Orthopaedic Surgery - Kyphosis

Basics

Kyphosis is a sagittal-plane curvature of the spine characterized by anterior concavity and posterior convexity.

Some degree of kyphosis is normal, particularly in the thoracic and sacral regions.

Normal thoracic kyphosis is approximately 20–45° in children, with somewhat greater values possible in adults.

When thoracic kyphosis becomes excessive, the deformity may be caused by:

Postural kyphosis, Scheuermann disease, congenital vertebral abnormalities, osteoporosis, ankylosing spondylitis, neuromuscular disease, myelomeningocele, trauma, infection, prior surgery, or malignancy.

Significant kyphotic deformity, particularly curves greater than approximately 50°, may be associated with increased back pain, compensatory lumbar lordosis, spondylolysis, and, in sharply angular congenital or infectious deformities, neurologic compromise.

Prevention

Postural Kyphosis

Postural kyphosis may be influenced by:

Attention to posture, strengthening, flexibility exercises, and avoidance of prolonged poor postural habits.

Osteoporotic Kyphosis

Prevention of osteoporosis and vertebral compression fractures can decrease the likelihood of progressive age-related kyphosis.

Important measures include:

Adequate calcium and vitamin D, weight-bearing exercise, fall prevention, and pharmacologic osteoporosis treatment when indicated.

Epidemiology

Kyphotic deformity may occur as part of numerous congenital, metabolic, inflammatory, or neurologic disorders.

Associated conditions include:

Neurofibromatosis, mucopolysaccharidoses, achondroplasia, myelomeningocele, ankylosing spondylitis, and benign or malignant spinal tumors.

Incidence and Prevalence

Osteoporotic vertebral compression fractures are an important cause of kyphosis in older adults.

Historical studies have reported kyphotic deformity related to osteoporotic fractures in approximately 15% of Caucasian women.

Spinal Tuberculosis

Tuberculous involvement of the spine may lead to vertebral destruction and angular kyphosis.

Spinal disease represents a minority of tuberculosis cases overall but is particularly important because of its potential to cause:

Severe deformity, abscess formation, and neurologic compromise.

Postural Kyphosis

Postural kyphosis is often seen in adolescents, particularly those who are taller than their peers.

The curve is usually flexible and does not result from structural vertebral abnormalities.

Congenital Kyphosis

Congenital kyphosis is uncommon.

It results from abnormal formation or segmentation of the vertebrae and may progress rapidly during growth.

Scheuermann Kyphosis

Scheuermann disease has historically been reported in approximately 0.4–8.3% of the population.

Males may be affected somewhat more often than females.

Osteoporosis

Osteoporosis is particularly common in patients who are:

Older, female, postmenopausal, of Caucasian or Asian ancestry, chronically exposed to corticosteroids, or affected by other disorders that reduce bone density.

Risk Factors

Important risk factors for abnormal kyphosis include:

Osteoporosis, family history of spinal deformity, previous vertebral fracture, repetitive heavy spinal loading during adolescence, exposure to tuberculosis, and malignancy.

Genetics

Some conditions associated with kyphosis have a genetic component.

Examples include:

Ankylosing spondylitis, osteoporosis, and Scheuermann disease.

The degree of heritability varies substantially according to the underlying disorder.

Etiology

Postural Kyphosis

Postural kyphosis results largely from:

Poor posture, ligamentous stretching, and muscular imbalance.

The vertebral bodies themselves remain normally formed.

The curve is generally flexible.

Scheuermann Kyphosis

Scheuermann kyphosis is a structural growth disorder involving anterior wedging of the vertebral bodies.

It typically appears during early adolescence.

Unlike postural kyphosis, the deformity is relatively rigid and cannot be fully corrected by voluntary posture.

Congenital Kyphosis

Congenital kyphosis is present from birth and results from abnormalities such as:

Failure of vertebral formation, hemivertebrae, or anterior failure of vertebral segmentation.

Because the deformity may be sharply angular, the spinal cord can be placed at substantial risk as the child grows.

