A Pertinent Guide To Basic Ankle Arthroscopy
Surgery in general seems to gravitate toward smaller and less invasive procedures. Obviously, the less tissue disruption that occurs during surgery, the less risk one has of postoperative complications such as scarring, infections, delayed healing, etc. Although this may not be true with every surgical advance, arthroscopy has revolutionized the treatment of joint disorders and allowed many of these common complications to be almost entirely eliminated. Increasing indications for this technique include the treatment of subtalar, calcaneal cuboid and first metatarsal disorders. However, for the purposes of this column, I’d like to offer a closer look at the basics of ankle arthroscopy. In my opinion, the purpose of ankle arthroscopy can be divided into diagnosis and treatment. As modalities such as MRI and CT continue to improve, there seems to be less of a need for direct arthroscopic visualization when it comes to making a simple diagnosis of ankle disorders.1 However, in the face of persistent pain and non-definitive imaging studies, arthroscopy can provide surgeons with an excellent opportunity to inspect the joint closely and arrive at an accurate diagnosis. The role of arthroscopic treatment is almost limitless. The most common indications I find for this procedure include synovitis, chondral lesions, loose intraarticular fragments, exostosis and chronic or acute instability. Numerous other indications such as severe arthrosis and fractures exist, but these involve more complex arthroscopic maneuvers and are beyond the scope of basic arthroscopy.2 Addressing Patient Placement And Ease Of Access Typically, you would give the patient a general anesthetic to employ a thigh tourniquet. You can complete this procedure with only intravenous sedation and local anesthetic, but I have found this to be more difficult due to having to place the tourniquet on the “high ankle” or calf. It’s also easier to assess instability of the ankle, especially following acute injury, when the patient is completely anesthetized. An arthroscopy is more difficult without using a tourniquet for hemostasis, due to hemorrhage constantly obscuring the field of vision. When treating patients who may benefit from not using a tourniquet, such as those who have a history of deep venous thrombosis, judicious use of local anesthetic with epinephrine will significantly lessen this problem. One may use both around the portals as well as intraarticularly. In a basic arthroscopic approach, you would place the patient in a supine position. Some surgeons prefer to place the affected side in a knee holder and drop the end of the operating table. This allows you to be seated during the procedure. I am inclined to have the patient’s heel approximately 3 to 4 inches off the table and to stand during the arthroscopy. This allows me to maneuver the ankle in any direction and to stabilize both arms against my own torso. Even with the patient in a supine position, you can easily access the posterolateral portal if the table is angled or if you place a pad below the hip on the operative side. This simply exaggerates internal rotation of the limb. In order to use this adjunctive portal to its full advantage, the patient may need to be further down on the table. Otherwise, the arthroscopic equipment will continue to contact the table and limit your movement. You may need to seek alternative positioning based on the patient’s particular pathology and your ability to address it.3 What You Should Know About Portal Placement Portal placement is the most important part of the procedure. Poorly placed incisions will limit access to the joint and increase the risk of neurovascular or tendinous injury. When approaching the anterior aspect of the ankle, it is best to identify topical landmarks. Typical marking should identify the anterior tibial tendon, the extensor hallucis longus tendon and the anterior tibial artery. One should do this prior to joint distention since the areas marked may become distorted. At this point, you would employ either a two- or three-portal approach. I choose to use an anteromedial and anterolateral approach. The anterocentral approach is an acceptable portal as well, but carries the added risk of being very close to the neurovascular bundle. Although you should be cautious with this approach, it is an excellent portal for viewing the ankle. When using the three portal approach, you may place the camera within the central incision. Typically, one does not have to remove it and place it in a different portal. Helpful Pointers For Minimizing Surgical Risks Some surgeons choose to distend the joint with a large syringe and saline or lactated Ringer’s solution. Distending the joint in this fashion serves to “inflate” the joint and ease the entrance of the equipment. Although the exact amount will vary in each patient, you will usually need 25 to 30 ml of fluid for distention. This may vary significantly if there is arthrosis or previous capsular damage. Although several types of pressurized inflow systems exist, many surgeons find saline or lactated Ringer’s solution and gravity flow are adequate to fully complete the procedure. If I do distend the joint prior to arthroscopy, I will place the skin incisions and bluntly dissect down to the joint capsule with a small pair of hemostats. At this point, I will introduce the syringe and fluid through the capsule. Again, this is a matter of preference. In many cases, I have found that the joint doesn’t