The benefits of MMP over TPLO for CCL Tears of Dog Knee

The cranial cruciate ligament, CCL, in dogs is the major stabilizing ligament of knee; just as the anterior cruciate ligament, ACL, is the major stabilizing ligament of the human knee.  Tear of the CCL is the most common cause of chronic hind limb lameness in medium, large and giant breed dogs.

While Tibial Plateau Leveling Osteotomy (TPLO) remains the most recommended surgical procedure for surgical stabilization of torn CCL in dogs, Modified Machet Procedure (MMP) is increasingly proving itself to be an excellent alternative to TPLO for surgical repair of CCL in dogs.  Truth be told, in my 20 years experience of performing CCL repair in dogs and two post-doctoral certifications in canine reconstructive knee surgery later, I never bought into TPLO, having always found it an exceedingly invasive and expensive means to repair a torn ligament.  Prior to performing MMP, I repaired CCL tears in dogs with the tightrope procedure and before that, the Securos lateral suture method.

What is TPLO?

Invasiveness and expense aside, TPLO is a rather ingenious concept.  TPLO inventor, Dr. Barclay Slocum, noted that the tibia on which the femur sits (the two long bones that comprise the knee joint), has a slope generally of about 21-24 degrees.  This is known as tibial slope.  He subsequently  viewed the canine knee as a wagon sitting on a hill, attached by a rope.  In this analogy, the tibial slope is the hill, the femur that sits upon it is the wagon, and the rope is the CCL.  When the rope (CCL) tears, the wagon (femur) slides down the hill.  This “slide” is what we call cranial thrust, the hallmark sign of CCL tear in dogs, and what is responsible for the instability and pain associated with the injury.  The various procedures to repair CCL tear in dogs at the time (1980’s) were aimed at replacing the rope.

Dr. Slocum discovered that, rather than focus on the rope, if he flattened the “hill” by cutting the top of the tibia and rotating it, the femur will no longer slide and cranial thrust is resolved.  In essence, the rope is no longer needed to keep the wagon on the hill.  The cut is made with an angled bone saw and fixed in its new position with a plate and screws.  Below is a diagram that illustrates the concept, as well as x-rays of post-operative TPLO.

In the hands of a skilled and experienced surgeon, TPLO is an effective surgical solution to stabilizing CCL tear in dogs.  However, healing time is 10-12 weeks, during which time the dog’s activity must be completely restricted.  Also, until the bone is healed, the head of the tibia is completely dependent on the surgical plate to hold it together, and plates can fail. To be fair, plate failure is rare, but when it occurs it can be very serious, even limb threatening.  The surgeon generally has one shot at going back in and fixing the complication.

What is MMP?

Modified Machet Procedure was named after Dr. Maquet, a Belgian human orthopedic surgeon that introduced the concepts used in MMP in surgical knee procedures he pioneered in people.  MMP surgery takes the pressure off the injured CCL by redirecting impact to the large and strong quadriceps muscle. This is done by changing the angle of the tibia and moving it forward to the patellar tendon.  To be more specific, a wedge is placed within the bone and held in place with one pin. The wedge is made of a porous alloy, allowing bone to grow through it. Then, the patellar tendon can take over and act as the CCL.

The benefits of MMP over TPLO

• MMP is a far less complex and precise surgery that subsequently requires much shorter surgical and anesthesia time (45 minute – 60 minutes versus 2 plus hours)
• Faster to weight bearing: most dogs are using the limb as quickly as same day to three days post-op
• Faster healing times typically with all restrictions lifted by 6 weeks (as opposed to 10-12 weeks with TPLO)
• MMP does not alter the articulating surface of the tibia, that is, the portion of the tibia that bears weight via direct impact of the femur
• Less potential for catastrophic complication
• Less expensive

I have been repairing CCL tears in dogs using the MMP technique since 2018 and have enjoyed incredible success rates.  No orthopedic surgical procedure is without potential complication, nor yields 100% success rates.  But in my vast experience performing knee surgery in dogs, MMP provides the least complication, fastest return function, and highest success rates for CCL tears in medium, large, and giant breed dogs.