Adult Degenerative Scoliosis

Overview

Adult degenerative scoliosis, sometimes called de novo degenerative scoliosis, is a sideways curvature of the spine (a Cobb angle of at least ten degrees) that develops in a spine that was straight in earlier life. It is distinct from the adolescent idiopathic form: rather than a constitutional curve that persists into adulthood, this condition arises entirely from the cumulative wear of lumbar discs and facet joints. The deformity is predominantly a disorder of older adults, with prevalence rising substantially after the sixth decade. It is more common in women, a pattern partly explained by the contribution of postmenopausal osteoporosis to vertebral and segmental collapse.

What causes it

The process begins with asymmetric degeneration of the intervertebral discs and facet joints. When one side of a disc or joint breaks down faster than the other, the load across that motion segment becomes uneven. Over time this produces lateral wedging of the vertebrae, rotatory subluxation, and a sideways shift of one vertebra relative to its neighbor (lateral listhesis). As the deformity progresses, the natural inward curve of the lower back (lumbar lordosis) is often lost and sagittal imbalance develops, causing the trunk to pitch forward. The narrowed side of the curve compresses the nerve canals, leading to both foraminal stenosis and central canal stenosis: the structural basis for the radicular and claudicatory symptoms that bring most patients to medical attention.

Established risk factors include advancing age, low bone mineral density, prior lumbar surgery or instrumented fusion that alters how the adjacent segments are loaded, and the accumulated degenerative changes of a lifetime. Because the drivers are mechanical and degenerative rather than constitutional, the curve typically progresses slowly over years.

Symptoms and warning signs

Most patients seek care for pain and neurologic symptoms rather than for concern about the shape of their spine. The most common presentation combines axial low back pain with one or more of the following:

• Lumbar radiculopathy: dermatomal leg pain, tingling, or numbness caused by nerve roots compressed through the stenotic foramina on the concave side of the curve.
• Neurogenic claudication: buttock and leg discomfort that builds with standing and walking and is relieved by sitting, resting, or leaning forward. This posture-dependent pattern reflects compression of the nerve roots in the central canal.
• Postural changes: a visible trunk shift, a palpable rotational prominence, or a forward-stooped posture adopted instinctively to decompress the spinal canal.
• Motor and reflex changes: focal weakness or diminished reflexes in the distribution of affected nerve roots.

Certain features demand urgent evaluation and must not be attributed to ordinary degenerative change. Saddle anesthesia (numbness in the groin and inner thighs), loss of bladder or bowel control, or weakness in both legs are warning signs of cauda equina syndrome and require emergency assessment. A rapidly progressive motor deficit is similarly urgent. Fever, night pain, and unexplained weight loss raise concern for spinal infection or malignancy and warrant prompt investigation.

How it's diagnosed

Diagnosis rests on correlating the clinical picture with imaging. Standing full-length (thirty-six-inch) anteroposterior and lateral radiographs are foundational: they allow measurement of the Cobb angle, lateral listhesis, and rotatory subluxation, and, crucially, assessment of overall coronal and sagittal balance through parameters such as pelvic incidence, lumbar lordosis, pelvic tilt, and sagittal vertical axis. Supine films understate the deformity, so weight-bearing imaging is essential.

MRI is the preferred study for characterizing central canal and foraminal stenosis and for evaluating the neural elements. It also helps exclude infection and tumor when red flags are present. CT, often with myelography in patients who cannot undergo MRI or who have prior spinal instrumentation, defines bony anatomy and the degree of stenosis in greater detail.

Because asymptomatic degenerative and stenotic findings are common in this age group, imaging abnormalities must be matched carefully to the patient's symptoms and examination. Hip osteoarthritis and sacroiliac joint pain are frequent mimics; dedicated hip radiographs or diagnostic injections may be needed to confirm that leg and groin pain truly originates from the spine.

Treatment options

Most patients are managed conservatively first. Initial care typically includes activity modification, anti-inflammatory medication, and structured physical therapy focused on core stabilization, posture correction, and aerobic conditioning. Coexisting osteoporosis should be identified and treated, as bone quality influences both disease progression and any future surgical planning.

Image-guided epidural or transforaminal steroid injections can provide diagnostic information and temporary relief of radicular and claudicatory symptoms in appropriately selected patients. While injections do not alter the underlying deformity, they may allow patients to engage more effectively in rehabilitation and can help clarify which spinal levels are driving symptoms.

When surgery is considered

Surgery is considered when disabling pain, progressive neurologic deficit, or significant functional limitation persists despite adequate non-operative care, when the curve or sagittal imbalance is clearly progressing, or when an emergent indication such as cauda equina syndrome is present.

Operative strategy is individualized. For patients with focal stenosis and a spine that is well balanced overall, a limited decompression may be sufficient. When instability, substantial coronal or sagittal malalignment, rotatory subluxation, or multiple-level stenosis is present, decompression is combined with instrumented fusion and, where needed, deformity correction to restore spinal balance.

Surgical decision-making in this population requires careful weighing of goals against risk. Restoring neural decompression and spinal balance must be balanced against the comorbidities, bone quality, and frailty that are common in older adults, given that larger reconstructive procedures carry meaningful perioperative risk. The recommended approach emphasizes individualized planning that aligns the extent of surgery with each patient's functional goals and overall health status.