Improving Cutout Resistance Through Precision Fixation: The Role of Vertex HFN’s Diverging Dual-Screw Fixation
Hip fractures, particularly intertrochanteric fractures in older patients, pose serious challenges for orthopaedic surgeons, with implant stability being critical to avoid mechanical complications such as screw cutout. OrthoXel aims to address this problem with the Vertex Hip Fracture Nailing System (Vertex HFN), now highlighting its novel dual-screw fixation to improve cutout resistance in this White Paper.
Vertex HFN's 3 Unique Constructs
The Vertex HFN employs two points of fixation within the femoral head: a lag screw and diverging screw, oriented at a 10° angle relative to each other. This configuration with diverging fixation aims to enhance mechanical stability and reduce the risk of cutout compared to traditional single or parallel screw designs. This design aims to provide both rotational and axial stability, particularly in osteoporotic bone.
Why Cutout Resistance Matters
Cutout is the most common mechanical complication in hip fracture fixation, occurring in up to 6% of cases. It typically results from loss of lag screw fixation in the femoral head, causing implant failure and jeopardizing patient recovery. The purpose of this white paper was to evaluate the resistance to cutout of the Vertex HFN’s dual-screw design compared to two leading market solutions: Zimmer Biomet AFFIXUS® and Stryker Gamma3®.
Tested Implant Configurations
Materials and Methods
Mechanical testing was conducted to evaluate cutout resistance using foam blocks that represented osteoporotic cancellous bone. This material has mechanical properties comparable to human cancellous bone and is recommended for fixation testing of orthopedic implants. The following systems were tested:
- Vertex HFN with three configurations: Superior, Inferior, and Single Screw
- Zimmer Biomet AFFIXUS® (single screw)
- Stryker Gamma3® (single screw)
Testing Setup Example Showing the Vertex HFN Superior
Each construct underwent cyclic loading until 4 mm of displacement, simulating failure via screw cutout. Key metrics such as cycles to failure and load at failure were evaluated under rigorous laboratory standards and statistically analyzed using ANOVA with post-hoc testing.
Key Findings from the White Paper
Vertex HFN demonstrated superior mechanical performance across all configurations, with the Diverging Superior screw orientation achieving the best results:
Cycles to failure:
- Vertex HFN Superior: 17,837 ± 677
- Gamma3®: 13,388 ± 858
- AFFIXUS®: 12,299 ± 736
Load at failure:
- Vertex HFN Superior: 2177 ± 67.1 N
- Gamma3®: 1733 ± 84.3 N
- AFFIXUS®: 1623 ± 74.6 N
Even the single-screw Vertex HFN outperformed both competitor systems, indicating a broader mechanical advantage beyond just the dual-screw design.
Setting a New Standard in Cutout Resistance
Dual-screw Vertex HFN devices outperformed single-screw designs overall, but even the 1-Screw Vertex HFN showed superior cutout resistance compared to Gamma3® and AFFIXUS® The data confirms that the Vertex HFN system significantly enhances fixation durability under load. Its dual-screw configuration increases resistance to cutout failure, while the single-screw version also delivers improved outcomes compared to traditional designs. This added stability may translate into reduced complication rates, longer implant survival, and better clinical outcomes, especially in patients with compromised bone quality. With a continued focus on design innovation and clinical impact, OrthoXel’s Vertex HFN is setting a new standard in hip fracture fixation.
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