Bearing area: a new indication for suture anchor pullout strength?

Area of Science:

• Biomechanics
• Orthopedic device engineering
• Surgical materials science

Background:

• Quantifying suture anchor pullout strength is crucial for surgical success.
• Existing studies lack clear definitions of parameters influencing monotonic pullout.
• Understanding these parameters is key to predicting device performance and failure modes.

Purpose of the Study:

• To establish a predictive model for suture anchor pullout strength using basic device parameters.
• To validate the relationship between bearing area and pullout strength in a soft-bone model.
• To assess the applicability of this model across various commercially available suture anchors.

Main Methods:

• Conical test samples of varying sizes were used to establish bearing area-pullout strength relationships in 5, 8, and 10 pcf sawbone models.
• These relationships were validated against nine commercial suture anchors (e.g., Mitek QuickAnchor, SpiraLok, Arthrex BioCorkscrew).
• The sawbone model's predictive capability was further confirmed using cadaveric humeral heads.

Main Results:

• A direct correlation was observed between the bearing area of suture anchors and their pullout strength.
• Increased insertion depth was identified as a secondary factor positively influencing pullout strength.
• The pullout strength of commercial anchors generally aligned with predictions based on their bearing areas.

Conclusions:

• Suture anchor bearing area is a reliable predictor of pullout strength in soft-bone models, independent of anchor design.
• This study provides a foundational understanding of the biomechanical principles governing suture anchor performance.
• The findings support the use of soft-bone models for predicting in vivo anchor behavior.