Osteoporotic Kyphosis

In osteoporosis, progressive kyphosis results from:

Anterior wedge compression fractures of thoracic or lumbar vertebral bodies.

Multiple adjacent compression fractures can produce substantial loss of height and a rounded thoracic posture.

Infectious Kyphosis

Tuberculosis and other spinal infections may destroy vertebral bodies and intervertebral discs.

Collapse of the anterior spinal column can produce a focal angular kyphosis or gibbus deformity.

Associated Conditions

Congenital Kyphosis

Congenital kyphosis may progress rapidly across a short spinal segment.

The resulting angular deformity can stretch or compress the spinal cord and lead to neurologic deterioration.

Patients should also be evaluated for associated:

Cardiac, renal, pulmonary, auditory, and other congenital abnormalities.

Intraspinal Abnormalities

Congenital scoliosis or kyphosis may be associated with intraspinal abnormalities in approximately 30% of patients in some series.

Examples include:

Tethered cord, syringomyelia, diastematomyelia, and other neural-axis anomalies.

Scheuermann Disease Associations

Patients with Scheuermann kyphosis commonly develop compensatory lumbar hyperlordosis.

Spondylolysis has historically been reported in a substantial proportion of affected patients.

Approximately one-third may also have a mild associated scoliosis, commonly around 10–20°.

Osteoporosis Associations

Patients with osteoporosis are also at increased risk for insufficiency fractures involving the:

Hip, pelvis, and wrist.

Diagnosis

Signs and Symptoms

Presentation depends on the underlying cause.

Congenital Kyphosis

Congenital deformity may occasionally be detected prenatally but is more commonly identified when a parent or physician notices:

A visible spinal prominence, abnormal posture, or progressive deformity.

Scheuermann Kyphosis

Typical findings include:

Apparent poor posture, a relatively sharp thoracic kyphotic apex, stiffness, and pain localized near the apex of the curve.

Osteoporotic Kyphosis

Patients may report:

Progressive loss of height, increasing spinal curvature, back pain, and previous fragility fractures.

Infection or Malignancy

Red-flag symptoms include:

Night sweats, weight loss, fever, progressive deformity, night pain, and new neurologic deficits.

These findings raise concern for infection or tumor.

Postsurgical Kyphosis

Postlaminectomy or other postsurgical deformity may be detected by comparing:

Previous examinations, prior radiographs, and serial changes in alignment.

History

Important historical features include:

Congenital abnormalities, family history of spinal deformity, progression of kyphosis, onset of neurologic symptoms, constitutional symptoms, chronic corticosteroid use, fragility fractures, trauma, infection exposure, and previous spine surgery.

Physical Examination

Standing Examination

Examine the patient in a neutral standing position.

Assess:

Overall sagittal balance, shoulder height, head position, thoracic contour, lumbar lordosis, pelvic position, and associated scoliosis.

Forward Bending

Forward bending accentuates a structural kyphotic deformity and may help identify:

A sharp angular apex or associated rotational deformity.

Flexibility Assessment

Curve flexibility may be assessed by:

Prone hyperextension or supported hyperextension over a bolster.

Interpretation

A flexible curve is more consistent with postural kyphosis, whereas a rigid curve suggests:

Scheuermann disease, congenital deformity, ankylosing spondylitis, or another structural abnormality.

Neurologic Examination

A complete neurologic examination is essential.

Assess:

Strength, sensation, reflexes, gait, balance, bowel and bladder symptoms, and signs of myelopathy or spinal cord compression.

Laboratory Tests

Routine laboratory tests are often normal in uncomplicated kyphosis.

Testing should be directed by the suspected cause.

Suspected Infection

Appropriate studies may include:

Complete blood count, ESR, CRP, and blood cultures.

Suspected Tuberculosis

Testing may include:

Tuberculosis skin testing or interferon-gamma release testing, depending on the clinical context.

If the causative organism remains uncertain, biopsy may be necessary.

Osteoporosis

Routine serum tests may be normal even when osteoporosis is present.

Additional studies may be ordered to identify secondary causes of low bone density.

