Adult Degenerative Scoliosis
Adult Degenerative Scoliosis
Scoliosis is a sideways curvature of the spine when looking at a person from behind (the frontal plane). There are various causes of scoliosis and “degenerative” scoliosis, also known as de novo scoliosis, is the result of arthritic changes in the joints of the spine (disc and facet joints). Degenerative scoliosis usually develops gradually over decades and can cause worsening posture, mechanical pain, and stenosis with back and leg pain from nerve compression. Non-operative treatment (medications, therapy, and steroid injections) is effective in most patients while progressive lesions with severe stenosis may require surgical management.
Causes
Degenerative scoliosis is the result of arthritic changes involving the joints of the lumbar spine which accumulate over many years. These changes include disc tears and herniations, enlarged facet joints, thickened ligaments, and bony spurs which usually involve the lower portion of the lumbar spine.
Figure 1
Illustration demonstrating the arthritic joint changes involved in degenerative scoliosis.
As these changes progress, especially if they do so asymmetrically, the joints develop excessive and abnormal motion which can lead to structural changes including forward slippage (spondylolisthesis), tilting or sideways bend (scoliosis), and flattening of the arch of the lower back (flatback or kyphosis). The degenerative changes (disc bulging, spurs and ligament thickening) also narrow the spinal canal compressing the spinal nerves (spinal stenosis, figure 2). The arthritis, structural changes, and stenosis can all be sources of disabling back and leg pain. Curves tend to progress slowly over time and tend to be mild –moderate in size (15-40 degrees). Both environmental and genetic factors are thought to play a role in the development and progression of degenerative scoliosis.
Symptoms
Degenerative scoliosis becomes more common with age and is thought to affect as many as 60% of the elderly. Pain is the most common complaint and can be related to the arthritis itself or mechanical back pain from spinal malalignment related to scoliosis and or kyphosis. Many patients develop neurogenic back and leg pain due to nerve compression in the spine (spinal stenosis) or nerve traction along the convexity or compression along the concavity of the curves. The pain is usually worse with activities especially standing and walking and may include leg numbness, tingling, and weakness. Some patients may complain of postural changes and many have other conditions contributing to their pain and disability including cervical stenosis, hip and knee arthritis, and osteoporosis.
Diagnosis
Diagnosis is made following a detailed history and physical examination with an experienced spine surgeon. This is especially important to identify and prioritize the various overlapping conditions that maybe related to the patients pain and disability. Scoliosis is defined as a sideways curve measuring more than 10 degrees on an AP xray using the Cobb measurement technique. Full length PA and lateral xrays are necessary to evaluate curve magnitude and both regional and global spinal alignment. Repeat xrays maybe needed to document and grade progression. MRI is study of choice to evaluate specific pathology involved in degenerative scoliosis include neurologic compression and rule exclude other diagnosis.
Treatment
Most patients with degenerative (de novo) scoliosis can be treated successfully with a range of non operative modalities. These include the prudent use of NSAIDs, pain medications, epidural steroid injections, and physical therapy. Surgical treatment may be an option for carefully selected patients who have failed a thorough course of non operative treatment and have continued disabling pain with significant functional limitations. The goals of surgery are neurologic decompression and restoration and stabilization of frontal and sagittal balance and failure to obtain proper sagittal balance is one f the more common causes of poor outcome. The techniques necessary to properly correct these deformities are complex and high risk procedures (long level fusions often necessitating osteotomies, neurologic decompression, and pelvic fixation) and complication rates can be as high as 20-40%. In addition this patient population frequently has many associated co morbidities and a detailed multi disciplinary approach is necessary to determine if the benefits outweigh the risks in each case. Nonetheless, in the properly selected patient treated with careful attention to the principles of spine deformity surgery patients can achieve excellent relief of pain with improved quality of life and functional outcome. Some of the surgical procedures that might be employed include ALIF, XLIF, TLIF, pedicle subtraction osteotomy, laminectomy, and posterolateral fusion instrumentation.
