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Published on: October 9, 2014
The effect of interference screw diameter on soft tissue graft fixation
Suk Namkoong1, Christian S Heywood, Jonathan T Bravman
1NYU-Hospital for Joint Diseases Department of Orthopaedic Surgery, 15th Floor, 301 East 17th Street, New York, New York 10003, USA.
Bulletin (Hospital for Joint Diseases (New York, N.Y.))
|August 2, 2006
Summary
Larger interference screw diameter improves anterior cruciate ligament graft fixation strength. Increasing screw diameter up to 11mm significantly enhanced load to failure, but slippage remained unaffected.
Area of Science:
- Orthopedic surgery
- Biomechanical engineering
- Sports medicine
Background:
- Tibial fixation of soft-tissue grafts is a critical factor in anterior cruciate ligament (ACL) reconstruction outcomes.
- Current methods for improving graft fixation include varying interference screw dimensions and tunnel sizes.
- Understanding the biomechanical properties of graft fixation is essential for optimizing surgical techniques.
Purpose of the Study:
- To investigate the effect of increasing interference screw diameter on the biomechanical properties of simulated hamstring grafts used in ACL reconstruction.
- To determine if larger screw diameters enhance the maximum load to failure and reduce initial graft slippage.
- To establish optimal interference screw diameter relative to tunnel size for robust graft fixation.
Main Methods:
- Seventy simulated 4-strand hamstring grafts were prepared from tibialis anterior and posterior tendons.
- Grafts were fixed into 8 mm bone tunnels using interference screws of varying diameters (8, 9, 10, 11, and 12 mm).
- Cyclic loading assessed initial slippage, followed by load-to-failure testing to determine fixation strength and failure modes.
Main Results:
- Interference screw diameter did not significantly affect initial graft slippage.
- Maximum load to failure increased with screw diameter up to 11 mm, with 11 mm screws demonstrating 20% greater strength than 8 mm screws.
- No further increase in fixation strength was observed when interference screw diameter exceeded tunnel diameter by more than 3 mm.
Conclusions:
- Increasing interference screw diameter, up to a certain limit, is an effective strategy to enhance graft fixation strength in ACL reconstruction.
- Optimal fixation strength is achieved when screw diameter is appropriately matched to tunnel size, suggesting a 3 mm differential.
- These findings provide valuable biomechanical data for guiding the selection of interference screws to improve the success of ACL reconstruction.
