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The deltoid ligament plays a key role in ankle fracture treatment.
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Superiority of suturing the deltoid ligament in all ruptures is not proven.
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There may be additional advantage of deltoid ligament repair in cases of deltoid and syndesmotic insufficiency.
Introduction
Deltoid ligament ruptures are seen in all shapes and sizes. In ankle fractures, a deep deltoid ligament rupture is the equivalent of a medial malleolus fracture. It usually renders the ankle joint unstable
and is therefore in most cases an indication for surgery: open reduction and internal fixation of the fibula fracture and in some cases fixation of the posterior malleolus or placement of syndesmotic screws.
If the deltoid ligament is partially ruptured, the ankle joint might be stable or unstable. Sometimes there is a combination of a medial malleolus (anterior colliculus) avulsion fracture and a deep deltoid ligament rupture.
Historically, there have been several steps in the evolution of understanding of ankle fractures. Maisonneuve, Danis, Weber, Lauge-Hansen and many others contributed greatly, and their names are forever bound to ankle fractures.
The importance of the deltoid ligament in ankle fractures has been subject to many investigations. To diagnose a deltoid ligament injury correctly is of paramount importance. Conservative treatment of unstable fractures renders poor outcomes compared with operative treatment.
The authors consider recognizing and understanding instability of the bimalleolar and trimalleolar ankle fractures the first priority. This article addresses the question of which acutely ruptured deltoid ligaments that are part of an ankle fracture could benefit from suturing in order to help restore ankle stability.
Epidemiology
Supination external rotation is the mechanism that causes approximately 80% of all ankle fractures. The frequency of injury to the deltoid ligament in supination external rotation fractures is higher than previously expected.
The most common injury mechanism for ankle fractures with concomitant deltoid ligament injury is a supination external rotation type 4 trauma according to the Lauge-Hansen classification. The mechanisms underlying supination external rotation and pronation external rotation fractures are similar. The difference is the position of the foot at the moment of external rotation. With a foot in pronation, there is initial tension on the medial structures. A lateral fracture resulting from pronation external rotation is unstable because there is always a medial fracture or deltoid rupture. Moreover, Rasmussen and colleagues
found that the deep portions of the deltoid ligament in particular, which are thought to be the main stabilizers, could rupture in external rotation, whereas the superficial components remain intact.
Diagnosis and imaging
In the acute setting, malalignment, ecchymosis, and profound edema of the affected ankle can be found. It has been shown that clinical examination is a poor indicator for deltoid ligament injury, with an accuracy of 42%,
so additional diagnostics are often a necessity. This finding is related to the specific portion of the deltoid that is injured: when clinical symptoms are present, it may be likely that there is a soft tissue injury. This injury could consist of only the superficial deltoid ligaments with intact deep structures. The superficial ligaments provide a minor contribution to the medial stability of the ankle. The deep deltoid often ruptures off the medial aspect of the talus, and the superficial deltoid usually ruptures off the anterior distal tibia. Additional diagnostics primarily consist of conventional imaging focusing on the medial clear space (MCS) where widening can be found; 4 mm in a nonstressed mortise view and/or a superior tibiotalar clear space greater than 1 mm are considered pathologic. Moreover, normal values are reported to vary from 1 to 5 mm.
An MCS of more than 4 mm, with that value being at least 1 mm greater than the superior tibiotalar space, is accepted to represent a deep deltoid ligament rupture. On stressed mortise views, an MCS greater than 5 mm is considered pathologic.
Indications for surgery have been an MCS greater than 4 mm, MCS 1 mm or greater than the superior tibiotalar clear space, or any lateral talar shift seen perioperatively after fracture fixation. Ultrasonography is a promising modality, with up to 100% sensitivity and specificity reported,
but is often difficult to incorporate in an emergency department setting because of its time-consuming nature and the expertise required. MRI is considered by many to be the gold standard,
but also has not found its way into standard emergency ankle fracture care because of the high costs. There has been no level 1 study performed assessing the role of ultrasonography and/or MRI in the initial diagnostic pathway of ankle fractures. Intraoperatively, the diagnosis of a deltoid ligament rupture can be made by manual stress testing under fluoroscopy, or with a hook test. The hook test is used mainly to test syndesmotic stability, but, when lateralization of the talus is seen, this is proof of a deltoid ligament rupture (Figs. 1 and 2). The role of arthroscopy in detecting medial ligamentous injuries has been well investigated.
