AANS Neurosurgeon : Gray Matters

Volume 20, Number 1, 2011

To Brace or Not to Brace?

Instrumented Lumbar Fusion in the Degenerative Spine

Aleksa Cenic, MD, and Rajiv Midha, MD

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The following case presentation is intended to assess current practice habits for common neurosurgical challenges when class I evidence is not available.

The Case

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A 60-year-old man presents with a progressive history of low back pain and bilateral leg discomfort. He says that over the last year his ability to walk long distances has decreased due to bilateral leg pain and paresthesias radiating from his buttocks to his thighs. He must sit down or lean forward to alleviate the leg symptoms. He definitely feels that he can walk longer distances when he is leaning forward such as when pushing a shopping cart or a lawn mower. He clearly states that his leg symptoms are more bothersome than the low back pain. On physical examination there are no focal neurological deficits. His symptoms are reproduced when he extends his lumbar spine, but they are alleviated when he flexes it.









(A) T2-weighted sagital MRI of the lumbosacral spine showing Grade I spondylolisthesis with associated central spinal stenosis at L4–L5. Standing lateral plain film X-rays of the lumbar spine showing (B) increased anterolisthesis on flexion, and (C) reduced anterolisthesis on extension. (D) Postoperative plain film X-rays reveal the posterior instrumentation at L4–L5.

MRI of the lumbar spine reveals spinal stenosis at the L4–L5 level due to ligament and facet hypertrophy and a Grade I degenerative spondylolisthesis. X-rays at this level show significant mobility with standing flexion and extension (greater than 4 mm movement with flexion which reduces in extension).

Clinical history, examination and MRI findings are consistent with a diagnosis of neurogenic claudication due to L4–L5 spinal stenosis. The patient agrees to a L4–L5 posterior decompression, instrumentation with pedicle screws and rods, and posterolateral autograft fusion. Upon signing the consent forms he asks whether he will need to wear a lumbar brace after surgery.

Discussion
Posterior decompression via laminectomy and partial facetectomy is a common neurosurgical procedure used to alleviate neurogenic claudication due to degenerative lumbar spinal stenosis. However, in associated cases of spondylolisthesis, many surgeons advocate for spinal stabilization through a posterolateral bone fusion. With the advent of posterior instrumentation methods to provide rigid internal fixation, posterolateral bone fusion rates have increased significantly in comparison to noninstrumented fusions (2). Some surgeons also advocate use of an external fixation device such as a canvas corset or a thoracolumbosacral orthosis (TLSO) in the postoperative period, believing that its use will increase fusion rates. With very limited evidence supporting or precluding the use of a brace, a surgeon’s decision to use or not to use a brace is largely subjective (3).

In a prospective randomized trial comparing fusion rates after instrumented posterior lumbar fusion for a degenerative spinal condition, 90 patients were randomly assigned to wear or not to wear a canvas corset for eight weeks. The authors found no significant difference between the two groups (8). However, the study group was prescribed a canvas corset rather than a more rigid TLSO, and patients only wore the brace for two months which may be inadequate duration for bone fusion to occur.

Advocates for a postoperative brace feel that a brace not only reduces mobility but also reduces the axial load on the lumbar spine, hence increasing the bone fusion rates. In a prospective comparative study patients with Grade 1–2 spondylolisthesis who wore a rigid TLSO for five months after having a noninstrumented posterolateral fusion had higher fusion rates than those who wore it for three months (4). In a study evaluating factors that affect fusion rates in lumbar spondylolisthesis patients treated with or without instrumentation, patients immobilized with a pantaloon spica cast had higher fusion rates than those treated in the less rigid TLSO (5).

Surgeons who do not prescribe a postoperative lumbar brace feel that instrumented internal fixation provides significant stabilization that does not need to be supplemented by an external brace. They see external braces as an unnecessary expense to the patient that also can cause patient discomfort and wound ulcers. Moreover, some studies reveal that external braces do not completely (or even significantly) immobilize the lumbosacral spine (6, 7). In a critical analysis of fusion trends for degenerative disc disease, researchers found no significant difference in overall fusion rates—including instrumented and noninstrumented fusions—between patients who were braced postoperatively and those who were not (2).

In a 2009 survey of 85 spine surgeons who perform posterior lumbar instrumented fusions for degenerative conditions, approximately 60 percent prescribed postoperative bracing (1). This clear lack of consensus among spine surgeons suggests that a prospective randomized controlled study is warranted to investigate whether postoperative bracing improves fusion rates in patients with instrumented lumbar fusions.

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Aleksa Cenic, MD, MSc, FRCSC, is a fellow in neurosurgery, and Rajiv Midha, MD, MSc, FAANS, FRCSC, is professor and deputy head of the Department of Clinical Neurosciences at the University of Calgary in Canada. Dr. Midha is a member of the AANS Neurosurgeon Editorial Board. The authors reported no conflicts for disclosure.

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