No midterm advantages in the middle term using small intestinal submucosa and human amniotic membrane in Achilles tendon transverse tenotomy

Abstract

Background: The study was aimed to compare the effects of small intestinal submucosa (SIS) and human amniotic membrane (HAM) on Achilles tendon healing.

Methods: A total of 48 New Zealand white rabbits were divided into two groups. A full-thickness transverse tenotomy was made at the right leg of the rabbits. Then, the laceration site was wrapped with HAM (P/A group) or SIS (P/S group). The ultimate stress (US) and Young's modulus (E) of the tendons were detected for biomechanical analysis. Histological evaluation was performed using hematoxylin and eosin, immunohistochemical, and immunofluorescent stain. Expression of collagen I was detected by western blot analysis, and levels of inflammatory cytokines IL-1β, IL-6, and TNF-α were measured. Finally, adhesion formation was evaluated.

Results: There were no significant differences in filamentous adhesion, cross-sectional areas of the laceration sites, levels of inflammatory response, and collagen type I expression between the P/A and P/S groups (p > 0.05). Compared with the P/A group, the US and E values were significantly higher in the P/S group at day 7 (p < 0.05) and at day 14 (p < 0.05). In addition, vascularity was significantly higher in the P/S group than that in the P/A group at day 3 (p < 0.05), day 7 (p < 0.01), and day 9 (p < 0.05).

Conclusions: SIS showed superior biomechanical properties and neovascularization over HAM in treatment of Achilles tendon injury in the early stage of healing.

Keywords: Achilles tendon injury; Human amniotic membrane; Small intestinal submucosa.

Fig. 1

Macroscopic findings of tendon repair from the frontal (a) and lateral (b) view of human amniotic membrane (HAM) and small intestinal submucosa (SIS) at different groups

Fig. 2

Post-surgical adhesion score at 28 and 56 days

Fig. 3

The ultimate stress and Young’s modulus of the tendons in the P/A and P/S groups at days 7, 14, 28, and 56. *p < 0.05

Fig. 4

The changes of IL-1β, IL-6, and TNF-α level in the P/A and P/S groups at days 7, 14, 28, and 56 after operation

Fig. 5

Histological sections with hematoxylin and eosin staining (a) and immunohistochemical staining (b) for collagen type I at 7, 14, 28, and 56 days. Scale bar, 100 μm. c The immunofluorescent stain of CD31 at postoperative 3, 7, and 9 days in two groups. *p < 0.05, **p < 0.01

Fig. 6

Western blotting assay for expression of collagen I at 7, 14, 28, and 56 days in the P/A and P/S groups