What is the pathophysiology of Scheuermann disease (juvenile kyphosis)?

Updated: Sep 08, 2020
  • Author: Jozef E Nowak, MD; Chief Editor: Stephen Kishner, MD, MHA  more...
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Answer

Scheuermann's disease refers to osteochondrosis of the secondary ossification centers of the vertebral bodies. The lower dorsal and upper lumbar vertebrae are involved initially. The process may be limited to several bodies or may involve the entire dorsal and lumbar spine.

Scheuermann's disease probably is heterogeneous (ie, not a single entity but a group of conditions sharing similar features). The etiology and pathogenesis are a matter of debate. Many theories have been advanced, including mechanical, metabolic, and endocrinologic causes.

A definite hereditary component is involved in the development of the condition, but the mode of inheritance has been debated. [8] Reports of identical radiologic changes in monozygotic twins and transmission over 3 generations suggested underlying heritability. In study by McKenzie and Sillence, 12 probands were referred, and upon radiologic examination of their parents and siblings, 7 were shown to have familial Scheuermann's disease with an autosomal dominant pattern of inheritance. [9] Of the remaining 5 probands, 4 had chromosomal anomalies.

Patients with Scheuermann's disease generally are affected at age 13-16 years, are taller [10] than comparably aged peers, and have advanced skeletal versus chronologic age. Some affected children have disproportionate limb lengths.

A Greek research report, however, found that although, in the study, children with Scheuermann's disease tended to be taller and weigh more than did other children, there seemed to be no correlation in children with the disease between these 2 factors and the magnitude and morphology of the main kyphotic curve. [10] The authors suggested that hormonal disturbances may be impacting the development of Scheuermann's disease and also causing, as a secondary result, height and weight increases.

A study by Hershkovich et al, however, suggested that height and body mass index (BMI) are associated with the risk and severity of spinal deformities in adolescents. The study, which involved the medical records of 829,791 males and females aged 17 years, including 103,249 who had been diagnosed with some degree of kyphosis or scoliosis, found a significantly higher rate of spinal deformities, and a greater likelihood of such deformities being severe, in underweight males and females. Greater height was also found to be associated with increased risk and greater severity of spinal deformities in males and females. [11]

In a Finnish study, left-handedness was found to be a powerful determinant of hyperkyphosis in school children before puberty. [12] An increased incidence of spondylolysis and spondylolisthesis also was reported in patients with Scheuermann's disease, and scoliosis in the region of kyphosis is reported in 20-30% of patients as well. [13]

According to some authors, the presence of an adjacent area of lordoscoliosis below the region of hyperkyphosis testifies to the common nature of the pathogenesis of idiopathic scoliosis and Scheuermann's disease. Scheuermann's disease may be associated with an epidural cyst with an ensuing neurologic deficit.

A retrospective study by Tyrakowski et al found no significant difference between skeletally mature and skeletally immature patients with Scheuermann’s disease with regard to radiographic sagittal spinopelvic parameters, including sagittal vertical axis, thoracic kyphosis, thoracolumbar kyphosis, lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. However, both groups (33 patients each) had a significantly lower pelvic incidence and sacral slope than did children, adolescents, and adults without Scheuermann’s disease, causing the investigators to question the use of pelvic incidence in predicting the desired lumbar lordosis in Scheuermann’s disease cases. [14]

A study by Peleg et al suggested that a greater horizontal orientation of the sacrum may lead to a change in spinal biomechanics that in turn contributes significantly to the development of Scheuermann’s disease. The study involved the evaluation of the sacral anatomical orientation in 183 persons with Scheuermann’s disease and 185 controls. [15]


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