Ankle Arthroscopy

CHAPTER PREVIEW

CHAPTER SYNOPSIS:

Ankle arthroscopy is becoming a more useful procedure to treat and possibly prevent ankle arthritis. Synovectomy, loose body removal, “meniscoid lesons,” repair of osteochondral lesions, and adjunctive to tibial plafond reconstruction are proving to be useful clinical tools against arthritis.

IMPORTANT POINTS:

1

Examine the ankle under anesthesia before and after the procedure.
2

Some degree of joint distraction is helpful; “soft traction” is best.
3

The smaller scopes (2.7 or 2.9 mm) are best to use for the ankle.
4

Portal location is important, not only to avoid injury but also to enhance joint visualization.

CLINICAL PEARLS:

1

Examine the joint in a systematic fashion and try to see the whole joint.
2

Learn to use the posterolateral portal.
3

Avoid overinflating the ankle; inflating the anterior fat pad may limit visualization.

CLINICAL/SURGICAL PITFALLS:

1

Avoid nerve injury through care placement and blunt dissection.
2

Clear soft tissues before using a bur on osteophytes.

VIDEO AVAILABLE:

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Ankle scope.

HISTORY/INTRODUCTION/SCOPE OF THE PROBLEM

Ankle arthritis in a young patient will likely be due to previous trauma. The degree of trauma that the ankle has undergone is highly variable but most frequently will consist of a history of recurrent ankle sprains. In the instances where the degeneration present is the result of a previous intra-articular fracture, the amount of arthritis found will likely be more pronounced and in a more diffused manner, which will make ankle arthroscopy a less than ideal surgical technique for treatment. For these cases, the authors refer the reader to some of the following chapters of this textbook.

The technique for ankle arthroscopy was developed in the late 1970s by the collaborators of Dr. Takagi. Since then, many portals have been defined and some of them continue to be controversial. The most universally accepted portals are the anteromedial and anterolateral portals. The central anterior portal has fallen out of favor because of a high number of complications. Similarly, accessory anteromedial and anterolateral portals have been described to increase access to the gutters of the ankle. Among the controversial portals are the posteromedial and, to a lesser degree, the posterolateral portals. The proximity of these portals to neurovascular structures increases the risk for intraoperative or postoperative complications. Several anatomic studies have proved that these portals are reasonable to be used, although they have a higher risk for complications than the anterior ones.

SURGICAL TECHNIQUE

The equipment required for ankle arthroscopy is fairly basic. It is recommended to use a 2.7-mm scope versus the standard 4.0-mm scope, to facilitate access to the ankle joint. The 4.0-mm scope will suffice to address pathology along the anterior compartment of the ankle joint, but for those joints without any significant laxity, it will be difficult to place the scope deep enough to have good visualization of the articular surfaces. A 30-degree scope will be the most frequently used lens, and in very few occasions, there will be a need for a 70-degree lens. Very rarely, the operator will require the more standard arthroscopic baskets or biters to address intra-articular pathology. The visualization of the ankle joint will be highly improved by the use of a high-pressure inflow. A high-pressure circuit may be created with the use of an arthroscopic pump or just simply with the use of gravity by having the saline bags at the highest possible level in the operating room. The ankle joint will not become a more difficult joint to work on after prolonged use of high-pressure inflow. When a pump is used, it can safely be set at 150 mm Hg with the advantage of keeping up with the high outflow from instruments like a bur or a shaver.

Ankle arthroscopy is more easily performed under some degree of joint distraction. To accomplish such distraction successfully, the patient will have to be placed supine on the operating table with his or her hips flexed to avoid translation of the patient toward the end of the table. The easiest way to position the table is by placing it in a Trendelenburg position and elevating the back of the table. Similarly, the foot of the table will have to be brought down. This position will reproduce a flexed hip while still maintaining adequate cerebral arterial flow and therefore not making it any more difficult for an anesthesiologist to manage the patient ( Fig. 5-1 ).

During the early years of ankle arthroscopy, the traction to the joint was applied to the ankle through skeletal distraction. Soft tissue distraction is currently more popular than the original rigid bony traction. Several soft tissue harnesses have been developed and are available, having very similar characteristics. The use of soft tissue traction not only makes its application significantly easier but also decreases the morbidity associated with the use of rigid traction. A total of 30 lb of traction may be applied to the ankle for 2 hours with a very low risk for developing neuropraxia of the nerves located around the ankle joint ( Fig. 5-2 A, B ). In some occasions, and especially when the majority of the work will be performed on the anterior compartment of the ankle, less traction may be applied to the ankle, just enough to keep the extremity stable during the procedure. In these circumstances, excessive traction may increase the tension across the most anterior structures, especially the neurovascular bundle, and increase the proximity to the anterior capsule, thereby also increasing the chances for an iatrogenic injury.

