Anatomic Deltoid Ligament Repair with Anchor-to-Post Suture Reinforcement: Technique Tip

Abstract

The deltoid ligament is the primary ligamentous stabilizer of the ankle joint. Both superficial and deep components of the ligament can be disrupted with a rotational ankle fracture, chronic ankle instability, or in late stage adult acquired flatfoot deformity. The role of deltoid ligament repair in these conditions has been limited and its contribution to arthritis is largely unknown. Neglect of the deltoid ligament in the treatment of ankle injuries may be due to difficulties in diagnosis and lack of an effective method for repair. Most acute repair techniques address the superficial deltoid ligament with direct end-to-end repair, fixation through bone tunnels, or suture anchor repair of avulsion injuries. Deep deltoid ligament repair has been described using direct end-to-end repair with sutures, as well as by autograft and allograft tendon reconstruction utilizing various techniques. Newer tenodesis techniques have been described for late reconstruction of both deep and superficial components in patients with stage 4 adult acquired flatfoot deformity.

We describe a technique that provides anatomic ligament-to-bone repair of the superficial and deep bundles of the deltoid ligament while reducing the talus toward the medial malleolar facet of the tibiotalar joint with anchor-to-post reinforcement of the ligamentous repair. This technique may protect and allow the horizontally oriented fibers of the deep deltoid ligament to heal with the appropriate resting length while providing immediate stability of the construct.

Introduction

The deltoid ligament is the primary ligamentous stabilizer of the ankle joint. Both superficial and deep components of the ligament can be disrupted with a rotational ankle fracture, chronic ankle instability, or in late stage adult acquired flatfoot deformity.^9,14 The role of deltoid ligament repair in these conditions has been limited and its contribution to arthritis is largely unknown. Neglect of the deltoid ligament in the treatment of ankle injuries may be due to difficulties in diagnosis and lack of an effective method for repair.

Operative management of deltoid ligament injuries may be indicated acutely in unstable bimalleolar equivalent ankle fractures, particularly when the mortise remains wide medially after anatomic fixation of the lateral side of the ankle. This has been associated with entrapment of the deltoid within the medial gutter of the ankle.^1,5,7,9,19 Delayed repair may be indicated for medial ankle instability with or without hindfoot malalignment.¹⁴ Most acute repair techniques address the superficial deltoid ligament with direct end-to-end repair, fixation through bone tunnels, or suture anchor repair of avulsion injuries. Deep deltoid ligament repair has been described using direct end-to-end repair with sutures, as well as by autograft and allograft tendon reconstruction utilizing various techniques.^{2,4,6,10,14,18} Newer tenodesis techniques have been described for late reconstruction of both deep and superficial components in patients with stage 4 adult acquired flatfoot deformity.^8,11,17

We describe a technique that provides anatomic ligament-to-bone repair of the superficial and deep bundles of the deltoid ligament while reducing the talus toward the medial malleolar facet of the tibiotalar joint with anchor-to-post reinforcement of the ligamentous repair. This technique may protect and allow the horizontally oriented fibers of the deep deltoid ligament to heal with the appropriate resting length while providing immediate stability of the construct.

Surgical Technique

An approximate 6cm longitudinal incision is centered over the posterior aspect of the medial malleolus oriented at a slight oblique angle from proximal-posterior to distalanterior, ending distally over the mid talus. Dissection is carefully performed to identify and protect the saphenous nerve and veins. The posterior tibial tendon sheath is incised longitudinally allowing posterior retraction of the tibialis posterior tendon and improved visualization of the deltoid ligament complex. Incising the tendon sheath posteriorly leaves a robust anterior sheath for later repair to prevent tendon subluxation. A small anteromedial capsulotomy is made along the anterior border of the superfcial deltoid ligament. This capsulotomy allows evaluation of the deltoid ligament injury, the medial gutter for osteochondral injuries, loose bodies, entrapment of the ruptured deltoid ligament, and joint reduction. After identifcation of the anatomy of the deltoid ligament injury the deep surgical approach is performed. In cases of deltoid avulsion from the medial malleolus the avulsion can be completed and the fap refected inferiorly. In less common cases of talar avulsion a reverse fap is created. If the superfcial deltoid tibio-calcaneal bundle is avulsed from its calcaneal insertion this can also be repaired with a separate suture anchor into the sustentaculum. After the deep exposure is completed, debridement of the medial gutter of loose bodies and/or scar tissue is undertaken. Every attempt should be made to delineate the deltoid ligament before debridement of the medial gutter to avoid iatrogenic injury to the ligament which could hinder later repair.

