State of the Art Lecture

J. L. Tomlinson, BS, DVM, MVSci

Virus Research Technician, Department of Microbiology, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, 1967-71; Intern, Small Animal, Department of Medicine and Surgery, College of Veterinary Medicine, University of Georgia, Athens, CA, 1972-73; Private Practitioner, Wolff Animal Hospital, Bloomington, MN, 1973-1977; Owner and Operator, River Ridge Pet Clinic, Burnsville, MN, 1977-1978; Resident, Small Animal Surgery, Department of Clinical Studies, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, 1978-1980; Instructor, Small Animal Surgery, Department of Clinical Studies, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada, 1980-1981; Assistant Professor, Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, 1981-1987.

Small Animal Hospital Coordinator, University of Missouri, Columbia, MO, 1990-1994; Head of Small Animal Surgery Section, University of Missouri, Columbia, MO, 1987-1996; Associate Professor, Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO, 1987-present.

Numerous reports of using arthroscopy for the diagnosis and treatment of diseases of the stifle, elbow, tarsus and shoulder have appeared in the veterinary literature in the 1990s attesting to its increase in popularity.(1-8) The first reported use of arthroscopy to explore canine joints in North America was reported in 1978.(9) Arthroscopy gained acceptance as a valuable tool in the diagnosis and treatment of various joint diseases in dogs during the late 1980s.

Shoulder

The shoulder joint is very amendable to arthroscopy because of its large size and anatomy. At present, arthroscopy of the shoulder joint is used primarily for exploration of the joint and for treatment of osteochondritis dissecans (OCD). Other possible uses for arthroscopy of the shoulder include diagnosis and treatment of bicipital tenosynovitis and joint instability problems (rotator cuff type injuries).

Arthroscopy allows for evaluation of the cartilage, the synovium, the medial glenohumeral ligament, the cartilaginous labrum, and tendons of the biceps brachii and subcapularis muscles for pathology. Exploration of the shoulder joint is useful to provide definitive diagnosis of the presence of an OCD lesion. Arthroscopy can replace arthrography as a diagnostic tool to confirm that a lesion is present and yet allow treatment of the lesion at the same time. Arthroscopy is useful in the diagnosis of shoulder instability problems. Bardet has recently reported on the arthroscopic findings in 47 dogs with shoulder instability.(4) Sixty-five percent of these dogs had no or minimal degenerative joint disease evident radiographically.(4) At present, no reports are available about arthroscopic correction of the pathology associated with shoulder instability in dogs.

At the University of Missouri, arthroscopy is used exclusively for treatment of OCD lesion of the shoulder. Advantages of using arthroscopy over arthrotomy for treating OCD lesions include decrease in soft tissue damage and associated pain, the joint is not destabilize and thus early postoperative weight-bearing can be encouraged, no risk of seroma formation, and excellent cosmetic appearance. Typically, the arthroscopic procedure takes only 30–45 minutes to complete. Descriptions of how to perform arthroscopy of the shoulder can be found in articles by Person and Van Ryssen.(5,10) The type of lesions that will be found include cartilage flaps located on the caudal aspect of the humeral head, joint mice (typically located in the caudal joint pouch), thickening of the cartilage without a fissure through the cartilage, cartilage erosions, and synovitis. It is not unusual to find cartilage fragments floating around the biceps tendon. The cartilage is removed with a grasping forceps. The edge and base of the defect are debrided with a curette or shaver. Free floating cartilage pieces are removed with a grasping forceps. A thorough lavage of the joint is performed at the end of the procedure. Arthroscopy can be performed bilaterally under the same anesthetic procedure. Typically, the patient will be ambulatory within a few hours of surgery even if performed bilaterally. By the time of suture removal, most dogs are significantly improved over their preoperative status. In most dogs, a normal gait will be present by one month after surgery.

