Degenerative scoliosis is a result of progressive degenerative changes in structural elements of the spine.
It also is known as adult-onset scoliosis but is different from curves of adolescent idiopathic scoliosis that adults have.
Adult scoliosis is a collective term inclusive of degenerative scoliosis comprising of all spinal deformities in a skeletally mature individual.
Technically, Adult scoliosis is defined as a spinal deformity in a skeletally mature patient with a Cobb angle of more than 10° in the coronal plane.
Scoliosis in the adult population is reported to be in a range of 2-32%. Recently, studies have suggested the prevalence to be more than 60% in the elderly.
Classification of Adult Scoliosis
Type I
It is also called the primary degenerative or de novo scoliosis which develops after skeletal maturity and occurs in the previously straight spine.
It is characterized by minimal structural vertebral deformities, advanced degenerative changes. It is more common in lumbar areas.
It results from asymmetric degeneration of disc and facet joints and osteoporotic compression fractures.
Type II
It is the progressive idiopathic deformity that develops before skeletal maturity but becomes symptomatic in adult life. It can involve the cervical and thoracic spine as well apart from lumbar spine.
It appears during childhood or adolescence and progresses into adult life. With age, can have secondary degeneration and imbalanced in its natural history
Type III
It is a type of secondary Degenerative Scoliosis
- Scoliosis following idiopathic or other forms of scoliosis or occurring in the context of a pelvic obliquity
- Leg-length discrepancy
- Hip pathology
- Lumbosacral transitional anomaly
- Scoliosis secondary to metabolic bone disease like osteoporosis
Pathophysiology and Natural History of Degenerative Scoliosis
Healthy facets joints provide motion to vertebral segments to help spine bend and intervertebral discs act as shock absorbers.
Aging leads to a natural degeneration of these joints and discs.
Asymmetric degeneration occurs when degeneration is more pronounced on one side of the spine. This leads to a curve, which when more than 10 degrees [as measured by the Cobb angle] is considered scoliosis.
The deformity may remain asymptomatic but may have a gradual onset of pain felt as recurring a dull ache or stiffness in the mid to low back.
[Degenerative scoliosis needs to be differentiated from adolescent idiopathic scoliosis which has continued into adulthood.]
Asymmetric degeneration of the disc and the facet joints at different levels leads to asymmetric loading of the spinal segment, triggering a vicious circle enhancing curve progression. Presence of osteoporosis may aggravate this asymmetric deformation. The osteoporotic collapse of vertebrae in osteoporosis may contribute.
Instability may occur due to the destruction of structural spinal elements like discs, facet joints, and joint capsules and may lead to listhesis.
The spine tends to stabilize by forming osteophytes at the facet joint and vertebral endplates and hypertrophy and calcification of ligamentum flavum and calcification. This may cause narrowing of the spinal canal and lateral recess leading to spinal stenosis or foraminal stenosis and may result in with radicular pain or neurogenic claudication.
The curve of degenerative scoliosis may progress at a rate of 3° or more per year [faster than idiopathic]. Following factors hasten the progression
- The curve is greater than 30°
- More than 30% apical vertebral rotation
- 6 mm or greater lateral listhesis
- Degenerative disc disease at the lumbosacral junction.
- Quality of bone
Clinical Presentation
- Pain
- Chief complaint in 90% of symptomatic patients.
- Insidious in onset
- Begins at the convexity of the curve, is diffuse in
- Result of
- muscle fatigue of the para-spinal musculature
- Spinal Instability
- Activity related
- Exacerbated with upright posture for a longer duration
- Para-spinal muscle fatigue is a marked symptom.
- Trigger point pain at muscle insertions
- Radicular leg pain
- Neurogenic claudication causing debilitating leg pain on standing or walking
- Neurologic deficit
- Infrequent
- Causes
- Curve progression
- Disc fragment herniation
- Acute curve decompensation
- Spinal deformities are cosmetically well tolerated in the elderly population, though it can be a presenting
Differential Diagnosis
- Arterial insufficiency
- Abdominal aortic aneurysm
- Malignancies
Imaging
Xrays
X-rays of the spine include full-length posteroanterior and lateral radiographs are done initially and then at regular intervals to monitor the curve progression.
