What is the best surgical approach for a 64-year-old female with diabetes mellitus (DM) and hypertension (HTN), who has a history of lumbar spine fusion from L2 to L5, and now presents with adjacent segment disease at L1/2 with severe central and foraminal stenosis, bilateral thigh dysesthesia and pain, and a diseased L5/S1 disc with vacuum phenomenon, considering her recent improvement in blood sugar control from an elevated Hemoglobin A1c (HbA1c) of 8.9?

Surgical Recommendation for Adjacent Segment Disease with Multi-Level Pathology

This patient requires staged surgical intervention: first, optimize glycemic control to achieve HbA1c <7.5 mg/dL, then proceed with extension of fusion from L1-S1 using a combined anterior-posterior approach (OLIF at L1-2 and L5-S1, with posterior instrumented fusion and decompression). 1, 2

Preoperative Optimization is Mandatory

Diabetic patients with HbA1c >7.5 mg/dL have significantly increased risk of reoperation and infection after spine surgery. 1 While her recent random blood sugars show improvement, the documented HbA1c of 8.9% represents a critical risk factor that must be addressed before proceeding with surgery.

• **Grade B recommendation: Delay surgery until HbA1c is documented <7.5 mg/dL** through repeat testing, as levels >7.5 mg/dL are associated with increased risk of reoperation and postoperative infection 1
• Diabetes increases the risk ratio for revision surgery due to non-union complications (RR 2.80) and adjacent segment disease progression (RR 2.26) 3
• Perioperative complication rates in diabetic patients undergoing lumbar instrumentation and fusion are significantly higher (53-56%) compared to controls (21%), with nonunion rates of 22-26% versus 5% 4

Target 4-8 weeks of documented glycemic control with HbA1c <7.5 mg/dL before proceeding with definitive surgery. 1

Surgical Indications Are Clear and Compelling

This patient has multiple absolute indications for fusion:

• Adjacent segment disease at L1-2 following L2-L5 fusion with severe stenosis and bilateral radiculopathy meets Grade B criteria for extension of fusion 2, 5
• Diseased L5-S1 disc with vacuum phenomenon indicates advanced degenerative disease requiring inclusion in the fusion construct 2
• Bilateral thigh dysesthesia and pain correlating with imaging findings of severe central and foraminal stenosis at both L1-2 and L5-S1 2, 5
• Previous fusion creates biomechanical stress at adjacent segments, with documented progression requiring surgical intervention 2, 6

Optimal Surgical Approach: Staged Combined Anterior-Posterior Technique

The recommended approach is staged OLIF (Oblique Lumbar Interbody Fusion) at L1-2 and L5-S1, followed by posterior instrumented fusion extending from L1 to S1 with decompression. 2, 7

Rationale for OLIF Approach:

• OLIF at L1-2 is technically feasible and safe with minimal complications when performed by experienced surgeons, though L1-2 carries higher technical demands 8, 7
• OLIF provides superior access to L5-S1 compared to posterior-only approaches, with minimal blood loss (57 ± 131 ml per level) and short operative times (32.5 ± 13.2 minutes per level) 7
• Minimally invasive OLIF reduces approach-related morbidity compared to traditional anterior approaches, avoiding abdominal wall weakness or herniation 7
• Combined anterior-posterior approaches provide superior stability with fusion rates up to 95%, particularly important given the patient's diabetes and increased nonunion risk 2

Specific Technical Considerations:

Stage 1: OLIF at L1-2 and L5-S1

• Perform OLIF through retroperitoneal approach at both levels to restore disc height and achieve anterior column support 2, 7
• Use structural interbody cages with local autograft and allograft to maximize fusion potential in diabetic patient 2
• Critical pitfall at L1-2: This level has unexpectedly poor fusion rates (58%) and high subsidence risk (25%) with posterior-only approaches, making anterior column support essential 8

Stage 2 (7-14 days later): Posterior instrumented fusion L1-S1 with decompression

• Extend posterior instrumentation from existing L2-L5 construct to include L1 and S1 2, 6
• Perform bilateral decompression at L1-2 for severe central and foraminal stenosis 2, 5
• Pedicle screw fixation provides optimal biomechanical stability with fusion rates up to 95% compared to non-instrumented approaches 2

Why Staged Rather Than Single-Stage:

• Staged surgery minimizes perioperative morbidity in complex multilevel circumferential fusion procedures, particularly important given diabetes and hypertension 2, 9
• Reduces operative time and blood loss compared to combined anterior-posterior single-stage procedures 2, 7
• Allows optimization between stages if glycemic control deteriorates 1

Alternative Approach if OLIF Expertise Unavailable:

If OLIF is not available, perform posterior-only approach with TLIF at L1-2 and L5-S1, extending instrumentation from L1-S1. 2

• TLIF provides high fusion rates (92-95%) and allows simultaneous decompression 2
• However, L1-2 TLIF carries higher technical difficulty and complication risk compared to lower lumbar levels 8
• Posterior-only approach increases operative time and blood loss compared to staged OLIF approach 2, 7

Critical Pitfalls to Avoid:

• Do not proceed with surgery until HbA1c is documented <7.5 mg/dL - the increased infection and nonunion risk is unacceptable 1, 3, 4
• Do not perform decompression alone at L1-2 - adjacent segment disease with previous fusion requires extension of fusion construct 2, 5
• Do not stop fusion at L5 - the diseased L5-S1 disc with vacuum phenomenon will rapidly progress and require revision surgery 2
• Do not underestimate L1-2 fusion difficulty - this level has documented poor fusion rates (58%) and requires meticulous technique 8
• Do not use single-stage combined approach in this diabetic patient with hypertension - staged approach reduces perioperative morbidity 2, 9

Expected Outcomes and Monitoring:

• Fusion rates of 89-95% are achievable with combined anterior-posterior techniques using appropriate graft materials, though diabetes reduces this to approximately 70-75% 2, 3, 4
• Clinical improvement occurs in 86-92% of patients undergoing interbody fusion for degenerative pathology with appropriate indications 2
• Monitor closely for adjacent segment disease at T12-L1 and below S1, as diabetes increases risk ratio for this complication (RR 2.26) 3, 6
• Postoperative CT with fine-cut axial and multiplanar reconstruction at 12 months is superior to plain radiographs for assessing fusion status 2

Inpatient Care is Mandatory:

This complex multilevel fusion with deformity correction requires inpatient admission due to:

• Multilevel fusion (≥2 levels) with dual surgical approach 9
• Age 64 with diabetes and hypertension increases complication risk 9, 4
• Combined anterior-posterior approaches have higher complication rates (31-40%) requiring close postoperative monitoring 2, 9
• Diabetes significantly increases perioperative complication rates necessitating intensive monitoring 4