Isolated L4-L5 fusions using the variable screw placement system: unilateral versus bilateral

Area of Science:

• Orthopedic Surgery
• Spinal Fusion Techniques
• Biomedical Engineering

Background:

• Isolated L4-L5 fusions are common in spinal surgery.
• Variable Screw Placement (VSP) instrumentation offers potential advantages in spinal fusion.
• Comparing unilateral versus bilateral VSP for L4-L5 fusion requires further investigation.

Purpose of the Study:

• To evaluate the relative effectiveness of unilateral versus bilateral Variable Screw Placement (VSP) instrumentation for isolated L4-L5 fusions.
• To assess fusion rates, complication rates, and clinical outcomes in patients undergoing L4-L5 fusion with VSP.

Main Methods:

• Retrospective follow-up of 36 patients for an average of 25.1 months.
• Patients were divided into unilateral (16) and bilateral (20) VSP instrumentation groups.
• Outcomes assessed via plain roentgenograms and self-report questionnaires.

Main Results:

• A 97% successful fusion rate was achieved with VSP instrumentation and autogenous posterolateral grafting.
• Unilateral and bilateral VSP groups showed nearly identical fusion results, both superior to historical non-instrumented controls.
• Clinical outcomes demonstrated 69% excellent and good results, with no significant difference between unilateral and bilateral VSP groups.

Conclusions:

• Variable Screw Placement (VSP) instrumentation is effective for L4-L5 fusions, achieving high fusion rates and good clinical outcomes.
• Unilateral and bilateral VSP demonstrate comparable effectiveness for isolated L4-L5 spinal fusions.
• Clinical outcomes were not significantly correlated with fusion status in this VSP cohort.