Page 22 - Slipped Capital Femoral Epiphysis Pathogenetic and Clinical aspects

Chapter 2
patients with valgus SCFE seems to be less than those with varus SCFE. The disorder might be more difficult to diagnose since the Klein’s line is normal (see radiological diagnosis). Only the lateral radiograph of the hip may reveal the slip. Valgus type SCFE may be associated with coxae valgae, hypopituitarism and stickler syndrome [57, 70, 125].
Bilateral disease in SCFE is reported in 18-50% of cases [69]. The risk of bilateral disease can be predicted by measuring the posterior sloping angle (PSA) on an axial radiological view of the contralateral physis [13, 58, 97, 102, 162]. Alternatively, as means of predicting the risk of bilateral disease, could the modified oxford bone age score be used in unilateral SCFE. This bone age score incorporates 3 consecutive stages of maturation for 5 features: the femoral epiphysis, the greater trochanter, the lesser trochanter, the triradiate cartilage and the ilium. The risk of a contralateral slip was an 89 % probability, if a wide open triradiate cartilage was present (score of 1). In these cases it was concluded that a prophylactic contralateral pinning of the femoral head was advisable [108]. Interestingly, children with obesity can lower the risk of bilateral disease when reducing weight after unilateral SCFE [91]. Biochemical processes and endocrine factors are associated with SCFE. The timing of this disease is around puberty, a time of hormonal imbalance and rapid growth. An increased incidence of SCFE has been found in children with hypothyroidism, hypogonadal states, vitamin D deficiency and renal osteodystrophy [69].
A definitive hereditary pattern in SCFE has never been established. Rennie et al. [112] proposed an autosomal dominant inheritance pattern with incomplete penetrance in SCFE. The risk of developing SCFE by a second family member was 7.1%. Tins et al. [138] claim that an abnormal cartilage formation might be related to SCFE. They found an increased thickness of both the cartilage of symphysis width and the unaffected hip joint width in SCFE compared with the normal widths. They concluded that either an increased cartilage formation or a decreased maturation could explain the vulnerability in SCFE.
In conclusion, SCFE is most likely the result of a multifactorial event during adolescence when height and weight increase dramatically and the delicate balance between the various hormonal equilibria can be disturbed. There are no biochemical screening or diagnostic tests available yet to predict patients at risk [151].
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