Augmentation of zone II flexor tendon repair using growth differentiation factor 5 in a rabbit model.
OBJECTIVE
Modulation of zone II flexor tendon repair healing using growth factors may reduce the incidence of complications, such as rupture and fibrosis. We hypothesized that sutures coated with growth differentiation factor 5 (GDF5) will stimulate the healing of zone II flexor tendon repairs.


METHODS
We created and immediately repaired zone II flexor tendon lacerations in the second and fourth toe of the right forepaw of 44 New Zealand White rabbits. One tendon was repaired with suture coated with GDF5, whereas the other tendon was repaired with suture without GDF5 (control). We randomized the allocation of GDF5 and control suture to either toe. A proximal tenotomy of the flexor digitorum profundus at the level of the wrist was performed to relieve tension on the more distal repairs. Rabbits were euthanized at 21 or 42 days after repair. Four rabbits (8 tendons) underwent histological analysis at each time point; the remaining repairs were tested biomechanically in a blinded fashion.


RESULTS
Control tendons demonstrated distinct borders at the transection site and less endogenous repair at 3 weeks. The Soslowsky histological score for collagen was better in the GDF5 group at both time points (p≤.003). All tendons failed at the repair site. The maximum load was significantly greater (p=.04) in the GDF5 group (11.6 ± 3.5 N) compared with control tendons (8.6 ± 3.0 N) at 3 weeks. The maximum load was not significantly different (p=.12) at 6 weeks. We observed no significant differences in stiffness at either time point (p>.11).


CONCLUSIONS
The results demonstrate that GDF5 has an early beneficial effect on tendon healing in zone II flexor tendon repairs in a rabbit flexor tendon injury model.
Hand and Upper Extremity Center, Hospital for Special Surgery, New York, NY 10021, USA.
R Frank
RF
Henn
Christina E
CE
Kuo
Michael W
MW
Kessler
Pasquale
P
Razzano
Daniel P
DP
Grande
Scott W
SW
Wolfe
D000818:Animals; D001696:Biomechanical Phenomena; D001707:Biopsy, Needle; D020099:Coated Materials, Biocompatible; D004195:Disease Models, Animal; D005260:Female; D055428:Growth Differentiation Factor 5 / Q000494:pharmacology*; D007150:Immunohistochemistry; D008297:Male; D011817:Rabbits; D011897:Random Allocation; D012016:Reference Values; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical; D013537:Sutures; D013708:Tendon Injuries / Q000473:pathology* / Q000601:surgery*; D058971:Tenotomy / Q000379:methods; D013718:Tensile Strength
D020099:Coated Materials, Biocompatible; D055428:Growth Differentiation Factor 5