Pre-axial / great toe / 15%
Central / 2-4 MT / 5%
Post-axial / 5th MT / 80%
Type A - articulated
Type B - rudimentary
2 in 1000 births
- 30% positive FHx
- autosomal dominant
Associated MT anomalies common
- block MT / Y-shaped / T-shaped /wide head
Condition present at birth
- ankle dorsiflexed & in valgus
- foot abducted
1 in 1000 births
Probably result of intrauterine positioning
- packaging defect
Oligohydramnios
DDH
STS composed of malignant lipoblasts
Common
- 10% of STS
- second only to MFH
Occurs almost exclusively in adults
Males age 40-60
Can be multiple origin -> examine patient
Rarely arise from lipoma
Treatment algorithm similar to OS
Overall prognosis similar to OS
- 70% long term survival
A malignant neoplasm composed of small round cells of uncertain histogenesis
Recent data suggests it is of neuroepithelial derivation
- ? neuroectodermal cells
It was described in 1983 by Dr. Nora, and is sometimes called Nora's disease or Nora's lesion
Bizarre parosteal osteochondromatous proliferation
Rare lesion
- occurs most commonly in the hands and feet
Adults in their 20's and 30's
Males = Females
Metaphyseal Enchondroma
Arise from the metaphyseal cortex of long bones
- most common in the proximal humerus
Difficult to DDx from Chondrosarcoma
Masses of cartilage nestling in a shallow crater in the periphery of the cortex
Don't ossify
- remain as immature cartilage
Benign lesion with a wide spectrum of behavior characterized by stromal cells and giant cells
Common
- 20% of benign tumours
More common females
- F:M = 1.5:1
- most tumours M>F
Usually patient in 20's
- usually after skeletal maturity
- 3% < epiphyseal closure
Rare cartilage tumour
1% of bone tumours / rare
- typically in adolescents
Usually benign
- but aggressive / frankly malignant behaviour reported
- locally aggressive
- can have pulmonary metastasis
Rare low-grade malignant tumour
- cell of origin unknown
Usually second or third decade of life
90% diaphysis of tibia
Mandible
Most common anterior cortex of tibia
A chronic systemic, autoimmune inflammatory disease of unknown cause
1% of population
M:F = 1:3
Peak onset 40 years
Most common inflammatory arthropathy
Autoimmune
- trigger not identified
- cell mediated immune response