and spinal changes, directly leading to the described posture. *Rickets* - **Rickets** is a childhood condition caused by a deficiency in vitamin D, calcium, or phosphate, leading to **softening and weakening of bones**. - While rickets can cause bone deformities like bowed legs and skeletal pain, it typically does not present with the specific **simian posturing** affecting the entire trunk and spine as described in an adult. *Achondroplasia* - **Achondroplasia** is a genetic disorder of bone growth resulting in **dwarfism**, characterized by short limbs and a normal-sized trunk. - While it causes skeletal abnormalities, it typically manifests differently from the described simian posturing, which involves advanced bone remodeling in the spine and pelvis, not primarily a growth disorder. *Osteoporosis* - **Osteoporosis** is a condition where bones become **brittle and fragile** due to loss of tissue, leading to an increased risk of fractures. - Although osteoporosis can lead to **kyphosis** (hunchback) due to vertebral compression fractures, it typically does not present with the global "simian posturing" involving the entire pelvis, spine, and flexed legs due to disordered bone turnover.

Q: Which of the following diseases will lead to the following appearance?

Paget's disease. ***Paget's disease*** - The image depicts a bowing of the legs and a generalized stooped posture, which are characteristic findings in advanced **Paget's disease of bone**. - **Paget's disease** is a chronic bone disorder characterized by abnormal bone remodeling, leading to enlarged and misshapen bones that can cause **kyphosis** and **bowed limbs**. *Polio* - **Polio** (poliomyelitis) primarily affects the nervous system, leading to **muscle weakness** and **paralysis**, which can result in limb deformities, but not typically the widespread bone enlargement and bowing seen here. - While polio can cause limb asymmetry and deformities due to muscle wasting, it does not involve the characteristic bone remodeling and generalized skeletal changes seen in the image. *Cerebellar lesion* - A **cerebellar lesion** primarily affects coordination, balance, and motor control, leading to ataxia, tremors, and gait disturbances. - It does not directly cause the skeletal deformities or bone bowing illustrated in the image. *Ankylosing Spondylitis* - **Ankylosing spondylitis** is a chronic inflammatory disease primarily affecting the axial skeleton, leading to progressive spinal stiffness and fusion (a "bamboo spine"). - While it can cause a significant **kyphosis** (forward curvature of the spine), it does not typically lead to the wide-set bowed legs or general bone enlargement often seen in Paget's disease.

Question 1

A 60-year-old person suffering from myositis ossificans progressive, what is the usual cause of death?

Accepted Answer

Lung disease

Answer

Nutritional deficiency

Answer

Bed sore

Answer

Septicemia

Question 2

Which of the following are characteristic features of childhood osteopetrosis?

Accepted Answer

Multiple fractures and hepatosplenomegaly

Answer

Hepatosplenomegaly

Answer

Bilateral frontal bossing and multiple fractures

Answer

Bilateral frontal bossing and cataracts

Question 3

An X-ray of a patient shows bulbous ends of long bones, normal appositional bone growth, and failure of physiologic root resorption. Laboratory findings show myelophthisic anemia. What is the probable diagnosis?

Accepted Answer

Osteopetrosis

Answer

Fibrous dysplasia

Answer

Osteomyelitis

Answer

Paget's disease

Question 4

In a rural posting, a 35-year-old farmer comes to the OPD. Identify the condition shown:

Accepted Answer

Skeletal fluorosis

Answer

Neurolathyrism

Answer

Tropical spastic paraparesis

Answer

Guillian-Barre syndrome

Question 5

Which of the following is correct about the report of bone densitometry shown?

Accepted Answer

The patient was diagnosed with osteoporosis initially based on a T-score of -2.5

Answer

The initial T-score of -2.5 places the patient in the osteopenia (yellow) zone

Answer

The green zone on the report indicates osteopenia (T-score between -1 and -2.5)

Answer

A T-score above -1 indicates osteoporosis on this report

Question 6

A 72-year-old woman presents with bone pain and tenderness in her lower extremities and left clavicle. Laboratory studies reveal elevated calcium, decreased phosphate, and elevated serum alkaline phosphatase. X-ray spine shows?

Accepted Answer

Osteitis fibrosa cystica

Answer

Paget's disease of the bone

Answer

Osteomalacia

Answer

Osteoporosis

Question 7

Identify the deformity seen in this child with rickets:

Accepted Answer

Genu varum (Bow legs)

Answer

Genu valgum (knock knees)

Answer

Windswept deformity

Answer

Gunstock deformity

Question 8

The appearance shown in the image is called as Simian Posturing. Notice the bent trunk, flexed legs and loss of spine normal axis. It occurs due to disordered bone turnover involving pelvis and vertebra. Which condition is most associated with this presentation?

Accepted Answer

Paget's disease

Answer

Rickets

Answer

Achondroplasia

Answer

Osteoporosis

Question 9

Which of the following diseases will lead to the following appearance?

Accepted Answer

Paget's disease

Answer

Polio

Answer

Cerebellar lesion

Answer

Ankylosing Spondylitis

Question 10

A 60-year-old elderly female with a previous history of a Colles fracture is now complaining of backache. Which of the following statements regarding the treatment of this patient is incorrect?

Accepted Answer

Teriparatide should be started before supplementing bisphosphonates

Answer

Oral vitamin D3 is given along with oral calcium

Answer

Calcium requirement is 1200 mg per day

Answer

Bisphosphonates can be given for 3-5 years depending on patient response and risk factors

Metabolic Bone Diseases — MCQs

Metabolic Bone Diseases — MCQs

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