Study Overview

The study aimed to evaluate whether bilateral transfacet pedicle screws (TFPS) using the FacetFuse system could provide immediate stability equivalent to or greater than that of traditional pedicle screw-rod (PSR) constructs at the L5–S1 level.

Three constructs were analyzed:

• Bilateral TFPS (FacetFuse) – 2 screws

• Unilateral PSR (UPSR) – 2 screws, 1 rod

• Bilateral PSR (BPSR) – 4 screws, 2 rods

All constructs used standardized 5.0 mm × 40 mm screws and were tested under pure moment loading to measure range of motion (ROM) in flexion-extension, lateral bending, and axial rotation.

Key Findings

• TFPS provided superior immediate stability compared to unilateral PSR in all loading directions.

• TFPS matched the performance of bilateral PSR in extension and axial rotation, which are essential for fusion integrity.

• Lateral bending was slightly less restricted in TFPS compared to BPSR, consistent with its medial screw head positioning.

This indicates that bilateral TFPS can achieve comparable biomechanical stability using just two screws, versus the traditional four-screw, two-rod setup.

Clinical Implications

The findings suggest a meaningful shift in posterior fixation strategy, particularly in minimally invasive or outpatient spine procedures:

• Reduced implant load without compromising immediate fixation

• Midline approach that preserves soft tissue and avoids the multifidus

• Decreased risk of adjacent segment facet violation, a known contributor to adjacent segment disease (ASD)

• Ease of construct extension in future ASD cases without rod removal or hardware disruption

Additionally, the lag screw trajectory across the facet joint in TFPS may enhance disc compression and promote lordosis restoration, aiding in sagittal balance.

Conclusion

This study reinforces that fewer implants do not mean less stability—when precision technique and construct design are optimized. Facet-based fixation with TFPS at L5–S1 can serve as a reliable, efficient alternative to traditional pedicle screw constructs, especially when procedural efficiency, tissue preservation, and future adaptability are priorities.

The data supports a refined approach to fixation—one that challenges volume-based constructs and favors biomechanical effectiveness with surgical simplicity.