Diagnostic Arthroscopic Examination



Diagnostic Arthroscopic Examination


RICHARD D. FERKEL

DAWSON S. BROWN



Arthroscopy of the ankle and foot is a useful diagnostic modality to evaluate pathology and determine appropriate treatment. However, it must not be used as a substitute for careful history, physical examination, and diagnostic testing. Its primary advantages over the other methods of evaluation are that it provides direct “eyeball” visualization of the internal structures of the ankle and foot and allows these structures to be evaluated dynamically. When used with the proper indications, it is virtually 100% accurate in diagnosing intra-articular disorders of the ankle and foot.


PORTALS

Portals provide an entry to visualize the structures of the ankle and foot. In this section, we will emphasize portals and diagnostic examination of the ankle; Chapters 14 and 16 discuss these principles in the hindfoot and forefoot.

Proper portal placement is critical to performing good diagnostic and therapeutic arthroscopy. If the portals are positioned improperly, visualization and instrumentation are impaired, making diagnosis and treatment more difficult. A thorough knowledge of ankle anatomy is necessary to avoid complications.


Anterior Portals

Three primary anterior portals are used in arthroscopy of the ankle: anteromedial, anterolateral, and anterocentral (Fig. 7-1A). The anteromedial portal is placed just medial to the anterior tibial tendon at the joint line. Care must be taken not to injure the saphenous vein and nerve traversing the ankle joint along the anterior edge of the medial malleolus. Just medial to the anterior tibial tendon at this site is a premalleolar depression or “soft spot” that often bulges in the presence of an effusion. The anterolateral portal is placed just lateral to the tendon of the peroneus tertius at or slightly proximal to the joint line. The position of this portal varies depending on the ankle pathology. Several nerve branches must be avoided during placement of this portal (see Fig. 5-11 in Chap. 5). The superficial peroneal nerve divides 6.5 cm proximal to the tip of the fibula into the intermediate dorsal and medial dorsal cutaneous branches.1 The intermediate dorsal cutaneous nerve passes over the inferior extensor retinaculum, crosses the common extensor tendons of the fourth and fifth digits, and runs in the direction of the third metatarsal space before dividing into the dorsal digital branches. The medial terminal branch of the superficial peroneal nerve, the medial dorsal cutaneous nerve, passes over the anterior aspect of the ankle overlying the common extensor tendons. It runs parallel to the extensor hallucis longus and divides distal to the inferior extensor retinaculum into the three dorsal digital branches. Between the anterolateral and anteromedial portals, an anterior central portal may be established between the tendons of the extensor digitorum communis. Placing the portal between the tendons helps to avoid injury to the neurovascular structures, including the dorsalis pedis artery and the deep branch of the peroneal nerve. The dorsalis pedis artery and the deep branch of the peroneal nerve lie deep in the interval between the extensor hallucis longus and the medial border of the extensor digitorum communis tendons. The medial branches of the superficial peroneal nerve must also be avoided when using this portal. In the past, use of this portal has been advocated to allow greater ease of passage of instruments and the arthroscope from the anterior and posterior compartment because of the different degree of concave curvature of the dome of the talus in the medial/lateral or coronal plane. However, in our experience, performing more than 2,500 ankle arthroscopies, use of this portal has never been necessary. Its use is strongly discouraged due to the increased potential for complications.


Accessory Anterior Portals

The accessory anterior portals are used in addition to the usual anteromedial and anterolateral portals. They can be useful while working in the tight spaces of the medial and lateral gutters for instrumentation or excision of soft tissue or bony lesions. Two accessory anterior portals are most commonly used: the anterolateral and the anteromedial (see Fig. 7-1B). The accessory anteromedial portal is established 0.5 to 1 cm inferior and 1 cm anterior to the anterior border of the medial malleolus. It is especially useful in facilitating the evaluation of the medial gutter and deltoid ligament, particularly for the removal of ossicles adherent to the deep portion of the deltoid ligament while visualizing from the anteromedial portal. The saphenous vein and nerve are at risk when establishing this portal.

The accessory anterolateral portal is established 1 cm anterior to and at or just below the tip of the anterior border of the lateral malleolus, in the area of the anterior talofibular
ligament. When visualizing ossicles from the anterolateral portal, an instrument can be inserted through the accessory anterolateral portal to facilitate removal as well as probing of the anterior talofibular ligament, the posterior talofibular ligament, and surrounding bony architecture. In addition, this portal can be used when performing arthroscopic lateral ankle stabilization (see Chap. 12).






FIGURE 7-1. Anterior anatomy. (A) Three anterior and two accessory anterior portals are used in ankle arthroscopy. (B) Surgery in the medial and lateral gutters can be done via the accessory portals. (Illustration by Susan Brust.)


Posterior Portals

Posterior portals are routinely used in ankle arthroscopy and may be established posteromedial, posterolateral, or directly through the Achilles tendon (trans-Achilles; Fig. 7-2A).

The posterolateral portal is the safest and most commonly used. It is located in the “soft spot” directly adjacent to the lateral edge of the Achilles tendon, ˜1.2 cm above the tip of the fibula; the exact level of the posterolateral portal varies depending on each patient’s anatomy. This portal is usually at or slightly below the joint line. Branches of the sural nerve and the small saphenous vein must be avoided with the posterolateral approach.