Deltoid ligament and tibiofibular syndesmosis injury in chronic lateral ankle instability: magnetic resonance imaging evaluation at 3T and comparison with arthroscopy.
Fig. 1The hook test is used mainly to test syndesmotic stability. (A) A typical trimalleolar fracture with a medial malleolus fracture, intact deltoid, and a Weber B–type fibula fracture. (B) After medial malleolus fixation, the talus is held underneath the talus. After fibula fixation, the syndesmosis can be tested. (C) A positive hook test shows syndesmotic insufficiency. Source: authors’ drawing.
Fig. 2When lateralization of the talus is seen, this is proof of a deltoid ligament rupture. (A) A typical trimalleolar fracture with a deltoid ligament rupture and a Weber B–type fibula fracture. (B) After plate fixation of the fibula, the interosseous membrane/ligament stabilizes the mortise, but usually not sufficiently. (C) A positive hook test shows syndesmotic and deltoid insufficiency. Source: authors’ drawing.
Many (narrative) reviews on whether to suture the deltoid ligament or not have been performed. There is a lack of high-quality studies with suturing the deltoid being the primary question. In 1987, Baird and Jackson
performed a review of the literature on this topic. They found 12 articles that advocated surgical repair of the ligament and 9 studies that reported adequate results without surgical repair. However, the primary objective of these studies was not to evaluate the need for deltoid reconstruction, and the outcomes reported were to current standards rather than being descriptive and surgeon centered.
More recent reviews do show a trend toward concluding that there is an indication to suture the deltoid ligament, but up to the choice of the surgeon in which selected cases this is necessary.
One recent meta-analysis including 3 studies concluded that deltoid ligament repair in ankle fractures with a widened MCS showed a better anatomic reduction of the ankle, lower pain scores at final follow-up, and no significant increase in complication rate.
Studies in Favor of Not Suturing the Deltoid Ligament
The authors found 4 comparative studies, with the need for suturing of the deltoid ligament as the primary question, that found it not necessary to explore and to reconstruct the deltoid ligament (Table 1).
The general consensus was that only if there is interposition on the medial side after adequate reduction in the fibular fracture is an exploration of the MCS required. Furthermore, there are several noncomparative studies specifically addressing the topic. Harper
treated 36 bimalleolar ankle fractures with the deltoid ligament equivalent without suturing the medial injury. The conclusion was that the deltoid ligament heals sufficiently with nonoperative treatment. Likewise, Zeegers and van der Werken
followed 28 patients with deltoid ruptures in ankle fractures for 18 months. All were not sutured. They concluded that, after anatomic reconstruction of the lateral malleolus with perfect congruity of the ankle mortise, there is no need to explore and suture the ruptured deltoid ligament. Another well-cited report is from Tourne and colleagues.
They treated 33 patients with fractures and followed them for 27 months, concluding to leave the ligament tears unexplored (medial, tibiofibular, and syndesmotic). As a result of these earlier studies, the current standard of practice in many centers is to restore the mortise anatomically and leave the deltoid complex to heal without direct surgical intervention.
Table 1Studies in favor of not suturing the deltoid ligament
The authors found 4 comparative studies with the need for suturing of the deltoid ligament as the primary question that found it necessary to explore and to reconstruct the deltoid ligament (Table 2).
The general consensus was that deltoid repair is able to restore congruity to the ankle joint, avoids the need to remove symptomatic syndesmotic implants, and is able to better reduce the MCS than syndesmotic implants. Furthermore, several noncomparative studies show that the deltoid ligament suture procedure is safe and effective.
