Normal Knee Anatomy

 

"An Illustrated Guide to Orthopedic Conditions," page 34

Novartis, 2005

 

Repair of Ruptured Cranial Cruciate Ligament (ACL) by TightRope Ligament Replacement

Just as in the human knee, the most critical stabilizing structure in the canine knee is the cranial cruciate ligament (CCL).  The primary function of the CCL is to prevent forward thrusting motion and inward rotation of the tibia during weight bearing and to prevent hyper-extension of the knee.

 

When the CCL is ruptured or partially torn, the abnormal, forward thrusting motion and inward rotation of the tibia during weight bearing results in an unstable, painful knee and ultimately, in debilitating, degenerative arthritic changes in the knee joint.

 

The newest procedure for repairing a ruptured CCL by ligament replacement is the TightRope Ligament technique.  This procedure has been developed by James L. Cook, DVM, PhD, Diplomat of the College of Veterinary Surgeons.  This procedure has been proven in over 200 knees and has been shown to be highly effective.

 

The TightRope CCL technique is minimally invasive, and more cost effective in comparison to the TPLO or TTA.  The data suggest that TightRope can be successfully performed in medium, large and giant breed dogs resulting in outcomes which are comparable or better than TPLO or TTA.  A MiniTightRope is also available for toy and small breeds.

 

The TightRope CCL counteracts the forward tibial thrust and inward rotation resulting from CCL damage, while providing optimal joint range of motion.

 

This procedure mimics the natural cruciate ligament functions, perhaps better than any other procedure developed to date.

 

The TightRope Ligament is produced by Arthrex Vet Systems.  It is an ultra-high strength,  flat, smooth, braided, ribbon-like ligament composed of a multi-stranded long chain ultra-high molecular weight polyethylene core with a braided jacket of polyester giving it unsurpassed strength, virtually eliminating ligament breakage.  The ligament provides an ultimate load of 225 lbs, approximately three times the strength of 80# nylon ligaments currently in use for CCL replacement.

 

Dr. Pullen is one of the few surgeons in Arizona that has been certified to perform the TightRope Ligament replacement procedure.

 

This procedure provides our clients another option when a less invasive, less radical and somewhat more cost effective procedure that does not cut bone.

 

Varying conditions in each patient and the activity and size of the patient will determine whether Dr. Pullen will recommend a TTA or the Tightrope procedure for your pet.  Both procedures are highly effective and both have their advantages.

 

Following are illustrations describing the TightRope Ligament replacement procedure for ruptured or partially torn cranial cruciate ligaments.

The illustration below shows the canine knee from a front view with the knee cap removed in order to illustrate the femoral tunnel with more clarity.  A tunnel is drilled in the femur beginning at a very precise anatomical point on the inside of the bone, at an upward angle, exiting on the inside surface of the shaft of the femur.

                                                                                          Illustrations provided by Arthrex Vet Systems

 

A second tunnel is drilled in the tibia beginning at a very precise anatomical point on the inside of the tibial crest in a downward direction, exiting on the inside surface of the shaft of the tibia.

 

The TightRope Ligament is passed from inside to outside through the femoral tunnel, then from outside to inside through the tibial tunnel.  The stainless steel tibial toggle button is then turned 90 degrees to the ligament, placed against the surface of the tibia, and the TightRope Ligament is pulled taut through the tibial tunnel.  The TightRope Ligament is then pulled taut through the femoral tunnel eliminating all “slack” in the ligament.  The stainless steel femoral button is then slid down the ligament until it is snug against the surface of the femur, the ligament pulled tight and anchored in this position by tying it down  against the femoral button.  The ligament is now in place, very secure and mimics very closely the function of the natural cranial cruciate ligament.

The illustration below shows the canine knee from the outside surface with the TightRope Ligament in place.  Note that the TightRope Ligament is placed under the long digital extensor tendon, allowing it to function normally and to prevent any damage to the tendon.

 

 

The illustration below shows the canine knee from the inside surface with the TightRope Ligament in place. The tibial toggle button and the femoral button are both securely anchored against the surface of the bone to prevent movement.