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Double-Screw Osteosynthesis in an Unstable Scaphoid Fracture Model: A Biomechanical Comparison of Two Screw
Carsten Surke1, Lachlan S Huntington2, Xin Zhang3
1Department of Plastic and Hand Surgery, Inselspital, University Hospital Bern, University of Bern, Switzerland; Hand and Wrist Biomechanics Laboratory, O'Brien Institute, Fitzroy, Victoria, Australia.
The Journal of Hand Surgery
|October 25, 2021
Summary
Double headless compression screws provide similar biomechanical stability for scaphoid fractures, regardless of sagittal or coronal alignment. Surgeon preference can guide screw placement in double-screw fixation for scaphoid fractures.
Area of Science:
- Orthopedic surgery
- Biomechanics
- Hand surgery
Background:
- Scaphoid fractures are common wrist injuries.
- Single headless compression screws are often sufficient for fixation.
- Double-screw osteosynthesis may offer higher strength and stiffness, but biomechanical effects of screw configuration are unclear.
Purpose of the Study:
- To determine the biomechanical effect of different screw configurations in double-screw fixation for scaphoid fractures.
- To compare the load to failure and stiffness of sagittal versus coronal aligned double headless compression screws.
Main Methods:
- A standardized unstable scaphoid fracture model was created in 28 cadaveric specimens.
- Specimens were randomized into sagittal or coronal double-screw fixation groups.
- Customized 3D-printed devices were used for screw placement based on CT scans.
- Mechanical testing evaluated load to failure, stiffness, and energy absorption.
Main Results:
- No significant differences in specimen size, weight, or density were found.
- The average distance between screws was greater in the sagittal group.
- No significant differences were observed in load to 2 mm displacement, load to failure, stiffness, or energy absorption between coronal and sagittal screw alignments.
Conclusions:
- Sagittal and coronal alignment of double headless compression screws yield comparable biomechanical performance in scaphoid fracture models with bone loss.
- Surgeons can choose screw placement based on accessibility, preference, and fracture orientation when considering double-screw fixation.