Ankylosing Spondylitis

HLA-B27 may be present in patients with ankylosing spondylitis, but diagnosis depends primarily on:

Clinical findings, imaging, and the overall inflammatory pattern rather than HLA-B27 alone.

Imaging

Standing Radiographs

For most forms of kyphosis, obtain:

Standing AP and lateral radiographs of the entire spine.

These allow measurement of:

Curve magnitude, sagittal balance, associated scoliosis, vertebral wedging, and compensatory alignment.

Focused Radiographs

Additional views may be used to assess:

Vertebral anomalies, fractures, focal destruction, or congenital abnormalities.

Hyperextension Radiographs

A lateral radiograph obtained while the patient hyperextends over a bolster may help determine:

The flexibility of the kyphotic curve.

Skeletal Maturity

The Risser sign can often be assessed on the AP radiograph and helps estimate remaining skeletal growth.

MRI

MRI is particularly indicated in patients with:

Congenital kyphosis, neurologic deficits, suspicion of malignancy, suspected infection, or concern for neural-axis abnormalities.

MRI evaluates:

The spinal cord, nerve roots, discs, marrow, epidural space, and surrounding soft tissues.

Renal Ultrasound

Children with congenital kyphosis may undergo renal ultrasound because congenital vertebral abnormalities can be associated with renal malformations.

DEXA

Bone-density testing with DEXA should be considered when osteoporotic kyphosis is suspected or when baseline bone mass assessment will influence treatment.

Pathological Findings

Scheuermann Kyphosis

Scheuermann disease has typical and atypical patterns.

Typical Scheuermann Disease

The classic radiographic criterion is:

Anterior wedging of at least 5° in three or more consecutive vertebral bodies.

The apex frequently lies between approximately T7 and T9.

Other findings may include:

Endplate irregularity and Schmorl nodes.

Atypical Scheuermann Disease

Atypical cases may demonstrate:

Endplate irregularities, Schmorl nodes, and disc-space narrowing

without meeting the classic criterion of three consecutively wedged vertebrae.

Osteoporotic Kyphosis

Osteoporosis commonly produces:

Anterior vertebral body wedging, compression fractures, and generalized reduction in bone density.

Ankylosing Spondylitis

Advanced ankylosing spondylitis may produce:

Rigid kyphotic alignment, vertebral wedging, syndesmophyte formation, and eventual spinal fusion.

Infection or Tumor

Infectious or neoplastic kyphosis may be associated with:

Vertebral body destruction, soft-tissue mass, epidural extension, or spinal canal narrowing.

Differential Diagnosis

Kyphosis should be distinguished from:

Scoliosis, neuromuscular spinal deformity, postsurgical deformity, vertebral fracture, congenital vertebral malformation, ankylosing spondylitis, infection, and malignancy.

Scoliosis

Thoracic scoliosis may create a prominent rib hump that superficially resembles kyphosis.

However, many patients with thoracic scoliosis actually have reduced rather than increased thoracic kyphosis.

Neuromuscular Kyphosis

Neuromuscular disorders may produce kyphosis because of:

Weak trunk musculature, poor postural control, or abnormal muscle tone.

Postlaminectomy Kyphosis

Removal of posterior spinal elements in a growing child can destabilize the spine and result in progressive kyphotic deformity.

Treatment

Observation

Mild, stable deformities may be managed with observation and periodic clinical or radiographic assessment.

This is particularly appropriate when:

The patient is asymptomatic, the curve is flexible, and there is little or no progression.

Exercise

Exercise is an important component of treatment for many patients with painful or flexible kyphosis.

Postural Kyphosis

Postural training and strengthening are the primary treatments.

Painful Kyphosis

Exercises may help reduce pain by improving:

Spinal mobility, posture, muscular endurance, and flexibility.

Bracing

The role of bracing depends on the type of kyphosis.

Congenital Kyphosis

Bracing is generally not effective because the deformity results from structural vertebral abnormalities.

Scheuermann Kyphosis

Bracing may be considered in growing adolescents with:

Flexible or partially flexible Scheuermann curves, particularly those approximately 40–70° and with substantial remaining growth.

Bracing is often most effective when the apex is below the upper thoracic region.

