Are Variable-Angle Locking Screws Stable Enough to Prevent Calcaneal Articular Surface Collapse? A Biomechanical...

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Trauma research

Background:

• Calcaneal fractures often involve the subtalar joint, requiring precise reduction and stable fixation.
• Fixed-angle locking plates offer predictable screw trajectories, while variable-angle plates allow for greater intraoperative flexibility.
• Understanding the biomechanical performance of different fixation options is crucial for optimizing surgical outcomes.

Purpose of the Study:

• To compare the biomechanical stability of fixed-angle versus variable-angle locking screws in calcaneal fracture fixation.
• To evaluate the resistance to articular surface displacement under cyclic loading for both screw types.

Main Methods:

• A sawbones biomechanical model simulating intra-articular calcaneal fractures was used.
• Three groups underwent reduction and fixation with either a fixed-angle locking plate or two different variable-angle locking plates.
• Cyclic loading (200 N, 600 N, 1000 N) was applied to assess subtalar articular surface displacement, stiffness, maximum displacement, and change in the angle of Gissane.

Main Results:

• No statistically significant differences were found in articular surface displacement between fixed-angle and variable-angle locking plates.
• Stiffness and maximum displacement measurements also showed no significant disparity between the groups.
• The change in the angle of Gissane indicated only minor displacement of the articular surface.

Conclusions:

• Variable-angle locking plates demonstrated comparable resistance to articular surface displacement as fixed-angle locking screws in this biomechanical model.
• The findings suggest that both fixed- and variable-angle locking screw systems provide similar stability for calcaneal fracture fixation.