TPLO Surgery to Repair Anterior Cruciate Rupture

Rupture of the anterior cruciate ligament (ACL) is the most commonly seen orthopedic injury of dogs. This injury is very similar to the knee injury often seen in football players. The injury destabilizes the knee, allowing damage to the cartilage of the joint and serious lameness. It can occur in any breed of dog, and without repair will nearly always cause significant loss of function and severe degenerative changes in the knee joint with time.

There have been many different surgical procedures utilized to repair this injury in dogs, some with more success than others. Early procedures often attempted to replace the broken ligament with grafts of the patient's fascia or patellar ligaments with mixed results. The grafts nearly always stretched resulting in instability and degenerative changes. More recently, synthetic materials and stainless steel wire has been used outside the joint (extracapsular) to replace the function of the broken ligament. This repair has resulted in reasonably good return to function in smaller or less active animals. In large or active dogs, however, there are often less satisfactory results or even failure.

A new procedure called Tibial Plateau Leveling Osteotomy or TPLO, was developed by Barclay Slocum, DVM. The procedure was a major departure from previous surgical techniques for the injury. Rather than attempting to replace the damaged ligament with grafts or artificial materials, TPLO alters the physical forces in the knee joint by "leveling" the top of the tibia to eliminate the need for the anterior cruciate ligament. TPLO eliminates the active forces that rupture the ACL known as cranial tibial thrust. The following illustrations attempt to explain how leveling the tibial plateau works.

In figure 1, we see a wagon on an incline. The incline represents the tibial plateau, the top of the tibia where the femur contacts it. The wagon represents the femoral condyles which contact the tibia. C represents the force applied by the body's weight. D represents the forces of cranial tibial thrust. E represents the stopping forces of the meniscal cartilage of the knee. F represents the anterior cruciate ligament. Figure 2 is a line representation of the same forces in the knee of the dog. The slope of the tibial plateau (the weight bearing surface of the tibia) is shown. The force of the body's weight is again represented by C. D is the force exerted by the femoral condyle, created by cranial tibial force, pushing against the rear horn of the meniscal cartilage, E.

Figure 3 shows what happens if the incline (the tibial plateau) is rotated clockwise to level the surface the wagon is on. The D force is eliminated, removing the force backwards which would be countered by F, the anterior cruciate ligament, and E, the meniscal cartilage. Figure 4 shows how this same rotation is produced in the TPLO surgery by making a circular cut and then fixing the bone in place with a special bone plate and bone screws.

A model may be viewed at Twin Maples showing how this works with the tibial plateau in its natural and repaired position, and how the surgery stops cranial tibial thrust.

TPLO surgery has been shown to be very successful in restoring full function and preventing further joint degeneration and can be performed on any size dog. The surgery can be performed only by surgeons trained and licensed in the procedure. Twin Maples is pleased to be the first practice licensed to perform the procedure in the Dayton, Ohio area.

The procedure usually results in the patient's leg feeling better soon after surgery. Strict rest and aftercare are required to prevent the pet from becoming too active until the bone heals. Detailed aftercare and rehabilitation instructions will be provided to help produce the best results.