We carried out a study to determine the effect of facet tropism on the development of adolescent and adult herniation of the lumbar disc. We assessed 149 levels in 140 adolescents aged between 13 and 18 years and 119 levels in 111 adults aged between 40 and 49 years with herniation. The facet tropism of each patient was measured at the level of the herniated disc by CT.

There was no significant difference in facet tropism between the herniated and the normal discs in both the adolescent and adult groups, except at the L4-L5 level in the adults. Facet tropism did not influence the development of herniation of the lumbar disc in either adolescents or adults.

We classified fixed pelvic obliquity in patients after poliomyelitis into two major types according to the level of the pelvis relative to the short leg. Each type was then divided into four subtypes according to the direction and severity of the scoliosis.

In 46 patients with type-I deformity the pelvis was lower and in nine with type II it was higher on the short-leg side. Subtype-A deformity was a straight spine with a compensatory angulation at the lower lumbar level, mainly at L4-L5, subtype B was a mild scoliosis with the convexity to the short-leg side, subtype C was a mild scoliosis with the convexity opposite the short-leg side, and subtype D was a moderate to severe paralytic scoliosis with the convexity to the short-leg side in type I and to the opposite side in type II.

A combination of surgical procedures improved the obliquity in most patients. These included lumbodorsal fasciotomy, abductor fasciotomy and stabilisation of the hip by triple innominate osteotomy with or without transiliac lengthening. In patients with type ID or type IID appropriate spinal fusion was usually necessary.