The trans-Achilles portal is established at the same level as the posterolateral but through the center of the Achilles tendon. It was originally designed to allow a two-portal instrumentation technique in the posterior aspect of the ankle, as well as to avoid injury to neurovascular structures lateral to the Achilles tendon. However, in our experience, this portal
does not allow easy mobility of the arthroscope and instruments and may lead to increased morbidity in the Achilles tendon region. It has been abandoned for these reasons.






FIGURE 7-2. Posterior anatomy. (A) There are three posterior portals and two accessory posterior portals in the ankle. Usually, only the posterolateral portal is used. (B) Note the relations of the posterior portals to the bony anatomy. (Illustration by Susan Brust.)

The posteromedial portal is made in the “soft spot” just medial to the Achilles tendon at the joint line, lateral to the flexor hallucis longus. This location protects the posterior tibial artery and tibial nerve. The calcaneal nerve and its branches may separate from the tibial nerve proximal to the ankle joint and traverse in an interval between the tibial nerve and the medial border of the Achilles tendon. Because of the potential for serious complications, the posteromedial portal is rarely used in supine arthroscopy, except in rare circumstances.



Accessory Posterior Portals

The accessory posterolateral portal is made at the same level as or slightly higher than the posterolateral portal. It is established 1 to 1.5 cm lateral to the posterolateral portal, and extreme caution must be exercised to avoid injury to the neurovascular structures (Fig. 7-2B). It is particularly useful for the removal of posterior loose bodies when posterior visualization is necessary and for the debridement and drilling of very posterior osteochondral lesions of the talus.






FIGURE 7-3. Preferred accessory posteromedial portal. (A) The portal is made between the posterior tibial tendon and flexor digitorum longus, behind the posteromedial corner of the medial malleolus. (B) and (C) Arthroscopic views in a right ankle showing the use of the posteromedial portal with excision and drilling of the posteromedial osteochondral lesion. B = arthroscopic view through the anteromedial portal of drilling the posteromedial osteochondral lesion through the accessory posteromedial portal. C = arthroscopic view from the posterolateral portal of the drillhole made in the posteromedial osteochondral lesion of the talus. (Illustration by Susan Brust.)

An alternative posteromedial portal (APM) through the bed of the posterior tibial tendon has been described.2 It is located just posterior to the posterior colliculus of the medial malleolus and requires incision and subsequent repair of the flexor tendon sheath, although the risk to the posteromedial neurovascular structures may be less than the traditional portal. We have developed a slightly different APM between the posterior tibial and flexor digitorum longus tendons, in the “soft spot” behind the posterior colliculus of the medial malleolus (Fig. 7-3A-C).







FIGURE 7-4. Double posteromedial portals for posterior ankle arthroscopy in the supine position. Notice the portals are placed in the trigonal area between the posterior aspect of the tibia and the anterior aspect of the Achilles tendon. These borders are palpated digitally. (Illustration by Susan Brust.)

Allegra and Maffulli have described double posteromedial portals for posterior ankle arthroscopy in the supine position. They used these two portals to treat pathology along the posteromedial hindfoot, including the ankle and subtalar region, with minimal complications3 (Fig. 7-4).






FIGURE 7-5. Anterior view. The transmalleolar and transtalar portals of the ankle. (Illustration by Susan Brust.)


Transmalleolar and Transtalar Portals

Transmalleolar portals may be used for various operative techniques to gain better access to osteochondral lesions of the talar dome. It is more frequently used on the medial side than on the lateral side because lateral talar dome lesions are located more anterior than those on the medial side, and the lateral malleolus is farther posterior than the medial malleolus. It is particularly useful for drilling Kirschner wires under arthroscopic control through the tibia or fibula into the talar dome using a small joint targeting drill guide. Bone grafting of certain osteochondral lesions of the medial dome of the talus has also been done through this portal (Fig. 7-5) (see Chap. 9 for a more detailed discussion of this subject).

Transtalar portals can be used to drill or bone-graft osteochondral lesions of the talus, especially medial lesions. The lateral transtalar portal is made in the sinus tarsi and is discussed further in Chapter 9 (Fig. 7-5).


SURGICAL TECHNIQUE (PREFERRED METHOD)

The patient is brought to the operating room and a popliteal block is performed by an anesthesiologist, as described in Chapter 6. Prophylactic antibiotics are given intravenously
and appropriate anesthesia is administered. The patient is then “paralyzed” by the anesthesiologist to facilitate maximum ankle distraction and is secured in the supine position with a thigh holder and hip support as detailed in Chapter 4. The extremity is then prepared and draped and all tendinous, bony, and neurovascular structures are carefully noted. Before starting the procedure, the ankle and foot, including the toes, should be plantar flexed and inverted so that the superficial peroneal nerve and its branches can be identified, if possible (Fig. 7-6).






FIGURE 7-6. The superficial peroneal nerve is checked preoperatively by plantar flexion and inversion of the ankle and foot. (Copyright, Richard D. Ferkel.)

After applying distraction across the ankle joint utilizing a noninvasive soft tissue strap, markings are made on the skin outlining the bony contours of the medial and lateral malleoli, the anterior joint line, and the course of the anterior tibial tendon. A line is drawn from the tip of the fibula to the Achilles tendon. The anteromedial portal is always established first because it is easier to access, has less risk of injuring neurovascular structures, and is most reproducible (Fig. 7-7).

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Sep 25, 2018 | Posted by in RHEUMATOLOGY | Comments Off on Diagnostic Arthroscopic Examination
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