Arthroscopy Gives a Valuable View

Utilizing an arthroscope--a slender instrument for visualizing the environment inside joints--can be a good move when radiographs fail to elucidate the bony cause of a horse's lameness. Dean Richardson, DVM, Dipl. ACVS, head of surgery at the George D. Widener Hospital for Large Animals at the University of Pennsylvania's New Bolton Center, presented several case examples comparing radiographs and arthroscopic findings at the Florida Association of Equine Practitioners (FAEP) Promoting Excellence Symposium. This meeting was held Sept. 27-29, 2007, at the Atlantis resort on Paradise Island, the Bahamas.

Richardson compared radiographs and arthroscopic findings on each of several joints. He noted that two joints with radiographs that look identical can be remarkably different on the inside.

"Radiographs are a two-dimensional representation of a three-dimensional structure," Richardson said. "When you're looking at radiographs, recognize their limitations."

In several of the case studies presented, the radiographs of the affected joints looked normal. But via arthroscopy, some of the final diagnoses on these same joints included meniscal (intrarticular cartilage or membrane) tears, damaged cartilage, chunks of cartilage floating freely within the joint, and osteochondrosis dissecans (OCD) lesions.

In one case, radiographs on a lame filly showed a loss of density along the sagittal ridge (a prominence of bone within the fetlock joint) with no clear cause. Upon scoping the joint, a hole in the otherwise healthy-looking cartilage was apparent and had led to an abscess in the underlying bone. In similar cases Richardson has seen, horses with these abscesses have had a Staphylococcus infection in the bone. Some of these bacterial infection cases progress to complete collapse of the surface. He noted that they require aggressive treatment and that arthroscopic debridement can be highly effective.

Another example of a case in which arthroscopy allowed for correct diagnosis, a hunter was brought in for lameness that blocked definitively to the fetlock. However, the radiographs didn't show significant problems--just some light spurring and a loss of joint space, but nothing to explain the lameness.

"You can look at those radiographs all day long, and it's still difficult to visualize what that joint's going to look like," Richardson noted.

Upon scoping the joint, Richardson found that the cartilage looked good, but the bone along the proximal ridge of P1 (the upper edge of the lower bone in the joint--the long pastern) was breaking off. The base of the joint was viable, however, and once Richardson shaved this area off the horse recovered and returned to the show ring.

Richardson used this case to illustrate another point: As well as giving a clear view of what's occurring within a joint, an arthroscope can allow a veterinarian to correct the damage occurring in the joint at the same time.

"When it comes to joint diagnostics, arthroscopy is still the gold standard," Richardson concluded.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care. She owns a portly gray gelding named Duncan and dabbles in several equestrian disciplines, with an emphasis on dressage.

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