Four-Strand Versus 2-Strand Suture-Button Constructs in First Carpometacarpal Arthroplasty: A Biomechanical Study.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Hand Surgery

Background:

• First carpometacarpal (CMC) arthritis treatment often involves trapeziectomy.
• Suture-button fixation is an alternative to other fixation methods like Kirschner wires.
• A 2-strand construct uses a smaller tunnel than a 4-strand construct, potentially reducing fracture risk.

Purpose of the Study:

• To compare the biomechanical stability and failure modes of 4-strand versus 2-strand suture-button constructs.
• To evaluate these constructs in a biomechanical model simulating first CMC joint arthroplasty.

Main Methods:

• Ten matched pairs of cadaveric hands were used.
• Hands were randomized to receive either a 4-strand or 2-strand suture-button device after trapeziectomy.
• Constructs underwent 1000 cycles of loading, followed by load-to-failure testing.

Main Results:

• No significant differences in joint height or load to failure were observed between the 4-strand and 2-strand groups.
• Failure mechanisms varied, with 4-strand constructs failing through the first ray and 2-strand constructs experiencing suture failure.
• Pinch pressure showed no significant difference between the groups.

Conclusions:

• Both 4-strand and 2-strand suture-button constructs demonstrate comparable biomechanical stability for first CMC arthroplasty.
• The 2-strand construct, utilizing a smaller tunnel, may offer an advantage due to potentially lower risk of metacarpal fracture.