Surgical repair of the deltoid ligament is helpful in decreasing the postoperative MCS and malreduction rate, especially for the AO/OTA type C ankle fractures
Although the clinical outcomes were not significantly different between the 2 groups, a more favorable final follow-up MCS was obtained in the deltoid repair group
Deltoid ligament repair with a suture anchor had good functional and radiologic outcomes comparable with those with syndesmotic screw fixation but has a lower malreduction rate
Abbreviation: AO/OTA, AO Foundation/Orthopaedic Trauma Association.
the general technique is as follows: an incision over the medial malleolus is made and an anteromedial arthrotomy is performed. The talar dome and medial gutter are inspected as well as the superficial and deep deltoid branches. The quality of the deltoid remnants is judged. Reinsertion to the medial malleolus or talus is performed by suturing directly to the bone, with suture anchors or with tape/graft through bone tunnels. In some cases, the tip of the malleolus or talus is prepared with a rongeur to promote osseoligamentous integration. In general, the primary ligamentous repair is achieved by using an absorbable suture material. Differences in surgical techniques are mostly related to the use of suture anchors to reinforce the repaired ligament, either which implant is used or whether implants are used at all. The suture anchors are used according to the manufacture’s guidelines. Fluoroscopy is almost always used to ensure proper positioning of anchors and of the talus in the mortise. Manual stress testing is often applied to confirm appropriate MCS. Postoperatively, it is common practice to immobilize the patient in a short-leg cast for 2 to 6 weeks followed by aggressive range-of-motion and strengthening exercises under physical therapist guidance.
performed a systematic review after deltoid ligament repair and found complication rates to be lower in the repair group versus the nonrepair group (P = .0225). Superficial infection, medial instability, medial suture intolerance, algodystrophy, degenerative arthritis, and reoperation because of syndesmotic screw malposition were seen in the repair group, adding up to a total complication rate of 6.6%.
The (extensive) medial approach results in a higher risk of wound breakdown and possible sequential wound infection. In nonaugmented non–allograft-reinforced repairs, the quality of the remnants is essential, as is the suture technique. In addition, the postoperative rehabilitation protocol should be as functional as possible to avoid a stiff ankle; however it must also protect the reconstruction.
found a complication rate of 15.3% in the nonrepair group. Superficial infection, medial instability, reoperation because of syndesmotic screw malposition, failure, and reoperation because of symptomatic malreduction were seen. Nonanatomic healing of the deltoid ligament is the main concern because it can lead to substantial ankle instability with forthcoming posttraumatic instability osteoarthritis. Zhao and colleagues
reported substantial complications in the nonrepair group, which were not seen in the repair group, and these were all related to malreduction, with some requiring reoperation. However, medial instability has also been shown to result after both repairing and not repairing the deltoid ligament.
The superficial component of the deltoid ligament is thin and weaker than the deep part and is under tension during external rotation of the ankle when the foot is in plantar flexion. Therefore, fixation of small anterior fractures of the medial malleolus, to which only the superficial portion of the ligament attaches, may not be sufficient to restore medial stability.
General principles of ankle fracture treatment are based on restoring the mortise congruity and stability, in an attempt to avoid future posttraumatic arthritis.
Historically, this is done by means of fracture fixation with or without ligamentous stabilization. If rendered stable, early range-of-motion exercises are commenced as soon as tolerated. If the bony fixation is not stable, surgery is followed by plaster immobilization. If the ligaments are not augmented or repaired strongly, the plaster immobilization indirectly and statically allows the ligaments to heal. Although the lateral column is important, restoring fibula length and position, the medial column is probably more essential because the deltoid ligament is the medial restraint holding the talus under the tibia firmly, allowing less than 1 mm of lateralization.
focusing on rapid recovery. They proposed to treat grade I and II sprains nonoperatively, whereas unstable grade III injuries with associated lateral ligament injuries may benefit from early surgical repair.