Cobb angles are measured on these radiographs by using a goniometer in the AP and lateral views.
Sagittal alignment is assessed by dropping a plumb line through the middle of the C7 vertebral body on the lateral view. This line passes through the posterior one-third of the superior endplate of S1 vertebral body.
Dynamic radiographs such as flexion–extension lateral projections may be needed or assessment of instability and spondylolisthesis.
Bending films help assess the extent of curve flexibility and the compensatory ability of the adjacent spinal segments.
CT/MRI
Stenosis is better visualized in CT/MRI.
Magnetic resonant imaging scans of the spine can provide additional information about the neural elements, discs and other soft tissues.
Treatment of Degenerative Scoliosis
Nonoperative Treatment
Asymptomatic patients do not require any treatment. They may be put on spine exercises for better loading biomechanics.
In symptomatic patients, the main goal of treatment is to reduce pain and/or any accompanying neurologic symptoms. Treatment does not tend to focus on correcting the curve.
Following are the treatment options used in degenerative scoliosis.
- Physical therapy which may include water therapy
- Drugs for Degenerative Scoliosis
- Analgesics
- NSAIDs
- Opioids
- Tricyclic antidepressants
- Gabapentin
- Spinal injections
- Weight loss
- Decreases the pressure across the facet joints.
- Bracing
- A corset brace
- It’s not corrective, only for relief
- Ice and/or heat. As needed for symptoms control, application of cold packs and/or heat packs can help with local pain.
If the symptoms do not improve surgery may be considered
Surgical Treatment
The goals of surgery are
- Decompression of neural elements
- Restoration and stabilization of spinal balance with arthrodesis
The outcomes of the surgical procedure are influenced by a number of variables like
- Age
- Medical comorbidities
- Previous surgical history
- Psychosocial factors
The surgical options for degenerative scoliosis tend to fall into two general categories.
Decompression surgery
This involves removal of structures [part of the vertebra, disc, and other spinal elements] compressing the cord and/or nerve root.
In modern surgical practice, decompression is often accompanied by fusion. But decompression alone is performed in selected cases.
Spinal stenosis without significant axial back pain, segmental instability, or progressively worsening deformity can be treated with stand-alone decompression surgery.
The procedures used for decompression are laminotomy, laminectomy, foraminal, and extra-foraminal decompression.
Decompression may be an option for elderly patients with medical comorbidities.
Decompression with fusion
This procedure is more commonly as a decompression alone in the setting of a scoliosis curvature, can make the spine more unstable and worsening of the curvature.
The fusion could be long short (fuse only one or two vertebral levels or long [more than two levels]
Fusion can halt curve progression and tackle instability.
Bone purchase is poor in osteoporosis which creates problems for carrying a secure fixation.
Polymethylmethacrylate may be used to augment screw purchase in the bone.
Reported complications of surgical treatment include pseudoarthrosis, infection, cerebrospinal fluid fistulas, pulmonary emboli, myocardial infarction, hardware failure, urinary tract infection, and revision surgery.
References
- Aebi M. The adult scoliosis. Eur Spine J. 2005;14(10):925–948. doi: 10.1007/s00586-005-1053-9
- Benner B, Ehni G. Degenerative lumbar scoliosis. Spine. 1979;4:548. doi: 10.1097/00007632-197911000-00018.
- Berven SH, Lowe T. The Scoliosis Research Society classification for adult spinal deformity. Neurosurg Clin N Am. 2007;18(2):207–213. doi: 10.1016/j.nec.2007.03.002.
- Kobayashi T, Atsuta Y, Takemitsu M, et al. A prospective study of de novo scoliosis in a community-based cohort. Spine. 2006;31:178–182. doi: 10.1097/01.brs.0000194777.87055.1b.
- Vaccaro AR, Ball ST. Indications for instrumentation in degenerative lumbar spinal disorders. Orthopedics. 2000;23:260–271.
