Spondylolysis and spondylolisthesis in children.

Spondylolysis is a common problem found in 5% of the general population. The etiology is a combination of two factors: (1) hereditary predisposition resulting from a congenital deficiency of the sacrum and posterior structures and (2) developmental factors, such as trauma, posture, or certain repetitive activities, that may precipitate a stress fracture of the pars interarticularis in susceptible individuals. Although the lesion occurs during the growth years, few individuals develop symptoms during childhood and adolescence. For the occasional child who develops symptoms, the onset usually coincides with the adolescent growth spurt, and similarly progression of spondylolisthesis occurs between the ages of 10 and 15. When symptoms develop, the child may complain of low back pain and to a lesser extent pain in the posterior buttock and thighs, usually without a neurologic deficit. A few seek medical attention because of the postural deformity or abnormal gait, secondary to hamstring tightness. Symptoms are usually initiated by strenuous activity and relieved by limitation of activity or rest. Children with spondylolisthesis appear to have more flexibility or looseness at the L5-S1 junction than their adult counterparts (Fig. 7-11). This increased mobility is reflected in the radiologic appearance of the vertebrae. There is gradual erosion of the anterior as well as the posterior aspect of the sacrum, which becomes domed or peaked in the middle. This inhibition of growth is mirrored in the trapezoid shape of the body of L5 and directly related to the degree of slip. The wear pattern suggests a teeter-totter type of instability of the fifth lumbar vertebra on the sacrum (Fig. 7-15). The sclerotic buttress appearance or reactive changes common in adults are uncommon in children (Fig. 7-17). As the slip advances to the higher grades, the sacrum and posterior aspect of the pelvis become more vertical (anterior inclination), again reflecting instability in combination with tight hamstrings and backward pulling of the pelvis (angle of tilt), giving rise to the marked physical changes and localized kyphosis of the lumbosacral spine. There is considerable evidence to suggest that when the spondylolisthesis exceeds 50%, there are many dynamic and anatomic factors at work to potentiate continued deformity and symptoms in the growing adolescent. This is reflected clinically by the frequent failure of conservative measures in controlling symptoms and the need for surgical intervention in a significant percentage of patients once the slip exceeds grade II.(ABSTRACT TRUNCATED AT 400 WORDS)