1 primary benign bone lesion
osteochondroma
causes osteonecrosis/AVN
osteonecrosis pathology progression
zone of cell death centrally
zone of ischemic injury
N bone marrow
normal alpha angle adult
~40
≥55 abN (CAM impingement)
normal centre edge angle
N <39 degrees
increased = pincer decreased = ddh
osteopoikilosis - bone scan features
cold
osteopoikilosis - bone segment prediliction
epiphyses & metaphyses
and carpus, tarsus, pelvis
most common site osteoma
frontoethmoid sinus region (75%)
genetic association multiple osteomas
gardner syndrome (APC gene 5q22)
osteoid osteoma on bone scintigraphy
hot, double density sign
median age osteoblastoma, M:F ratio
18 yo, 2-3:1 M:F
most common location of osteoblastoma in spine
posterior elements (>60%)
normal thickness plantar fascia
<3 mm
rugger jersey spine is seen in…
renal osteodystrophy
rhizomelia means…
shortening of proximal appendicular skeleton
hand site predilection for OA & erosive OA
- DIP
hand site predilection for psoriatic arthritis
hand site predilection for RA
- PIP
hand site predilection for gout
hand site predilection for CPPD
hand site predilection for scleroderma
most common bone dysplasia
achondroplasia
inheritance pattern multiple hereditary exostoses
chance of malignant degeneration
autosomal dominant
1-10%
bone scan and xray of pagets
lytic phase: bone scan hot, xray negative
mixed: both positive
sclerotic: bone scan less, xray findings