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Cranial Cruciate Injuries Part 2 – Surgical Options

By April Guille, DVM, DACVS - Portland Veterinary Specialists | Jul 01, 2018

Last month we discussed cranial cruciate tears and how they are diagnosed. In this article, we will cover some of the surgical options available for this condition.

Many surgeries have been developed over the years to help deal with instability (cranial drawer or cranial tibial thrust) in the knee created by a cranial cruciate ligament rupture. The first thing to realize is that there is no silver bullet, meaning no one surgery can reverse the changes that have already occurred within the joint and more than one surgery may be appropriate for a patient. One common procedure that has been around since the 1970s is the lateral fabellar suture technique (extracapsular repair). This procedure uses a heavy duty nylon line that is anchored around the lateral fabella, a small bone behind the femur, and passes through a hole in the tibia. It acts as a prosthesis for the cranial cruciate ligament and prevents cranial drawer in the short term. The body adds periarticular fibrosis, or scar tissue, over the next several weeks and ultimately provides long term stability for the knee.

In the 1980s, Dr. Barclay Slocum developed the tibial plateau leveling osteotomy (TPLO). Whereas all of the surgeries up to this point attempted to replicate the cruciate ligament in some way, the TPLO changed the alignment and therefore the biomechanics of the stifle joint through a curved cut (osteotomy) in the tibial bone. In a TPLO, the cut piece of bone is rotated to reduce the slope of the tibia where the femur sits, thus eliminating cranial tibial thrust. The cut bone is held in place by a plate and several screws while healing in its new position.

The development of the TPLO opened the door for a series of new surgical procedures. These include tibial tuberosity advancement (TTA), closing wedge osteotomy (CWO), and triple tibial osteotomy (TTO). All of these procedures can be thought of as different roads to the same destination. That is, they all alter the angles within the stifle joint to neutralize the cranial tibial thrust that Slocum concentrated on in the 1980s. We perform the TTA at Portland Veterinary Specialists in addition to the TPLO and lateral fabellar suture technique. The TTA creates stability through changing the angle of the patellar tendon in relation to the joint. The tibial crest, where the patellar tendon attaches, is cut and advanced forward. The bone is held in place with a titanium spacer “cage” and either a “fork” or a bone plate. Like the TPLO, special equipment is required. Similar recoveries are seen relative to the TPLO.

All of these procedures have their pluses and minuses. These differences have been a hot topic in veterinary surgery for the last 25 years. For many years, no one procedure has been shown to be superior to any of the others, but this should be related to appropriate patient selection. Most surgeons would agree that larger, more active dogs do better with a biomechanical stabilization over the lateral fabellar suture. Three recent studies found significant differences comparing the lateral fabellar suture and the TPLO (other procedures were not examined). The TPLO group showed a higher owner satisfaction and better force plate values at a walk and a trot. But even if these last 3 studies show the TPLO offering the best chance over an extracapsular repair for an excellent outcome, it remains that the lateral fabellar suture is a good procedure, and dogs show improvement with this procedure over no surgical intervention. The key point is that surgical selection should be performed taking into account individual patient factors. The pros and cons of each surgery should be discussed with an owner to make the best informed decision.