Does loading velocity affect failure strength after tendon repair?

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Tendon repair research

Background:

• Tensile testing is standard for evaluating tendon repair efficacy.
• Functional finger movements occur at higher rates than typical laboratory testing speeds.

Purpose of the Study:

• To investigate the influence of varying loading rates on the failure strength of repaired canine flexor tendons.
• To determine if faster loading rates enhance the measured strength of tendon repairs.

Main Methods:

• Thirty-six canine flexor digitorum profundus tendons were surgically repaired.
• Repaired tendons underwent tensile testing at three distinct displacement rates: 0.33 mm/s, 84 mm/s, and 590 mm/s.
• Peak force and stiffness were measured to evaluate repair integrity.

Main Results:

• Peak force was significantly higher (p<0.05) in tendons tested at 590 mm/s compared to 0.33 mm/s.
• Crosshead stiffness showed significant increases at 590 mm/s versus both 84 mm/s and 0.33 mm/s.
• The primary failure mechanism observed was the untying of core suture knots.

Conclusions:

• Testing repaired tendons at slower rates yields a conservative estimate of their true strength.
• Loading rate is a critical factor influencing the biomechanical properties of repaired tendons.
• Understanding these effects aids in predicting clinical outcomes and optimizing repair strategies.