- 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
- reference:
- 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-Calvé-Perthes disease. A critical review of the literature.
Legg Calve Perthes Disease.
- 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