A suture anchor double-loaded with heavy non-absorbable sutures is placed in the talus at the talar insertion of the deep deltoid ligament. The intercollicular groove can be used as an antero-posterior guide for anchor placement. This location is usually in the center of the talar body when observed from a true lateral fuoroscopic image with the ankle near neutral dorsifexion. Through the proximal end of the incision or a separate stab incision, a 3.5mm post screw with or without a washer is placed medially in a central position of the medial malleolus just proximal to its fare to decrease the risk of hardware prominence. Alternatively a small plate may be placed in this position for the same purpose.

The ankle mortise is reduced with the ankle in neutral dorsifexion. Should the deep deltoid injury be at the medial malleolar origin or in the mid-substance (Figure 1), all four suture limbs are passed through the intercollicular groove in an extra-osseous fashion and tied around the post with the ankle reduced. The screw is advanced until tight. A combination of fuoroscopic and direct visualization through the anteromedial capsulotomy should be performed to verify anatomic reduction of the ankle. Once this is verifed, the four suture limbs that are now tied to the medial malleolar post are placed in the deltoid ligament in a fan-like fashion incorporating the superfcial and deep components and approximating them to the medial malleolus. The initial tying of the suture limbs to the post prior to soft tissue repair accomplishes a direct anchor-to-post reinforcement of the repair while still allowing for anatomic repair of the deltoid itself.

Figure 1. In this case, the deltoid injury is near the medial malleolar attachment, which is most common. The star represents the talar insertion of the deep deltoid, the x demonstrates the superfcial deltoid. The four suture limbs are frst tied around the tibial post prior to repairing the deep and superfcial deltoid ligaments.

Less commonly, the deltoid ligament is disrupted or attenuated near its talar insertion (Figure 2). In this case two suture limbs are initially used to repair the deep deltoid back to its insertion using horizontal mattress technique. The four suture limbs including the two from the tied knot are passed through the intercollicular groove and tied over the post. The four suture limbs are then managed in the same fashion as above.

Figure 2. In this case, the deltoid injury is near the talar insertion, which is less common. The star represents the talar insertion of the deep deltoid, the x demonstrates the superfcial deltoid. The deep deltoid is frst tied down to its talar insertion and then further repair proceeds as in Figure 1, parts c and D.

Once the repair is completed, the tibialis posterior tendon is replaced within its tendon sheath and the tendon sheath is repaired with two simple interrupted 2-0 absorbable sutures to prevent tendon subluxation. The wound is thoroughly irrigated and closed. A dry sterile dressing is applied with an overlying well padded short leg splint. Preoperative and postoperative radiographs of an SER IV-equivalent ankle fracture treated with fibular ORIF and anatomic repair of the deltoid ligament with this technique are shown in Figure 3 and Figure 4.

Figure 3. Preoperative xrays of an SER IV-equivalent ankle fracture.

Figure 4. Postoperative xrays following fibular ORIF and anatomic repair of the deltoid ligament.

Postoperative protocol: The patient remains nonweightbearing to the surgical extremity initially in the postoperative splint. They return to clinic for a wound check 2 weeks postoperatively. The patient is nonweightbearing in a CAM boot from 2 to 6 weeks postoperatively but begins to perform active range of motion of the ankle out of the boot when seated/lying. At the 6 week postoperative visit the patient begins to bear weight as tolerated and weans from the CAM boot based on their comfort.

Discussion

There have been many descriptions of the anatomy of the deltoid ligament which often vary in their details.^3,9,12 Despite these variations, the modern paradigm is based on a cadaveric study that described three superficial and two deep deltoid ligaments.¹³ The relationship between form and function is well demonstrated in regard to the layers of the deltoid ligament. The superficial deltoid ligament has been shown to resist talar abduction while the deep deltoid has been shown to be more closely related to rotational stability of the talus within the mortise.^15,16

While the indications for deltoid ligament repair are evolving, the goal of surgery should involve anatomic restoration of both deep and superficial deltoid ligaments. The technique described in this article has become the standard method by which the senior authors address deltoid ligament repair. In contrast to previously described techniques, it allows for repair of the deep deltoid along its entire course including medial malleolar avulsion, intrasubstance, and medial talar avulsion injuries. In addition to anatomic repair of the deep and superficial deltoid ligament, the technique also provides protection of the repair through a direct anchor-to-post suture reinforcement.