Platelet-rich plasma for zone II flexor tendon repair

Platelet-rich plasma (PRP) has shown promise in the treatment of tendinopathy, including rotator cuff and lateral epicondylitis. Here, we evaluate the effect of PRP on healing in a rabbit zone II flexor tendon model.

Thirty New Zealand white rabbits underwent transection and repair of the second and fourth flexor digitorum profundus. Half of the rabbits received autologous PRP intraoperatively, while the other half underwent standard four-strand tendon repair. Tendons were examined at 2, 4, and 8 weeks postoperatively. Range of motion and ultimate tensile strength were assessed on the fourth toes, while second toes underwent histologic analysis with hematoxylin and eosin, Masson Trichrome, and Picrosirius Red, for assessment of cell count, collagen content, and collagen maturity.

There were no significant differences in ultimate tensile strength between treatments at 2, 4, or 8 weeks. There was a trend towards lower tensile strength in the PRP group at 2 weeks. There was no statistically significant difference in excursion or range of motion between PRP and control tendons. Cell counts at 4 weeks were statistically significantly reduced in the PRP tendons as compared to controls. No difference in collagen content or maturity was detected.

In contrast to previous studies, PRP did not significantly improve ultimate tensile strength. PRP-treated tendons exhibited trends towards reduced healing, including a significant reduction in cell counts as well as a smaller increase in collagen deposition over time as compared to controls. Further study is needed to determine the precise effect of PRP on intrasynovial flexor tendon repairs.