Biomechanical and histologic characteristics of canine flexor tendon repair using early postoperative mobilization

The purpose of this experimental study was to evaluate the mechanical and histologic healing of flexor tendon repairs using an early active motion protocol. Three different flexor tendon repair techniques in zone II were used. Forty-seven lacerated canine flexor profundus tendons from 25 dogs were repaired and evaluated at 5, 10, and 21 days after surgery. Eight of 9 Kessler repairs ruptured at days 5 and 10. None of the 19 Savage repairs or the 19 dorsal tendon splint repairs ruptured; 3 of 19 dorsal tendon splint repairs failed owing to adhesions. Smooth tendon gliding was obtained in all specimens in which repair was successful. The gap strength values for both the Savage and dorsal tendon splint repairs improved significantly for day-21 specimens compared to day-5 or day-10 specimens. The ultimate tensile strength showed no reduction during the 3-week period of tendon healing for both repairs. Histologically, there was evidence of progressive healing without surrounding adhesions. The improved suture techniques have the potential to withstand the stress produced by active digital motion protocols.