Normal Knee Anatomy

                                       

"An Illustrated Guide to Orthopedic Conditions," page 34

Novartis, 2005

 

The Newest Treatment for Ruptured Cranial Cruciate Ligament (CCL) in the Canine Knee is the

Tibial Tuberosity Advancement “TTA” 

                                                         

Model courtesy of Kyon TTA Products

VIEWER DISCRETION ADVISED. There are medically graphic photographs that are a part of the following overview.

Overview of the Tibial Tuberosity Advancement (TTA) 

The TTA is a new, revolutionary surgical procedure developed at the University of Zurich, Switzerland, for repairing ruptured cranial cruciate ligaments in the canine  knee.  This is the most common orthopedic injury in the dog.

Rather than replacing the ruptured ligament, as older techniques do, this surgery changes the geometry and angles of the knee joint, allowing it to function normally without a cranial cruciate ligament.  This is accomplished by the installation of Titanium implants. 

This procedure allows unrestricted activity even in the most athletic dogs, without the development of arthritis that results from all older techniques of ligament replacement. 

Unlike the TPLO which severely compromises the weight bearing surface of the tibia, the TTA is a much less radical, less invasive procedure that preserves this vital weight bearing surface, allowing for more rapid recovery and earlier weight bearing.  The TTA offers a number of other advantages over the TPLO as well. 

Dr. Pullen received his TTA training and certification directly from Dr. Slobodan Tepic and Dr. Pierre Montavon who developed this procedure.  He also spoke at a recent seminar held in Boston to teach and update 150 surgeons on this procedure.

Dr. Pullen has performed approximately 4000 knee surgeries during his career. He has performed about 200 TTA’s.

Bio mechanics of the Tibial Tuberosity Advancement (How the TTA works)

	1. A side view of the knee joint [the joint between the femur (thigh bone) above and the tibia (shin bone) below] shows the top of the tibia (tibial plateau), and the patellar tendon which attaches the patella to the tibia at the tibial tuberosity.  The angle between the patellar tendon and the tibial plateau in most dogs is greater than 90 degrees, usually in the 115 – 120 degree range.
	2. During weight bearing in the normal canine knee, the femur tends to slide down the backward slope of the tibial plateau, allowing the tibia to thrust forward (cranial drawer motion).  The function of the cranial cruciate ligament (CCL) is to prevent this movement and is therefore under constant stress, predisposing it to partial tears or ruptures.  When the CCL is partially torn or ruptured, the abnormal movement in the knee results in an unstable, painful knee and ultimately, in debilitating, degenerative arthritic changes in the knee joint.
	3. When the patellar tendon is placed at 90 degrees to the tibial plateau, this abnormal,  forward thrusting motion of the tibia and the backward sliding motion of the femur is eliminated, even in the absence of the cranial cruciate ligament.  Therefore, the purpose of the TTA is to change the geometry or bio mechanics of the knee joint, allowing it to function normally without a cranial cruciate ligament.  This is accomplished by making a cut (osteotomy) in the non-weight bearing portion of the tibia where the patellar tendon attaches (the tibial tuberosity), and advancing the tibial tuberosity forward a pre-determined distance, until the patellar tendon is 90 degrees to the tibial plateau.
	4. The tibial tuberosity is securely anchored in its new position using specially designed titanium implants (a cage, fork and plate), and a bone graft installed into the open space created which stimulates very rapid healing.  Thus the shape of the tibia is changed, placing the patellar tendon 90 degrees to the tibial plateau, which eliminates all abnormal movement in the knee when weight bearing takes place, allowing even the most athletic dogs full, pain free mobility with very minimal arthritic changes resulting.  Most patients are completely sound on the operated leg 6–10 weeks following surgery.      Models courtesy of Kyon TTA Products

Advantages of the TTA over the TPLO:

 

While the TPLO continues to be a widely used and successful procedure for repair of the ruptured CCL, the Tibial Tuberosity Advancement (TTA) has a number of distinct advantages, including the following:

  

• Does not compromise the weight bearing portion of the tibia.
• Less invasive procedure with fewer post-operative complications.
• Better range of motion is maintained.
• Does not require cutting of a normal meniscus.
• Does not change the conformation of the tibial plateau
• Earlier  return to clinical function and weight bearing.
• The TTA decreases the joint forces, the TPLO increases them.
• Less likelihood of patellar tendonitis.
• Implants are more bio mechanically compatible (Titanium).
• Patients return to unrestricted activity in 6 weeks. 
  
  

VIEWER DISCRETION ADVISED. Following the "Frequently Asked Questions Concerning the TTA" are medically graphic photographs.

Frequently Asked Questions Concerning the TTA:

 

1. What is the length of the hospital stay? 

Most patients are hospitalized in ICU for 24 – 48 hours following surgery, to better control post-operative pain prior to discharge and transition to oral pain medication. 

2. What impact does this procedure have on the opposite knee? 

 

We feel that of all the procedures for CCL repair, the TTA, relieves stress on the opposite knee best, because the patient returns to full weight bearing on the operated leg very early.  The risk of ruptured CCL in the opposite knee at some future time, following rupture in the first knee is about 40%.  We feel the TTA may very well lower this risk, due to the very early weight bearing that is achieved. 

3. How long is the recuperative period and what care is required in the post-operative recovery period?

 

The leg is bandaged for 2 weeks, during which time the patient is strictly confined and sedated if needed.  Following bandage removal your pet resumes very limited activity and you are taught how to perform physical therapy on the knee consisting of ice packing and flexion and extension exercises.  At six weeks post-operatively, a follow up x-ray is taken.  In almost all cases, the bone has healed very nicely at this time.   Your pet can then begin unrestricted house activity and moderate leash walks, gradually building to unrestricted activity at 10 weeks following surgery.

4. What level of pain will my pet experience?

 

Your pet will be hospitalized where we can strictly control their discomfort with pain management protocols such as Morphine infusions combined with intra muscular pain injections and pain patches.  They are sedated and enjoy a very peaceful sleep during the first night following surgery. The following morning, we continue their pain management protocol throughout each day, to keep them comfortable.  Only when we feel that oral pain medications will control their discomfort, are they discharged to home care.  We will make sure that your pet’s discomfort is very minimal following this procedure.

5. What is the success rate for this procedure? 

 

We have experienced a 98+% recovery to full function on the operated leg with this procedure.  As with any major orthopedic procedure, complications are always an inherent risk  However, we have found complications to be very minimal with the TTA.