SCHEUERMANN’S KYPHOSIS

Hitesh Gopalan U, Senthilnathan T, Ramesh Dalwai, Shamsul Hoda

Introduction

Scheuermann disease is a structural kyphosis of the thoracic or thoracolumbar spine, of unknown aetiology, is characterized by vertebral body wedging, thoracic kyphosis of > 40° & > 5° of anterior wedging of 3 consecutive adjacent vertebral bodies at the apex of the kyphosis, having presence of Schmorl’s nodes, irregular endplates, and a narrowing of verterbral disc space, and increased verterbral anterior/posterior diameter at the apex.
History

– Holger Werfel Scheuermann (1921) at a Danish Home for Crippled Children described ‘kyphosis dorsalis juvenilis’ which was before him known as ‘apprentice or muscular kyphosis’.

– He believed that the sagittal deformity is secondary to disturbances in the vertebral epiphyses and not as earlier suggested by spinal muscular insufficiency.

Aetio-Pathogenesis (Theories)

After Scheuermann’s vertebral epiphyseal disturbance theory, various theories for etiology were given denoting there could be multiple etiological factors playing a role.
Schmorl et al- vertebral wedging caused by herniation of disc material into the vertebral body.
Ferguson et al.- persistence of anterior vascular grooves in the vertebral bodies creates a point of structural weakness in the vertebral body leading to wedging and kyphosis.
Bradford et al – secondary to vertebral osteoporosis during the juvenile period rather than intrinsic deformity of disc or ring apophysis.
Ippolito and Ponseti et al.- biochemical abnormality of the collagen and matrix of the vertebral endplate cartilage.
Frank Damborg et al – major genetic contribution to its etiology.
Mechanical factor – supported by bracing therapy, common in heavy weight lifting or manual labour.
Although many theories have been described historically, there is no established cause-effect relationship till date.

Anatomic and Histological changes

Gross – Thickened anterior longitudinal ligament, narrowed vertebral disks, and wedged vertebral bodies.
Histological – abnormalities of the cartilaginous endplate include disorganized endochondral ossification which probably is the result of kyphosis rather than the cause.
Collagen : Proteoglycan ratio in endplate matrix is below normal.
Relative decrease in collagen results in alteration in the ossification of the endplate causing altered vertical growth of the vertebral body.

Demographics

Incidence – 0.4 – 10% of adolescents, between 10 – 14 years age.
Onset – during the prepubertal growth spurt, apparent at around 10–12 years of age.
Sex – M > F.

Definition of Kyphosis

Scoliosis Research Society – normal kyphosis of the throracic spine as an angle between 20-45 ° (T1-T12).
Any angulation of > 45° is considered hyperkyphosis.
Normal Lumbar Lordosis is 50-70° (L1-S1).
Thoraco-Lumbar Junction is 0-10° (T10-L2).
Sagittal Gravity Line passes through spinous process of T1, T12 & Sacral promontory.

Types

1. Typical Scheuermann disease:

Usually involves thoracic spine, this classic form has > 3 consecutive vertebrae, each wedged > 5°, producing a structural kyphosis. Thoracic Scheuermann is the most common form.

2. Atypical Scheuermann disease:

Usually located in the thoracolumbar junction or the lumbar spine, is characterized by vertebral end plate changes, disc space narrowing, and anterior Schmorl nodes but does not necessarily have 3 consecutively wedged vertebrae of 5°.

Clinical Features:

Patient usually presents for pain, deformity or its progression, neurologic compromise, cardiopulmonary compromise, and cosmetic problem.
Adolescents often present on the urging of parents, teachers, or friends, primarily for cosmetic or postural complaints.
Pain is more commonly the chief complaint of adults.
- Typically, pain is located just distal to the apex of the deformity in a paraspinal location.
- Commonly activity related and presents as either pain in the typical area associated with Scheuermann’s kyphosis or simply early fatigue.
- Symptoms usually relieved immediately with rest and usually are not activity-limiting.
- In adults, pain is more common presenting complaint.
- Adolescents with lumbar Scheuermann’s disease typically present with progressive low back pain that precludes involvement in athletic activity and may interfere with activities of daily living.
- They may also complain of radiating pain into the buttocks and lower extremities, and may have pain that awakens them from sleep.
Hyperlordosis distal to the thoracic deformity and subsequent degenerative disc and facet arthropathy predispose adults to low back pain; the typical pain over the deformity may coexist or predominate.
Progression of the deformity is an additional cause for patients seeking treatment.
- Patient’s perception of increasing deformity and previous radiographic evaluation can provide concrete evidence of progression of the deformity.
Cord compression secondary to Scheuermann’s kyphosis is rare, may mandate surgical treatment.
Neurologic compromise onset is quite variable, ranging from acute onset of unilateral radiculopathy to insidious onset of spastic paraplegia.
The underlying cause is that the spinal cord is draped over the apex of the deformity.
Patients may also present with extradural cysts or acute thoracic disk herniations, exacerbated by the underlying deformity and may cause neurologic compromise.
Cardiopulmonary complaints are extremely rare on initial presentation.
- Restrictive pulmonary disease is documented in patients with kyphosis measuring >100°, with the apex of the curve in the upper thoracic region.
Cosmetic issues related to the curve should also be addressed.
- Caution should be exercised when cosmesis is isolated indication for treatment, esp. surgical intervention.

Physical Examination:

Erect patient will demonstrate increased thoracic kyphosis with sloping shoulders.
Forward posturing of the head and neck is secondary to increased cervical lordosis.
Increased lumbar lordosis seen with weakened abdominal muscles causing a mildly protuberant abdomen.
The Adam’s forward bend test may demonstrate slight truncal asymmetry associated with mild scoliosis.

In side view, abrupt posterior angulation of thoracic spine gives a characteristic ‘A-frame’ deformity.

This deformity is not easily corrected with postural changes or passive manipulation. The lumbar lordosis is usually reversible, flexible and corrects with forward bending, but the cervical lordosis may become fixed.
Although the nuerological exam is normal, tight or contracted hamstrings and pectoral muscles are seen.
The arms and legs will appear relatively long compared with the shortened trunk.

Radiographic Evaluation:

Standard views

Standing PA View

May show mild scoliosis that rarely > 25° and shows minimal vertebral rotation.
This view allows assessment of skeletal maturity by estimation of the Risser sign.
Arms resting at shoulder height on a crossbar positioned directly in front of them.
This view reveals thoracic kyphosis over 40 (Cobb Technique) and the radiographic criteria defined by Sorensen in 1964:
- >5° of anterior wedging of 3 consecutive adjacent vertebral bodies at the apex of the kyphosis.
- Irregular vertebral apophyseal lines, with flattening and wedging.
- Narrowing of the intervertebral disk spaces and a variable presence of Schmorl’s nodes. The lateral radiograph should also evaluate other associated conditions as hyperlordosis of the lumbar spine, spondylolisthesis, and degenerative changes in the lumbar spine.
  - Lateral radiograph in hyperextension assess flexibility of the kyphosis.
  - The same vertebral endplates used to assess the standing lateral kyphosis can be selected for the hyperextension lateral view.

2. Lateral 36-inch (90 cm) spine radiographs erect with hips and knees extended.

3. Hyperextension lateral image of the thoracic spine.

Lumbar Scheurmann’s Disease

Lateral view show decreased lumbar lordosis and possible kyphotic deformity at the thoracolumbar junction.
The lumbar vertebrae is scalloped with lucent defects at the anterosuperior corners.
Schmorl’s nodes and end plate irregularities may be seen.
A preoperative MRI should be done for atypical or rapidly progressive kyphosis, or any neurologic signs and symptoms.

Natural history:

Untreated kyphosis in adult may progress if the deformity is severe, although the true natural history is unknown at this time.
Travaglini & Come followed 43 patients for 25 years; the kyphosis increased in 80% of the patients in adulthood, although severe deformity did not develop in most of them.
Adults who have mild residual kyphosis secondary to Scheuermann disease will have little, if any, difficulty and are not likely to seek medical attention.
Pain in adults is frequently due to degenerative spondylosis, often a sequel of untreated Scheuermann disease, usually resistant to non-operative treatment, not usually seen in patients having kyphosis <60°.
Pulmonary compromise occurs if the curve is >100°.
Patients with type II Scheuermann’s kyphosis almost never require surgery.

