Please confirm topic selection

Are you sure you want to trigger topic in your Anconeus AI algorithm?

Please confirm action

You are done for today with this topic.

Would you like to start learning session with this topic items scheduled for future?

Updated: Dec 2 2023

Osteopetrosis

Images
https://upload.orthobullets.com/topic/4103/images/Xray - hand - colorado_moved.jpg
https://upload.orthobullets.com/topic/4103/images/Xray - spine - colorado_moved.jpg
https://upload.orthobullets.com/topic/4103/images/Xray - femur - colorado_moved.jpg
https://upload.orthobullets.com/topic/4103/images/pathology 1 - colorado_moved.jpg
https://upload.orthobullets.com/topic/4103/images/pathology 2 - colorado_moved.jpg
  • summary
    • Osteopetrosis is a congenital metabolic bone disease caused by defective osteoclastic resorption of immature bone that presents with increased frequency of long bone fractures, cranial nerve palsies, and low back pain. 
    • Diagnosis is made radiographically with increased cortical thickening, increased overall bone density, and loss of medullary canal diameter.
    • Treatment is multidisciplinary approach to address fracture management, and cranial nerve abnormalities.
  • Epidemiology
    • Prevalence
      • approximately 1 in 20,000 for autosomal dominant form
      • approximately 1 in 200,000 for autosomal recessive form
    • Demographics
      • genetic inheritance (3 types)
        • malignant autosomal recessive
        • intermediate autosomal recessive
        • benign autosomal dominant (most common)
      • Penetrance
        • may skip generations
        • 75% gene penetrance
  • Etiology
    • Pathophysiology
      • pathoanatomy
        • osteoclast dysfunction leads to dense bone and obliterated medullary canals
          • caused by osteoclast inability to acidify Howship's lacuna
            • due to defective carbonic anhydrase II or chloride channel dysfunction
        • leads to predisposition to fracture
          • lower extremity > upper extremity > axial skeleton
          • lifelong prevalence of fracture ~ 40-50%
      • Associated conditions
        • head
          • cranial nerve palsies
            • from overgrowth of skull foramina
            • optic n. > auditory n. > trigeminal n. > facial n.
          • osteomyelitis
            • due to lack of marrow vascularity and impaired WBC function
          • caffey disease
            • infantile cortical hyperostosis affecting mandible in addition to clavicle, ribs, and scapulae
        • spine
          • lower lumbar pain
            • increased prevalence of spondylolysis
        • pelvis
          • coxa vara
            • commonly due to femoral neck fracture nonunion or repeated stress fractures
            • increased risk of degenerative joint arthritis
        • extremities
          • increased tendency for long bone fractures
            • often low energy
            • transverse
            • increased risk of delayed union and malunion
          • carpal tunnel syndrome
  • Classification
      • Classification of Osteopetrosis
      • Type
      • Genetic
      • Clinical Presentation
      • Malignant
      • Autosomal recessive
      • Proton pump or chloride channel dysfunction
      • Pancytopenia, hepatosplenomegaly and infection
      • Fatal at an early age without bone marrow transplant
      • Intermediate
      • Autosomal recessive
      • Carbonic anhydrase II dysfunction or chloride channel dysfunction
      •  Usually live into adulthood
      • Benign
      • Autosomal dominant
      • Chloride channel dysfunction
      •  Type I does not have increased fracture risk
      • Type II is known as Albers-Schonberg disease (anemia, pathologic fractures, and premature osteoarthritis)
      • General health, life span, mental function, and physique are normal
      •  Most common form to be managed by orthopaedic surgeon
  • Presentation
    • Autosomal recessive forms
      • symptoms
        • frequent fractures
        • progressive deafness and blindness
        • severe anemia (caused by encroachment of bone on marrow) beginning in early infancy or in utero
          • bleeding risk
          • frequent infections
      • physical exam
        • macrocephaly
        • hepatosplenomegaly (caused by compensatory extramedullary hematopoiesis)
        • dental abscesses and osteomyelitis of the mandible
    • Autosomal dominant form
      • symptoms
        • usually asymptomatic
        • fractures
          • first learn of disease after fracture
          • usually a low energy pathologic fracture to lower extremity
        • anemia (fatigue)
        • joint pain
          • lower back pain common
          • early hip osteoarthritis
      • physical exam
        • general
          • normal height and appearance
          • generalized osteosclerosis
        • range of motion
          • usually normal unless underlying osteoarthritis
        • head and neck
          • high risk of cranial nerve palsy
  • Imaging
    • Radiographs
      • recommended views
        • AP and lateral of bone of interest
      • general findings
        • increased cortical thickening
        • increased overall bone density
        • loss of medullary canal diameter
          • bone-in-bone appearance
      • additional findings
        • "erlenmeyer flask" proximal humerus and distal femur
        • "rugger jersey spine" with very dense bone
        • block femoral metaphysis
        • coxa vara
  • Studies
    • Histology
      • histology shows defective osteoclasts
        • lack ruffled border and clear zone
        • islands of calcified cartilage within mature trabeculae
      • empty lacunae and plugging of the haversian canals also seen
    • Laboratory studies
      • autosomal recessive
        • increases acid phosphatase
        • may have increased PTH +/- calcium
      • autosomal dominant
        • usually normal
  • Treatment
    • Medical management
      • bone marrow transplant
        • indications
          • autosomal recessive (infantile-malignant) form
      • high dose calcitriol (1,25 dihydroxy vitamin D), bone marrow transplant
        • indications
          • autosomal recessive (infantile-malignant) form
      • interferon gamma-1beta
        • indications
          • autosomal dominant form
    • Cranial nerve impingment
      • Neurosurgical decompression
    • Fracture management
      • nonoperative
        • indications
          • diaphyseal long bone fractures
          • upper extremity fractures
        • techniques
          • prolonged casting and non-weight bearing
          • acceptable bone alignment, rotation and length
        • outcomes
          • healing may be delayed
          • fracture remodeling limited
            • increased risk of malunion and refracture
      • operative
        • indications
          • proximal femur fractures
        • techniques
          • plate and screws
            • avoid intramedullary devices
            • slow steady drilling
            • constant cooling and change of drill bit
        • outcomes
          • increased risk of hardware failure
          • higher union rates and lower malunion rates compared to non-operative management
            • decreased risk of coxa vara
    • Degenerative joint disease
      • total hip arthroplasty
        • indication
          • end stage osteoarthritis
        • techniques
          • femur
            • cannulated reamers under fluoroscopy
            • short stemmed implants
            • usually uncemented components are used
          • acetabulum
            • small, sharp reamers
            • irrigation
            • multiple screws
      • total knee arthroplasty indication
        • indications
          • end stage osteoarthritis
        • technique
          • consider navigation
  • Complications
    • Refracture
      • caused by
        • hard brittle bones
        • hardware failure
    • Infection
      • increased risk due to reduced tissue vascularity
    • Malunion
    • Non-union
Card
1 of 6
Question
1 of 10
Private Note

Attach Treatment Poll
Treatment poll is required to gain more useful feedback from members.
Please enter Question Text
Please enter at least 2 unique options
Please enter at least 2 unique options
Please enter at least 2 unique options