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Primary stability of hamstring graft fixation with biodegradable suspension versus interference screws
Andre Weimann1, Mareike Rodieck, Thore Zantop
1Department of Orthopaedic Surgery, Christian-Albrechts University Kiel, Kiel, Germany.
Summary
A new biodegradable suspension screw offers superior initial fixation strength for hamstring grafts in anterior cruciate ligament (ACL) reconstruction compared to traditional interference screws.
Area of Science:
- Orthopedic surgery
- Biomaterials science
- Biomechanics
Background:
- Graft fixation stability is crucial for early rehabilitation after anterior cruciate ligament (ACL) reconstruction.
- Hamstring tendon grafts are commonly used, and their secure fixation to the bone tunnel is paramount.
Purpose of the Study:
- To compare the initial fixation strength of a novel biodegradable poly-L-lactide/tri-calcium phosphate (PLLA/TCP) suspension screw with standard biodegradable interference screws.
- To evaluate the biomechanical performance of these fixation methods in hamstring ACL reconstruction.
Main Methods:
- An experimental laboratory study utilizing bovine knees.
- Single-cycle and cyclic loading tests were conducted using a materials testing machine to assess fixation strength and displacement.
Main Results:
- The suspension screw demonstrated significantly higher yield and ultimate failure loads compared to the interference screw.
- While stiffness was comparable, the suspension screw exhibited less displacement under cyclic loading and withstood higher loads (400 N vs. 250 N).
- Failure modes differed, with suspension screw failure typically being screw fracture and interference screw failure being graft slippage.
Conclusions:
- Biodegradable PLLA/TCP suspension screws provide a biomechanically robust alternative for hamstring graft fixation in ACL reconstruction.
- This novel fixation method shows potential for improving early graft stability and patient rehabilitation outcomes.