Cm. Schnitzler et al., BONE-DISEASE IN AFRICAN CHILDREN WITH SLIPPED CAPITAL FEMORAL EPIPHYSIS - HISTOMORPHOMETRY OF ILIAC CREST BIOPSIES, Bone, 22(3), 1998, pp. 259-265
African teenagers with slipped capital femoral epiphysis (SCFE) not in
frequently also have genu valgum (knockknee). Because we had previousl
y demonstrated metabolic bone disease attributable to dietary calcium
deficiency in black teenagers with genu valgum, we examined 29 black t
eenagers (15 male, 14 female) with SCFE for metabolic bone disease. Ea
ch patient had an iliac crest bone biopsy taken (after double tetracyc
line labeling) for routine histomorphometry, and blood and urine sampl
es for bone biochemistry. Spinal bone mineral density was measured in
13 patients. Compared to reported data, we found our patients to be se
xually more immature, older, at least as obese, and to have more sever
e and more frequently bilateral hip disease. Eighty percent of the chi
ldren took dairy products only once or twice a week or less frequently
, and 37.9 % had genu valgum. Compared with race-and age-matched South
Africans, bone biopsies in our patients showed lower bone volume (BV/
TV, p = 0.0003), wall thickness (p = 0.0002), and trabecular thickness
(Tb.Th, p = 0.0002), and a tendency to greater trabecular spacing (Tb
.Sp,p = 0.053). Lower osteoid volume (OV/BV, p = 0.0001), osteoid surf
ace (OS/BS, p = 0.0001), osteoid thickness (O.Th, p = 0.0002), double
labeled surface (dLS/BS, p = 0.029), and bone formation rate (BFR/BS,
p 0.037) suggested poorer bone forming capacity in our patients. No ev
idence of hyperparathyroid bone disease or osteomalacia was found. BV/
TV was below the reference range (14.2%) in 65.5% of cases; these pati
ents had lower values for Tb.Th (p = 0.037) and Tb.N (p = 0.0003), gre
ater Tb.Sp (p = 0.0002), a tendency to lower adjusted apposition rate
(Aj.AR, p = 0.057), and had had less frequent intake of dairy products
than those with normal BV/TV (p = 0.024). Furthermore, months since m
enarche correlated with histomorphometric variables BV/TV (I = 0.667,
p = 0.009), Tb.Th (r = 0.745, p = 0.002), Tb.Sp (r = -0.549, p = 0.042
), O.Th (r = 0.784, p = 0.0009), and Aj.AR (r = 0.549, p = 0.042). The
correlation between Tb.Th and spinal bone mineral content (r = 0.656,
p = 0.015) suggests that the reduced trabecular thickness reflected a
generalized bone condition. A greater than normal proportion of patie
nts had spinal bone mineral density values below -1 standard deviation
(SD) of the mean (osteopenia) (p = 0.001). Patients tested for parath
yroid hormone and 25-hydroxyvitamin D levels were found to have normal
values. Parathyroid hormone correlated with Aj.AR (r = 0.661, p = 0.0
38) and serum phosphorus (r= -0.764, p = 0.010). We conclude that sexu
al immaturity and possibly past dietary calcium deficiency contributed
to osteopenia, and that this, together with obesity, led to the devel
opment of more severe and more frequently bilateral SCFE in our patien
ts than in reported series of black and white children. (C) 1998 by El
sevier Science Inc. All rights reserved.