A new technique, called the dynamic tibial plateau leveling procedure (TPLP), can be used to treat cranial cruciate ligament rupture in growing immature dogs
The timing of the surgery is critical, and is specific to the breed of dog
This technique involves placing a screw in the cranial aspect of the growth plate of the tibial plateau
As the dog grows the top of the tibia levels, in essence the final result is the same as the TPLO, but with a much less aggressive surgery
Causes of cranial cruciate rupture in dogs
- Cruciate ligament rupture can occur in all ages of animals, including very young dogs. The etiology of this problem is multi-factorial. Bow-legged conformation, patellar luxation, narrow intercondylar notch, trauma, nonisometric ligament attachments to the bones, and steep tibial plateau are contributing factors.
- Bow-legged hind limb conformation and medial patellar luxation cause excessive internal tibial rotation which strains the ligament and may lead to cranial cruciate ligament rupture.
- The cranial cruciate ligament passes through the intercondylar notch of the femur bone. A narrow intercondylar notch can impinge the cranial cruciate ligament which results in continual friction and fraying of the ligament.
- Ligaments must be attached to isometric points on the bones. This means that the ligament is not stretched during extension versus flexion or visa versa. If the bone growth is such that these isometric points are altered, increased forces are exerted on the ligament, which results in permanent elongation of the ligament with resultant instability of the joint.
- The slope of the tibial plateau plays a significant role in stressing the cranial cruciate ligament. The steeper the plateau slope, the greater the forces that are exerted on the cranial cruciate ligament. A comparative example is this: greater force is required to pull a wagon up a steep hill than on a level surface. A steep slope results in repeated maximal loading of the ligament, which ultimately stretches the ligament beyond its elastic phase into the plastic phase resulting in permanent elongation and weakening of the ligament.
Methods of Repair
- Many repair methods exist for cranial cruciate rupture. Extracapsular repair has been the most popular technique for a number of years. Many extracapsular techniques exist, however most surgeons use the “Flo” and the lateral imbrication technique. Board-certified Surgeons in the United States have recognized that these and many other traditional techniques do not allow dogs to return to working or athletic activities without lameness. In our experience, dogs treated with the tibial plateau leveling osteotomy (TPLO) technique have an excellent chance to successfully return back to these types of activities.
Progression of Arthritis
- Another study evaluated the progression of degenerative joint disease in dogs following intra- and extra-capsular surgical techniques and a group of cranial cruciate ligament deficient dogs having no surgery. Interestingly, all groups of dogs developed the same degree of degenerative joint disease. In contrast, a study that evaluated the progression of arthritis in dogs receiving the TPLO versus the imbrication technique demonstrated four times less progression of degenerative joint disease with the TPLO technique. We have also noted in our clinical cases that arthritic changes in most cases progresses very slowly or is arrested.
Very young dogs and cruciate injury
- One of the challenges that the orthopedist faces is rupture of the cranial cruciate ligament in very young dogs (6 months or less). As mentioned above, arthritic changes progress rapidly with the traditional techniques that have been used in the past. As a result, this is not an ideal treatment. The standard TPLO is also not ideal for very young dogs either, as the growth plate is cut during the procedure, which may result in continued flattening of the tibial plateau as the dog grows.
Dynamic tibial plateau leveling procedure
- A new technique, called the dynamic tibial plateau leveling procedure (TPLP), can be used to treat cranial cruciate ligament rupture in growing immature dogs. The timing of the surgery is critical, and is specific to the breed of dog. This technique involves placing a screw in the cranial aspect of the growth plate of the tibial plateau. Growth is stopped at this region of the tibial plateau, yet the caudal aspect continues to grow. Over time the tibial plateau angle is leveled. The amount of leveling of the plateau is dependant on the preoperative tibial slope and the age of the dog at which the procedure is performed.
- Below is a preoperative and postoperative dynamic TPLP radiographs. Take note of the 26 degree slope at the time of surgery; the cancellous screw is placed at the cranial aspect of the tibial plateau. Four months later the tibial slope has decreased to about 4 degrees.
- Typically patients receiving the dynamic TPLP have a fairly low morbidity rate associated with the procedure. Postoperative pain appears to be fairly low, as minimally invasive techniques are used to perform the procedure; therefore, these patients can return home the same day as the procedure is performed. Exercise is limited to leash walks for about 2 months. Typically, this is the period of time during which the lameness resolves. To evaluate the effect of the procedure, radiographs of the tibia are taken initially at 8 weeks after surgery, and then every 1 to 2 months until the dog has matured.
Benefits of the dynamic TPLP
- Advantages of this technique include short recovery from surgery, minimal pain, and less cost for the procedure in comparison to the standard TPLO procedure used to treat cranial cruciate rupture. If indicated, the procedure can also be safely performed bilaterally.