For the less experienced ankle arthroscopist, it is recommended at the beginning of the procedure to outline the profile of the ankle with a marker to delineate the tendinous and neurologic structures. The dorsal cutaneous branch of the superficial peroneal nerve can be easily identified by forced plantarflexion of the foot combined with forced plantarflexion of the fourth toe. In most occasions, the nerve can be visualized traveling near the lateral gutter of the ankle joint, and almost invariably it can be gently felt with palpation of this area. Following the identification of vital structures, it is also recommended to inject the ankle joint with 20 mL normal saline to facilitate the creation of the portals.

The anteromedial portal is created first. The location for the anteromedial portal is the “soft spot” of the ankle joint. The anatomic landmarks of that area are the most medial aspect of the anterior tibialis tendon and the most lateral aspect of the shoulder of the medial malleolus. Special precaution to avoid damage to nearby traveling saphenous vein is always recommended. Following the anteromedial portal, the anterolateral portal will be created. Insertion of a spinal needle helps to locate the skin incision for the portal. Having located the dorsal cutaneous branch of the superficial peroneal nerve should also help to determine whether placement of the portal should be medial or lateral to it. When addressing anterior pathology, it should be placed as lateral as possible. For access to the articular surfaces, especially medial lesions, it is more practical to locate the anterolateral portal more medially. After ideal placement of the portal is established, the spinal needle should then be introduced into the joint and placed in the joint space. Next, the orientation of the needle should be assessed. A needle pointing proximal means a too distal entry point and therefore the portal skin incision should have to be moved proximal. Similarly, a needle pointing distal should make the operator to move the skin incision for the portal distal for better access to the joint. Following creation of the anteromedial and anterolateral portals, the joint should be inspected with a probe.

Once the joint is entered, a few principles should be applied to facilitate the procedure. First, it is important to remember that the ankle joint is a very “shallow” joint. After a proper setup, the ankle joint and lower leg should remain horizontal. If a coronal plane at the level of the ankle is being visualized, the instruments should be positioned at least at 45 degrees or more from the vertical created by the coronal plane. Unlike the knee or the shoulder, any attempt to place the instruments in a more vertical position will make it increasingly difficult to get in and out of the joint and it will also increase the chances for chondral damage to the joint. Second, the working instrument should be placed in the portal on the same side as the pathology being addressed is located. The camera should be placed in the opposite portal. The shallowness of the ankle will not allow the surgeon to go across the joint and work on a lateral osteochondral lesion (OCL) from the medial portal. The most anterior aspect of the talus will be damaged if further efforts are made to reach across the ankle joint with an instrument.

The methodology for exploration and assessment of the ankle joint varies and depends on each individual. Several different methods have been described, and as long as the surgeon is consistent, any method should be valid. Special attention should be paid to the status of the joint as a whole and especially to the presence of loose bodies and the condition of the gutters. It is not infrequent, especially for the less experienced arthroscopist, to have some component of “tunnel vision” and to address only the area of pathology without having a sense for the condition of the remainder of the joint. Unexpected pathology amenable to treatment may be found during the initial inspection of the joint, and providing adequate treatment to it will only improve the benefit from surgery to the patient.

Posterior portals should be created to access the posterior aspect of the ankle joint. The patient should be placed prone with just enough traction to keep the extremity stable. Both the posteromedial and posterolateral portals should be placed at a level just a few millimeters proximal to the superior to the superior margin of the calcaneus tuberosity and next to the Achilles tendon margins. Because of the location of the medial neurovascular bundle, the medial portal carries a higher risk for complications during the procedure than the lateral one. Therefore, the lateral portal should be created first. Unlike the anterior portals, the instruments should remain in a more vertical position to identify the most posterior aspect of the ankle joint. It is unusual to find an anatomic space along the posterior aspect of the ankle joint and to have clear identification of the joint by simple placement of the scope. Prior to any debridement is absolutely critical to identify the flexor hallucis longus tendon or tendon sheath as a way to avoid creating any injuries to the posterior neurovascular bundle.

For the sake of facilitating the remaining of the description, it will be assumed that the lower leg and ankle are positioned prone and they will remain in a horizontal plane with the ankle in a neutral alignment. During the creation of the posteromedial portal, the instruments should be placed along the horizontal plane during the penetration of the skin and subcutaneous space, and eventually they should be rotated into a more vertical position once they approach the most posterior aspect of the ankle joint. To get instruments in and out through the posteromedial portal any other way will significantly increase the chances for complications and potential damage to the posterior neurovascular bundle. Once both portals are created and the instruments can be visualized, the area should be debrided to improve the visualization of the most posterior aspect of the ankle and to properly address the pertinent pathology. Constant visualization of the flexor hallucis longus tendon is imperative to avoid inadvertent damage to the posterior neurovascular bundle.