At present, arthroscopic treatment of dogs with bicipital tenosynovitis is being evaluated at the University of Missouri. Treatment consists of debridement of the biceps tendon beginning at its attachment to the scapular tuberosity to as far distal into the bursa as possible of synovial hypertrophy and osteophytes. The shaver is used to perform the debridement. A positive outcome has been seen in most dogs treated this way. A large number of cases need to be evaluated to determine the efficacy of this treatment modality.

Elbow Joint

Arthroscopy of the elbow joint is used to explore the elbow, and treat fragmented medial coronoid process of the ulna and osteochondritis dissecans lesions of the medial aspect of the humeral condyle. In that a high percentage of the dogs with elbow dysplasia lesions are affected bilaterally, arthroscopy is an ideal method of confirming the diagnosis and treating the lesions in both elbows while allowing an early return to function. In a study by Van Ryssen et al., arthroscopy was used to establish a diagnosis of fragmented medial coronoid process in 15 cases where no radiographic signs of elbow dysplasia were present.(3) Arthroscopy of the elbow joint allows visualization of parts of the joint that cannot be seen with any of the standard arthrotomies employed for treatment of elbow dysplasia lesions. Because of magnification, arthroscopy affords a better appreciation of the extent of the injury to the cartilage surfaces. A better estimation of prognosis can be given to the owner once an accurate assessment of the cartilage damage has been made. Arthroscopy does not destabilize the elbow joint like the arthrotomy approaches that require transection of the medial collateral ligament and flexor tendons of the elbow. As a result, arthroscopy allows early return to activity. Surgically induced instability in the elbow, even though minor, may lead to the progression of arthritic changes within the joint.

The elbow joint is easier to arthroscope than the shoulder joint in that there is little soft tissue between the skin and the joint. However, the space inside of the elbow joint is smaller than the shoulder joint making manipulation of surgical instruments more challenging. The arthroscope and instrument portals are established on the medial side of the joint. The technique for performing elbow arthroscopy has been described by Van Ryssen.(2) The type of lesions that can be found inside of the joint include fragmented medial coronoid process, chondromalacia of the cartilage covering the medial coronoid process, areas with full-thickness cartilage loss, OCD lesions of the medial aspect of the humeral condyle, “kiss lesions” of the cartilage of the medial aspect of the humeral condyle associated with an coronoid process, and varying degrees of synovitis. In cases of fragmented medial coronoid process, changes to the cartilage are not limited to the immediate area of the medial coronoid process of the ulna and opposing humeral surface. Widespread cartilage changes may be found. In ununited anconeal process, the separation point of the anconeal process with the rest of the ulna is also visible arthroscopically. The fragment piece(s) of the medial coronoid process and OCD cartilage flaps are removed with a grasping forceps or shaver. Chondromalacic areas of cartilage are debrided with a curette or shaver. A thorough lavage of the joint is performed at the end of the procedure to remove any cartilage or bone debris.

Stifle

Up until recently, arthroscopy of the stifle has been used as an exploratory diagnostic tool and for treatment of OCD lesions of the stifle. (11-16) Accuracy of diagnostic arthroscopy for diagnosis of cranial cruciate ligament injury and meniscal injury is high.(13,14) In one study, arthroscopy agreed with subsequent arthrotomy findings in 92% of the cases.(14) A technique to arthroscopically replace the cranial cruciate ligament in dogs has recently been reported. (1) No information is available about the long-term clinical success of arthroscopic replacement of the cranial cruciate ligament and it should be considered an experimental procedure at this time. Meniscal release and meniscectomy can also be preformed arthroscopically.

