Histopathological and biomechanical parameters of repaired rat achilles tendons treated with and without...

Flexor tendon repairs are plagued by the formation of peripheral adhesions that limit motion. No current adjunct therapy is available to prevent this complication. Mannose-6-phosphate (M6P) is a natural sugar that has been shown to interact with the M6P/IGF-II receptor on fibroblasts. It is hypothesized that the addition of M6P to healing tendons would downregulate the production of unorganized scar collagen, allowing the tenocytes to guide tendon repair. Thirty-two (32) Sprague-Dawley rats underwent right Achilles tendon transection and suture repair. M6P was directly applied to the tendons of half of the rats prior to skin closure. Half of the animals in each treatment group were sacrificed after two weeks of healing, and the rest after four weeks. There were no post-operative complications (rupture, seroma, hematoma, infection). Histopathologic analysis was performed with H&E and elastin stains. Biomechanical analysis was performed to determine stress, strain, and elastic modulus. M6P was found to increase elastin production, decrease callus cross-sectional area, increase strain, and increase peak stress at failure. These changes were most evident at the two-week time point. The findings from this study support the continued investigation of M6P as an adjunct therapy to flexor tendon repair.