How should lumbar anterolisthesis in an adult with low back pain and possible leg symptoms be evaluated and managed?

Evaluation and Management of Lumbar Anterolisthesis in Adults

Initial Imaging Evaluation

For adults with low back pain and possible leg symptoms who have failed 6 weeks of conservative therapy and are surgical candidates, MRI lumbar spine without contrast is the initial imaging modality of choice. 1

• MRI accurately depicts disc degeneration, spinal stenosis, neural compression, and the degree of vertebral slippage 1
• Upright flexion-extension radiographs are essential to identify dynamic instability (>3-4mm translation or >10 degrees angulation), which determines whether fusion is needed in addition to decompression 2
• CT lumbar spine without contrast is useful for preoperative planning to assess bony anatomy and trajectory planning for hardware fixation 1

Common pitfall: Ordering MRI in patients who have not completed 6 weeks of conservative management, as many MRI abnormalities are seen in asymptomatic individuals and early imaging rarely changes management 1

Conservative Management Requirements

All patients must complete comprehensive conservative treatment for at least 6 weeks to 3 months before surgical intervention is considered, regardless of imaging findings. 2, 3

Conservative management must include:

• Formal supervised physical therapy (not just home exercises) for minimum 6 weeks 2, 3
• Flexion-based strengthening exercises (abdominal curl-ups, posterior pelvic tilts) are superior to extension exercises for symptomatic spondylolisthesis, with only 19% having moderate/severe pain at 3 years versus 67% in extension groups 4
• NSAIDs and analgesics for pain control 5
• Trial of neuropathic pain medications (gabapentin or pregabalin) if radicular symptoms present 3
• Epidural steroid injections may provide short-term relief (<2 weeks) but have limited evidence for chronic low back pain without radiculopathy 3, 5

The prognosis without surgery is generally favorable for degenerative spondylolisthesis, though patients with neurological symptoms (intermittent claudication, bowel/bladder dysfunction) will likely experience neurological deterioration without surgical intervention 5

Indications for Decompression Alone (No Fusion)

Decompression without fusion is appropriate when no spondylolisthesis of any grade is present on static imaging and dynamic flexion-extension radiographs demonstrate no translational motion (>3-4mm) or angulation (>10 degrees). 2

• Isolated lumbar stenosis without instability achieves 70% success rates with decompression alone 2
• Adding fusion in the absence of instability increases operative time, blood loss, and complications without improving outcomes 2, 3
• Only 9% of patients without preoperative instability develop delayed slippage after decompression alone 2

Indications for Decompression Plus Fusion

Fusion must be added to decompression when any of the following are present: 2, 3

Absolute Indications:

• Any degree of spondylolisthesis (Grade I or higher) documented on imaging 2, 3
• Dynamic instability on flexion-extension films (>3-4mm translation or >10 degrees angulation) 2
• Degenerative scoliosis or kyphotic deformity requiring correction 2

Relative Indications:

• Extensive bilateral facetectomy required (>50% facet removal) to achieve adequate neural decompression, which creates iatrogenic instability with ≈37.5% risk if fusion not performed 2
• Multilevel decompression with severe facet arthropathy at contiguous levels 2
• Recurrent disc herniation with associated instability or chronic axial back pain 3
• Manual laborers or athletes with chronic axial back pain plus radiculopathy and severe degenerative changes 3

Evidence Supporting Fusion in Spondylolisthesis

Patients with stenosis and any degree of spondylolisthesis achieve 93-96% excellent/good outcomes with decompression plus fusion versus only 44% with decompression alone, with statistically significant reductions in both back pain (p=0.01) and leg pain (p=0.002). 2, 3

• Preoperative spondylolisthesis is a documented risk factor for 5-year clinical and radiographic failure after decompression alone, with up to 73% risk of progressive slippage 2, 3
• Pedicle screw instrumentation improves fusion success rates from 45% to 83% (p=0.0015) in patients with spondylolisthesis 2, 3

Surgical Technique Selection

For patients meeting fusion criteria, transforaminal lumbar interbody fusion (TLIF) is an appropriate technique offering 92-95% fusion rates with unilateral approach minimizing dural retraction. 3

• TLIF allows simultaneous decompression of neural elements while stabilizing the spine 3
• Alternative interbody techniques (PLIF, ALIF, XLIF) have comparable fusion rates but different approach-related risks 3
• Pedicle screw fixation provides optimal biomechanical stability and is recommended when spondylolisthesis or instability exists 2, 3

Critical pitfall: Performing fusion for isolated stenosis without documented instability increases surgical risk, cost, and complications without delivering better clinical outcomes 2, 3

Special Considerations

Degenerative spondylolisthesis most commonly occurs at L4-5 in women over age 40, while isthmic spondylolisthesis typically affects L5-S1. 4, 6

• MRI features distinguishing lytic from degenerative spondylolisthesis include the "step-off" sign, "wide canal" sign, and epidural fat interposition 6
• Bilateral pars defects constitute documented spinal instability and represent a Grade B indication for fusion 3
• Traumatic multilevel anterolisthesis from pedicle avulsion (rather than facet/pars disruption) is rare but relatively stable due to intact posterior ligamentous complex 7