have to be distended prior to the arthroscopy. Appropriate placement of the equipment and ensuring the inflow of fluid is adequate to distend the joint. Several surgeons make the incisions for the portals vertically. I choose to make them within the skin lines in a horizontal fashion. This seems to lessen the postoperative scarring, but does slightly increase the chances of venous and nerve injury. In positioning the anteromedial portal, you should make it medial to the anterior tibial tendon and lateral to the medial malleolus. The anterolateral portal is situated just lateral to the peroneus tertius tendon and medial to the lateral malleolus. In the medial portal, you should avoid the saphenous nerve and vein. In the lateral portal, avoid the intermediate dorsal cutaneous nerve, the perforating peroneal artery and the lesser saphenous vein. After using hemostats to bluntly dissect to the joint capsule, you can use the obturator (a rod with a blunt, cone-shaped tip) or trocar (a rod with a sharp tip) to pierce the capsule. Most surgeons suggest using the obturator to reduce the possibilities of iatrogenic cartilage damage. It is important to bear in mind that the obturator, although blunt, can still cause significant cartilage disruption. Proceed to remove the obturator or trocar from the canula. If you have distended the joint prior to entry, you may notice back flow of the saline or lactated Ringer’s solution. This tells you that you are within the joint capsule. Key Equipment Considerations For Obtaining The Best View The most common arthroscopes are 2.7 mm and 4.0 mm in diameter. Although the 2.7-mm size is more maneuverable within the ankle joint, one must exercise a considerable amount of caution in order to avoid damaging the scope. It is easy to concentrate solely on the viewing screen and not realize the camera is torqued. I use the 4-mm arthroscope for most ankle procedures unless there is significant joint damage and little joint space is available. There are several lenses that are angled to varying degrees. The angles create obliquity within the field of vision. Once a surgeon is experienced with arthroscopy, altering the obliquity to gain vision of different areas within the joint is extremely helpful. The most common angle to use on the 4-mm arthroscope is 30 degrees. Whether you place the camera within the medial or lateral portal will typically be dictated by the pathology you are treating. In general, placing the camera within the anteromedial portal will allow you to see the medial gutter, the anterior joint line and some portions of the lateral gutter. Placing the camera laterally will only emphasize the opposite structures. Other Essential Pearls To Keep In Mind It is important to remember that not all ankle joints will be easy to enter. In certain instances, debridement of hypertrophic synovium or adhesed capsule may be necessary to adequately maneuver within the joint. A common surgical error is not fully entering the ankle joint and assuming that hypertrophic tissue is obscuring the view. This leads to debridement of healthy capsule and allows fluid within the joint to spread into the subcutaneous tissues. Once you are inside the joint, you should first orient yourself and then routinely check for synovitis, instability and cartilage derangement. One may also evaluate numerous other intraarticular problems based on the patient’s particular pathology. Using distraction devices, both invasive and noninvasive, can enhance access to different areas of the ankle joints. However, be aware that these devices can increase complications associated with this procedure as well.4 When employing the two-portal technique, you may need to exchange the camera between portals to evaluate the joint completely. Hand instruments include varying forceps, probes and knives. Surgeons often use power instruments in arthroscopic ankle procedures with the most common instrument being a shaver. A shaver can significantly reduce the amount of time needed to thoroughly debride an inflamed joint. Closure of the incisions is based on preference. Often, one may not suture one portal, leaving it open or steri-stripped in order to allow drainage of excess fluid. In Conclusion Post-op care following ankle arthroscopy is based on the type of pathology you are treating. In simple diagnostic procedures with debridement, I usually allow full weightbearing and encourage active range of motion. In more extensive procedures, including chondroplasty or cartilage transfer, non-weightbearing is vitally important to the surgical success. Although arthroscopy may have lower complication rates than comparable open procedures, there are potential problems that you should keep in mind. Neurovascular, tendinous and cartilaginous damage have all been reported as well as infections, painful scarring and broken equipment.5,6,7 My own complication rate seems to increase when I use invasive distraction devices. Ankle arthroscopy is a versatile surgical tool for both diagnosis and treatment of articular disorders. When it is used effectively, it can provide many patients with a quicker recovery and less perioperative morbidity than many traditional surgical approaches. Dr. Burks is a Fellow of the American College of Foot And Ankle Surgeons, and is board-certified in foot and ankle surgery. Dr. Burks practices in Little Rock, Ark. Editor’s Note: For previous “Surgical Pearls” columns, check out the archives at www.podiatrytoday.com.
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