Ross Hauser, MD

Adolescent idiopathic scoliosis (AIS) is commonly thought of as a sideways curvature of the spine. The Cobb angle is measured, progression of the curve is monitored, and depending on the severity of the scoliosis and skeletal maturity of the patient. A February 2025 study noted (1) treatment may include observation, scoliosis-specific exercise, bracing, or surgery.

However, scoliosis is not simply a two-dimensional, side-to-side curve. It is a three-dimensional spinal deformity that can influence the alignment of the thoracic spine, cervical spine, lumbar spine, pelvis, and ultimately the position of the head.

This becomes particularly important in patients with thoracic hypokyphosis, or loss of the normal thoracic curve. As the thoracic spine becomes flatter, the cervical spine may compensate by losing its normal lordosis and becoming straight or kyphotic. New research is providing stronger evidence for this relationship.

For patients who also develop chronic neck pain, headaches, muscle tightness, clicking, grinding, or other symptoms suggestive of abnormal cervical motion, another question may need to be asked: Is cervical kyphosis simply a compensation for scoliosis, or could cervical ligament instability be contributing to the patient’s inability to maintain normal cervical alignment?

At Caring Medical, this distinction can become important when determining whether a patient may have a cervical problem requiring evaluation and treatment separate from the scoliosis itself.

2026 research: cervical compensation in 1,779 patients with scoliosis

A 2026 study in the European Spine Journal (2) provides important new information about the relationship between adolescent idiopathic scoliosis, thoracic kyphosis, and cervical alignment.

Researchers compared 1,779 patients with adolescent idiopathic scoliosis with 1,115 normal adolescents and young adults. The investigators evaluated thoracic kyphosis, lumbar lordosis, global sagittal alignment, and multiple measurements of cervical alignment.

Patients with Lenke type 1, 2, 3, and 6 scoliosis demonstrated decreased C2-C7 cervical lordosis. This was associated with decreased thoracic kyphosis and reduced C7 and T1 slopes. Importantly, thoracic kyphosis correlated strongly with alignment of the lower, or caudal, cervical spine.

The researchers concluded that cervical sagittal compensations in AIS occur predominantly in the lower cervical spine and are closely related to thoracic kyphosis. This may provide important evidence for something that can be overlooked when scoliosis is viewed primarily through the Cobb angle: What happens in the thoracic spine can influence what happens in the cervical spine?

Thoracic hypokyphosis and the cervical spine

Additional research published in the European spine journal (3) from the same international research group evaluated sagittal alignment in 1,779 AIS patients and 1,115 controls.

Primary thoracic curves, particularly Lenke types 1 and 2, demonstrated the lowest thoracic kyphosis in the T5-T10 region. The thoracic curves were therefore not simply displaced sideways. Their normal sagittal configuration was also altered. Taken together with the cervical study, these findings help demonstrate the interconnected nature of spinal alignment.

A patient does not necessarily have a thoracic curve and an unrelated cervical curve. The spine attempts to maintain balance as a continuous structure. A potential compensatory pattern may be:

• Thoracic scoliosis → thoracic hypokyphosis → altered T1 slope → loss of cervical lordosis → cervical straightening or kyphosis.

This should not be interpreted as an inevitable sequence in every patient. Scoliosis patterns vary considerably. It does, however, demonstrate why the cervical spine should be considered when evaluating patients with significant thoracic scoliosis and loss of thoracic kyphosis.

Cervical kyphosis and degenerative cervical discs in teenagers

Perhaps even more concerning is research showing that abnormal cervical alignment in AIS can be associated with degenerative changes at a surprisingly young age. Researchers at Children’s Orthopaedic Center at Children’s Hospital Los Angeles and the Department of Orthopaedics at Cedars-Sinai Medical Center evaluated 80 consecutive AIS patients before scoliosis surgery. Their average age was approximately 14 years. The study was published in the April 2024 issue of Spine. (4)

Increasing cervical kyphosis correlated with decreasing thoracic kyphosis. But the researchers found something else.

• Forty-five of the 80 adolescents—56%—already demonstrated cervical degenerative disc disease.
• Greater cervical kyphosis was associated with greater severity of cervical disc degeneration.
• Nine patients also demonstrated ventral spinal cord effacement, and these patients had the greatest degree of cervical kyphosis.

This is significant because cervical degenerative disc disease is usually discussed as an age-related condition. These patients were teenagers.  The question then becomes:

Why are cervical discs in some adolescents already demonstrating degenerative changes?

This study does not establish that cervical instability caused the degeneration. It does, however, demonstrate an association between abnormal cervical alignment and cervical disc degeneration in young AIS patients.

A 2024 European Spine Journal study (5) examined MRI findings in 968 nonsurgical AIS patients between 10 and 16 years old. Ninety-three patients, or approximately 9.6%, demonstrated evidence of degenerative disc disease. Patients with disc degeneration also reported worse pain and function scores. Most of the degeneration identified in this study occurred in the lumbar spine, particularly at L5-S1, rather than in the cervical spine.

Nevertheless, these findings reinforce an important point: Degenerative disc changes can already be present during adolescence in patients with idiopathic scoliosis.

An abnormal disc on MRI does not automatically identify the cause of a patient’s pain. However, these findings raise legitimate questions about the long-term effects of abnormal spinal mechanics and loading.

2025 research further connects thoracic and cervical alignment

A 2025 study published in Neurospine (6) examined 102 female patients with Lenke type 2 AIS undergoing posterior corrective surgery.

• Before surgery, 57 patients, or 55.9%, were classified as having cervical malalignment.

