Mechanical Evaluation of Four Internal Fixation Constructs for Scaphoid Fractures

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Hand surgery

Background:

• Oblique scaphoid fractures are common injuries.
• Optimal fixation methods require mechanical evaluation.

Purpose of the Study:

• To compare the mechanical performance of four distinct fixation constructs for oblique scaphoid fractures.
• Evaluate stiffness, load-to-failure, and displacement of each construct.

Main Methods:

• Twenty-eight synthetic scaphoids underwent osteotomy and fixation with one of four methods: two 1.5-mm screws, one 2.2-mm screw, one 3-mm screw, or a 1.5-mm volar plate.
• Scaphoids were subjected to mechanical loading until failure to measure construct performance.

Main Results:

• No significant differences in stiffness were observed among the four fixation methods.
• Constructs using 2.2-mm and 3-mm screws exhibited significantly higher loads-to-failure compared to two 1.5-mm screws.
• The volar plate construct approached, but did not reach, statistical significance in load-to-failure compared to 1.5-mm screws.

Conclusions:

• All tested fixation constructs demonstrated comparable mechanical properties suitable for clinical use.
• For unstable scaphoid fractures, 2.2-mm or 3-mm screws may offer superior fixation due to higher load-to-failure.
• Volar plates did not show superior mechanical characteristics compared to compression screws in this study.