Scheuermann's Disease
Scheuermann's disease (SD) is a developmental disorder in adolescence that causes hyperkyphosis of the thoracic and thoracolumbar spine. It is characterised by vertebral body wedging, vertebral endplate irregularities, diminished anterior vertebral growth, Schmorl's nodes, narrowing of the intervertebral disc space, and premature disc degeneration. It most commonly occurs in the adolescent growth spurt between the ages of 12 and 15, but can occur as early as late preschool.[1]
Aetiology
The aetiology is not completely understood. Theories include:
- Genetic: It seems to have an autosomal dominant inheritance pattern with high penetrance and variable expressivity. A large twin study that looked at self-reported previous diagnoses of SD found that there was a major genetic contribution with odds ratios of 32.92 in monozygotic and 6.25 in dizygotic twins, and heritability of 74%. [2]
- Mechanical factors: Repetitive activities including repetitive loading in the immature spine. It is thought that there may be an altered remodelling response to abnormal biomechanical stress. Individuals with SD tend to be heavier and taller but this may be a consequence of other upstream factors (e.g. hormonal), rather than a cause of SD itself.
- Increased growth hormone levels
- Defective collagen fibril formation and resultant weakened vertebral end plate
- Juvenile osteoporosis: many studies have found lower bone mineral density in SD patients. However it isn't known if this is a consequence of decreased physical activity due to pain, or a primary causative factor of SD.
- Sternum length: There is an association of shorter sternums with SD development. It isn't known if this is a primary cause, but if it is it could be explained by the shorter sternum causing increased forces on the anterior aspect of the thoracic vertebrae.
- Trauma
- Vitamin A deficiency
- Poliomyelitis
- Epiphysitis
Epidemiology
Prevalence studies report a range of 0.4 to 8%. These figures may be a lower limit due to the condition being generally underdiagnosed. Most studies indicate a male predominance. [1]
Diagnosis
Most studies use the 1964 Sorenson criteria which stipulates wedging of a minimum of 5° of three or more adjacent apical vertebrae. The 1987 Drummond criteria only required two or more adjacent vertebrae. The 1987 Sachs criteria only require one vertebra to be wedged along with a thoracic kyphosis of more than 45° (T3-T12).[1]
Classification
There are two curve patterns. [1]
- Thoracic pattern: the most common. Associated with a non-structural hyperlordosis of the lumbar and cervical spine.
- Thoracolumbar pattern: this is rare, and is more likely to progress during adult life. Also known as lumbar type 2 Scheuermann's disease, or Apprentice kyphosis. This is more common in athletic adolescent males or in those that do heavy lifting. There is no significant kyphosis clinically.
Treatment
The rarer lumbar Scheuermann's disease is non-progressive and typically resolves with rest, activity modification, and time. [1]
- ↑ 1.0 1.1 1.2 1.3 1.4 Russell & Phillips. A preliminary comparison of front and back squat exercises. Research quarterly for exercise and sport 1989. 60:201-8. PMID: 2489844. DOI.
- ↑ Damborg et al.. Prevalence, concordance, and heritability of Scheuermann kyphosis based on a study of twins. The Journal of bone and joint surgery. American volume 2006. 88:2133-6. PMID: 17015588. DOI.