The procedure for performing arthroscopy of the stifle has been described.(5,18) A portal is placed just lateral and medial to the distal aspect of the patellar ligament for arthroscope and instrument insertion. Another portal is usually established proximal and medial to the patella for egress of the lavage fluid. Using a fluid pump greatly enhances joint distension and visualization of the interior of the joint. Arthroscopy of the stifle is much more difficult than arthroscopy of the shoulder or elbow and requires considerable practice. The stifle of the dog is much smaller in comparison to a human stifle plus it has a larger fat pad. Because of the small interior working room in the stifle, exploration of the joint can be challenging. Partial removal of the fat pad may be necessary to adequately visualize certain structures like the menisci. Visualization within a diseased joint (cranial cruciate deficient stifle) is also more difficult due to synovial proliferation. Stress manipulation of the joint facilitates visualization of some areas within the joint. Structures that can be visualized include the cranial and caudal cruciate ligament, the medial and lateral meniscus, intercondylar notch, trochlear groove, patella, femoral condyles and tibial plateau, fat pad, joint capsule, and long digital extensor tendon.

Osteochondritis dissecans cartilage flaps are removed from the joint with a grasping forceps or by shaving them with a motorized bur. Curettes can be used to debride the cartilage edges and base of the lesion. Prognosis for normal or near normal leg use after arthroscopic treatment of OCD lesions of the stifle is good. Recovery time following arthroscopy is typically two to four times shorter than for arthrotomy.(15) Combination of results from two studies showed that the lameness resolved completely in eight out of ten legs while two legs continued to have mild intermittent lameness.(15,16) Dogs with cranial cruciate ruptures (complete or partial) need exploration of the joint to determine if a meniscal tear is present. Removal of damaged parts of the meniscus is required or the dog will remain lame. Typically, the remnants of the cranial cruciate ligament are also removed. This will prevent the body from having to reabsorb the torn part of the ligament and to prevent the ligament from becoming interposed between the femur and tibia during weight bearing. Another procedure that has become popular is a meniscal release. In this procedure, the caudal meniscal tibial ligament of the medial meniscus is severed. The benefits of meniscal release to prevent meniscal injury following cranial cruciate rupture have not been documented. No reports are available to definitively establish that arthroscopy is superior to arthrotomy for any of the about purposes. However, if one believes in the superiority of arthroscopy versus arthrotomy in minimizing pain and morbidity, then arthroscopy is a superior technique.

For dogs with cruciate disease, damaged parts of the meniscus and remnants of the cranial cruciate ligament are removed with a shaver, meniscectomy knife, and electrosurgical. A meniscal release can be performed with a meniscectomy knife or electrosurgical unit.

The cranial cruciate ligament can be replaced arthroscopically. The grafts (allografts and synthetics) have consistently failed, however. In the future, arthroscopic replacement of the cranial cruciate ligament may become a viable method of treatment for cranial cruciate ruptures. At the present time, arthroscopic replacement of the cranial cruciate is not a proven treatment for cranial cruciate rupture. Considerable improvement in grafts and postoperative care (rehabilitation) will need to be made before this becomes a viable procedure.

Hock

Arthroscopy of the tarsocrural joint is the least common arthroscopy performed in the dog due to the low incidence of disease and the difficulty in performing the procedure in the hock. The joint space is very small making visualization and treatment of lesions difficult. The main indication for arthroscopy of the hock is confirmation and treatment of OCD lesions. Most OCD lesions will be located on the medial trochlear ridge of the talus but occasionally will be present on the lateral trochlear ridge.

A description of the technique for performing arthroscopy of the hock has been reported.(19) Three different portal sites are available depending on which part of the hock needs to be visualized. Because of the small size of the joint, a smaller arthroscope (1.9 mm or 2.2 mm) than the standard 2.7 mm arthroscope typically used in the other joints may be helpful. Lesions of the dorsal aspect of the medial talar ridge are the most amendable to removal. Small grasping forceps can be used to remove small fragments. Larger osteochondral fragments can removed by shaving with a 2 mm diameter blade attached to a shaver. At times, removal of the lesion may not be possible via arthroscopy and thus an arthrotomy will need to be performed. Prognosis for limb function after arthroscopic treatment of OCD lesions of the hock has not been reported. We have treated two giant breed dogs arthroscopically with an excellent outcome.

REFERENCES are AVAILABLE ON REQUEST