Diagnostic and Surgical Arthroscopy in the Horse

Arthroscopic surgery, developed in the horse in the 1970s, is the keyhole technique by which surgery is performed on equine joints for traumatic injury, fractures within joints, soft tissue injury, and abnormal joint development in young horses, such as osteochondritis dissecans (OCD).

Arthroscopic surgery involves inserting an instrument known as an arthroscope through small stab incisions to view and complete surgery within a joint, such as removing a cartilage fragment. An arthroscope is four millimeters in diameter.

Diagnostic arthroscopy was developed for human orthopedics, and involved the insertion of a small endoscope within a sheath into the joint, distending the joint with liquid, and enabling a clear view of the inside of the joint. At first, examination of the human knee was used to confirm a suspected tear of the meniscus (a fibrocartilaginous pad within a joint). Once confirmed, the meniscus was removed through an open incision known as an arthrotomy. Arthrotomies, which were the commonly accepted technique before arthroscopy, gave very poor visualization of the joint, and consequently, some normal menisci were inadvertently removed before the use of arthroscopy.

arthroscopic view of a horse's stifle joint

Arthroscopic view of a horse's stifle joint. This joint shows chronic synovitis, which has led to thickening of the synovial fronds (fingerlike projections of the synovial membrane).

Now, clear definition of the injury is made with the arthroscope, and, depending on the location and size of the tear, a portion of meniscus may be removed or alternatively the meniscus may be repaired. Fortunately, open incisions for joint surgery are no long used.

Dr. S.W. Casscells, a human orthopedic surgeon, in his 1987 article "The Early Days of Arthroscopy," wrote: "In the United States, diagnostic arthroscopy and even more important, arthroscopic surgery constitute what is probably the outstanding achievement in orthopedic surgery in the past decade." The same statement could be made for arthroscopic surgery in the horse. Use of the arthroscope for diagnosis of equine joint disease commenced in the mid-1970s, while performing surgery under arthroscopic visualization began in the late 1970s. By 1984, both diagnostic and surgical arthroscopy were being performed clinically in the horse with arthroscopic techniques completed successfully in the carpus (knee), fetlock, hock and stifle joints, with techniques for other joints following shortly thereafter. Currently, arthroscopy is used to diagnose and treat diseased joints more successfully than with incisional techniques used earlier.

During arthroscopic surgery in the horse, a complete examination of as much of the joint as can be visualized is completed first. Even though radiographs might have detected a fracture fragment or an obvious OCD lesion, it is common for the surgeon to find other changes or injuries with the arthroscope. The advent of arthroscopic surgery techniques gained more prominence for this procedure once Spend a Buck won the 1985 Kentucky Derby by six lengths, just five months after arthroscopic surgery for removal of a small fracture fragment in his knee.

Diagnostic arthroscopy is a critical part of every surgical procedure and also in joints such as the femorotibial joint in the stifle where the arthroscope is used to detect problems that cannot be diagnosed with radiographs or ultrasound.

Arthroscopic techniques have now been developed to treat all joint conditions in the horse. Descriptions of diagnostic and surgical arthroscopy were first detailed in textbook form in 1984. The use of arthroscopic surgery combined with screw fixation of third carpal slab fractures was reported in 1986 and its use to treat medial condyle cysts of the femur in these small medial femorotibial joints of the horse was originally described in 1987. Techniques for arthroscopy of the shoulder to treat OCD were also described in 1987. By 1990, arthroscopy was also being performed on the distal interphalangeal, proximal interphalangeal, elbow, femorotibial and hip joints, as well as being used in tendon sheaths. More importantly, success rates have been defined based on retrospective studies with large numbers of cases for these common conditions.

Arthroscopy is a good example of how research into new techniques can help provide improved diagnostic techniques and treatments for horses. Though some of the information on human arthroscopy was used to help develop the technique for horses, the techniques and procedures used today were developed through research and collaboration among researchers and clinicians. New knowledge about joint injury and arthritis has also been made possible with the use of arthroscopy. It is important for horse owners to understand that this type of research requires funding for dedicated investigators to make new discoveries that can be applied to medical care for the horse.

More than 50 joints and conditions can now be operated on arthroscopically. For a complete list, visit the Equine Research Coordination Group Web site.

The veterinary community needs your assistance to increase funding for research joint disease and other equine diseases.

Please contact the Grayson Jockey-Club Research Foundation, American Quarter Horse Foundation, Morris Animal Foundation, the American Association of Equine Practitioners Foundation, or your favorite veterinary school to make a contribution.

Contact the AAEP Foundation for information about supporting equine research, or call 800/443-0177 (within the U.S.) or 859/233-0147. This is one of the many efforts that the AAEP is coordinating on behalf of the industry through the Equine Research Coordination Group (ERCG), which is comprised of researchers and organizations that support equine research. Formally organized in 2006, the ERCG has a mission of advancing the health and welfare of horses by promoting the discovery and sharing of new knowledge, enhancing awareness of the need for targeted research, educating the public, expanding fundraising opportunities and facilitating cooperation among funding agencies.

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