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Flexible syndesmotic fixation is new gold standard to restore syndesmosis anatomy
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The distal tibiofibular syndesmosis uniquely contributes to ankle joint function by constraining the lateral articulation with the talus while its own conformation shifts throughout ankle range of motion. Altered syndesmotic alignment and constraint have been associated with diminished outcomes after surgery. Indeed, the incidence of postoperative syndesmotic malreduction has been variously reported and may be as high as 52%. Although the threshold parameters for diminished outcomes are not well defined, the acceptable tolerances are thought to be small.
Syndesmosis anatomy is principally comprised of the distal tibia incisura, lateral malleolus, anterior and posterior inferior tibiofibular ligaments, inferior transverse ligament and interosseous ligaments. A spectrum of anatomic variation has been described for each of these elements. Additionally, a large number of reports investigating various modes of surgically restoring syndesmosis anatomy and function have come out in the last decade. As a result, the use of anatomic ligament repair and suture button fixation are now supported as tools in the syndesmosis fixation armamentarium.
This article describes two-level suture button syndesmotic fixation, which is increasingly replacing traditional screw fixation of syndesmotic injuries in modern practice (Figure 1). The key updates on the technique include guidance on position of the fixation (Figure 2) and avoidance of medial neurovascular injury. These are described in surgical technique steps 5, 6 and 7.
Technique
1. Anatomic restoration of fibula length, alignment and rotation is the obligate first step in primary and revision fixation of the syndesmosis.
2. Various parameters and techniques have been described for assessment of syndesmosis alignment and stability. Whereas axial plane CT with comparison to contralateral limb is most accurate, it is not widely available intraoperatively. Intraoperative right and left ankle fluoroscopic comparison views incorporating the lateral projection are recommended. Open reduction of the syndesmosis is also recommended and corroborates the fluoroscopic assessment (Figure 3).
3. Prepositioning the foot in dorsiflexion is needed to reduce ankle subluxation, which may occur intraoperatively after higher energy injuries, such as ankle fracture dislocations. However, doing so to prevent overtightening of the syndesmosis has been dispelled as a value-added step and this maneuver has been shown to create a posteriorly subluxated fibula, thereby potentially contributing to malreduction.
4. A large reduction forceps may be used to align and provisionally compress the syndesmosis, but it should be used with caution as both the axis and magnitude of compression can independently contribute to syndesmosis malreduction through fibula rotation and translation (Figure 4).
5. Suture button fixation of the syndesmosis at divergent angles offers additional fibula rotational control over single-plane fixation without compromising tibiofibular mobility (Figure 5). These buttons should be inserted superior to the cartilaginous area of the syndesmosis. One suture button should be oriented in the anatomic axis of the syndesmosis, which has been shown to vary between individuals, but generally lies between the lateral apex of the fibula and the anterior half of the medial malleolus.
6. It is advisable to make a 1-cm long medial approach prior to drilling or passing the suture button medially due to the high risk of injury to the saphenous structures, which frequently lie on the anterior half of the medial malleolus (Figure 6).
7. It is important to not over-tension the buttons as this can overly constrain the syndesmosis. Once seated, the suture buttons do not freely toggle and shift.
8. Favorable indicators that the syndesmosis is functionally restored include a congruently reduced ankle on all fluoroscopic views, restored fluoroscopic syndesmosis alignment and stability compared to the contralateral side, and a syndesmosis that is well-aligned upon direct inspection.
Sources: Christopher W. Reb, DO; and Gregory C. Berlet, MD
Fixation aftercare
Following syndesmosis repair, early postoperative weight-bearing protocols have been shown to be safe and effective, particularly when flexible fixation was used, because implant fracture is not a concern. As soon as wound healing allows, weight-bearing to tolerance is initiated in a walking boot with physical therapy (PT) performed with open-chain, active ankle therapy exercises. As tolerated, the patient may transition to a lace-up ankle brace and PT with increasing levels of intensity.
Pearls and pitfalls
Whether to perform open deltoid ligament repair is a controversial area. Anatomic restoration of the deltoid ligament has been demonstrated to restore ankle kinematics and stability. Strategically, this can be used to help diminish talar subluxation in unstable ankles while undertaking syndesmosis reduction and fixation. Finally, the medial arthrotomy provides an opportunity for ankle cartilage inspection given the association of traumatic osteochondral defects with ankle fractures.
It is important not to overtighten the suture button. Just as positional and not compression screws were traditionally used for syndesmotic fixation, the suture button is functioning in a positional mode, preventing syndesmosis widening or too much translation. Over-compression of the syndesmosis has been demonstrated and is more common when the posterior malleolus has been fractured.
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- For more information:
- Gregory C. Berlet, MD, can be reached at Orthopedic Foot & Ankle Center, Westerville Medical Campus, 300 Polaris Pkwy., Suite 2000, Westerville, OH 43082; email: gberlet@gmail.com.
- Christopher W. Reb, DO, can be reached at Department of Orthopaedics and Rehabilitation, Division of Foot and Ankle Surgery, University of Florida College of Medicine, 3450 Hull Rd., Gainesville, FL 32607; email: christopher.reb@gmail.com.
Disclosures: Berlet reports he is a paid consultant for and receives research support from DJO Global; is a paid consultant for Artelon; receives IP royalties from and is a paid consultant for Stryker; is a paid presenter and receives research support from TissueTech; receives IP royalties from, is a paid consultant and paid presenter or speaker for and receives stock/stock options from Wright Medical Technology; and receives IP royalties and is a paid consultant and paid presenter/speaker for Zimmer Biomet. Reb reports no relevant financial disclosures.