Cyclic testing of flexor tendon repairs: an in vitro biomechanical study

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Hand Surgery

Background:

• Flexor digitorum profundus tendon injuries require robust surgical repair.
• Early active motion is crucial for optimal hand function recovery.
• Comparing the biomechanical stability of different flexor tendon repair techniques is essential.

Purpose of the Study:

• To evaluate and compare the biomechanical performance of four flexor tendon repair techniques under cyclic loading.
• To determine which repair method best withstands simulated early active motion.

Main Methods:

• Forty cadaveric flexor digitorum profundus tendons were repaired using Tajima, Halsted, Silfverskiold, or Savage techniques.
• Repaired tendons underwent cyclic loading tests, starting at 25 N and increasing by 10-N increments until failure.
• Gap formation at the repair site was continuously monitored using an extensiometer.

Main Results:

• Only the Savage repair technique consistently withstood 4,000 cycles at 25 N without exceeding a 2-mm gap or rupturing.
• Cyclic loading revealed that tendon repairs failed at lower loads compared to static testing.
• The Savage technique demonstrated superior resistance to gap formation and rupture under simulated motion.

Conclusions:

• The Savage technique is the most effective method for flexor digitorum profundus tendon repair among those tested.
• Savage repair offers superior biomechanical stability, potentially allowing for earlier and safer initiation of active motion.
• Current flexor tendon repair methods may not be adequately robust for early active mobilization based on cyclic loading performance.