Syndesmosis Injury From Diagnosis to Repair

Physical Examination, Diagnosis, and Arthroscopic-Assisted Reduction

Jeffrey Wake, DO; Kevin D. Martin, DO, FAAOS

Disclosures

J Am Acad Orthop Surg. 2020;28(13):517-527. 

In This Article

Treatment

Nonoperative

In the absence of gross instability or diastasis on imaging, nonsurgical management should be pursued. In lateral ankle sprains, early range of motion is ideal; by contrast, early mobilization in syndesmosis injuries may place unwanted stress at the distal tibiofibular joint. Nonoperative management should begin with immobilization and nonweight-bearing during the acute phase, first 4 days, and progressed to protected weight-bearing on days four through seven, followed by a focus on functional rehabilitation and return to sport/activity. During the immobilization period patients may participate in open-chain lower extremity exercises so long as they remain pain free and in controlled ankle motion (CAM) boot. Recovery from syndesmotic injury generally takes longer to recover than lateral ankle sprains. In an observational study of NFL players over a 5-year span, there was an average time loss of 2.5 weeks, 11.7 practices, and 1.4 games from syndesmotic injury compared with 1.25 weeks, 3.5 practices, and 0.3 games from lateral ankle sprains.[12] Recovery time for syndesmosis injuries can exceed 31 days.[13]

Operative

The first step in operative management of syndesmosis ligament injuries is reduction of the syndesmosis. This can be done open, arthroscopic, or closed. In isolated ligamentous injuries without fibula fracture, the fibula is typically externally rotated and laterally translated. Reduction is done with a bone clamp on the distal fibula to apply internal rotation and a second two-point reduction clamp from the anteromedial tibia to the posterolateral fibula 3 cm proximal to the plafond.[24,25] Reduction should be confirmed fluroscopically. Recent literature has suggested that previous methods of syndesmotic reduction have not been as effective as believed by the operating surgeon.[26] Definitive fixation can then be achieved by methods outlined below. When a Maisonneuve pattern exists, proximal fibula fracture associated with syndesmosis injury, it is important to restore length to the fibula as well as internal rotation and medial translation. When a distal fibula fracture exists with syndesmotic instability, anatomic reduction and stable fixation of the malleolar fractures should be obtained first and reduction of the syndesmosis as described above.

Syndesmotic Screw Fixation. Syndesmotic screw fixation (SSF) is a common technique to stabilize the syndesmosis; this is a proven method with decades of use, demonstrating good to excellent outcomes.[27] SSF provides immediate stability allowing healing at a low initial cost while the technique and equipment is also familiar to surgeons ensuring confidence. With the syndesmosis reduced and the ankle in a neutral position, the trans-syndesmosis screws are drilled lateral to medial at approximately 2 to 5 cm proximal and parallel to the joint line. The screw(s) should be angulated obliquely posterior to anterior at approximately 25° to 30°. An abundance of literature exists looking at multiple aspects regarding size, number of screws, cortices involved, location, and need for screw removal. Commonly, 4.5 mm or 3.5 mm screws are used; however, no evidence exists demonstrating the superiority of using larger screw size, although using 4.5 mm screws may allow for easier removal and may be less likely to break.[28] A concern with larger screws is that they may potentate a stress riser when compared with small screws on removal. Regarding the removal of screws, it is recommended to remove them once healing has taken place unless the hardware is broken.[29,30] SSF has also been associated with a significant percentage of malreduction, which has been suggested to be the strongest independent predictor of poor clinical outcomes (lower The American Orthopaedic Foot & Ankle Society [AOFAS] scores, decreased range of motion). The point must also be emphasized that the screws themselves do not cause malreduction, they simply maintain the position of fixation. The reduction before fixation is paramount in a fixed SSF. If malreduction is noted postoperatively, screw removal has been shown to allow for in situ reduction and restoration of syndesmosis motion.[31,32] Although hardware removal seems like a simple procedure, this may predispose the patient to additional unnecessary risks and costs. Lalli et al[33] concluded that the syndesmosis hardware removal places a substantial economic burden on both the patients and the healthcare system as a whole.

