Biomechanical Comparison of Fixed- versus Variable-Angle Locking Screws for Distal Humerus Comminuted Fractures

Area of Science:

• Orthopedic surgery
• Biomechanics
• Trauma surgery

Background:

• Comminuted distal humerus fractures pose significant treatment challenges.
• Assessing the biomechanical stability of fixation constructs is crucial for optimal patient outcomes.

Purpose of the Study:

• To compare the biomechanical stability of fixed- versus variable-angle locking constructs in treating comminuted distal humerus fractures (AO/OTA 13-A3).

Main Methods:

• Eight human humeri were biomechanically tested using fixed- and variable-angle locking plates.
• Specimens underwent axial loading to failure to assess stiffness and displacement resistance.
• Failure modes and load at specific displacements were recorded.

Main Results:

• No significant difference in construct stiffness was observed between fixed- and variable-angle constructs.
• Similar forces were required for 2-mm and 4-mm displacement in both construct types.
• Failure predominantly occurred through plate bending, with some instances of screw pull-out.

Conclusions:

• Biomechanical stability is comparable between fixed- and variable-angle locking constructs for these fractures.
• Neither construct type showed screw breakage or plate-screw interface failure.
• These findings suggest equivalent stability for both fixation methods in this fracture pattern.