Evaluation of radiological indices of the spine and pelvis ratios in children with a severe form of slipped capital femoral epiphysis

BACKGROUND: Slipped capital femoral epiphysis is one of the most severe diseases of the hip joint in children and is characterized by the displacement of the proximal femoral epiphysis, occurring as a result of a decrease in the mechanical strength of its growth plate. Some pathological processes in the hip joints and lumbosacral spine cause changes in the position (vergence) of the pelvis in the sagittal plane and the development of degenerative dystrophic diseases. The analysis of the spinepelvis relationships in children with slipped capital femoral epiphysis may provide the basis for the development of new approaches to the surgical correction of the deformity of the hip component of the affected joint. 
AIM: To assess the radiological parameters of the frontal and sagittal spinepelvis relations in children with proximal femur deformity in slipped capital femoral epiphysis. 
MATERIALS AND METHODS: The study included 30 patients (30 hips) aged 1114 years with a severe form of slipped capital femoral epiphysis characterized by the presence of a posterior displacement of the epiphysis of 60 combined with the downward displacement of no more than 10 in one of the joints and absence of displacement (pre-slip stage) in the other. Patients underwent clinical and radiological examinations. The radiographs taken in the standing position were used to assess the values of thoracic kyphosis and lumbar lordosis, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), sagittal vertical axis (SVA), and spinesacral angle (SSA). The obtained data were subjected to statistical processing. 
RESULTS: The patients had pelvic retroversion (decreased values of the PI and SS indices and increased PT index) and formed hypolordotic type of vertical posture according to P. Roussouly classification. In addition, thoracic hyperkyphosis occurred, and the SVA shifted to the front, which can be considered a mechanism of trunk balance compensation for the existing pelvic retroversion and reduction of lumbar lordosis to maintain the ability to move in an upright position. 
CONCLUSIONS: Children with this severe form of slipped capital femoral epiphysis are characterized by pelvic retroversion, decreased lumbar lordosis and increased thoracic kyphosis, positive trunk imbalance, and PT toward the affected limb. Planning and reconstructive restorative interventions on the affected hip joint should consider existing pathological changes to restore the correct spinepelvis relationships and prevent degenerative dystrophic processes in the lumbosacral spine.