What is the recommended treatment for a patient with Grade 1 anterolisthesis of L5 on S1 with bilateral pars defects and moderate bilateral neural foraminal stenosis at L5-S1?

Treatment for Grade 1 Anterolisthesis L5-S1 with Bilateral Pars Defects and Moderate Foraminal Stenosis

Conservative management with structured physical therapy for at least 6 weeks should be the initial treatment, and surgical fusion should only be considered if conservative measures fail and the patient has persistent disabling symptoms that correlate with imaging findings. 1

Initial Conservative Management (First-Line Treatment)

Conservative treatment must be comprehensive and sustained before any surgical consideration:

• Structured physical therapy program for minimum 6 weeks focusing on core strengthening, hamstring stretching, and spine range of motion exercises 2, 3
• Activity modification with restriction of offending activities, particularly those involving lumbar extension and rotation 3
• Pharmacologic management including NSAIDs (diclofenac or similar) and consideration of neuropathic pain medications (gabapentin or pregabalin) for radicular symptoms 1, 4
• Epidural steroid injections may provide short-term relief for radicular symptoms, though evidence shows duration of relief is typically less than 2 weeks for chronic low back pain without radiculopathy 1, 5

The evidence strongly supports this approach: 96% of patients with symptomatic spondylolysis and grade I spondylolisthesis achieved minimal disability scores with conservative management alone, and 78% reported complete resolution of pain 3. Physical therapy and epidural steroid injections both demonstrate significant improvement in pain and functional parameters up to 6 months 5.

Indications for Surgical Fusion

Fusion should only be considered when ALL of the following criteria are met:

• Failed comprehensive conservative management for at least 3-6 months including formal physical therapy, medication trials, and potentially epidural steroid injections 1, 4
• Persistent disabling symptoms with documented functional impairment on validated measures (Oswestry Disability Index, Visual Analog Scale) 1
• Imaging findings that directly correlate with clinical presentation - in this case, the moderate bilateral neural foraminal stenosis at L5-S1 must correspond to the patient's radicular symptoms 1
• Patient is a surgical candidate willing to undergo intervention 2

The presence of bilateral pars defects with grade 1 anterolisthesis represents documented instability, which is a Grade B indication for fusion when combined with failed conservative management 1. However, the critical pitfall is proceeding to surgery without adequate conservative treatment - this is explicitly identified as a deficiency that negates medical necessity 1.

Surgical Approach When Indicated

If fusion becomes necessary after failed conservative management:

• Transforaminal lumbar interbody fusion (TLIF) at L5-S1 is the appropriate technique, providing high fusion rates (92-95%) while allowing simultaneous decompression of the neural foramina and stabilization of the spondylolisthesis 1
• Pedicle screw instrumentation provides optimal biomechanical stability with fusion rates up to 95% 1
• Decompression of bilateral neural foramina should be performed to address the moderate foraminal stenosis 1, 6

The Modic 1 endplate changes indicate active vertebral inflammation and advanced degenerative disease, which supports the diagnosis but does not independently mandate fusion 1.

Critical Considerations and Pitfalls

Do not proceed to fusion without documented failure of comprehensive conservative management - this is the most common error and renders the surgery medically unnecessary 1. The patient must complete formal physical therapy, not just home exercises, and trial appropriate medications 1.

Decompression alone is insufficient in the presence of documented spondylolisthesis with bilateral pars defects, as this represents structural instability requiring fusion 1. However, fusion without adequate conservative treatment first is equally inappropriate 1.

Complication rates for instrumented fusion are significant (31-40% in some studies), which underscores the importance of exhausting conservative options first 1. Most patients with grade 1 spondylolisthesis can be managed successfully without surgery 3.

The presence of disc bulge with central protrusion and disc height loss at L5-S1 supports the degenerative nature of the condition but does not change the treatment algorithm - conservative management remains first-line 1, 4.