- Scheuermann’s Kyphosis involves wedging of vertebrae (generally thoracic) which creates a kyphotic deformity >45 degrees
- True etiology is unknown, but is likely a mix a hereditary and environmental factors
- Natural history is fairly benign for kyphosis <100 degrees with pain being the main complaint
- Bracing is the mainstay of non-operative treatment
- Operative treatment is most commonly a posterior spinal instrumentation and fusion (PSIF); although, anterior spinal fusion (ASF), and combinations of the two techniques are also options.
Description:Scheuermann’s Kyphosis, also known as Scheuermann Disease, was originally described in 1919 and refers to a rigid juvenile or adolescent kyphosis with wedging of the vertebral bodies over the affected segments in the thoracic spine. The apex of the kyphosis is typically located between T7 and T9. It is often associated with back pain, although that back pain is expected to improve by age 20-30. It is believed to be caused by a growth disturbance at the end-plates of the vertebral body. Much like AIS, the age of onset of Scheuermann’s kyphosis is most often during the prepubertal growth spurt and clinical detection is typically shortly after this time point. It is difficult to diagnose Scheuermann’s kyphosis before the prepubertal growth spurt as the characteristic vertebral wedging cannot yet be detected radiographically until the ring apophysis is ossified (approximately 10 years).
Epidemiology:A range of incidence from 0.4–10% has been reported with varying rates of male-to-female ratios. As previously stated, age of onset is during the prepubertal growth spurt and diagnosis is most often after 10 years of age. An associated mild scoliosis is noted in 20% to 30% of patients, but this lateral curve rarely progresses to require treatment. Progression of kyphosis has been documented during the growth spurt and later in adult life. In contrast to idiopathic scoliosis, the risk for kyphosis progression currently is unknown and warrants further study. Data reported by Murray suggest that the natural history is fairly benign, except for a known increase in back pain (Murray, 1993). Patients with thoracic kyphosis below 100 degrees actually have an increase in pulmonary function due to the increase in chest circumference. Once there is progression past 100 degrees of kyphosis, patients will exhibit restrictive cardiopulmonary pathology.
Clinical Findings:History: In general, presentation is in the peri-pubertal years, or anytime thereafter as dictated by pain and appearance. Patients with kyphosis have a wide range of body morphology and body mass index; therefore, deformity will be evident at a lower degree of kyphosis in some patients. In patients who have not yet developed pain at the level of kyphosis or in the lower back, the presenting symptom is often poor posture or rounded shoulders that has alarmed the parents or primary care giver. Patients who present with pain will commonly complain of pain at the apex of the deformity as well as in the lower back; particularly if there is a concomitant increase in lumbar lordosis.
Physical Examination: In addition to the standard neuromuscular spine examination, the Adam’s forward bend test can be used to assess coronal and axial deformity when viewing a patient from behind, and can assess sagittal deformity/kyphosis when viewed from the side. Tests of thoracic hyperextension, either standing or on an examination table, can give the examiner information on the rigidity of the curvature. True Scheuermann’s kyphosis will be rigid and not correct with hyperextension, but very immature patients may have more flexible, early forms of Scheuermann’s kyphosis.
Imaging Studies:The standard radiographic evaluation of kyphotic patients should include PA and lateral films obtained on a full length (36 inch) cassette. Normal thoracic kyphosis is described as 20-45 degrees with normal lumbar lordosis being 30-60 degrees. The following features of Scheuermann’s kyphosis are seen on the lateral radiograph:
- Anterior wedging (>5 degrees) of three or more consecutive vertebral bodies
- Increased kyphosis (>45 degrees), which can be measured by the Cobb method on the lateral x-ray
- Irregularity of vertebral end plates
- Schmorl’s nodes—depressions in the vertebral bodies that represent disc herniation into the end plate
Treatment:The reasons to initiate treatment in Scheuermann’s kyphosis are pain, dissatisfaction with appearance, progression of deformity and neurologic or cardiopulmonary compromise. The most common of these are pain and appearance.
- Serial observation: Appropriate treatment method for immature patients with smaller, flexible curves, or mature patients with stable asymptomatic curves
- Physical therapy with stretching: Therapy regimens aim to strengthen back and core musculature while stretching the hamstring muscles. No study has clearly shown that this is an efficacious treatment, but, in theory, it can work to decrease lumbar lordosis. It is less clear if stretching and therapy have any effect on a rigid kyphosis.
- Bracing: Bracing is the mainstay of non-operative management. Patients with mild-to-moderate kyphosis (<75 degrees) may consider a trial of conservative treatment to control symptoms and minimize deformity. A kyphosis brace applies three-point bending forces that decrease thoracic kyphosis. In skeletally immature patients with thoracic kyphosis greater than 45 degrees and less than 75 degrees, bracing can be considered. Studies on the efficacy of bracing in this population do not provide convincing supportive evidence and the discomfort of the brace limits patient compliance.
Operative intervention for Scheuermann’s kyphosis can be in the form of posterior spinal fusion (PSF) – most common, anterior spinal fusion (ASF), or a combination of the two. The principles of surgical correction are based on shortening the posterior column, lengthening the anterior column, or both. Other than physiologic compromise, neurologic or cardiopulmonary, there are no absolute indications for surgical intervention in Scheuermann’s kyphosis. Each patient must be treated individually based on the patient’s clinical examination, radiographic parameters, pain, and appearance. Tribus suggested the following five reasons to consider surgical treatment in thoracic Scheuermann’s kyphosis (Tribus, 1998):
- Progressive curve
- Neurologic compromise
- Cardiopulmonary compromise
- Trunk deformity
Complications:Reported complications of surgical correction of Scheuermann’s kyphosis include death, gastrointestinal obstruction, hardware failure, pseudoarthrosis, junctional kyphosis, progression of the deformity, hemothorax, pneumothorax, pulmonary emboli, neurologic injury, infection, and persistent postoperative back pain. The most feared complication is neurologic injury, including paralysis. Vascular insults to the cord and mechanical damage have led to paraplegia. Correction of kyphosis carries a higher than usual risk of neurologic injury, which is related directly to the amount of correction. Intraoperative neurologic monitoring is crucial during any surgery to correct kyphosis because the thoracic cord is at risk during correction and instrumentation. Motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) are used in most spine centers. The Stagnara wake-up test is the gold standard for motor monitoring if there are any concerns during surgery. If monitoring or the wake-up test indicates a neurologic deficit, any corrective maneuvers should be reversed. There are significant risks to surgical correction of thoracic kyphosis that must be weighed carefully when considering surgery because the natural history of mild to moderate Scheuermann’s kyphosis still is not yet well defined. Corrective kyphosis surgery has benefited immensely from new developments in spine instrumentation (e.g., pedicle screws, in-situ bending). Perhaps even more than idiopathic scoliosis, surgical management of Scheuermann’s kyphosis requires treatment by experienced spinal deformity surgeons.
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