Surgical Management of Thoracolumbar Deformity in Ankylosing Spondylitis

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An Ancient Disease

Ankylosing Spondylitis (AS) is a chronic inflammatory disease resulting in the ossification (bone formation) of joints and sites where tendons and ligaments attach to bone. It is certainly not a disease new to the human family. The first signs of AS were found in the skeletal remains of a 5000 year-old Egyptian mummy. Notable physicians in the 1800's also rendered descriptions of AS including W. von Bechterew (1883), Adolph Strumpell (1897), and Pierre Marie (1898). Therefore AS is also known as Bechterew Disease or Marie-Strumpell Disease.

A Form of Chronic Arthritis
Ankylosing Spondylitis is part of a group of rheumatic diseases termed 'seronegative spondyloarthropathies' (vertebral joints) that share the human antigen HLA-B27. Most people with the HLA-B27 antigen do not develop AS. It is known to affect approximately 1.4% of the general population, males more often than females. The severity of the disease and remission varies among individuals.

Spinal Havoc
AS can be a painful insidious disease causing fusion of the costovertebral joints (ribs), destruction of vertebral endplates, subchondral sclerosis (hardening of cartilage), narrowing of joints, and osteoporosis. The disease may initially present as low back pain, stiffness, and tenderness in the sacral joints (sacrum). AS is known to progressively move upward into the cervical spine.

patient, spondylitis, ankylosing spondylitis, as, color photo

Unnatural formation of bone can cause squaring of the vertebral bodies resulting in a condition termed Bamboo Spine. Over time the spine may take on the appearance of a long inflexible bone easily susceptible to fracture.

As the spine undergoes inflammation and structural change, deformity may result in the form of pronounced curvature leading to irregular posture and/or a chin on chest appearance. When the thoracic spine is affected, chest expansion may be limited. Further, the deformity may lead to loss of horizontal gaze, difficulty breathing, and places the patient at a higher risk for trauma.

Figure 1: Preoperative lateral view of an ankylosing spondylitic patient.
mri, spine
Figure 2: Preoperative sagittal MRI of an ankylosing spondylitic patient.

Chin-Brow Measurement

The chin-brow technique is one method the physician uses to measure the angle of the curve. A more pronounced curvature will equal a greater angle. The physician periodically takes a chin-brow measurement and compares it to baseline to monitor progressive changes in the spine. This is just one test used to determine if surgical intervention is necessary.

Non-Surgical Disease Management

Relieving the patient's symptoms (e.g. pain, stiffness) and preventing spinal deformity is paramount. Conservative treatment may include nonsteroidal anti-inflammatory agents (NSAIDs) and physical therapy.


Certain NSAIDs work by inhibiting cyclooxygenase (sigh-clo-oxee-jen-aye-z). Cyclooxygenase is an enzyme that helps to make prostaglandins (pros-tah-glan-dinz), active substances responsible for inflammation. These drugs include, but are not limited to Indomethacin (in-do-meth-a-sin), Naprosyn (nah-prox-in), Diclofenac (die-clo-fen-ack), and Fenoprofen (fen-oh-pro-fen).

Physical therapy helps the patient to strengthen back muscles, increase flexibility and range of motion. Patients may be taught to how enhance respiration. Increased daily activity and exercise may help circumvent fusion and improves posture.

Indications for Surgery
Most patients with AS do not require surgery. However, when medication does not relieve pain or pain becomes excruciating, neurologic deficit exists, spinal stability becomes compromised, there is a decrease in horizontal gaze, or spinal deformity inhibits daily activity - surgery is indicated.

The surgeon evaluates the patient's age, sex, occupation, deformity, quality of life, appropriateness of the operation, and post-operative rehabilitation. Each patient is unique. The surgery in itself is delicate and potentially harmful. The potential benefits to the patient include reduced pain, increased function and mobility, and less physical embarrassment.

Surgical Management
Several procedures are available to the surgeon. The type of surgery performed is dependent on the angle of the deformity, spinal stability, neurologic considerations and compromise, and a host of other variables.

Spinal osteotomy involves the removal and/or resection of bone (vertebra). The bone is cut to correct the angular deformity (ies). Bone is realigned and allowed to heal. Spinal instrumentation and fusion are combined with osteotomy to stabilize the spine during healing and fusion.

osteotomy, smith-peterson, posterior
osteotomy, smith-peterson, lateral view
Figure 3: Smith-Petersen V-shaped
posterior wedge osteotomy.
Figure 4: Lateral aspect of a
Smith-Petersen V-shaped wedge osteotomy.


osteotomy, closed smith-peterson
osteotomy, thomasen
Figure 5: Posterior aspect of a closed
Smith-Petersen wedge osteotomy.
Figure 6: Lateral aspect of a Thomasen
wedge osteotomy and verbal corpectomy.


osteotomy, thomasen
x-ray, rod and screw fixation, instrumentation
Figure 7: Lateral aspect of a closed
Thomasen osteotomy.
Figure 8: Postoperative lateral
aspect of transpedicular screw-rod
fixation and Thomasen subtraction osteotomy.

Restoring the spine to a more normal order may require surgical procedures involving more than one spinal region. For example, the lumbar and thoracic regions may be modified to produce a better correction. Once again, the procedures and levels to be corrected are dependent on the individual patient's needs.

Following thoracolumbar surgery, the patient wears a jacket-like brace for several months. The brace stabilizes the spine during the healing process.

patient, post operative, instrumentation
Figure 9: Postoperative lateral view of
an ankylosing spondylitic patient.

In Conclusion
Although Ankylosing Spondylitis can result in severe spinal deformity, for most patients surgery is not necessary. Often the symptoms of AS can be managed with medication and exercise. Lifestyle changes, such as complete cessation of smoking can be beneficial.

For the few that may face surgical correction of a spinal deformity, keep in mind that it is not an easy task and requires a highly experienced surgeon.

To learn about Dr. An’s practice, click here.

Updated on: 10/18/16
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Baron S. Lonner, MD
Dr. An and Mr. Samartzis provide an excellent description of surgical indications and options for thoracolumbar deformity caused by ankylosing spondylitis. Beyond the scope of their presentation is the treatment of chin-on-chest deformity that requires an osteotomy at the junction of the neck and thoracic (ribbed) spine.
David S. Bradford, MD
The authors offer a brief review of ankylosing spondylitis and surgical options for care. The surgical management of fixed sagittal plane deformity caused by ankylosing spondylitis is an important challenge for the spinal deformity physician. An initial evaluation should include an assessment to determine the primary cause of deformity. Sagittal imbalance may result from hip contractures, cervicothoracic deformity, or thoracolumbar as discussed in this article, and the management of each is different. At UCSF, I have operated on over 50 patients with fixed deformity due to ankylosing spondylitis, including cervical and lumbar osteotomies. We currently favor a transpedicular wedge resection procedure as described by Thomasen. Evaluation of this procedure for fixed sagittal deformity demonstrates an average correction of sagittal imbalance of over 10cm.

Important advances have also been made in the non-operative management of ankylosing spondylitis and at UCSF we are studying the effect of TNF alpha inhibition on reducing the progression of axial involvement for patients with ankylosing spondylitis.

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