Compared with patients without cervical malalignment, these patients had more cervical kyphosis, less proximal thoracic kyphosis, and a smaller T1 slope. Following surgery, changes in proximal thoracic kyphosis influenced cervical sagittal alignment. The researchers concluded that increasing proximal thoracic kyphosis influenced the T1 slope and subsequent cervical alignment.

In other words, it may not simply be the presence of scoliosis that matters. The location and nature of the sagittal deformity can influence how the cervical spine compensates.

How common is cervical kyphosis in adolescent idiopathic scoliosis?

Earlier research demonstrated how common cervical deformity can be in AIS.

A July 2019 study (7) of 112 AIS patients and 40 asymptomatic controls found cervical kyphosis in 60.7% of the scoliosis patients compared with 35% of controls. The investigators identified several factors associated with cervical kyphosis, including the main thoracic Cobb angle, thoracic kyphosis, sagittal vertical axis, and other measures of spinal alignment.

March 2018 study of 99 AIS patients (8) found cervical kyphosis in 49%. Cervical kyphosis was present in 75% of patients whose thoracic kyphosis measured 20 degrees or less, compared with 32% of patients with greater thoracic kyphosis. Again, the association between a flatter thoracic spine and cervical kyphosis becomes apparent.

When does cervical compensation become cervical dysfunction?

The cervical spine has an extraordinary ability to compensate.

The 2026 research suggests that much of this compensation occurs in the lower cervical spine while upper cervical alignment remains relatively close to normal, helping the patient preserve horizontal gaze (2).

Initially, compensation serves a purpose. The question is what happens when the cervical spine must maintain abnormal mechanics for years—or when another problem, such as ligament injury or ligament laxity, interferes with the neck’s ability to stabilize itself. This is where our more than thirty years clinical interest in cervical instability becomes relevant. Could cervical ligament instability contribute to loss of the cervical curve?

The cervical vertebrae are not stabilized by muscles alone.

Ligaments and joint capsules help guide and limit cervical motion. These structures permit normal movement while preventing excessive translation and rotation between the vertebrae. When cervical ligaments are injured or become excessively lax, muscles may be required to perform additional work to stabilize the neck. The patient may consequently develop chronic muscle tightness and spasms. The muscles may be blamed as the problem when, in some patients, they may be attempting to compensate for an underlying stability problem.

In our 2024 paper in the journal Frontiers in Neurology (9) we discussed a proposed mechanism linking chronic cervical ligament stress, instability, and progressive deterioration of normal cervical structure. We described how prolonged loading can produce ligament “creep”—progressive ligament elongation under sustained mechanical stress and proposed that ligamentous instability can contribute to deterioration of cervical lordosis, cervical straightening, forward head posture, and eventually more significant cervical dysstructure.

This does not demonstrate that cervical instability causes adolescent idiopathic scoliosis. Nor does cervical kyphosis automatically mean that a patient has cervical instability. Instead, it raises a separate clinical question:

• Could some symptomatic patients have scoliosis-related cervical compensation and a coexisting cervical ligament problem?

2026 Caring Medical research on cervical instability and cervical structure

In our 2026 retrospective study published in the Journal of clinical medicine, (10) we examined cervical spine and neurovascular findings in 84 consecutive patients with hypermobile Ehlers-Danlos syndrome.

We reported frequent co-occurrence of forward head posture, decreased cervical curve depth, and ligamentous cervical instability. This study involved adults with hEDS rather than adolescents with idiopathic scoliosis, so its findings cannot be directly applied to AIS. However, it provides clinical evidence that abnormal cervical curvature and ligamentous instability can coexist in a population predisposed to ligamentous laxity. Our 2026 study in the journal Frontiers in neurology (11) examined 227 young adults reporting persistent brain-based symptoms. Imaging identified forward head posture in 100%, decreased depth of cervical lordosis in 90%, and C1-C2 ligamentous cervical instability in 87%. Again, this was not an AIS study and does not demonstrate that scoliosis causes cervical instability. The study was retrospective and involved patients evaluated at a specialized neck clinic, making selection bias an important limitation. Nevertheless, these observations support continued investigation into relationships among cervical structure, abnormal cervical motion, and ligamentous instability.

A possible cycle of cervical instability and abnormal loading

From our clinical perspective, a potential biomechanical cycle may develop in selected patients:

Ligament injury or laxity → abnormal vertebral motion → muscular compensation → difficulty maintaining normal cervical alignment → abnormal joint and disc loading → continued mechanical stress.

Now consider what may happen if the patient already has thoracic hypokyphosis associated with scoliosis. The cervical spine may already be compensating for altered thoracic mechanics. If cervical ligament instability is also present, maintaining normal cervical alignment may become increasingly difficult.

This proposed mechanism has not been established in prospective controlled trials involving AIS patients. It should therefore be viewed as a clinical hypothesis requiring further investigation rather than an established cause of scoliosis or cervical kyphosis. The newer research connecting thoracic and cervical alignment, however, makes investigation of cervical mechanics reasonable in selected symptomatic patients.

Prolotherapy

When an evaluation identifies painful or functionally significant cervical ligament injury and instability, the goal of Prolotherapy is to address the compromised ligament structures rather than the scoliosis itself. Dextrose Prolotherapy involves injections at injured ligament and tendon attachments with the objective of stimulating a localized healing response. In this clinical model, the goal is not to force a curved spine straight. The goal is to improve the stability of cervical segments when injured or lax ligaments are believed to be allowing excessive motion.

References

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