BMI02 - Musculoskeletal Disorders

What is osteogenesis imperfecta?

A group of genetic diseases known as brittle bone disease characterized by defective type I collagen causing inadequate bone formation and extreme skeletal fragility

What collagen defect occurs in osteogenesis imperfecta?

Type I collagen is defective, either not enough collagen is produced or it is abnormal

What bone changes occur in osteogenesis imperfecta?

Inadequate bone formation resulting in thin cortices and trabeculae

What is the inheritance pattern of most osteogenesis imperfecta cases?

Usually autosomal dominant inheritance, with some autosomal recessive forms

What eye finding is common in osteogenesis imperfecta?

Blue sclera due to thin scleral collagen

Why are bones fragile in osteogenesis imperfecta?

Because defective collagen causes weak bones that break easily

What is another name for osteogenesis imperfecta?

Brittle Bone Disease

What sex distribution is seen in osteogenesis imperfecta?

Males equal females

What age group is commonly affected by osteogenesis imperfecta?

Infants and young children

How many clinical subtypes of osteogenesis imperfecta are classically recognized?

Four clinical subtypes

What are the characteristics of Type I osteogenesis imperfecta?

Most common and mildest form with 10% having fractures at birth, blue sclera, hearing loss, and opalescent teeth

What percentage of Type I osteogenesis imperfecta patients have fractures at birth?

10%

What dental finding is associated with Type I osteogenesis imperfecta?

Opalescent teeth

What hearing problem may occur in Type I osteogenesis imperfecta?

Hearing loss

What are the characteristics of Type II osteogenesis imperfecta?

Most severe form with 90% stillborn or dying within 4 weeks

What is the prognosis of Type II osteogenesis imperfecta?

90% are stillborn or die within 4 weeks

What are the characteristics of Type III osteogenesis imperfecta?

Second most severe form usually noticed after 6 months with most dying before adulthood due to cardiopulmonary complications

When is Type III osteogenesis imperfecta usually noticed?

Usually after 6 months of age

What commonly causes death in Type III osteogenesis imperfecta?

Cardiopulmonary complications

What are the characteristics of Type IV osteogenesis imperfecta?

Fractures in 50% at birth with blue sclera that usually fades over time

What percentage of Type IV osteogenesis imperfecta patients have fractures at birth?

50%

What happens to the blue sclera in Type IV osteogenesis imperfecta?

It usually fades with time

What is osteopetrosis?

A genetic disease also called Marble Bone Disease or Albers-Schonberg Disease characterized by defective osteoclast remodeling

What is another name for osteopetrosis?

Marble Bone Disease or Albers-Schonberg Disease

What is the most common inheritance pattern of osteopetrosis?

Autosomal dominant

What cellular defect occurs in osteopetrosis?

Osteoclasts cannot remodel bone properly

What happens to marrow spaces in osteopetrosis?

Obliteration of marrow spaces

What mutation mechanism occurs in osteopetrosis?

Mutation prevents acid dissolution of bone matrix by attached osteoclasts

Why do bones fracture easily in osteopetrosis despite increased density?

Tubular bones become brittle despite being dense

Why are dense bones easily infected in osteopetrosis?

Because they are prone to osteomyelitis

What radiographic appearance is seen in osteopetrosis?

Densely opaque and solid tubular bones

What is the treatment for osteopetrosis?

Hematopoietic stem cell transplant

What is osteopenia?

Decreased bone mass

How is osteoporosis defined?

Osteopenia severe enough to significantly increase fracture risk

What radiographic definition is used for osteoporosis?

Bone mass at least 2.5 standard deviations below mean peak bone mass

What radiographic definition is used for osteopenia?

Bone mass 1 to 2.5 standard deviations below mean peak bone mass

What signifies osteoporosis clinically?

Presence of an atraumatic fracture

What are the common forms of osteoporosis?

Senile and postmenopausal osteoporosis

What microscopic feature is seen in osteoporotic bone?

Extremely thin trabeculae

What medications are commonly used to treat osteoporosis?

Bisphosphonates

What are examples of bisphosphonates used for osteoporosis?

Alendronate (Fosamax), ibandronate, risendronate, and zoledronic acid

How do bisphosphonates reduce fractures?

They significantly reduce fracture risk by suppressing bone resorption

How do bisphosphonates suppress bone resorption?

By binding to active sites of bone remodeling and inhibiting osteoclasts

What does MRONJ stand for?

Medication Related Osteonecrosis of the Jaws

What are the diagnostic features of MRONJ?

Unhealed exposed necrotic jaw bone for more than 8 weeks, history of bisphosphonate or antiresorptive use, and no history of jaw radiation

How long must exposed necrotic bone persist for MRONJ diagnosis?

