(1a) Proximal attachment is done at the origin of the lateral collateral ligament on the lateral femoral condyle. This site is located at the caudal extent of the condyle and at the same level as the distal pole of the lateral fabella of the gastrocnemius muscle. Attachment around the lateral gastrocnemius fabella is also acceptable.
(1b) Distal attachment occurs at the proximal tibia, just caudal or cranial to the long digital extensor tendon.
(2a & b) The prosthetic ligament can be anchored in traditional fashion around the lateral gastrocnemius fabella (arrow), which is adjacent to the isometric location identified in the lateral femoral condyle. To attach the prosthetic ligament directly to the lateral femoral condyle, use a suture anchor, bone tunnel, or screw and washer. This article describes use of a suture anchor for proximal attachment of the ligament. Many types of suture anchors can be used.
(3a) The Bone Biter suture anchor (Innovative Animal Products, Rochester, MN) has been used for stabilization of cruciate-deficient stifles in dogs.1
The no. 5 anchor is generally used for this application, but toy breeds may require a no. 2 anchor.
(4a-c) Load the no. 5 anchor with the suture material of choice and insert it into a predrilled 2.5-mm hole in the lateral femoral condyle. The no. 5 anchor accommodates up to 60-pound monofilament or no. 5 suture. Instrumentation is minimal, and placement of the anchor is relatively simple.
(4d) Anchor the prosthetic ligament to the proximal tibia using a bone tunnel technique. Form two bone tunnels by drilling two 1.5- to 2.0-mm holes across the tibial tuberosity using a pin or drill bit.
(5a & b) Pass the prosthetic ligament lateral to medial through one hole and medial to lateral through the second hole. Position the stifle at a weight-bearing angle. Tension and tie the suture using six to eight square knots. Alternatively, apply a stainless steel crimp (Securos Veterinary Orthopedics, Charlton, MA) to secure the suture; this technique avoids a bulky knot.7 Ensure that the prosthetic ligament has sufficient tension to eliminate abnormal cranial drawer; however, too much tension may overconstrain the stifle, leading to abnormal range of motion, ligament failure, and osteoarthritis. It is best to maintain normal craniocaudal translation of 1 to 4 mm.
(6a) Imbricate the deep fascia using 0 or 2-0 absorbable monofilament suture placed in a vest-over-pants pattern.