The healing effects of thymoquinone on experimentally induced traumatic tendinopathy in rabbits

Objectives: Thymoquinone is a major bioactive compound present in the black seeds of the Nigella sativa. Tendon injuries are almost 50% of all musculoskeletal injuries. The recovery of tendon after surgery has become a significant challenge in orthopedics.

Design: The purpose of this study was to investigate the healing effect of thymoquinone injections in 40 New Zealand rabbits tendon traumatic models.

Materials and methods: Tendinopathy was induced by trauma using surgical forceps on the Achilles tendon. Animals were randomly divided into 4 groups: (1) normal saline injection (control), (2) DMSO injection, (3) thymoquinone 5% w/w injection, and (4) thymoquinone 10% w/w injection. Forty-two days after surgery, biochemical and histopathological evaluations were done, and biomechanical evaluation was conducted 70 days after surgery.

Results: Breakpoint and yield points in treatment groups were significantly higher compared to control and DMSO groups. Hydroxyproline content in the 10% thymoquinone receiving group was higher than all groups. Edema and hemorrhage in the histopathological evaluation were significantly lower in the thymoquinone 10% and thymoquinone 5% receiving groups compared to control and DMSO groups. Collagen fibers, collagen fibers with fibrocytes, and collagen fibers with fibroblasts were significantly higher in the thymoquinone 10% and thymoquinone 5% receiving groups compared to control groups.

Conclusions: Thymoquinone injection in the tendon in the concentration of 10% w/w is a simple and low-cost healing agent that could enhance mechanical and collagen synthesis in traumatic tendinopathy models in rabbit.