Related Experiment Video
Updated: Dec 4, 2025
10:09
Adjustable Stiffness, External Fixator for the Rat Femur Osteotomy and Segmental Bone Defect Models
Published on: October 9, 2014
23.0K
Variable Fixation Technology Provides Rigid as Well as Progressive Dynamic Fixation: A Biomechanical Investigation
A Frank1,2, S Brianza3, M Plecko4
1Department of Trauma, Hand and Reconstructive Surgery, University Hospital Muenster, Muenster, Germany.
The Journal of Bone and Joint Surgery. American Volume
|October 21, 2020
Summary
The Variable Fixation Locking Screw (VFLS) initially offers rigid fixation comparable to standard screws. Its resorbable sleeve enables progressive dynamic stabilization, potentially enhancing secondary fracture healing.
Area of Science:
- Orthopedic biomechanics
- Biomaterials science
- Surgical innovation
Background:
- A novel Variable Fixation Locking Screw (VFLS) was developed to promote secondary fracture healing.
- The VFLS incorporates a resorbable sleeve that gradually degrades, altering mechanical properties over time.
- This study evaluates the VFLS's capacity for both rigid and progressive dynamic fixation.
Purpose of the Study:
- To assess the interfragmentary stability of the VFLS under various loading conditions.
- To compare the VFLS fixation with standard locking screws and combined technologies.
- To investigate the effect of sleeve resorption on fracture gap dynamization.
Main Methods:
- A simulated fracture-gap model was used to test VFLS stability.
- Compression and torsional loading were applied to test constructs.
- An optical measurement system quantified interfragmentary movements before and after sleeve dissolution.
Main Results:
- Initial axial stiffness was similar across all tested screw configurations.
- Sleeve resorption significantly reduced construct stiffness and increased axial displacement.
- VFLS alone demonstrated a substantial increase in dynamic axial displacement post-resorption.
Conclusions:
- The VFLS provides initial rigid fixation comparable to standard locking screws.
- Sleeve degradation results in reproducible, progressive dynamization of the fracture gap.
- This variable fixation may positively influence secondary fracture healing processes.
