Background: Clinical and experimental studies have demonstrated that
restrictive adhesions and poor digital motion are common complications after
extrasynovial tendon grafting in an intrasynovial environment. The purpose of
this study was to test the hypothesis that surface modification of an
extrasynovial tendon with use of a carbodiimide-derivatized hyaluronic
acid-gelatin polymer (cd-HA) improves gliding ability and digital function
after tendon grafting in a canine model in vivo.
Methods: The peroneus longus tendons from both hindpaws of
twenty-four dogs were harvested and transplanted to replace the flexor
digitorum profundus tendons in the second and fifth digits of one forepaw.
Prior to grafting, one of the peroneus longus tendons was coated with cd-HA,
which consists of 1% hyaluronic acid, 10% gelatin, 0.25%
1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), and 0.25%
N-hydroxysuccinimide (NHS), while the other was immersed in saline solution
only. Eight dogs were killed at one, three, and six weeks. Digital normalized
work of flexion, tendon gliding resistance, and hyaluronic acid quantification
(with the hyaluronic acid-binding-protein staining technique) were the outcome
Results: The normalized work of flexion of the tendons treated with
cd-HA was significantly lower than that of the saline-solution-treated
controls at each time-point (p < 0.05). The gliding resistance of the cd-HA
group was significantly lower than that of the saline-solution group at three
and six weeks (p < 0.05). The ratio between the intensity of staining of
the cd-HA-treated tendons with that of the saline-solution-treated controls
was significantly greater at time-0 than at three or six weeks (p < 0.05),
but there was no significant difference between time-0 and one-week
Conclusions: Treating the surface of an extrasynovial tendon
autograft with a carbodiimide-derivatized hyaluronic acid-gelatin polymer
decreases digital work of flexion and tendon gliding resistance in this flexor
tendon graft model in vivo.
Clinical Relevance: cd-HA gelatin may provide surgeons with a new
and useful method to improve the quality of tendon graft surgery.