More than 8 weeks

What medication history is associated with MRONJ?

Bisphosphonate or antiresorptive agent use

What radiation history must be absent in MRONJ?

No history of radiation to the jaws

What is Paget disease of bone?

A disorder of abnormal bone resorption and deposition also called osteitis deformans

What is another name for Paget disease of bone?

Osteitis deformans

What is the net effect in Paget disease of bone?

Net deposition of bone

How does Paget disease affect bones?

It distorts and weakens bones

What age group is commonly affected by Paget disease?

Older people, rarely under age 40

What are possible causes of Paget disease?

Inflammatory, genetic, endocrine, and viral factors

Are most cases of Paget disease monostotic or polyostotic?

Polyostotic

What laboratory finding is associated with Paget disease?

Marked elevation in serum alkaline phosphatase

What common clinical complaint occurs in Paget disease involving the skull?

Need for a bigger hat or denture

Which jaw is more commonly enlarged in Paget disease?

Maxilla more than mandible

What is leontiasis ossea?

Enlargement of the craniofacial skeleton producing a lion-like face

What dental changes occur in Paget disease?

Teeth may migrate and loosen

What symptom can occur in Paget disease bones?

Severe bone pain

What radiographic appearance is classic for Paget disease?

Patchy sclerotic “cotton wool” appearance

What dental radiographic finding occurs in Paget disease?

Hypercementosis

How do alveolar ridges appear in Paget disease?

Grossly and symmetrically enlarged

What histopathologic appearance is seen in Paget disease?

Uncontrolled alternating bone resorption and formation producing a jigsaw puzzle or mosaic appearance

What is the course of Paget disease?

Chronic, slowly progressive, and seldom fatal

When is no treatment required in Paget disease?

When involvement is limited and asymptomatic

What hormone therapy may be used in Paget disease?

Calcitonin to stop remodeling

What other medications are used in Paget disease?

Bisphosphonates

What malignant transformation risk exists in Paget disease?

1% or less develop osteosarcoma

What is osteomyelitis?

An acute or chronic inflammatory bone process secondary to infection, usually Staphylococcus aureus

What organism most commonly causes osteomyelitis?

Staphylococcus aureus

What are the mechanisms of osteomyelitis spread?

Hematogenous spread by bacteremia and direct extension of infection

What is an example of direct extension causing osteomyelitis?

Dental infection

What diseases predispose to osteomyelitis?

Sickle cell anemia and osteopetrosis

What specific infections can cause osteomyelitis?

Tuberculosis, syphilis, actinomycosis, and AIDS

What lifestyle or medical factors predispose to osteomyelitis?

Tobacco, alcohol, diabetes, and radiation

What defines acute osteomyelitis duration?

Signs and symptoms lasting less than 1 month

What symptoms occur in acute osteomyelitis?

Fever, swelling, and lymphadenopathy

What radiographic findings occur in acute osteomyelitis?

Unremarkable x-ray or ill-defined radiolucency

What may drain from acute osteomyelitis lesions?

Fragments of necrotic bone

What is a sequestrum?

Necrotic bone fragment with empty lacunae and neutrophils

What happens after the first week in chronic osteomyelitis?

Chronic inflammatory cells release cytokines

What do cytokines stimulate in chronic osteomyelitis?

Osteoclastic bone resorption, sequestrum detachment, fibrous tissue ingrowth, and involucrum deposition

What is involucrum?

Reactive viable bone deposited at the periphery in chronic osteomyelitis

What is an osteoma?

A benign tumor of compact or cancellous bone

Where are osteomas usually located?

Craniofacial skeleton

What syndrome is associated with multiple osteomas?

Gardner syndrome

Are tori and exostoses considered osteomas?

No, although they are histologically identical

How are large osteomas treated?

Surgical excision

How are small osteomas managed?

Periodic observation

What is an osteoid osteoma?

A benign central bone tumor containing a nidus of nerve tissue

What is the size of osteoid osteoma?

Less than 2 cm

Who commonly develops osteoid osteoma?

Young men in their teens and 20s

What causes pain in osteoid osteoma?

Prostaglandin E2 produced by proliferating osteoblasts

What type of pain is classic for osteoid osteoma?

Severe nocturnal pain relieved by aspirin and NSAIDs

What is an osteoblastoma?

A benign tumor arising from osteoblasts

How is osteoblastoma related to osteoid osteoma?

Similar but larger

How common are osteoblastomas?

Rare, less than 1% of bone tumors

What symptoms occur with osteoblastoma?

Pain, tenderness, and swelling