- Discussion:
- bone scan and MRI may help early involvement, but may not correlate with the extent of involvement;
- bone scans are highly sensitive for Perthes disease;
- Radiographic Findings: (Waldenstrom):
-
initial findings:
- ossific nucleus fails to grow and looks smaller;
- surrounding bone may become osteopenic, causing nucleus to look more dense;
- cartilage of femoral head continues to grow and therefore medial joint space looks widened;
- crescent sign (Caffey's sign) may be seen;
- represents pathologic frx of resorbing femoral head and is best seen on a frog leg view of the pelvis;
-
avascular stage: ossific nucleus is small, dense, and uniform;
-
fragmentation stage:
- epiphysis is seen to fragment;
- the dense avascular bone is replaced by radiolucent granulation tissue;
-
re-ossification stage:
- radiodense areas replace radiolucent areas;
- normal bone density returns;
Perthes in 6 yo female
later at 7 yrs
later at 8 yrs
later at 9 yrs
- Radiographic Predictors:
- radiographic findings associated with poor prognosis "head at risk"
- lateral subluxation (most important)
- calcification lateral to the epiphysis;
- Gage's sign: V shaped defect laterally;
- metaphyseal cysts
- horizontal growth plate
-
Caterall & Salter Stages: (based on amount of femoral involvement)
- Caterall
Salter/Thompson
Location
Prognosis
I
A
Anterior (lat view)
Good
II
A
Ant/partial lateral
Good
III
B
Ant & lateral margin
Poor
IV
B
Thruout Cap Fem Epiphysis Dome
Poor
- references:
-
Legg-Calve-Perthes disease. The prognostic significance of the
subchondral fracture and a two-group classification of the femoral head involvement.
-
Herring Classification:
- most useful in the fragmentation stage;
- compares the height of lateral epiphyseal pillar to the height of the contra-lateral epiphysis;
-
Group A there is no collapse of the lateral pillar;
-
Group B lateral pillar margins has more than 50% of original height;
-
Group C collapse of lateral pillar more than 50%;
- references:
The treatment of Legg Calve Perthes Disease: A critical review.
JA Herring.
JBJS Vol 76-A. 1994. p448-458.
Legg Calve Perthes Disease.
DR Wenger et al. JBJS Vol 73-A. 1991. p 778-788.
- Case Examples:
Perthes in 5 yo male;
Perthes in 6 yo male
later at 6 1/2 yrs
later at 7 yrs
Perthes in 6 yo female
later at 7 yrs
later at 8 yrs
later at 9 yrs