Osteoporotic Compression Fracture

Temporary bracing may be used in selected patients with an acute painful osteoporotic vertebral fracture.

Congenital Kyphosis

Progressive congenital kyphosis in a growing child often requires surgical treatment because severe progression can produce neurologic compromise.

Physical Therapy

Physical therapy can improve pain and function in many patients.

Stretching

Programs may include stretching of:

Hamstrings, anterior chest and shoulder structures, hip flexors, and other tight tissues contributing to compensatory posture.

Strengthening

Strengthening should emphasize:

Back extensors, abdominal musculature, scapular stabilizers, and core muscles.

Medication

Analgesics

Intermittent back pain may be managed with:

NSAIDs or acetaminophen, provided there are no contraindications.

Osteoporosis Treatment

Patients at risk for osteoporosis should receive appropriate bone-health management.

This may include:

Calcium and vitamin D supplementation and antiresorptive or anabolic osteoporosis therapy when indicated.

Older references described estrogen therapy and diphosphonates; current treatment should be individualized according to age, sex, fracture risk, and medical status.

Tuberculosis Treatment

Tuberculous spinal infection requires multidrug antituberculous therapy.

Surgical treatment is added when indicated by instability, deformity, abscess, or neurologic compromise.

Surgery

Surgery is considered when kyphosis causes:

Progressive deformity, neurologic compromise, severe refractory pain, cardiopulmonary compromise, or unacceptable functional or cosmetic disability.

Congenital Kyphosis Surgery

Progressive congenital kyphosis often requires surgery except in very mild stable cases.

Options may include:

In situ fusion, corrective osteotomy, posterior instrumentation, or combined anterior and posterior reconstruction.

Scheuermann Kyphosis Surgery

Indications may include:

Persistent severe pain despite nonoperative care, progressive deformity, neurologic compromise, cardiopulmonary limitation, or severe unacceptable kyphosis.

Modern treatment typically uses posterior spinal fusion with instrumentation, sometimes combined with osteotomies to improve correction.

Osteoporotic Vertebral Fractures

Most osteoporotic compression fractures are managed nonoperatively.

Selected patients with persistent severe pain from an acute compression fracture may be considered for vertebral augmentation procedures.

Kyphoplasty

Kyphoplasty may provide pain relief and can sometimes restore a portion of vertebral body height.

Vertebroplasty

Vertebroplasty may provide pain relief in selected patients, although patient selection is important.

Infection and Malignancy

When spinal infection or tumor causes neurologic compromise or mechanical instability, treatment may require:

Decompression, deformity correction, stabilization, and disease-specific medical or oncologic therapy.

Follow-Up

Prognosis

The natural history depends strongly on the underlying cause.

Kyphosis may progress with age, particularly when structural deformity, osteoporosis, or degenerative disease is present.

Pain and Function

Back and neck pain can range from mild and intermittent to chronic.

Most patients remain capable of independent activity and employment, although heavy physical work may become limited in more severe cases.

Complications

Neurologic Compromise

Severe, sharply angular kyphosis may compress or stretch the spinal cord at the apex.

Neurologic decline may occur gradually or be precipitated by:

A fall, fracture, or other traumatic event.

Surgical Neurologic Risk

Corrective surgery for severe kyphosis carries a meaningful risk of neurologic injury because:

The spinal cord may already be stretched across a rigid angular deformity.

This risk may be greater than for a scoliosis of comparable angular magnitude.

Pseudarthrosis

Failure of the intended spinal fusion can result in:

Persistent pain, implant failure, and progressive deformity.

Curve Progression

Progressive kyphosis may occur despite treatment, particularly in:

Young children with congenital deformity, severe Scheuermann disease, osteoporosis, or persistent underlying disease.

Patient Monitoring

Growing patients should be followed regularly to identify progression.

Clinical and radiographic reassessment approximately every 4–6 months may be appropriate during periods of rapid growth.

Monitoring should include:

Curve magnitude, skeletal maturity, pain, neurologic status, balance, and associated deformity.

Adults with stable kyphosis may be reviewed according to symptoms and the underlying cause.