Biomechanical assessment of compression screws

Area of Science:

• Orthopedic biomechanics
• Biomaterials science
• Surgical implant technology

Background:

• Bone fracture fixation relies on implants to achieve stability and promote healing.
• Cancellous bone screws are commonly used for fracture fixation, with various designs available.
• Evaluating the mechanical performance of different screw designs is crucial for optimizing clinical outcomes.

Purpose of the Study:

• To compare the mechanical performance of the Acutrak compression screw against the AO 4-mm cancellous screw and the Herbert screw.
• To assess fragment compression, maintenance of compression under cyclic loading, pushout force, and torque to break fragment contact.

Main Methods:

• Mechanical testing of anatomic specimen cancellous bone and cancellous bonelike foam.
• Evaluation of three screw types: Acutrak, AO 4-mm cancellous, and Herbert screws.
• Application of cyclic loading and measurement of various biomechanical parameters.

Main Results:

• Acutrak and AO screws achieved similar fragment compression, superior to the Herbert screw.
• Acutrak demonstrated significantly better maintenance of compression after cyclic loading compared to AO and Herbert screws.
• Acutrak and AO screws exhibited greater pushout force than the Herbert screw.
• Acutrak required higher torque to break fragment contact than AO and Herbert screws.

Conclusions:

• The Acutrak screw effectively produces and maintains compression in bone fracture fixation.
• Acutrak screw exhibits superior mechanical characteristics compared to the Herbert screw across all tested modes.
• Acutrak screw offers comparable or superior performance to the AO screw in key mechanical aspects, without overtightening or significant compression loss.