Page 21 - Slipped Capital Femoral Epiphysis Pathogenetic and Clinical aspects

Etiology.
Previous reviews suggest that the cause of SCFE is probably multifactorial. Biomechanical and biochemical processes both influence the adolescent physis.
Being overweight or obesity are considered a biomechanical factor, since at least 2 50% of the children with SCFE are above the 95th percentile for weight, based on
age and length [69]. Other mechanical factors associated with SCFE are femoral
retroversion and increased physeal obliquity [109]. In a finite element model, a
varus hip load in combination with femoral retroversion in an overweight child can
create physeal strains above the yield point, possibly resulting in a slip [31, 38]. The
slope of the femoral growth plate on an AP radiograph shows the main increase in
steepness between 9 and 12 years old which may be a factor contributing to SCFE
within this time span [83].
Other studies have focused on the shape of the femoral physes and acetabula. The
changing shape of the physis from a pleated towards a more spherical physis in
puberty could be one of the risk factors for SCFE [53]. The epiphyseal tubercle on
the inferior surface of the capital femoral epiphysis relatively decreases relative in
height and surface area with increasing age. This may also explain the vulnerability
of SCFE in adolescence [67].
In addition, changes in the acetabulum in SCFE are described. CT scans have shown
increased retroversion of the upper quarter of the acetabulum in SCFE patients.
Whether this is a primary or secondary response is unclear [86]. The acetabular
version between the affected and unaffected side does not appear to differ [76].
Interestingly, the contralateral acetabulum in unilateral SCFE compared to age and
sex-matched controls has significantly higher prevalence of acetabular retroversion
[117]. Gehart et al. [36] could not confirm the acetabular retroversion in SCFE. In this
study, the acetabular version of 14 cadaveric pelvis with post-SCFE deformity were
compared to 200 normal cadaveric pelvis, all age, sex and race-matched, and there
were no differences between affected and unaffected sides, in a same specimen
as well as in specimen with or without SCFE. Poseszwa [107] describes patients
with SCFE as appearing to have, based on a radiographic standardized supine AP
view of the pelvis, a deep acetabulum where the medial edge of the acetabulum is
medial of the ilioischial line. This could lead to physeal instability as SCFE develops.
In the literature, the valgus type SCFE accounts for approximately 4% of all SCFE
cases (most are varus type SCFE). Valgus SCFE patients were younger, had lower
risk of bilateral disease and females were more susceptible to it. The severity of
Slipped Capital Femoral Epiphysis
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