Mini-symposium: Spinal deformity(iii) Adult degenerative scoliosis
Section snippets
Definitions
Scoliosis is a complex three-dimensional rotational deformity affecting the spine in the coronal, sagittal, and axial planes. Treatment paradigms must address all three components.
Adult scoliosis, be it Adult Idiopathic Scoliosis (AIS) or Adult Degenerative Scoliosis (ADS) is a spinal deformity in a skeletally mature individual, with a curve measuring >10° measured by the Cobb method.1 AIS arises as progression of infantile or adolescent idiopathic scoliosis, but ADS develops during adulthood
Epidemiology & demographics
Reported prevalence of adult scoliosis ranges from 1 to 10%.2 Such new-onset deformity is observed in more than 30% of elderly patients with no past history of spinal deformity. Degenerative scoliosis is typically diagnosed in patients older than 40 years, with a mean age of 70.5 years. They are lumbar curves measuring >10° with associated distal fractional curves. Although the curves are not associated with structural thoracic curves, compensatory thoracic curves can occur. As in AIS, curve
Clinical presentation & natural history
Symptoms of degenerative scoliosis are most frequently progressive back pain with radiculopathy and neurogenic claudication.5 Ageing progressively affects all structures of the spinal unit, eventually leading to spondylolisthesis, spinal stenosis and scoliosis. Due to multiple degenerative pathologies, identifying the exact source of pain is difficult. Relationships between scoliotic pattern and patient symptoms are unclear, although speculations on such relationships are frequently made.5, 6, 7
Pathogenesis
Degenerative scoliosis is assumed to be caused by asymmetric disc degeneration and facet joint degeneration.5, 10, 13, 14 The onset is marked by disc degeneration.10 This distinguishes degenerative scoliosis from other types of scoliosis, such as adolescent idiopathic scoliosis and scoliosis secondary to neuromuscular disease.
Vertebral rotation and lateral deviation of the spine are coupled phenomena, with the rotation of vertebral bodies directed into the convexity of the curve.15 It has been
Classification of adult degenerative scoliosis17
Most classification systems are for adolescent scoliosis and as yet there is no generally accepted classification system for adult degenerative scoliosis. The Lenke classification is widely accepted for adolescent scoliosis and has addressed all the drawbacks of previous classification systems. Recently described classifications of adult scoliosis offer specific advantages, for example, the simple pathogenesis-based system of Aebi, the strong clinical relevance of the Schwab system, and the
Quantifying the deformity
The apical vertebra is the vertebra associated with the greatest segmental angulation at both its rostral (cephalad) and caudal disc interspaces when compared with all other disc interspaces in the curve. Generally it is in the mid-portion of the curve. Conversely, the neutral vertebrae are those with little or no angulation at the rostral and caudal disc spaces of the curve. In general, an instrumentation construct should not terminate at or near an apical vertebra and should extend to a
Clinical assessment
The clinical evaluation starts with a full history. In particular a history of idiopathic scoliosis should be sought to exclude the possibility of a degenerative idiopathic deformity. Patients should be asked if they have experienced any changes in body habitus, gait, or fit of their clothes. Particular note should be taken of a rapidly progressing curve because such may be due to an underlying neurological condition.
It is very important to ascertain whether the pain is purely axial or is also
Radiological investigation
Full-length (36-inch) including standing posterior–anterior and lateral X-rays images should be obtained and compared with any previous films to assess curve progression. The Cobb angle and the superior and inferior extent of the measurement should be recorded. These films with bending films are used to define the structural and compensatory curves as well as the overall balance, both coronal and sagittal. If surgery is being considered, flexion/extension and lateral bending films will define
Treatment
Adult degenerative scoliosis presents a variety of treatment challenges. Due to the degenerative changes, the curves are more rigid than in adolescent curves and thus require more extensive releases and osteotomies to improve balance. Patients are older with medical co-morbidities and problems like osteoporosis which make surgical fixation difficult. Thus proper patient selection and a rational approach form the cornerstone for successful outcomes in these patients.
Lenke–Silva treatment algorithm (Table 2)
Level I treatment: decompression alone: this is usually suitable for patients with neurogenic claudication due to central stenosis who require a limited decompression. Radiographically anterior osteophytes should be present with no more than 2 mm of subluxation and reasonable sagittal/coronal balance. There should be minimal or no back pain and/or deformity, and the curve should be <30° without thoracic hyper-kyphosis and/or imbalance, because decompression alone for stenosis with associated
Complications
The results of operative correction of adult deformity have improved significantly with better instrumentation systems, improved anaesthesia and blood salvage. The incidence of complications depends on the approach, level of deformity, age of the patient, and experience of the surgeon.5 For example, there was a 500% increase in major complications between the youngest and eldest patient populations. The risk of complications increases in the older group because of many associated medical
Conclusion
Adult degenerative scoliosis is an increasing problem due to an ageing population. It poses very different challenges to those of adolescent scoliosis to spinal surgeons. There is a high risk of complications associated with surgical intervention. In properly selected patients a beneficial outcome can be expected.
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Cited by (2)
Quality of life outcomes in surgically treated adult scoliosis patients: a systematic review
2015, European Spine JournalSelection of suitable procedure in the treatment of degenerative lumbar scoliosis based upon imaging studies
2013, National Medical Journal of China