by Gary Thompson
Occasionally people will ask me about a connection between bone cancer and the placement of a bone plate. Bone plates and screws are used in the repair of broken bones and commonly with a procedure in larger dogs for a torn ACL called a tibial plateau leveling osteotomy (TPLO).
The most common bone cancer is a type of aggressive tumor called osteosarcoma (OSA), and it has a genetic link in many large and giant breed dogs. There is also a genetic link predisposing large and giant breed dogs to ACL tears and the TPLO is the procedure most commonly recommended for the larger dogs. The TPLO procedure involves cutting the upper part of the tibia and rotating the bone to stabilize the knee. A bone plate is placed on the inside surface of the tibia to secure the two pieces of the upper tibia while the bones heal together in their new position. This location on the upper part of the tibia is also one of the locations that osteosarcoma is more commonly diagnosed.
This brings to attention one of the more difficult dilemmas in medical research which is the link between causation and association. This boils down to whether or not a disease, in this case osteosarcoma, is caused by a certain singular factor or is simply associated with two conditions that have a common link, which in this instance would be large breed dogs.
Many large breed dogs tear ACLs that are treated with the TPLO procedure and a bone plate on the upper part of the tibia and osteosarcoma is frequently seen in large breed dogs near the upper part of the tibia. In these cases did the TPLO plate cause the osteosarcoma or are the simply associated with a common breed-specific factor? Unfortunately, there is no simple answer to that question.
There was an older TPLO plate manufactured by the company that originally patented the procedure that had some metal properties that triggered more bone inflammation around the plate and chronic inflammation of bone in predisposed breeds can be a risk factor for development of osteosarcoma. However, this bone plate has not been manufactured and sold for more than decade and all TPLO plates currently manufactured and sold are made of a completely inert type of stainless steel or titanium that does not trigger any local inflammation, so there is unlikely to be any connection with the newer plates.
As someone who performs this procedure more than 400 times a year, this is a question I take very seriously since osteosarcoma is a devastating cancer. Most often there is just an association between the type patients that are susceptible to developing osteosarcoma and having torn an ACL that was treated with the TPLO procedure.
While this is a reasonable question to ask if your dog is having the procedure, the odds of your dog ever developing this cancer are exceedingly low and dogs that are treated with the TPLO procedure generally have a good to excellent return to function.
Questions for Dr. Gary Thompson can be emailed to askthevet@theblade.com or mailed to The Blade, Attn. Ask the Vet, 541 N. Superior St. Toledo, OH., 43660. Dr. Thompson regrets that he cannot answer individual letters.
From The Toledo Blade
