Sagittal spinal alignment in patients with Legg-Calve-Perthes disease

Legg-Calve-Perthes disease (LCPD) is an avascular necrosis of the capital femoral epiphysis in children. Several studies found a pathophysiological relationship between LCPD and juvenile Scheuermann's kyphosis, suggesting an abnormal spinal condition related to osteochondrogenesis. In the present study sagittal spinal alignment of the patients with LCPD was analyzed to examine associated spinal involvement.

A standing lateral radiograph of the spine was evaluated in 78 patients who had a history of LCPD. Various parameters of sagittal spinal alignment, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral inclination (SI), apex of thoracic kyphosis (TK-apex) and lumbar lordosis (LL-apex), and sagittal balance (SB; positive SB values represent a sagittal balance in front of the sacrum) were measured and compared between the patients with and without vertebral abnormalities.

Compared to previously published normative data, relatively decreased LL was evident in LCPD. Most of the patients (65%) had negative SB, which was correlated with decreased SI, more proximal TK-apex, and more distal LL-apex. Vertebral abnormalities including end-plate irregularities and wedging vertebrae were observed in 20 patients. Decreased SI, more distal LL-apex, and more negative SB were remarkable in the patients with vertebral abnormalities.

The patients tended to stand in greater negative sagittal balance associated with decreased LL. The characteristic sagittal alignment was prominent especially in the patients with vertebral abnormalities. Wedging vertebrae, probably due to growth disturbance of the vertebral bodies, could result in decreased LL, which leads to posterior pelvic tilt and posterior shift of sagittal balance.