Inion Hexalon vs Titanium EndoButton: No Evidence-Based Difference
Based on available evidence, there is no direct comparative data between Inion Hexalon polymer buttons and titanium EndoButtons regarding postoperative strength recovery or immunologic response in ACL reconstruction. The choice between these fixation devices should be guided by surgeon experience and technical considerations rather than expected differences in clinical outcomes.
Key Evidence Findings
Fixation Device Comparisons
The available research demonstrates that different cortical button systems (titanium-based EndoButton, TightRope variants, PEEK buttons) show comparable clinical outcomes in terms of:
- Anterior knee laxity: No significant differences at 6 months postoperatively between TightRope II RT, TightRope RT, and EndoButton CL 1
- Functional outcomes: Similar Lysholm scores, IKDC grades, and side-to-side laxity measurements between cortical button and cross-pin fixation at long-term follow-up (>10 years) 2
- Safety profile: Titanium and PEEK button systems demonstrate effective performance with no adverse device effects 3
Tunnel Widening Considerations
Cortical button fixation (including EndoButton systems) demonstrates less femoral tunnel widening compared to interference screw fixation 4. This is clinically relevant as:
- Femoral tunnel widening at proximal and middle levels is significantly reduced with EndoButton-Continuous Loop® fixation
- Tibial tunnel widening shows no difference between fixation methods
- Less tunnel widening may facilitate future revision surgery if needed
Immunologic/Inflammatory Response
The inflammatory response after ACL reconstruction is primarily driven by dying graft cells, not the fixation hardware 5. Key points:
- Fresh autografts release both pro- and anti-inflammatory cytokines from dying resident cells
- This cellular response is patient-specific and not age-related
- Fixation device material (polymer vs titanium) has not been shown to significantly influence the inflammatory cascade
Clinical Implications
Strength Recovery
- Rehabilitation protocols, not fixation device choice, determine strength recovery 6
- Exercise interventions are the mainstay of ACLR rehabilitation
- Strength training should begin early and progress based on objective criteria, not hardware type
Device Selection Algorithm
Choose based on:
- Surgeon familiarity and technical preference - Most important factor given equivalent outcomes
- Revision surgery considerations - Cortical buttons allow easier hardware removal if needed
- Cost and availability - No clinical benefit justifies significant cost differences
- Graft type compatibility - Ensure device matches your graft preparation technique
Common Pitfalls to Avoid
- Do not delay rehabilitation based on fixation device type - All modern cortical buttons provide adequate initial fixation
- Do not attribute poor outcomes to hardware choice - Focus on tunnel placement, graft selection, and rehabilitation compliance 7, 8
- Do not assume polymer devices reduce inflammation - No evidence supports this claim
Bottom Line
Both Inion Hexalon polymer buttons and titanium EndoButtons are acceptable fixation options with no demonstrated differences in postoperative strength recovery or immunologic response. The 2023 AAOS guidelines emphasize that graft choice (BTB vs hamstring) matters more than fixation device for outcomes like graft failure and anterior knee pain 9. Focus your clinical decision-making on proven factors: early surgical timing for isolated ACL tears, appropriate graft selection, anatomic tunnel placement, and aggressive rehabilitation protocols 6.