Reconstruction of the tendon-bone insertion with decellularized tendon-bone composite grafts: comparison with conventional repair.
OBJECTIVE
Injuries involving the tendon-bone interface (TBI) are difficult to address. Standard techniques typically lead to diminished strength of the healed insertion site. We hypothesized that these injuries would benefit from being reconstructed with decellularized composite grafts replacing both tendon and bone. To test this hypothesis, decellularized grafts were compared with conventional pullout repairs in an in vivo animal model.


METHODS
We harvested 48 Achilles TBI grafts from rats and decellularized them. Tendon-bone interface graft reconstruction and pullout repairs were compared using a pair-matched design. Biomechanical properties were evaluated at 2, 4, 8, and 12 weeks. We evaluated histological analysis of insertion morphology and collagen type I/III content.


RESULTS
There was a significant increase in ultimate failure load (35 ± 11 vs 24 ± 7 N) and ultimate tensile stress (1.5 ± 0.3 vs 1.0 ± 0.4 N/mm(2)) of the TBI grafts compared with pullout repairs at 2 weeks. These differences remained at 4 weeks. At 12 weeks, both TBI grafts and pullout repairs were as strong as native tissue and not significantly different from each other. Histology showed a more organized extracellular matrix in the TBI graft group at the early time points. Repopulation of the decellularized grafts increased over time. At 12 weeks, the insertion points of both groups were richly populated with cells that possessed morphologies similar to those found in native TBI.


CONCLUSIONS
This study showed that decellularized TBI grafts were stronger compared with conventional pullout repairs at 2 and 4 weeks but were comparable at 12 weeks. A more organized extracellular matrix and different collagen composition in the early time points may explain the observed differences in strength.


CONCLUSIONS
In the future, decellularized TBI grafts may be used to reconstruct tendon-bone insertion tears in multiple areas including the flexor tendon system.
Division of Plastic Surgery, VA Palo Alto Health Care System; and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, CA. Electronic address: simon.farnebo@lio.se.
Simon
S
Farnebo
Division of Plastic Surgery, VA Palo Alto Health Care System; and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, CA.
Colin Y
CY
Woon
Division of Plastic Surgery, VA Palo Alto Health Care System; and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, CA.
Maxwell
M
Kim
Division of Plastic Surgery, VA Palo Alto Health Care System; and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, CA.
Hung
H
Pham
Division of Plastic Surgery, VA Palo Alto Health Care System; and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, CA.
James
J
Chang
D000818:Animals; D001696:Biomechanical Phenomena; D016025:Bone Transplantation / Q000379:methods*; D064595:Composite Tissue Allografts / Q000473:pathology / Q000503:physiopathology; D004195:Disease Models, Animal; D006230:Hand Injuries / Q000601:surgery*; D006801:Humans; D051379:Mice; D011475:Prosthesis Failure; D051381:Rats; D017208:Rats, Wistar; D013710:Tendons / Q000473:pathology / Q000503:physiopathology / Q000637:transplantation*; D053656:Tenodesis / Q000379:methods*; D020858:Tissue and Organ Harvesting
Flexor tendon; reconstructive hand surgery; tendon–bone interface; tissue engineering