By Lydia F. Gray, DVM

Arthroscopic surgery is the best tool veterinarians have for visually inspecting the condition of a joint. That gives it a place not only in the treatment of joint lameness, but also in its diagnosis.

"The typical lameness work-up begins with a history-taking, a general physical examination and an evaluation of the musculoskeletal system," says Dr. Mark Martinelli, DVM, PhD, Dipl ACVS.  "The musculoskeletal evaluation may include palpation, observation in motion, and flexion tests," he says. Based on the results, the veterinarian may try to identify the location of the lameness with diagnostic anesthesia, commonly referred to as nerve or joint blocks. Radiographs or ultrasound may be the next step. Inconclusive findings here may send the horse to nuclear scintigraphy, where a computer-generated picture of "hot spots" (inflamed areas that have taken up more of an intravenously injected, safe, radioactive compound) may help localize the problem. Most recently, MRI has become popular for musculoskeletal imaging, providing more detail about the joint, including the articular cartilage and underlying bone.  However, none of these techniques ensure that the joint is the root of the lameness or indicate how severely affected the joint is. Because arthroscopic surgery has many benefits and few disadvantages, veterinarians may recommend this procedure in the work-up of a lameness that appears to be joint-related.

"Arthroscopic surgery is minimally invasive and has few drawbacks," says Dr. Martinelli. Because the horse usually undergoes general anesthesia for the procedure, there is some risk involved, but with today’s modern screening techniques, safer compounds, and improved monitoring during surgery, that risk is slight. In addition, whenever surgery is performed on a horse there is always the risk of infection, but this, too, is minimized with arthroscopy due to high volumes of fluid flushing through the joint as part of the procedure.

Compared to the earlier surgical procedure for examining a joint, arthrotomy, arthroscopy provides:

• A better view of the joint and all its components
• Decreased after effects of surgery (that is, the horse goes home sooner)
• Improved cosmetic appearance afterwards
• Quicker return to full function

In medical language, "arth" means joint. "Scope" refers to an instrument for observing or examining and "otomy" refers to a surgical incision into an organ or part. Together, an "arthroscope" is an instrument inserted into the cavity of a joint in order to inspect the contents and an "arthrotomy" is the surgical incision of a joint capsule in order to inspect the contents.

In an arthroscopic surgery, two to three tiny "nicks" are made through the skin and joint capsule in order to insert the arthroscope and other instruments as needed. The joint cavity is inspected, any bone chips or loose cartilage are removed, and the area is flushed to remove small fragments and inflammatory products. The "nicks" are usually closed with one suture each and rarely can signs of this surgery be detected afterwards.

On the other hand, an arthrotomy involves one or more large incisions over the entire joint to allow the veterinarian to see inside firsthand, without the aid of a magnifying scope that can reach from one end of the joint to another. Not only does the skin require an entire row of sutures, but the joint capsule itself must be sutured back together. Recovery is prolonged due to pain, swelling, and weakened structures. In addition, there may be permanent loss of range of motion and scarring.

"After arthroscopic surgery, most horses act like they’ve not had anything done to them," says Dr. Martinelli. Horses walk back to their stalls following the procedure and most go home the next day. A minimum of two weeks stall rest is usually recommended, but the type and length of aftercare depends on the horse, the specific joint and condition being treated, and the extent of the surgery. While pain-killers are not usually necessary, some joint therapy may be indicated; consult your veterinarian before starting or even continuing injections or oral supplements.

Science and technology continue to provide us with better and better tools for prolonging the athletic life of horses (as well as humans). But in order to get the most benefit out of arthroscopic surgery or any procedure, early recognition that there is a problem is vital. Just as important is knowing what can be done to help prevent problems. In the case of joint disease, proper footing, training, and conditioning—together with close observation and regular veterinary care—are your best strategies.

Reviewed and updated by Drs. Lydia Gray and Mark Martinelli in 2016.