Arthroscopy in Small Animal Orthopedics

Amy Kapatkin, DVM, Dip ACVS, Assistant Professor of Surgery
University of Pennsylvania, Philadelphia, PA 19104-6010

 

The first arthroscopy used in the humans was in the early 1900's. Routine use in humans developed in the 1970's. The first veterinary use of arthroscopy was also in the 1970's but it was not widely used in small animal specialty practices until the mid-1990's. As equipment for small joint use developed in the human field, it became apparent that these smaller instruments were applicable for small animal joints. As public awareness of the technique rises, demand for its use increases.

Arthroscopy is useful for diagnosis of joint conditions as well as treatment of those conditions identified. The reported advantages of arthroscopy over arthrotomy are that since it is minimally invasive with less periarticular tissue destruction, recovery is faster, less painful and multiple joints can be treated at the same time. Visualization of the joint is significantly improved via the arthroscope. There is magnification as well as a light source that enhances the image and therefore pathology on cartilage or ligaments, that would be difficult on direct visualization, can be easily seen. This has been especially helpful in ligamentous injuries that other imaging modalities cannot identify. Previously, surgeons had to do arthrotomies to try to locate the problems.

Disadvantages of arthroscopy are its cost to buy all the equipment ($40,000- $100,000) and the difficulty in learning the techniques. Some of the difficulties in learning the techniques are due to the small joints, and that we are not use to working surgically without direct visualization.

The usual scope sizes used for small animal arthroscopy are the 2.7 mm, 2.4 mm and the 1.9 mm scopes. The 1.9 mm scope is extremely delicate but can be useful when scoping a carpus or tarsus. The viewing field can be straight, 30-degree fore oblique and 70- degree retrograde. The 30-degree oblique is the scope most often utilized. Most practices are using video arthroscopy. This allows magnification of the image, multiple people to see the image, sterility of the procedure and freedom to perform the surgical correction of the problem. The video camera and a light source attach to the arthroscope and project the image on a monitor. In- flow of lactated ringers or saline is necessary. This can be done via gravity, pressure bags or by special fluid pumps. The fluid pumps allow complete control of expanding the joint and flushing the joint and helps with visualization. Cannulas to protect the arthroscope and outflow of fluids from the joint are needed. Hand- instrumentation to treat surgical lesions is needed; there is a large array of different grabbers, ronguers, knives, curettes and probes. A motorized shaver is extremely useful to debride, flush and suction debris, cartilage and bone from the joint.

Clipping, surgical preparation and draping of the patient are the same as an arthrotomy. Finding the access to the joint portals is first done with a needle to ensure the correct location. Joint distension is done and the outflow and arthroscopy cannulas inserted. A third portal will be made for instruments to definitively treat any lesions found. A complete examination of the joint should be done before any specific treatment is instituted. Most practices will be able to document the lesions via printers, digital capture systems or VCR's. Once the joint has been treated, many surgeons will use bupivicaine directly into the joint to help alleviate postoperative pain. Then all the instruments are pulled from the ports and a single skin suture closes each portal. A modified Robert-Jones bandage is usually used overnight to keep any swelling down and to help make the patient comfortable when working on distal joints.

The following are the joints and pathology that arthroscopy can be used for. Examples of these lesions and treatments will be presented in the talk as a case-based discussion. For all joints, synovial biopsies and flushing of septic joints are indications for arthroscopy too.

Shoulder joint:

1.  OCD lesion

2.  Bicepital tenosynovitis

3.  Pathology of medial joint capsule ligaments

4.  Septic arthritis

Elbow joint:

1.  FMCP

2.  OCD

3.  UAP

Carpal joint:

1.  Cartilage lesions

Hip joint:

1.  Cartilage lesions

Stifle joint:

1.  OCD

2.  Torn cranial cruciate ligament

3.  Torn meniscus

Hock joint:

1.  OCD