Syndesmotic injuries often result from an external rotation force applied to a hyperdorsiflexed ankle while the foot is planted. This mechanism causes the fibula to externally rotate while translating posteriorly and laterally, resulting in rupture of the anterior inferior tibiofibular ligament (AITFL) first, followed by the deep deltoid ligament, interosseous ligament (IOL), and lastly posterior talofibular ligament.24 Most syndesmotic injuries involve rupture of only the AITFL and IOL.25 Multiple clinical stress tests have been designed to assess syndesmotic stability, including the squeeze test, external rotation stress test, crossed-leg test, and fibula-translation test.26-29 However, no physical examination maneuver has been shown to reliably predict the presence or degree of syndesmotic injury and therefore imaging studies are necessary.30
Initial imaging should include standing radiographs of the affected ankle. An increase in the medial clear space between the medial malleolus and talus can occur with a combined syndesmotic and deltoid disruption. In the case of subtle syndesmotic injuries, contralateral comparison weight-bearing radiographs are recommended. CT and MRI can provide additional information, but these static imaging tests cannot identify instability. Fluoroscopic stress evaluation is beneficial but has a high false-negative rate in low-grade injuries and may not detect partial rupture of the AITFL and IOL.31 It has been shown that malrotation of as much as 30° of external rotation can occur if relying on intraoperative fluoroscopy alone.32 It has been our practice to recommend surgical reduction and stabilization for any syndesmotic injury with documented diastasis or instability seen on imaging and/or arthroscopy.
Nonoperative treatment is indicated for truly stable grade I syndesmotic injuries. This involves rest and immobilization followed by a progressive rehabilitation program consisting of stretching, strengthening, and proprioceptive exercises.33 After 1 week of protected weight-bearing in a cast or tall CAM boot, progression to full weight-bearing should occur over the following week. Active-assisted ankle ROM exercises and light proprioceptive training should then be initiated followed by sport-specific exercises 2 to 3 weeks after injury.
Arthroscopy can be a valuable diagnostic tool in the setting of subtle syndesmotic injury with negative radiographs, positive MRI for edema, and a protracted recovery course with vague pain (Figures W5A-W5E).
Figures W5A-W5E
Implants are placed above the true syndesmotic joint (at least 15 mm above the tibial plafond) angled 30° posterior to anterior to follow the normal relationship of the fibula to the distal tibia in the incisura. Typically 2 suture-buttons are used, with the devices placed in a divergent fashion. We highly recommend the use of a fibular buttress plate with button placement in individuals returning to contact activity. This construct increases surface area distribution while preventing stress risers and the risk of fibula fractures. In a cadaver model with deliberate syndesmotic malreduction, suture-button stabilization resulted in decreased postoperative displacement as opposed to conventional screw fixation.34 Therefore, dynamic syndesmotic fixation may help to decrease the negative sequelae of iatrogenic clamp malreduction. Postoperative rehabilitation involves NWB in a cast or tall CAM boot for 4 weeks followed by ankle ROM exercises and progressive weight-bearing and physical therapy. Patients are transitioned to a lace-up ankle brace and athletic shoe from 6 to 12 weeks postoperative with increasing activity. Running and jumping is permitted 4 months after surgery with RTP typically at 6 to 7 months. Athletes who have had surgical stabilization for documented instability without any diastasis may engage in a more rapid recovery and RTP as symptoms and function allow.
Deltoid Complex Avulsion
Missed or neglected deltoid ligament injuries can lead to progressive chondral injury and joint degeneration. These injuries are often subtle and difficult to diagnose. An inability to perform a single limb heel rise, persistent pain with activity, and lack of normal functional improvement despite appropriate care are indicators of subtle ligament instability. These injuries often require an examination under anesthesia with combined ankle arthroscopy. Valgus stress testing of the ankle while directly visualizing the deltoid ligament from the anterolateral portal can reveal medial laxity in addition to potential osteochondral lesions along the anterolateral talar dome.
In American football players, we have observed that infolding and retraction of an avulsed superficial deltoid ligament complex after an ankle fracture, Maisonneuve injury, or severe high ankle sprain can be a source of persistent increased medial clear space, malreduction, and postoperative pain and medial instability. We have found that there is often complete avulsion of the superficial deltoid complex off the proximal aspect of the medial malleolus during high-energy ankle fractures in football players that is amenable to direct repair to bone (Figures W6A-W6E).
Figures W6A-W6E
During surgical repair, an incision is made along the anterior aspect of the medial malleolus and the superficial deltoid ligament complex can often be found flipped and interposed in the medial gutter. A rongeur is used to create a bleeding cancellous bone surface for soft-tissue healing and 1 to 2 suture anchors are used to repair and imbricate the deltoid ligament complex back to the medial malleolus. The goal of these sutures is to repair the tibionavicular and tibial spring ligaments back to the medial malleolus. We believe that superficial deltoid complex avulsion during high-energy ankle fractures is a distinct injury pattern that should be recognized and may benefit from primary open repair.
We currently open explore every deltoid ligament complex in athletes with unstable syndesmotic injuries, as we believe that deltoid avulsion injuries are underrecognized and do not heal in an anatomic fashion if left alone. Postoperative recovery follows the same immobilization, progressive weight-bearing, and physical therapy protocol as that for syndesmotic disruption.