1. Title of abstract

Calcaneal-tibial suture for temporal augmentation of Achilles tendon repair initial experience.

A. Short Abstract

The aim of this study was to develop a minimal invasive and simple technique to augment the Achilles tendon repair and to evaluate the feasibility for the management of these cases.
Four cats (mean age of 14.5years) with a gastrocnemius tendon avulsion from the tuber calcanei and two heavy dogs (body weight 39 and 49kg) have been treated. After adaptation of the Achilles tendon with a modified Kessler suture (polydioxanone size 2 metric gauge in cats and size 3.5 in dogs) the repair was augmented with a calcaneo-tibial suture to limit the maximum flexion angle of the tarsal joint. In two cats no primary repair of the Achilles tendon was attempted. Braided polyester suture (three cats) and monofilament nylon with a crimp (four cases) through 1.5mm (cats) or 2.0mm (dogs) bone tunnels through the tuber calcanei and tibia were used. In cats no additional support was applied. In the dogs a Soft Cast has been maintained for eight weeks.
An excellent clinical result has been achieved in these seven cases. During the follow up time of 1 Ð 24 months (mean 9.7 months) all patients have had good clinical function. No recurrence has been recorded.

B. Long Abstract

Introduction
Several techniques for the repair of Achilles tendon ruptures in dogs and cats have been described, including primary repair with non-absorbable suture material and protection by a splint, cast, Schroeder-Thomas splint or transarticular external fixator. Internal temporal fixation techniques for the tibio-tarsal joint have included a positional bone screw or orthopedic wire, placed between the calcaneus and tibia. Complications have been documented with each technique.
The aim of this study was to develop a minimal invasive and simple technique for augmentation of primary Achilles tendon repair or in selected cases as a sole method of repair and to evaluate the feasibility for the management of these injuries.

Materials and methods
Four cats and two large breed dogs with Achilles tendon rupture have been treated.

#	signalment	calcaneo-tibial suture	diagnosis	follow up
1	15y,fs,ESH	polyester 5, modified toggle pin	right gastrocnemius tendon avulsion from calcaneus, pull out of 2.0mm calcaneo-tibial screw	14 months
2	13y,f,ESH,4.9kg	polyester 5, modified toggle pin	left gastrocnemius tendon avulsion from calcaneus	24 months
3	14y,fs,ESH,3.5kg	polyester 5, modified toggle pin	left gastrocnemius tendon avulsion from calcaneus	17 months
4	16y,fs,ESH,3.6kg	27kg nylon leader line, Securos crimp	left gastrocnemius tendon avulsion from calcaneus	1 month
5	16y,fs,ESH,3.6kg	23kg nylon leader line, Securos crimp	right gastrocnemius tendon avulsion from calcaneus	1 month
6	5y,m,Bobtail,39kg	60kg nylon leader line, Securos crimp	right rupture of gastrocnemius tendon at muscle-tendon junction	6 months
7	6y,m,Irish Wolshound,49kg	60kg nylon leader line, Securos crimp	left complete cut of CCT 3cm prox.of calocaneal tuber	5 months

: typical plantigrade stance, case #6

In all cats an avulsion of the gastrocnemius tendon from the tuber calcanei was diagnosed. In one cat the avulsion occurred bilaterally (case #4 and #5). The mean age of the cats was 14.5 years, suggesting age related changes. In case #6 the rupture occurred at the musculotendinous junction of the gastrocnemius muscle and in case #7 all parts of the common calcaneal tendon were severed 3cm proximal to the tuber calcanei due to direct trauma by a sharp object.

In the surgery the tendon ends were debrided and adapted by a modified Kessler suture with polydioxanone (PDS, Ethicon) of size 2 (metric gauge) in two cats (case #3, #4 and #5) and size 3.5 in the dogs. In case of an avulsion from the tuber calcanei these sutures were transfixed through 1.1mm calcaneal drill holes. The paradentinous tissue was adapted using fine Polydioxanone suture of size 1 or 1.5 in a continuous pattern. In case #1 and #2 no primary repair was attempted, the calcaneo-tibial suture was the sole method of repair. In case #1, #2 and #3 braided polyester (Mersilene, Ethicon) of size 5 through 1.5mm drill holes of the calcaneus and tibia and a shortened toggle pin were used. In case #4, #5, #6 and #7 monofilament nylon (hard type nylon leader material, Mason) through a 1.5mm drill hole (cats) or 2mm drill holes (dogs) was used. A long needle with an outer diameter of slightly less than 1.5mm respectively 2mm was used to guide the nylon suture. The ends of the suture were joined medially, tensioned to bring the hock to an extended position of at least 140¡ and fixed to each other with a crimp (Securos company).

In cats a Robert Jones bandage was applied for a few days. In the dogs a short Soft Cast has been maintained for 8 weeks. Activity was restricted to indoors in cats and leash walk in dogs.

Results/Discussion

The mean age of 14.5 years of the cats suggests age related changes for the avulsion of the gastrocnemius tendon from the tuber calcanei.
In cats no additional protection by a splint, cast or transarticular external fixator during the healing period was needed, simplifying postoperative management and reducing morbidity. Early controlled movement has been advocated to accelerate parallel alignment and polymerisation of collagen fibrils, thereby augmenting the tensile strength in healing tendons. Many authors suggest three to six weeks of immediate post-operative tarsocrural immobilisation, followed by four to six weeks of restricted exercise, in order to protect the tendon during the initial stages of healing. In the two heavy dogs a Soft Cast was used for additional external support.
The desired limited range of motion of the hock joint in flexion has been achieved for the healing period. At 14 (case #1), 24 (case #2) and 17months (case #3) following surgery normal flexion angles of the hock joint were observed, assuming implant breaking some time down the road occurred in these cases. No implant removal was necessary in these cases. In case #6 the maximum flexion angle of the operated right tarsal joint with the stifle in flexion was 90¡, compared to 45¡ at the left side six months postoperatively. In case #7 the maximal flexion angle of the operated hock joint was 140¡ compared to 45¡ at the other limb at the follow up five months postoperatively. In case #6 a periosteal reaction around the crimp and in case #7 at the caudal aspect of the tibia were observed on radiographs. In both cases suture removal was scheduled.
Because of easier handling, greater elasticity and the fixation with a crimp rather than a knot monofilament nylon has been the preferred material in case #4, #5, #6 and #7. An excellent clinical result has been achieved in these seven cases. During the follow up time of 1 Ð 24 months (mean 9.7 months) all patients have had good clinical function. No recurrence was recorded, assuming that the tendons healed.

Outlook

A closed or limited open technique without primary tendon repair should be considered for selected cases. Investigations for the recommendation of appropriate size of suture material, ideal position of the tibial drill hole and for the need of additional support in heavy dogs are yet to be made. After tendon healing removal of the suture through a small skin incision could be scheduled.