Tibial Plateau Levelling Osteotomy (TPLO)

Surgical repair of anterior cruciate ligament (ACL) injuries in dogs has seen many additions and refinements over the last 25 years. Tibial plateau levelling procedures such as the tibial plateau levelling osteotomy (TPLO) , the tibial tuberosity advancement (TTA), the triple tibial osteotomy (TTO), and the closing wedge osteotomy have revolutionised the treatment if this disease. Dogs treated with these procedures generally have faster return to weight-bearing, reach peak performance earlier, reach higher peak performance and develop less post surgical arthritis.

The normal tibial plateau (TP) angle is 25 degrees (see diagram below). Due to this slope weight bearing forces cause a resultant tibial thrust which the anterior cruciate ligament neutralises. When this ligament is ruptured, tibial thrust causes the tibia to move forward in relation to the femur causing pain and injury to the joint structures including the cartilages (menisci).
The aim of levelling procedures is to realign the tibial plateau almost perpendicular to the long axis of the bone and the patella tendon. When this is done the resultant tibial thrust is zero and there is no longer a need for a anterior cruciate ligament.  

Dr David Broomfield performs three ACL repair procedures in dogs. The TPLO is most suited to large and giant breed dogs and working/gun dogs such as German Shorthaired Pointers with normal to steep TP angles. David has performed more than 700 TPLOs. The cost of a TPLO is around $3300 at the Murray Street Veterinary Clinic and covers all after care costs at the Murray Street Veterinary Clinic. The TTA is suited to medium to large breed dogs and can be performed in giant breed dogs with a shallow to normal TP angle. The traditional lateral suture technique is most suited to small breeds and is the cheapest. David uses locking plates and screws for the TPLO which provides additional strength and reduces the chance of screws loosening. 

Menisci (cartilages) are shock absorbent structures of the knee joint that are often torn at the same time as the ACL injury. Meniscal tears can also occur after knee reconstructions. All procedures start with inspection of the menisci. If there is a tear it is removed. If a torn cartilage is not surgically removed a poor result will occur. This is one of the most common reasons dogs may not recover well form cruciate surgery. Approximately 10% of dogs will tear a menisci in the few months after a TPLO repair without a meniscal release. If this occurs the dog will become suddenly lame and will need to have the tear to be removed surgically. 

A meniscal release procedure will prevent the menisci from tearing after surgery avoiding the most common complication that will require further surgery. There is still debate between experts in the field if this should be done with every cruciate ligament repair. The meniscal release makes the part of the menisci that tears more mobile so it can't become trapped during weight bearing and tear.