Repair of Tendon Disruption Using a Novel Synthetic Fiber Implant in Dogs and Cats: The Surgical Procedure and Three Case Reports

Abstract

Surgical management of tendon rupture is challenging. One concern is to provide adequate tensile strength to prevent distraction during weight-bearing and gap formation following repair, associated with an increased risk of repair failure. Additional challenges may arise from the nature or the chronicity of the lesion. In the event of avulsion, when the tendon is torn off at the bone insertion, its reinsertion on the bone is generally difficult and may even be impossible in the presence of an avulsion fracture, especially when the bone fragment is too small or fragmented. Repair management is also complicated in chronic cases, as degeneration of the tendon may lead to excessive scar tissue formation, tendon retraction, and muscle atrophy, resulting in a large gap and inadequate tissue for reconstruction. The authors describe the surgical procedure for implanting a novel implant, illustrated by three characteristic clinical cases: (1) an acute Achilles tendon avulsion; (2) a chronic patellar tendon rupture; and (3) a chronic avulsion fracture of the triceps tendon. In these three cases, complete recovery of the function was observed at the last clinical evaluation (6 or 8 months), and no complication was noted. A splinted dressing (6 to 8 weeks) was used successfully in two cases. A resin cast (8 weeks) was preferred in case 1, a very active dog. In conclusion, this novel implant represents a simple procedure for the effective repair of chronic tendon rupture, as well as an effective tendon reinsertion on the bone and adequate support for bone tendon healing in the treatment of tendon avulsion, even in cases of fragmented bone fracture. The thinness of the implant facilitates its insertion into the native tendon, while the bone-screw-implant interface provides immediate and lasting mechanical support. This may facilitate the healing process and potentially shorten the period of immobilization.

Figure 1

Implant (Novaten®, Novetech Surgery, Monaco). The implant has two components: (a) the implanted section designed to be sutured at its proximal part to the musculotendinous junction and secured at its distal end into the bone using an interference screw; (b) a puller wire allowing the insertion of the implant in bone tunnels.

Figure 2

Complete rupture of Achilles tendon in a canine patient with plantigrade stance.

Figure 3

Preoperative ultrasound of a canine patient with acute Achilles tendon avulsion. The black line shows bone tearing at enthesis. Distance between two white crosses shows an abnormally wide thickness of the tendon at the level of rupture.

Figure 4

Immediate postoperative lateral (a) and frontal (b) conventional radiography of a canine patient after repair of an acute Achilles tendon avulsion. The interference screw is perfectly positioned. The profile view (a) shows the axis of the bone tunnel outlet at the proximal level of the calcaneus and screw located at the midheight of calcaneus, proximally and caudally to the talocrural joint. The frontal view (b) shows a bicortical characteristic of the interference screw at the level of implantation in calcaneus.

Figure 5

Eight-week postoperative conventional lateral radiography of a feline patient after repair of a patellar tendon rupture, showing the axis of the bone tunnel outlet at the caudal level of tibia and the level of implantation of the interference screw in the tibial crest through metaphysis (almost closed). Note the satisfactory implant position, without enlargement of the bone tunnel at the entry point of the interference screw. Radiolucency at the tip of the screw revealed slight distal displacement, considered as not significant.

Figure 6

Eight-week postoperative lateral conventional radiography of a canine patient after repair of the chronic avulsion fracture of the triceps tendon, showing the position of the interference screw. The image confirms comminuted avulsion fracture of the olecranon.

Figure 7

Ten-week postoperative ultrasound of a canine patient after repair of the chronic avulsion fracture of the triceps. The black line shows tendon and implant thickness, revealing good tendon healing and the absence of edema.