Suture-button Fixation. Suture-button fixation (SBF) of the distal tibiofibular joint has gained wide popularity over the use of syndesmotic screws. Although these techniques both achieve similar outcomes, mechanical and anatomic advantages exist to the SBF. After reduction of the fibula within the incisura, a guidewire is placed in the same position as a standard screw, 2 cm proximal to the joint line in approximately 25° to 30° of posterior-anterior direction. After the guidewire position is verified with fluoroscopy, a cannulated drill is passed ensuring all four cortices are breached. With multiple manufactures making SBF devices the surgeon must ensure familiarity with the chosen device. In general, a passing guidewire is used to position an oblong button device on the medial cortex of the tibia that is then flipped across the tunnel providing cortical fixation. The lateral button is sequentially tightening to lateral cortex of the fibula or fibular buttress plate. SBF is not without complications; osteolysis of the bone adjacent to the implant has been described along with subsequent subsidence of the device.[34] Early devices required multiple knots to ensure fixation that often left patients with palpable painful suture stacks and reports of abscess formation leading to osteomyelitis; however, newer devices have knotless suture fixation which has helped reduce these complications.[35,36] SBF does have a higher initial cost, but when compared with routine SSF hardware removal, the costs are much less. A study by Neary et al[37] evaluated the cost effectiveness between these two operative options demonstrating that treatment with SBF cost on average $1,482 less than patients treated with SSF. They go on to state that SSF only became more cost effective when the screw removal rate was less than 10%. Mechanically, the SBF mitigates malreduction even with poor clamp placement in a cadaveric study.[38] A randomized controlled trial also looked at this and found that there may be the same incidence of malreduction intraoperatively. However, owing to the dynamic nature of SBF fixation at the 2-year follow-up, there were markedly more cases of malreduction in the SSF group as demonstrated by CT.[39] Anatomically, SBF also allows microfibular motion because the native fibula externally rotates 3° with dorsiflexion. Owing to the more anatomic motion allotted with SBF, it does not need to be removed preventing the need for hardware removal or concerns of broken hardware.[40] Outcomes of SBF are favorable, multiple meta-analyses have been published demonstrating higher AOFAS scores and lower rates of postoperative complications, even earlier time to full weight-bearing when compared with SSF.[27,41] Anderson et al[42] published a randomized trial comparing SBF and SSF which demonstrated higher AOFAS scores, Olerud-Molander Ankle scores, lower VAS scores, and less widening at the minimum 2-year follow-up than did SSF. There have been questions regarding the use of one versus two suture buttons, studies have shown that one suture button has comparable outcomes with SSF and that using a second suture button may not significantly contribute to stability.[43,44]

Suture-button Fixation Plus Anterior-inferior Tibiofibular Ligament Augmentation. With the noted successes of SBF, some authors have founded concerns that the micromotion allowed may lead to inadequate stability,[45–48] but functional clinical studies are needed to define stability. Through the observation of lateral ankle ligament augmentation with suture tape for lateral ankle instability, it has been proposed that suture button fixation with additional suture tape augmentation of the AITFL may restore stability while preserving motion.[49] Teramoto et al first described this surgical technique in 2017 and we outline this technique (Video 1, Supplemental Digital Content 1, https://links.lww.com/JAAOS/A468). Using cadaveric models, Shoji et al[50] went on to complete a biomechanical study of this technique compared with suture-button fixation alone and screw fixation. They found that suture-button fixation alone did not provide stability to the syndesmosis and screw fixation was too rigid. Using suture-button fixation and additional AITFL augmentation, they achieved dynamic stability similar to intact models (Figure 7). This technique is yet to have long-term studies evaluating outcomes. In a study conducted looking at syndesmotic instability with posterior malleolus involvement, it was demonstrated that AITFL anatomic repair and augmentation had equivalent outcomes, reduction, earlier rehabilitation, and fewer complications when compared with SSF.[51] We have found this to be a beneficial technique in patients with a shallow tibial incisura (25% to 40%)[52,53] because of the inherent instability and predisposition to malreduction.[54]

Figure 7.

Photograph showing a revision suture button fixation with AITFL suture tape augmentation. A, Proximal insertion of the AITFL on the anterolateral tibia, Chaput tubercle; B, Distal insertion of AITFL at Wagstaffe tubercle on the fibula. AITFL = anterior-inferior tibiofibular ligament

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