Posterior Ankle Arthroscopy for Conditions Causing Ankle Pain: Os Trigonum, Posterior Ankle Soft Tissue Impingement, Flexor Hallucis Longus Stenosis, Haglund

CHAPTER 8 Posterior Ankle Arthroscopy for Conditions Causing Ankle Pain

Os Trigonum, Posterior Ankle Soft Tissue Impingement, Flexor Hallucis Longus Stenosis, Haglund’s Deformity, and Other Considerations

Posterior ankle arthroscopy is an increasingly used technique that allows the orthopedic surgeon to address a number of causes of posterior ankle pain.14 This minimally invasive technique has several advantages over traditional open surgical approaches to the posterior ankle, which can involve extensive dissection because of the depth of the ankle from the posterior skin. Concerns for wound healing problems in this hightensile area of skin are minimized by the use of small arthroscopy portals, which often eliminates the need for postoperative immobilization and speeding recovery. One concern with using arthroscopic techniques in the posterior ankle region is the potential for neurovascular injuries.5 However, with application of good anatomic knowledge of the posterior ankle region and the use of proper technique, this approach has proved to be safe and effective.36 The magnification provided by the arthroscope allows the surgeon to work with greater precision and enhances the safety of the procedure. Several common causes of posterior ankle pain that are readily treated with posterior ankle arthroscopy are described in this chapter.


Os trigonum syndrome has been described in association with posterior ankle impingement in activities involving extreme plantar flexion, such as classical ballet and soccer. Also, a symptomatic os trigonum can be associated with tenosynovitis of the flexor hallucis longus (FHL) tendon.710

Treatment Options

Arthroscopic Technique

The patient is placed in the prone position, and a thigh tourniquet is typically used to avoid tethering of the muscles of the posterior leg. The knees are padded, and a bump is placed anterior to the distal tibia, with the ankle and foot allowed to hang over the end of the table so that the ankle and hallux can be passively dorsiflexed during the procedure. Distraction is not needed, and the arthroscopist can lean against the sole of the foot to increase dorsiflexion, minimizing the need for assistance.

The ankle joint is marked anteriorly by placing a skin marker across the joint line of the dorsiflexed ankle. Two portals are made on either side of the Achilles tendon, 1 to 2 cm inferior to the anterior ankle joint line at approximately the level of the tip of the fibula (Fig. 8-2). This position allows adequate access to the ankle and subtalar joints. Alternatively, fluoroscopy can be used to confirm portal position. After the skin incisions are made, it is essential to use a fine, straight hemostat to spread tissues anterior to the Achilles tendon and make a puncture directly in the midline through the fascia separating the superficial and deep posterior compartments (Figs. 8-3 and 8-4). After this ventral fascia is penetrated, the hemostat is directed laterally and then advanced anteriorly in a posterolateral position behind the ankle. The hemostat can then be spread during removal to open the fascial opening. This is performed from both portals. It is important to maintain this method of placing instruments into the deep posterior compartment. Introducing instruments through this midline fascial opening from the superficial posterior compartment and initially directing instruments laterally protects the posteromedial neurovascular structures (Fig. 8-5).

Initially, the arthroscope is placed through the medial portal and a soft tissue débrider through the lateral portal. Loose connective tissues behind the ankle joint are removed to demonstrate the superficial posterior tibiofibular ligament (PTFL) (Fig. 8-6). The ankle is dorsi and plantar flexed to identify the articular margin, and the os trigonum posterior to this point can then be cleared of lateral soft tissues. Some fibers of the posterior talofibular ligament are attached to the os trigonum, but the remainder of the PTFL attachment onto the talus should be preserved (Fig. 8-7). The subtalar joint is identified, and the clearing of soft tissues around the os trigonum continues, using the joint line of the ankle and subtalar joint as boundaries. Medially, the FHL tendon can be identified by moving the great toe into dorsiflexion. The FHL is used to mark the most medial boundary of the dissection (Fig. 8-8). The proximal attachment of the FHL tunnel is released from the os trigonum, which also serves to release the FHL, relieving any stenosis of the muscle or tendon simultaneously. At this point, the scope should be able to visualize the os trigonum well, and a freer elevator or similar blunt elevator can be used to probe the os and the fibrous junction between the os and the posterior talus (Fig. 8-9). In many cases, this junction can be loosened with a combination of the freer elevator and the shaver. Alternatively, a bipolar or unipolar cautery device may be used to strip the soft tissues, including the posterior talofibular ligament and the attachment of the FHL tendon sheath, from the os trigonum. After it is free, the os trigonum can be removed with a hemostat through either portal, although the posterolateral portal often works better (Fig. 8-10). It may be necessary to extend the portal enough to allow for the removal of a large os in some cases. Final inspection and débridement of the edges of the excision site can be performed. It is not uncommon for the calcaneal articular surface of the subtalar joint to be exposed posteriorly, because the os trigonum often has an articular surface that corresponds to the calcaneal side of the joint (Fig. 8-11).

A word of caution is warranted about the use of an osteotome in cases of partially fused os trigonum or large trigonal processes. The angle achieved with an osteotome is often not steep enough to avoid penetration of the posterior talar body and can extend too far anteriorly, even with extreme dorsiflexion of the ankle joint. A curved osteotome may give a false sense of avoiding this problem. In some cases, it is best to use an arthroscopic burr to remove bony prominences rather than to perform an unintended osteotomy into the talar body. The portals can be closed with 3-0 nonabsorbable suture, and a bulky, soft dressing can be placed.



“Posterior ankle impingement syndrome” was long used as a general phrase to describe posterior ankle pain that is worsened with plantar flexion of the ankle.15,16 Over time, a more anatomic approach to diagnosing the cause of posterior ankle pain has evolved, and posterior ankle soft tissue impingement is now recognized as a separate, although often associated, condition resulting from posterior bony impingement. Posterior ankle soft tissue impingement results from either a tear of the deep portion of the PTFL from the posterior rim of the tibial plafond or a tear of the posterior portion of the deep deltoid ligament (DDL).1719

Normal and Pathologic Anatomy

The ligaments of the posterior ankle have been well described and are pictured in Figure 8-6.20 The PTFL is composed of a deep and a superficial component. The superficial fibers are visible from the posterior view and fan out in a superior and medial direction from the fibular attachment to attach broadly on the tibia. The deep portion is a thick band that lies anterior to the superficial ligament and extends across the back of the ankle joint to the medial malleolus. It is not easily seen from the posterior view in an intact specimen. The deep band forms a labral rim of the posterior tibial plafond and increases the coverage of the posterior talus.

When the deep band is torn from the attachment on the tibial plafond, it becomes hypermobile and can displace into or out of the ankle joint, creating painful impingement symptoms. If the torn ligament is unstable, it usually lies in an inferior and more posterior position and can then be readily visualized from the posterior arthroscopic view (Fig. 8-12). If posterior impingement is suspected and the ligament is not visualized in this manner, a probe can be passed into the ankle joint and stability can be tested by pulling posteriorly on the ligament to determine whether it is displaced out of the joint. From the anterior arthroscopic view, posterior impingement is often not easily visualized with joint distention, but the ligament can be displaced into the ankle joint with posterior pressure, giving clear evidence of the instability and impingement.

After débridement of the unstable deep PTFL is completed, the posterolateral talar dome is well visualized (Fig. 8-13

Jun 19, 2016 | Posted by in MUSCULOSKELETAL MEDICINE | Comments Off on Posterior Ankle Arthroscopy for Conditions Causing Ankle Pain: Os Trigonum, Posterior Ankle Soft Tissue Impingement, Flexor Hallucis Longus Stenosis, Haglund
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