What is the appropriate treatment for a patient with MRI showing moderate to marked lumbar spondylosis and a grade 1 anterolisthesis of L4 on L5 without dynamic instability?

Treatment of Moderate to Marked Lumbar Spondylosis with Grade 1 Anterolisthesis L4 on L5

Begin with a minimum of 6 weeks of comprehensive conservative management including formal physical therapy, anti-inflammatory medications, and activity modification before considering any surgical intervention. 1, 2

Initial Conservative Management (Mandatory First-Line)

All patients must complete structured conservative therapy for 3-6 months before surgical consideration:

• Formal physical therapy focusing on core strengthening and flexion-based exercises for at least 6 weeks 1, 2
• Pharmacologic management including NSAIDs and trial of neuropathic pain medications (gabapentin or pregabalin) if radicular symptoms present 2
• Activity modification avoiding heavy lifting and repetitive lumbar extension 3, 4
• Epidural steroid injections may provide short-term relief (less than 2 weeks) but do not constitute adequate conservative management alone 2, 3

The flexion exercise program (abdominal strengthening, posterior pelvic tilts) demonstrates superior outcomes compared to extension exercises, with only 19% reporting moderate-to-severe pain at 3-year follow-up versus 67% in extension groups 4. A minimum 3-4 month trial is required before declaring conservative failure. 4

Imaging Evaluation for Instability

Dynamic imaging is essential to determine surgical candidacy:

• Flexion-extension radiographs remain the standard to identify segmental motion, with translational instability defined as ≥8% slip change 1, 5
• Natural sitting lateral radiographs combined with supine MRI detect instability in 61% of patients versus only 19% with traditional flexion-extension views 5
• Grade 1 anterolisthesis (5-25% slip) without dynamic instability on flexion-extension films does not automatically warrant fusion 1, 2

Surgical Indications (Only After Conservative Failure)

Fusion is indicated when ALL of the following criteria are met:

1. Documented failure of comprehensive conservative management for 3-6 months 1, 2
2. Persistent disabling symptoms with functional impairment 2
3. Radiographic evidence of either:
   • Dynamic instability (≥8% translational motion) on flexion-extension films 5
   • OR spondylolisthesis of any grade with symptomatic stenosis requiring extensive decompression 1, 2

Critical distinction: Grade 1 spondylolisthesis without dynamic instability does not meet fusion criteria—decompression alone is appropriate if stenosis is present 1, 2. Studies show no significant outcome difference between decompression alone versus decompression with fusion in patients without preoperative instability (65% satisfaction in both groups at 7-year follow-up) 1.

Surgical Approach When Indicated

If fusion criteria are met:

• Decompression with instrumented fusion provides 93-96% excellent/good outcomes versus only 44% with decompression alone in patients with spondylolisthesis and stenosis 2
• Transforaminal lumbar interbody fusion (TLIF) achieves 92-95% fusion rates with pedicle screw fixation 2
• Patients report statistically significant improvements in back pain (p=0.01) and leg pain (p=0.002) with fusion versus decompression alone 2

Common Pitfalls to Avoid

• Do not fuse based on imaging alone—static Grade 1 anterolisthesis without dynamic instability or failed conservative management does not warrant surgery 1, 2
• Do not accept inadequate conservative therapy—single epidural injections or brief physical therapy trials do not satisfy guideline requirements 2
• Do not skip flexion-extension radiographs—static MRI cannot assess dynamic instability, which is the key determinant for fusion 1, 5
• Avoid multilevel fusion unless each level independently meets all fusion criteria with documented instability 2

The incidence of progressive slippage after decompression alone ranges from only 9% in patients without preoperative instability to 73% in those with existing spondylolisthesis 1. Your patient's lack of dynamic instability places them in the low-risk category where conservative management should be exhausted first.