Is lumbar artificial disc replacement a suitable treatment option for a patient with severe concordant pain at L4-5, posterior bulge, and annular tear, who has failed conservative treatments and has normal bone density?

Lumbar Artificial Disc Replacement at L4-5: Not Recommended

For this patient with severe concordant pain at L4-5, posterior bulge, and annular tear who has failed conservative treatments, lumbar artificial disc replacement should NOT be performed; instead, interbody fusion (TLIF or ALIF) with posterior instrumentation is the appropriate surgical intervention. 1

Critical Contraindications for Artificial Disc Replacement

This patient has absolute contraindications that preclude artificial disc replacement:

• Prior lumbar disc replacement at L5-S1: The presence of an existing artificial disc at an adjacent level creates biomechanical constraints and significantly increases the complexity and risk of placing another prosthesis at L4-5 2
• Moderate central canal stenosis at L4-5 (11 mm): Artificial disc replacement is contraindicated in patients with spinal stenosis, as the device does not address neural compression and may worsen symptoms 1
• Right lower extremity weakness (4/5 to 4-/5 strength): Neurological deficits indicate neural compression requiring decompression, which cannot be adequately addressed with disc replacement alone 1
• Adjacent segment disease: The patient has developed symptomatic adjacent level disease after prior L5-S1 disc replacement, demonstrating the failure of motion preservation to prevent this complication 2, 3

Evidence Against Artificial Disc Replacement

The available evidence does not support artificial disc replacement in this clinical scenario:

• No superiority over fusion: Systematic reviews demonstrate that total disc replacement has not been shown to be superior to spinal fusion in terms of clinical outcomes, with only 57% of patients meeting success criteria at 2 years 3
• Equivalent outcomes to fusion: At best, artificial disc replacement is noninferior to fusion for single-level degenerative disc disease at L4-5 or L5-S1 in carefully selected patients without stenosis or neurological deficits 4, 5
• Unproven prevention of adjacent segment disease: The theoretical benefit of preventing adjacent level degeneration has not been realized in clinical practice, as evidenced by this patient's presentation 3, 5
• Limited long-term data: Complications of total disc replacement may not be known for many years, and outcome data beyond 2-year follow-up are not yet available 3, 5

Recommended Surgical Approach: Interbody Fusion

The appropriate surgical intervention is single-level interbody fusion at L4-5 (TLIF or ALIF) with posterior instrumentation and decompression. 6, 1

Rationale for Fusion Over Disc Replacement:

• Addresses neural compression: Fusion with decompression will address the moderate central canal stenosis and posterior disc bulge causing concordant pain 1
• Resolves neurological deficits: Adequate decompression of neural elements will address the right lower extremity weakness 1
• Proven efficacy: Interbody fusion techniques have demonstrated higher fusion rates (89-95%) and improved functional outcomes in patients with degenerative disc disease 6, 1
• Compatible with existing hardware: Fusion at L4-5 is biomechanically sound adjacent to the existing L5-S1 disc replacement 1

Specific Technical Recommendations:

• TLIF approach: Provides simultaneous posterior decompression of neural elements while achieving circumferential fusion, with fusion rates of 92-95% 1
• Pedicle screw instrumentation: Provides optimal biomechanical stability with fusion rates up to 95% 1
• Adequate decompression: Complete removal of posterior disc bulge and decompression of the 11 mm central canal to address neurological symptoms 1
• Bone graft options: Local autograft combined with allograft or bone graft substitutes achieves fusion rates of 89-95% in single-level instrumented fusion 1

Critical Pitfalls to Avoid

• Do not place artificial disc at L4-5: This would fail to address stenosis, neurological deficits, and is contraindicated with adjacent level disc replacement 2, 3
• Do not perform stand-alone disc replacement: The patient requires neural decompression that cannot be achieved with disc replacement alone 1
• Avoid inadequate decompression: Ensure complete removal of compressive pathology to address concordant pain and weakness 1

Expected Outcomes with Fusion

• Pain improvement: Patients undergoing fusion for appropriate indications achieve significantly better outcomes on validated measures (ODI, VAS) compared to non-operative management 1
• Neurological recovery: Resolution of weakness is expected with adequate decompression 1
• High fusion rates: 89-95% fusion rates are achievable with appropriate instrumentation and technique 6, 1
• Functional improvement: Significant improvements in disability scores and return to activities are expected 1

Inpatient Setting Justification

This procedure requires inpatient admission due to:

• Surgical complexity: Single-level instrumented fusion with decompression adjacent to existing hardware requires close postoperative monitoring 1
• Neurological monitoring: Bilateral lower extremity weakness necessitates careful postoperative neurological assessment 1
• Pain management: Adequate postoperative pain control and early mobilization are best achieved in an inpatient setting 1