Is surgical intervention, specifically minimally invasive posterior lumbar interbody fusion, indicated for a 59-year-old female patient with spinal stenosis in the lumbar region, neurogenic claudication, and severe symptoms despite conservative management?

Surgical Intervention with Fusion is Medically Necessary for This Patient

This 59-year-old female with severe multilevel lumbar stenosis (worst at L4-5), grade I spondylolisthesis at L4-5, neurogenic claudication with significant functional impairment (recurrent falls, foot drop, walker/cane dependence), and failed 12 weeks of conservative management meets clear criteria for minimally invasive posterior lumbar interbody fusion at L4-5 with bilateral pedicle screw instrumentation. 1

Primary Justification for Fusion Rather Than Decompression Alone

The critical distinction in this case is the combination of severe stenosis AND spondylolisthesis at L4-5, which fundamentally changes the surgical approach:

• Fusion is recommended as a treatment option in addition to decompression in patients with lumbar stenosis when there is evidence of spinal instability, and spondylolisthesis of any grade constitutes documented instability 1

• The presence of spondylolisthesis is a risk factor for delayed clinical and radiographic failure after lumbar decompressive procedures, with studies showing up to 73% risk of progressive slippage and 5-year clinical failure when decompression alone is performed 1

• Class II medical evidence demonstrates that 96% of patients with spondylolisthesis and stenosis treated with decompression plus fusion reported excellent or good outcomes, compared to only 44% with decompression alone 1

Why Decompression Alone Would Be Inappropriate

• Decompression alone is the recommended treatment for lumbar spinal stenosis with neurogenic claudication WITHOUT evidence of instability, but this patient has documented spondylolisthesis which represents clear instability 1

• Patients with spondylolisthesis who undergo decompression alone have higher rates of poor outcomes due to progression of spinal deformity 1

Justification for Instrumentation with Pedicle Screws

The planned bilateral facetectomy creates an additional compelling reason for instrumentation:

• The plan to perform complete facetectomy on both sides would cause iatrogenic instability in the face of pre-existing listhesis, making instrumented fusion mandatory rather than optional 1

• Extensive decompression without fusion can lead to iatrogenic instability in approximately 38% of cases, and complete bilateral facetectomy represents the most extensive form of decompression 1

• Pedicle screw fixation improves fusion success rates from 45% to 83% (p=0.0015) compared to non-instrumented fusion 1

• Instrumentation helps prevent progression of spinal deformity, which is associated with poor outcomes following decompression alone 1

Conservative Management Requirements Met

The patient has exhausted appropriate conservative measures:

• Patients with severe symptoms should undergo surgery if conservative treatment proves ineffective after 3-6 months 2

• This patient completed 12 weeks of physical therapy, multiple medication trials (gabapentin, Lyrica, oxycodone, percocet, robaxin), steroid pack, home exercise program, and weight loss attempts without success 1

• The presence of recurrent falls (3 documented falls), bilateral foot numbness 24/7, progressive symptoms now affecting the contralateral leg, foot drop requiring assistive devices, and significant ADL impairment represent severe symptoms warranting surgical intervention 1, 2

Addressing the Multilevel Stenosis Question

A critical consideration is whether fusion should extend beyond L4-5:

• The imaging shows stenosis is "most pronounced at L3-L4 and L4-L5 where severe narrowing is noted", but the spondylolisthesis is documented only at L4-5 1

• Fusion should be added to decompression only when specific biomechanical instability is present, such as spondylolisthesis of any grade, radiographic instability on flexion-extension films, or significant deformity 1

• The flexion-extension radiographs showed "no evidence of positional instability" and "no positional instability elicited with flexion and extension imaging", suggesting instability is limited to L4-5 where the spondylolisthesis exists 1

• Decompression at L3-4 without fusion would be appropriate if no instability is documented at that level, as patients with less extensive surgery tend to have better outcomes than those with extensive decompression and fusion when instability is absent 1

Recommended Surgical Approach

The evidence-based approach is decompression at L3-4 and L4-5 with fusion limited to L4-5 (the documented unstable level with spondylolisthesis), unless intraoperative assessment reveals that the extent of decompression required at L3-4 will create iatrogenic instability 1

Common Pitfalls to Avoid

• Do not perform decompression alone at L4-5 in the presence of spondylolisthesis, as this carries unacceptable risk of progressive deformity and clinical failure 1

• Do not extend fusion beyond levels with documented instability without clear justification, as blood loss and operative duration are significantly higher in fusion procedures, and patients with less extensive surgery tend to have better outcomes 1

• Do not perform complete bilateral facetectomy without fusion, as this creates iatrogenic instability requiring stabilization 1

Interbody Cage Justification

• Interbody fusion devices are appropriate when used with bone graft in patients meeting criteria for lumbar fusion, and provide anterior column support, restore disc height, and improve foraminal dimensions 1

• Circumferential fusion (360-degree) with interbody support has demonstrated higher fusion rates compared to posterolateral fusion alone 1

• The severe stenosis at L4-5 with "significant spinal stenosis" and foraminal narrowing supports the use of interbody technique to maximize decompression and restore anatomy 1

Level of Care Justification

• The American Association of Neurological Surgeons recommends inpatient level of care for patients with severe spinal stenosis requiring extensive multilevel lumbar fusion surgery, due to the complexity of the procedure and the need for close monitoring 3

• The planned procedure involves multiple surgical components including lumbar spine fusion, bone grafting, posterior segmental instrumentation, and laminectomy with facetectomy, which increases the risk of complications and necessitates inpatient care 3