Cruciate Injury and the Tibial Tuberosity Advancement (TTA)

Cruciate Injury and the Tibial Tuberosity Advancement (TTA)
The Normal Knee:

The normal Knee Joint (also know as the Stifle joint), has multiple structures which are important to its function. This drawing shows a view from the front with the muscles removed. It is important to note that the Patellar Tendon, a vital structure in the joint has been removed, so that you can see “behind” it. The Patellar Tendon is a thick, tough band that runs from the Patella (green dot) to the Tibial Tuberosity (red dot).

Cruciate injury:

The most common knee injury in the dog is rupture of the Cranial Cruciate Ligament (CCL.  This injury can occur at any age and in any breed, but most frequently occurs in middle aged, overweight, medium to large breed dogs.  This ligament frequently can suffer a partial tear, leading to slight instability of the knee. If this damage goes untreated, it most commonly leads to complete rupture and possibly damage to the medial meniscus of the knee.  The meniscus acts as a cushion in the knee.  Complete rupture results in front-to-back instability, commonly called Tibial Thrust, and internal rotation of the lower leg, commonly called Pivot Shift. Untreated legs usually become very arthritic and painful from the instability.

A completely ruptured Cruciate Ligament can only be corrected by surgery, partial tears may also require surgery but management case by case is the best course of action with cruciate damage. 

What are the options for Cranial cruciate repair in dogs?

Cruciate surgery is performed to repair a torn cranial cruciate ligament (CCL) in the stifle (knee).CCL surgery is the most common orthopaedic surgery performed in dogs. Given that this is such a common injury, several procedures have been developed over the years to repair the ligament. Each technique comes with its advantages and disadvantages.

There are several things that should be considered when choosing the right surgery. Here is a list of things to consider:

  • Age of the dog
  • Size and weight of the dog
  • Activity level of the dog
  • Financial considerations
  • Post-operative care
  • Degree of joint disease (arthritis or other concurrent joint disease/injury)

In some cases, the anatomy and conformation of the stifle may make certain procedures not feasible or not effective.

We offer two techniques for cruciate rupture repair:

  • Extracapsular Ligament Repair/Suture Stabilization Suitable for smaller dogs or when there are financial constraints
  • Tibial Tuberosity Advancement (TTA)

Tibial Tuberosity Advancement (TTA) SURGERY:

Unlike other procedures, the goal of this surgery is not to recreate or repair the ligament itself, but rather change the dynamics of the knee so that the cranial cruciate ligament is no longer necessary for stabilizing the joint. In this procedure, a linear cut is made along the length of the tibial tuberosity, which is the front part of the tibia. This cut bone is then advanced forward, and a specialized bone spacer is placed in the open space between the tibia and the tibial tuberosity. Finally, a stainless steel metal plate is applied in order to secure the bone in place. Because the patellar tendon attaches to this tibial tuberosity, once it is advanced, the tendon keeps the femur from sliding back and forth and therefore stabilizes the knee joint, and eliminates the need for an intact cranial cruciate ligament.

Additionally, rupturing the cranial cruciate ligament leads to instability in the knee, which can lead to damage to other structures within the joint, including meniscal tears. This is where appropriate diagnostics become important. Finding the extent of the injury will aid in choosing the correct procedure for your dog, and will increase the chances of a successful recovery

Tibial Tuberosity Advancement (TTA) RECOVERY:

Regardless of which surgery you choose, it’s the post-operative care that will determine how successful the procedure is. Dogs that are non-weight bearing will quickly begin to lose muscle mass and range of motion in the affected leg. The sooner the knee is stabilized, the less muscle atrophy that occurs, and the faster the recovery post-op.

Current evidence suggests that TTA surgery allows for a more rapid return to full function than extracapsular repair. Recovery from a TTA differs from extracapsular repair in that follow-up radiographs (x-rays) must be performed to ensure that the bone is healing as expected, and that the implant remains in place. Dogs that have undergone TTA must be restricted in their exercise for 16 weeks, until healing of the bone is confirmed via x-rays. Once the bone is healed, more vigorous rehabilitation exercises can be used In the last 20 years, human physical therapy principles and techniques have been developed and adapted to help dogs recover properly after major orthopedic surgery. These exercises focus on safe weight bearing of the limb, combating muscle atrophy, and improving range of motion, while taking care not to damage the metal implant in the knee.

Keep in mind that like humans, not all dogs recover at the same speed. It is best to be conservative and consistent. Do not force your dog to do certain exercises if they are unwilling. It is always best to seek professional guidance if available. It is important to note that while recovery takes up to 16 weeks, it may take longer to have complete healing and return to function

Complications of Tibial Tuberosity Advancement (TTA) surgery.

One main complication in any cruciate surgery is rupture of the contra-lateral cruciate in the other leg. So strict adherence to rehab and exercise restriction is a must.

The long term prognosis for animals undergoing surgical repair of the cranial cruciate ligament is good, with reports of improvement in 85-90% of the cases. However, all surgical procedures carry the risk of complications. The most common complications encountered with this particular procedure are infection, lack of stabilization, and implant failure. The most common complication caused by a torn cranial cruciate ligament is osteoarthritis of the affected joint. Unfortunately, arthritis progresses regardless of treatment, but is much slower when surgery is performed and the knee is stabilized. It is important to realize that arthritis is a progressive disease and develops fairly quickly in an injured stifle joint.  Therefore, arthritis management and prevention and joint supplements are recommended for any dog with this injury, no matter which surgical procedure is chosen. Complications that can arise which are specific to TTA surgery include delayed healing of the bone, non-healing of the bone, healing in an incorrect position , fracture of the bone, and failure or breaking of the metal implants. Although they are uncommon, these complications can be serious and may require corrective surgeries.

 

 

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