Tenorrhaphy of the Common Calcaneal Tendon in Dogs and Cats

Abstract

Background: Common calcaneal tendon (CCT) is usually affected by injuries in dogs and less frequently in cats. The Achilles mechanism consists of the convergence of three distinct structures: the tendons of the gastrocnemius muscle, superficial digital flexor muscle and the common tendons of the biceps femoris, gracilis, and semitendinosus muscles. Classification of lesions is based upon their location, severity and chronicity. Clinical signs include lameness, plantigrade stance and various degrees of tarsal hyperflexion according to the injury’s severity. The purpose of this study is to report four cases of reconstruction of the common calcaneus in three dogs and a cat.

Cases: Case 1. A 10-year-old male canine, Brazilian Terrier, 7.7 kg of body weight, with a 6-month history of nonweightbearing lameness of the right hind limb attended consultation. Orthopedic examination showed plantigrade stance, hyperflexion of the right tibial-tarsal joint (TTJ) and swelling with fibrous thickening of the distal portion of the CCT. Surgical tendon repair was achieved through insertion of a locking screw on the calcaneo-tibial, tenorrhaphy and suture of a titanium plate on the caudal aspect of the CCT. Case 2. A 2-year-old female mongrel canine, with 13.3 kg of body weight was presented with the complaint of chronic left hind leg lameness. The owner described trauma at the area of the hock six months prior to consultation. On orthopedic exam, severe lameness was noted, swelling with fibrous thickening of the distal portion of the common calcaneal tendon and hyperflexion of the left TTJ (plantigrade position) were visible. Tendon repair was performed in the same manner as in case 1, except that in this case a bovine pericardium graft preserved in glycerin 98% was sutured over the tendon/plate conjunction. Case 3. A 6-year-old female mongrel canine, with 18.6 kg of body weight was attended with a 22-day history of right hind limb lameness. On physical exam intermittent lameness during gait performance and non-weight-bearing position in stance were noted. The distal portion of the limb was internally rotated with plantigrade stance and discontinuity of the CCT was palpable. Tenorrhaphy was performed similarly to case 2. Case 4. A 6 kg, 3-year-old, mixed breed male feline was admitted with a wound on the CCT region for 7 days. The wound was originated after animal interaction with a stray feline. On clinical examination the animal was non-weight bearing on the right hind limb, with plantigrade posture and with a 1 cm wound on the caudal portion of the CCT with tendon exposure. Surgical repair was performed by tenorrhaphy with placement of a surgical steel plate on the caudal aspect of the CCT. A bovine pericardium graft preserved in glycerin 98% was sutured on top of the plate. The TTJ was immobilized with a type II transarticular external fixator.

Discussion: Ultrasonography is the test of choice to monitor tendon healing after tenorrhaphy. At this report, this exam was crucial to determine when the calcaneal-tibial screw could be removed. Two dogs and the cat from this report received an association of plate and bovine pericardium preserved in glycerin 98%. The purpose of this association was to increase the strength of the tenorrhaphy, and the pericardium graft had also the function of reducing the formation of peritendinous adhesions. Immobilization of the TTJ has the purpose of opposing muscle forces to avoid stress at tenorrhaphy suture increasing the strength of the healed tendon allowing early weight bear while minimizing the recurrence risk and avoiding limb contracture. We chose to perform the procedure with hyperextension of the TTJ in order to promote greater relaxation of the tendon since there was need to remove large portions of calcaneal fibrous tissues of the dogs and devitalized tissue in the cat from this report. Surgical treatment of injuries of the Achilles mechanism has good prognosis in complete closed lesions treated by tenorrhaphy associated with suture of a plate, suture of bovine pericardial graft preserved in 98% glycerin, calcaneal-tibial locking screw and splint for six weeks.

Keywords: Achilles tendon, rupture, calcaneo-tibial screw, locking-loop suture pattern.