Tibial plateau leveling operation (TPLO)

The long bones of the leg either side of the knee joint, the femur (thigh bone) and tibia (shin bone) are held together by a number of ligaments, including the cranial cruciate ligament. In a normal knee joint the cranial cruciate ligament stops the shin bone below the knee moving forward of the thigh bone when weight is placed on the knee. This ligament can be torn or broken (a common injury in footballers) which makes the knee unstable, causing lameness. In dogs however, whilst injury as a result of trauma can occur, the most common reason the cruciate ligament fails is a long standing degenerative condition that gradually weakens the ligament. As the ligament gets weaker it suddenly becomes unable to cope with normal day-to-day activity and it either partially tears or completely tears. There are a number of techniques that can be used to help stabilize the knee after a ligament injury, including a tibial plateau leveling operation (TPLO).

If your dog has damaged their cruciate ligament they may have a persistent lameness. Some smaller dogs are able to recover to good function without surgery but in large dogs some form of surgery is usually needed to correct the problem. If TPLO surgery is performed early it can help stop further damage being done to the knee and reduce arthritis development in later life. Despite this however, arthritis will progress.

A complete workup is essential before TPLO surgery is planned. This can include:

• A full clinical examination to look for any other conditions that may impact recovery from surgery.
• X-rays / CT scan of the leg to help plan surgery and exclude other causes of lameness.
• Possibly blood tests to assess kidney and liver function before anesthesia.

TPLO is a surgical procedure performed under general anesthesia. The fur is clipped from the leg and the skin prepared with antiseptic surgical scrub. An incision is made in the skin on the inside of the knee so the surgeon can access the bones. After checking the shock absorbers (menisci) for damage the surgeon cuts the top of the bone below the knee (the tibia), repositions it, and fixes it in place using a metal plate and screws. This operation changes the angle of the bones in the knee to stop the abnormal movement between the thigh bone and shin bone. The cruciate ligament is not replaced, however the altered angle means that the cruciate ligament is not required.

There are many possible complications from TPLO surgery and these must be carefully considered before surgery. As for all surgeries there is the risk of an anesthetic, but in the hands of an experienced veterinary team this will be low in provided your pet is otherwise fit and healthy.

The risks from the surgery itself include:

Surgical site infection which can happen in up to a quarter of dogs depending on the technique and whether the dog has any particular risk factors. Dogs which may be more at risk are German shepherd dogs or any heavy dogs and the risk of infection increases if surgery times are prolonged. If your dog has any skin disease the surgeon may want to delay surgery until this has been treated to minimize the risk of infection being carried from the skin to the joint during surgery. Infection is a serious complication and can mean that the plate and screws need to be removed.

During surgery there are risks due to bleeding or damage to other structures around the area of the knee. In a very small number of cases the screw used to attach the plate may penetrate the joint. X-rays are taken immediately after the operation to check that the plate and screws are in the right place, and if any problems are identified these are corrected immediately

After any surgery there is always the risk of wounds opening (especially if your dog licks at the stitches) until the skin is fully healed. Occasionally the implant may break or one of the bones weakened during surgery could fracture and sometimes the bone fails to heal properly after it has been cut. Sometimes the shock absorbers in the knee can tear after surgery requiring a surgeon to go back in through a key-hole incision to remove the torn piece.

TPLO is a major surgical procedure and must never be embarked upon without serious thought and commitment.

Your dog will be kept in the hospital until your veterinarian is happy that you will be able to continue their care at home. Your pet will have pain relief and, in some cases antibiotics. These may need to be given for several weeks after surgery. Wound care is very important, and you will need to ensure the wound is kept clean and that your pet cannot interfere with it. Some form of protective collar (buster collar) or sticking plaster will be needed to stop your dog damaging the stitches. The Buster collar will have to stay on until the stitches are removed and the wound has healed.

Your dog’s exercise will have to be severely restricted for around 8 weeks after surgery. This will start with your pet being confined to a small area in the house with short lead walks only. Gradually the length of the lead walks can be increased and your veterinarian may recommend other forms of strengthening exercises such as hydrotherapy to help your pet’s rehabilitation.

X-rays will be taken approximately 8 weeks after surgery to check on healing of the bones and to identify any complications with the plate or screws.

The outcome is generally good if appropriate surgery is undertaken quickly. Most dogs will be sound within a few weeks of the surgery and quickly return to a normal life.

If your pet remains lame after surgery it is important to get them checked by your veterinarian. There will always be a small risk of post-operative infections and if any of the screws have moved there may be persistent pain.

Most dogs develop thickening of the ligament that attaches the patella to the knee after TPLO surgery. In a few cases there is pain and lameness associated with this thickening; this can be treated with anti-inflammatory drugs and rest and in most cases improves as dogs return to exercise again.

Osteoarthritis is common in dogs after TPLO surgery. This osteoarthritis will progress with time despite treatment and may result in stiffness and lameness in older animals and long-term anti-inflammatory treatments may be needed for pain relief. Weight control is an essential part of managing arthritis with obesity increasing the resulting pain.

Up to 6 out of 10 dogs that suffer rupture of a cruciate ligament in one leg will develop the same problem in the other leg at some time. If your dog has had surgery to correct a torn ligament make sure you contact your veterinarian if they develop any lameness on the other leg later in life.