INDICATIONS

Anterior Ankle Impingement

Ankle impingement may be found on the anterior or posterior aspect of the ankle joint. When the impingement is located posteriorly, either an os trigonum or a prominent posterior process of the talus will be frequently found. This condition will not be covered in this chapter as it is not related to an arthritic process of the ankle and more likely to an overuse injury or syndrome of the ankle posterior joint.

Anterior ankle impingement (AAI) may be soft tissue or bony in nature. When a soft tissue AAI takes place, it is frequently secondary to previous trauma to the ankle joint and the creation of an increased and abnormal inflammatory response. The synovial tissue will have an excessive respond to an intra-articular hematoma. In some instances, formation of tissue may take place. Pseudo meniscus tissue has been described as a source of residual pain after an ankle sprain. The soft tissue AAI will not be discussed in this chapter.

Bony AAI was originally coined as “footballer’s ankle.” A clear etiology of the formation of anterior bone spurs for both the distal tibia and superior aspect of the talus is still unknown. For a long time, it was hypothesized that it was the result of traction osteophytes from the most anterior aspect of the capsule of the ankle joint. However, it has been point out recently that if this were the case, visualization of the osteophytes during an arthroscopic approach would be very difficult and the osteophytes could have not been visualized in their entirety. However, it is well accepted that the osteophytes remain 100% intra-articular for both the dorsal aspect of the talus and the distal aspect of the tibia. Visualization of the osteophytes usually is not a problem. In some instances, some hypertrophic synovitis may make visualization a little bit more demanding, but after debridement of synovial tissue, both osteophytes should be rather accessible.

Berberian et al. reported very elegantly on an anatomic description of the location and shape of the anterior osteophytes of the ankle joint. They reviewed a total of nine computed tomography (CT) scans from patients who underwent surgical resection of their anterior ankle osteophytes. They concluded that the distal tibia osteophyte will be located lateral to the midline and the dorsal talar osteophyte will occur more medial to the midline. They also emphasized the fact that the osteophytes do not contact each other and they have a more “scissoring” effect between the two. In addition, the distal tibia osteophyte has a wider base than the talar one.

The population most likely affected by AAI is constituted by athletic individuals with a history of being ankle abusers. Most likely, they would present in the late portion of their third decade of life or some time along their fourth decade. It is unusual for these patients to report on a single injury as a source of discomfort. A history of multiple episodes of minor trauma to the ankle will likely be present. Symptoms are described as pain and stiffness and having difficulties with dorsiflexion of the ankle joint. For those involved in jumping activities, most of the problems will arise from their limited ability to proceed with powerful takeoffs or vertical jumps due to the limited dorsiflexion. Chronic irritation will be present, and some occasional diffuse anterior edema may also be reported.

On physical examination, the patient will have some limited dorsiflexion and particularly some pain and difficulties with palpation of the most anterior aspect of the ankle joint. The ankle will not necessarily be unstable, although the presence of diffuse pain in an active individual should always trigger the clinician to consider instability among the differential diagnosis. Overall, the examination may be somewhat underwhelming and not impressive except for the presence of pain with palpation of the anterior osteophytes.

Imaging studies of the ankle can help to confirm the diagnosis. Plain radiographs of the ankle will show a long distal tibia anterior osteophyte and likely a dorsal talar osteophyte. It is unusual to need any other type of more sophisticated imaging to come to a definitive diagnosis. Scranton and McDermott described a radiographic classification with limited clinical use. The surgical treatment of the bone spurs will not be dictated or changed necessarily because of their descriptive classification, but it definitely helps to bring some uniformity and standardization when communicating among clinicians. Stage I represents a distal tibia osteophyte of less than 3 mm, stage II is an osteophyte along the distal tibia of more than 3 mm with osteochondral reaction, stage III is the presence of any tibial osteophyte along a talar osteophyte, and stage IV is the presence of anterior, lateral, medial, and posterior osteophyte formation with reduction of the joint space and serious arthritic changes ( Table 5-1 ).

TABLE 5-1

Classification of Anterior Bony Impingement of the Ankle Joint According to Scranton and McDermott

Grade	Description
Grade I	Synovial impingement: Radiographs show inflammatory reaction, up to 3-mm spur formation. Dorsiflexion stress view confirms impingement. Bright-light examination of lateral view confirms anterior soft tissue swelling.
Grade II	Osteochondral reaction exostosis: Radiographs show osseous spur formation larger than 3 mm. No talar spur present. Dorsiflexion view shows impingement. MRI confirms moderate osteoblastic and chondral hyperplastic reaction.
Grade III	Significant exostosis with or without fragmentation, with secondary spur formation on dorsum of talus, often with fragmentation of osteophytes.
Grade IV	Pantalocrural arthritic destruction: Radiographs suggest medial, lateral, or posterior degenerative arthritic changes.