Torn ACL Surgical Options

In humans, an anterior cruciate ligament (ACL) injury is typically an acute traumatic tear from an athletic event. In companion animals, the Cranial Cruciate Ligament (CCL) usually undergoes a progressive, long-term cellular degeneration over months or years. This gradual weakening makes the joint highly susceptible to partial or complete structural failures from minor daily activities like running or jumping.

Instead of replacing the torn ligament with an artificial graft, a TPLO changes the geometry of the leg bone. The surgeon makes a curved cut in the top of the tibia, rotates the plateau angle to make it flatter, and secures it with an orthopedic plate. This mechanical adjustment stops the femur from sliding down backward when the animal puts weight on the foot, neutralizing the need for the missing ligament.

Tibial Tuberosity Advancement (TTA) and Modified Maquet Procedure (MMP) utilize a different structural approach than TPLO. These techniques physically shift the front portion of the tibia (the tibial tuberosity) forward to change the pull angle of the major patellar tendon. Shifting this mechanism brings the tendon to a 90-degree angle relative to the joint line, allowing the large thigh muscle to take over and prevent forward slipping of the tibia during movement.

Orthopedic procedures require cutting and reshaping structural bone matrices. The internal metal plates and screws keep the bone stable initially, but long-term success requires the animal's body to grow new bone across the gap to fuse it solid. Unrestricted running, climbing, or twisting forces can cause the hardware components to fail or shift out of position before the natural bone has completely healed.