Does methylene blue reduce adhesion during the healing process after tendon repair?

Abstract

Objectives: This study aims to biomechanically and histopathologically investigate the effects of methylene blue (MB) on preventing postoperative adhesion in chickens undergoing full- thickness flexor tendon incision.

Materials and methods: This study was performed between June 2017 and June 2018 on Hubbard JA 57 type chickens (age, 6 months; weight, 2.2±0.3 kg). Sixty-four tendons were studied in 32 chickens, including 16 in the control group and 16 in the experimental group. The second and third finger flexor digitorum profundus tendons of the left foot of each chicken were repaired primarily after a full-thickness incision approximately 1 cm proximal to the distal adhesion area. In the control (n=32) and experimental groups (n=32), 0.25 mL of normal saline and 0.25 mL of 1% MB solutions were applied locally to the surgical site, respectively. The operated limb was immobilized using a circular cast. 16 chickens were randomly selected in each group and examined at the fourth week, and the remaining 16 chickens were examined at the sixth week. Thirty-two of these tendons were evaluated using the Tang histopathological adhesion classification system, and the other 32 were evaluated with a biomechanical pull system.

Results: Adhesion was found to be less in the experimental group compared to the control group at the end of the fourth and sixth weeks both histopathologically and biomechanically. Furthermore, adhesion was significantly less in the experimental group at the end of the sixth week compared to the fourth week both histopathologically and biomechanically.

Conclusion: Histopathological and biomechanical results show that MB, which has anti-inflammatory, antiseptic, antimicrobial and antioxidant effects, reduces adhesion during the healing process after tendon repair. We think that local MB application, particularly in surgeries performed after this type of injury, will be beneficial on early rehabilitation and functional results.

Figure 1. (a) Housing conditions of experimental animals. (b) Image after transverse incision of tendon. (c) Modified Kessler method. (d) Repair with modified Kessler method.

Figure 2. (a) Methylene blue injection after tendon repair. (b) Primary skin suturing after tendon repair. (c) Circular cast front view. (d) Circular cast lateral view.

Figure 3. (a) Mechanical test device and tendon pull apparatus (Universal Mechanical Test device, Zemic Load Cell). (b) Tendon sample placed in mechanical test device. (c) Sample image showing movement-force screen of device. (d) Tendon placed in tendon pulling apparatus we designed.

Figure 4. (a) Control group, (H-E x40): Peritendinous space is obliterated, with marked adhesion, there is inflammation and suture material (arrow adhesion area, arrow head suture material and inflammation around it). (b) Experimental group, (H-E x40): Although adhesion is observed, peritendinous space has begun to become apparent (arrows peritendinous space). (c) Control group (H-E x100): Moderate adhesion, inflammation around suture material (arrows peritendinous space, arrow head inflammation). (d) Experimental group, (H-E x40): Peritendinous space is preserved in most areas, suture material is present with minimal adhesion (thin arrows minimal adhesion, thick arrows preserved peritendinous space, arrowhead inflammation around suture material).