Early surgical repair has been advocated in athletes to ensure a rapid return to activity; although these studies are small regarding power and low in level of evidence, their reports on the low number of complications is favorable for surgical reconstruction adepts.
Future work should focus on 2 elements: the quality of direct repair/nonrepair comparative studies must be strengthened by means of level I randomized trials. Second, because research and development on anchors has improved over the years, these must be evaluated by means of rigorous clinical trials. Based on the currently available evidence, it is impossible to state whether there is a superior technique.
In cadaveric models of ankle fractures with deltoid ligament and/or syndesmotic disruption, joint contact forces remained abnormal even after anatomic reduction of the syndesmosis. Deltoid ligament repair after fibular fixation restored the position and stability of the talus in all planes of motion compared with the intact state. This outcome was not achieved with fibular fixation alone.
showed that joint contact areas were decreased by 43% and peak cartilage pressures were increased by 30% after sectioning of the deltoid ligament. These findings support the clinical notion that a deltoid ligament rupture has to be put in a cast to heal, whereas a sutured deltoid ligament could render the ankle stable to perform early range-of-motion exercises.
The deltoid ligament has a close relationship with the syndesmotic ligaments.
When the syndesmosis is injured in isolation, an intact deltoid ligament restrains lateral talar displacement, and thereby tibiofibular diastasis, by indirectly tethering the distal fibula through the talus. In turn, when the deltoid ligament is additionally disrupted, this restraint is lost, generating the opportunity for syndesmotic instability. In cases where the syndesmotic stabilization is insufficient, the combination of deltoid ligament and syndesmotic rupture is a recipe for failure (Fig. 3). In these cases, additional deltoid ligament repair could strengthen the construct and stabilize the mortise. The study by Woo and colleagues
supports this clinically: a post hoc subgroup analysis was conducted in which only patients who also had syndesmotic injury were included. In this subgroup analysis, clinical outcomes were all superior in the deltoid repair group. These results suggest that deltoid repair may be clinically beneficial in patients who not only have deltoid rupture but also have syndesmotic injury.
The 2 repairs may reinforce each other and facilitate healing, especially in high fibula fractures (such as Maisonneuve fractures).
Fig. 3In patients with deltoid and syndesmotic insufficiency (such as this Maisonneuve fracture seen in image A), syndesmotic stabilization alone (B) might not be sufficient (screw failure and lateralization of the talus as seen in C). A deltoid ligament repair can enhance the construct in these cases.
The current literature supports both repair of the deltoid ligament and not repairing the deltoid in ankle fracture treatment. Exploration and reconstruction of the deltoid ligament are necessary if there is interposition on the medial side after adequate reduction of the fibular fracture. There may be an additional advantage of adding deltoid ligament repair for patients with obvious deltoid and syndesmotic injury. There also may be selected cases in which the deltoid ligament repair adds to the strength of the construct. Repositioning of the talus under the tibia (normalization of the MCS) is mandatory for a good outcome. In cases of doubt, arthroscopy could be of assistance to determine interposition when the MCS remains wide after proper reduction. There is no evidence proving superiority of suturing the deltoid ligament in all ruptures.
Clinics care points
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Diagnosing deltoid and syndesmotic ligament ruptures as part of ankle fractures is of paramount importance.
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The current literature supports both repair of the deltoid ligament and not repairing the deltoid in ankle fracture treatment.
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In small anterior colliculus fractures, be aware of concomitant deep deltoid ligament ruptures. Fixation of the small fragment alone does not provide medial stability.
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Exploration and reconstruction of the deltoid ligament are necessary if there is interposition on the medial side.
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There may be an additional advantage of adding deltoid ligament repair for patients with obvious deltoid and syndesmotic insufficiency.
Disclosure
The authors have nothing to disclose.
References
Michelson J.D.
Magid D.
McHale K.
Clinical utility of a stability-based ankle fracture classification system.
Deltoid ligament and tibiofibular syndesmosis injury in chronic lateral ankle instability: magnetic resonance imaging evaluation at 3T and comparison with arthroscopy.
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