Children with acute Perthes' disease have asymmetrical lower leg growth and abnormal collagen turnover.
BACKGROUND
Abnormalities in distal growth and low levels of insulin-like growth factor (IGF)-I have been reported in children with Perthes' disease. Our aim was to establish whether the acute phase of Perthes' disease is associated with abnormalities of growth, of bone or of collagen turnover.


METHODS
We performed a cross-sectional study of 15 children (3-11 years of age, 13 boys) at acute presentation and a longitudinal cohort study of 9 children. We measured (1) the lengths of both lower legs (by knemometry) at weeks 1, 2, 6 and 12, (2) height and weight at presentation and at the second-year follow-up, and (3) levels of IGF-I, IGFBP-3, collagen markers and bone alkaline phosphatase at weeks 1 and 12, and in year 2.


RESULTS
Height SD scores were normal at presentation but declined thereafter. Lower leg growth was not impaired at presentation but was asymmetrical, ceased during weeks 2-6, and then resumed symmetrically. Patients had persistently low IGF-I, low soft tissue collagen synthesis and enhanced collagen breakdown compared with age- and sex-related reference data. Markers of bone formation increased during follow-up.


CONCLUSIONS
Acute changes in lower leg growth reflected differential weight bearing, then immobilization and remobilization. Persistently low IGF-I may have contributed to low soft tissue collagen synthesis and growth. Changes in bone formation markers most likely reflected bone healing.
Department of Paediatric Biochemistry, Royal Hospital for Sick Children, Edinburgh, UK. patricia.crofton@luht.scot.nhs.uk
Patricia M
PM
Crofton
Catherine
C
Macfarlane
Barbara
B
Wardhaugh
Michael B
MB
Ranke
Martin W
MW
Elmlinger
Christopher J H
CJ
Kelnar
Malcolm F
MF
Macnicol
D000208:Acute Disease; D000469:Alkaline Phosphatase / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism*; D001827:Body Height; D001842:Bone and Bones / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000378:metabolism*; D003430:Cross-Sectional Studies; D005500:Follow-Up Studies; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007866:Leg / Q000254:growth & development*; D007873:Legg-Calve-Perthes Disease / Q000378:metabolism / Q000503:physiopathology*; D008137:Longitudinal Studies; D011347:Procollagen / Q000378:metabolism; D011446:Prospective Studies; D016474:Weight-Bearing
D015415:Biomarkers; D011347:Procollagen; D007334:Insulin-Like Growth Factor I; D003094:Collagen; D000469:Alkaline Phosphatase