Systemic corticosteroids improve tendon healing when given after the early inflammatory phase.

Area of Science:

• Orthopedics
• Regenerative Medicine
• Biomaterials Science

Background:

• Tendon healing involves inflammation, which typically resolves.
• Persistent inflammation may impair the tendon remodeling process.
• Early intervention with anti-inflammatories could potentially enhance healing outcomes.

Purpose of the Study:

• To investigate the effect of dexamethasone, a corticosteroid, on Achilles tendon healing in rats.
• To determine if dexamethasone administration during the early inflammatory or remodeling phase impacts healing.
• To evaluate mechanical, histological, and cellular changes post-treatment.

Main Methods:

• Achilles tendon transection was performed on 89 rats.
• Rats received systemic dexamethasone or saline during either the early inflammatory phase (days 0-4) or early remodeling phase (days 5-9).
• Evaluations included mechanical testing, histology, and flow cytometry at specific time points.

Main Results:

• Early dexamethasone treatment (days 0-4) impaired healing, reducing cross-sectional area, peak force, and stiffness.
• Late dexamethasone treatment (days 5-9) significantly improved mechanical properties, including peak force, stiffness, peak stress, and elastic modulus.
• Histology showed improved collagen alignment, and flow cytometry indicated reduced cytotoxic T cells with late treatment.

Conclusions:

• Dexamethasone administration during the early inflammatory phase is detrimental to tendon healing.
• Suppression of inflammation during the early remodeling phase with dexamethasone enhances tendon healing and mechanical properties.
• Targeting lingering inflammation in the remodeling phase offers a promising therapeutic strategy for improving tendon repair.