Biyomechanical comparison of suture techniques in flexor tendon repairs

OBJECTİVE: In cases of flexor tendon injuries, the success of surgical treatment is not only related to the characteristics of the repair technique used but also to the rehabilitation program applied after the repair. Early initiation of motion after tendon repair accelerates tendon healing and prevents adhesions. In this study, we aimed to compare three different suture techniques biomechanically and to identify the technique that would allow early active motion. MATHERİAL and METHODS: In our study, the flexor digitorum profundus (FDP) tendons from 9 sheep, totaling 18 forearms, were utilized. The forearms were obtained from the abattoir immediately after amputation at the elbow joint, and dissection was performed. Tendons approximately 15 cm in length were obtained. The tendons were marked 6 cm proximally from their distal attachment site and were subjected to a full- thickness cut. A 10 mm margin was marked both proximal and distal to the incision as the core suture exit zone. Tendons repaired using the Double Modified Kessler, Locking Cruciate, and 4-pass Savage core suture techniques were tested in three groups. A tensile test was conducted using a motorized testing machine, initiating at a speed of 20 mm/min. The test continued until the sutures failed or the tendons detached from the clamps. The maximum tensile strength, which created a 2 mm gap at the tenorrhaphy site and caused core suture failure, was evaluated. RESULTS: In our study, the maximum tensile strength was highest in the 4-strand Savage group among all the groups. Both the Locking Cruciate and 4-strand Savage groups showed significantly higher maximum tensile values compared to the Double Modified Kessler group (p<0.05). The maximum tensile strength for the Double Modified Kessler group was 6.53±1.46 N, for the Locking Cruciate group it was 11.97±2.81 N, and for the 4-strand Savage group it was 15.31±1.2 N. When comparing the forces that resulted in a 2 mm gap formation among the groups, there was no statistically significant difference between them (p > 0.05). CONCLUSION: The Double Modified Kessler group allows only passive flexion, while the Locking Cruciate group is designed to permit flexion against mild resistance, and the 4-strand Savage group is designed to allow flexion against moderate resistance. These results indicate that the values are below the strength required for strong gripping, preventing active flexion but demonstrating the ability to induce passive flexion in the tendon. KEY WORDS: Flexor tendon, biomechanics, suture technique, Double Modified Kessler, Locking Cruciate, 4-strand Savage.