The Early Effects of Sustained Platelet-Derived Growth Factor Administration on the Functional and Structural Properties of Repaired Intrasynovial Flexor Tendons: An In Vivo Biomechanic Study at 3 Weeks in Canines

PurposeA bioactive fibrin-based delivery system was used to provide sustained administration of platelet-derived growth factor (PDGF-BB) in a clinically relevant model of intrasynovial flexor tendon repair. We hypothesized that PDGF-BB administered in this manner would improve the sutured tendon’s functional and structural properties 3 weeks after repair.MethodsA delivery system consisting of 30 μL of fibrin matrix, peptide, heparin, and 100 ng of PDGF-BB was incorporated into the repair sites of randomly selected medial or lateral forepaw flexor digitorum profundus tendons of 8 adult mongrel dogs. The remaining forepaw flexor digitorum profundus tendons were repaired without the growth-factor and fibrin-based delivery system and served as controls. The surgically treated forelimbs were treated with controlled passive motion rehabilitation. The animals were killed at 3 weeks, at which time the tendons were tested for range of motion with a motion analysis system and for tensile properties with a materials testing machine.ResultsProximal interphalangeal joint and distal interphalangeal joint rotation values were significantly higher for the PDGF-BB–treated tendons compared with the repair-alone tendons. Excursion values were also significantly higher in the PDGF-BB–treated tendons. There were no significant differences in tensile properties when comparing PDGF-BB–treated with repair-alone tendons.ConclusionsThe functional properties of repaired intrasynovial flexor tendons were significantly improved with the sustained administration of PDGF-BB. The failure to achieve improvements in ultimate load, stiffness, and strain in the experimental group may have been due to suboptimal PDGF-BB dosage or suboptimal release kinetics.