Classification

Broadly 2 forms-

Thoracic type

Pure thoracic type has apex at the mid-thoracic spine.
When the kyphosis is <75°, chance of progression is less without significant pain.
When the angle is >80° it continues to progress with increased pain.
More common in adolescents as well as in adults.
There can be a Thoraco-Lumbar pattern with its apex at the thoraco-lumbar junction with high propensity to progress and can be significantly painful.
- Generally males with back pain as initial complaint.
- Benign prognosis

2. Lumbar type

Differential Diagnosis:
1. Postural kyphosis:
– In forward bending test

– kyphotic deformity is accentuated, and the apex appears as a sharp angulation, in contrast to the smooth curve of a patient with postural kyphosis.

– also exposes any associated scoliosis.

–Hyperextension test helps understand the rigidity of the curve.
– A curve that is flexible or reduces significantly with hyperextension is typically postural and not Scheuermann’s kyphosis, although in younger children a flexible round-back deformity may be the first sign of evolution to true Scheuermann’s kyphosis.

Non-OperativeTreatment:

Indications:

Relative skeletal immaturity (? Risser grade II) and a progressive deformity that is cosmetically or functionally unacceptable (usually >60 °).
Goals of nonoperative management: To control the deformity and to attempt to reconstitute the anterior vertebral height by applying hyperextension forces.

– Anti-Inflammatory Medications

– Exercises

– Bracing

Apical vertebra at or above T7, the Milwaukee brace is recommended because
- it only can effectively apply three-point corrective force to a midthoracic apical vertebra,
- also decrease the lumbar lordosis and help correct the negative sagittal balance.
Apical vertebra below T7, a thoracolumbar-sacral orthosis (TLSO) can be tried, usually supplemented with anterior sternal or infraclavicular outriggers to provide an extension moment cephalic to the apex.
With a decrease in lumbar lordosis, the patient is encouraged to actively hyperextend the spine to maintain the head in a more upright position.
Initially, bracing is done full-time, with the patient allowed to remove the brace 1-2 hrs/d for exercises.
Radiographs to be done every 3-4 months, with progressive correction bent into the posterior kyphosis pads as tolerated. Brace treatment to continue until skeletal maturity is achieved, which for boys may require to wear the orthosis until Risser grade V.
All kyphosis braces require careful orthotist attention to ensure fit and to recontour the posterior bars and pads every 2 months to gain further correction progressively.

Cast Treatment

When passive correction on lateral bolster radiograph is <40%, brace treatment is not likely to be effective.
Risser casts can be applied in a serial fashion to produce more correction of the kyphosis.
Following 6–9 month period of casting, patient is then treated with a Milwaukee brace or other retention brace to maintain the correction during the remainder of the growth.
With such a regime, not only is the deformity improved by as much as 40%, but there is less loss of correction. In a series reported by Ponte and associates, only 4° of correction was lost.
The use of cast treatment in an adolescent rests largely on the patient’s desire to achieve maximum correction without resorting to surgery.
Because of the prolonged and relatively inconvenient treatment period (6–9 months in casts and a minimum of 6 additional months in a brace), such therapy will never succeed without the total compliance and desire of the adolescent.

Surgical Management

Indications:

Kyphosis >80 ° in T spine

>65 ° in T-L Spine

Symptomatic (persistent pain, neurologic deficit, cosmetic problem) of T spine >75 ° or T-L Spine >60 ° not controlled by non-operative methods
Significant sagittal imbalance

Principles

Release the tethers of anterior column and achieving fusion.
Shorten and stabilize posterior column.

Goals

Maximize safe correction of kyphosis
Achieve sagittal balance
Provide rigid fixation

Determining Fusion Levels

Fusion levels are determined from the standing lateral radiograph.
The upper limit of fusion must include the most proximal vertebra that is tilted into the kyphosis, which generally means fusion to T2.
- If the fusion stops distal to this level, there is a risk that a postoperative junctional kyphosis will develop.
The caudal extent of the fusion should include the first lordotic disk space, which commonly includes one level distal to the measured end vertebra of the kyphosis.
Failure to extend into the lumbar lordosis similarly risks a caudal junctional kyphosis
Concept of Stable Vertebra– The distal fusion level is extended to the stable vertebra (The first vertebra bisected or intersected by the posterior sacral vertical line).
On some occasions, the stable vertebra is distal to the level of determined fusion. The instrumentation need not be extended to the stable vertebra if the disk above it is lordotic or atleast neutral.

SURGICAL TECHNIQUE OPTIONS

ANTERIOR RELEASE & FUSION

Indication

When the kyphosis is rigid on hyperextension films

Levels of Anterior release

Include the rigid apical segment based on hyperextension films.

Technique

Right sided Thoracotomy or Thoracoscopic

Procedure

The disc spaces exposed and curetted preserving the bony endplate.
Bone graft placed at each disc space.

POSTERIOR INSTRUMENTED CORRECTION

Posterior procedure is done as a standalone procedure or combined with anterior procedure either as a single stage (usually Thoracoscopic anterior release– Both being done in prone position) or as staged procedure.

Indication for Posterior Instrumentation alone:

Patient is skeletally immature (< Risser grade III) and has some anterior growth potential remaining and if the kyphosis is corrected to <50° on a hyperextension lateral radiograph.
However this stands the risk of loss of correction

Principle of Posterior Instrumentation and Fusion

The correcting maneuver used is cantilevering the rod on to the spine and segmental compression (from apex to the ends) to achieve both sagittal and coronal balanced spine.
The typical posterior construct includes a minimum of 8 anchors above and below the apex of the kyphosis
3-5 pairs of pedicle hook–transverse process claws cephalad to the apex of the kyphosis, and similar number of paired pedicle screws caudad to the apex of the kyphosis.

Surgical Technique

Segmental sublaminar wiring (Luque Instrumentation) is not advisable anymore because of its propensity to cause junctional kyphosis especially at the cephalad end and increased incidence of neurologic injury.
The multisegment hook rod system (Cotrel Doubousset system, TSRH or ISOLA) is commonly used because of its capacity to increase stability during a cantilever maneuver by taking advantage of the ability to “claw” adjacent laminae and the ability to achieve compression between segments as well.
Now with the advent of all pedicle screw system the amount of correction achievable with posterior only surgery has improved obviating the need for anterior release and additional morbidity.
Always avoid implants which encroach the spinal canal (sub-laminar wires & laminar hooks) especially at the apex of the deformity as they can damage the cord which is displaced posteriorly at the apex.
There is renewed interest in the Harrington rod system with use of a larger diameter threaded rod (4.8mm rod as against older 3.125 mm rod), which does not cause any loss of correction unlike the traditional system.
The amount of correction achieved can be increased by osteotomizing the facets, excising the ligamentum flavum (Ponte Osteotomy) and closing them during cantilevering and segmental compression (similar to closed wedge osteotomy of long bones- shortens the convex longer side without stretching the concave short side).

Posterior correction with or without osteotomy and fusion.

Anterior release has been recommended for deformities that do not correct to 50° on stress views.
Fusion level: Current recommendations are to include the proximal end vertebra (determined by the modified Cobb method) and to extend the fusion past the transitional zone to the first lordotic disc distally
Traditional teaching is to restrict the correction to 40° to prevent proximal or distal junctional kyphosis and implant pull out.
Intraoperative neurologic monitoring is crucial during any surgery to correct kyphosis because the thoracic cord is at risk during correction and instrumentation.
NMEPs and SSEPs are used for this postoperative bracing for approximately 3-6 months.
Relative indications for surgery:
Kyphosis >70°, deformity progression despite bracing, cosmesis, neurologic deficits and failure of conservative treatment for pain.

Contraindications: Asymptomatic patient without cosmetic concerns.

References

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