Postoperative Stability in Displaced Ankle Fractures With Concomitant Ligamentous Injuries

Ankle instability, which can be attributed to either the deltoid or lateral ligamentous complex, may be both a cause and a consequence of ankle fractures. This study aimed to assess postoperative ankle instability in patients with displaced ankle fractures. A total of 54 patients with displaced ankle fractures were included. Malleolar fractures were surgically reduced and fixated, and if necessary, the syndesmosis was stabilized. Concomitant deltoid injuries were left unrepaired. Ankle stress radiographs were taken approximately 25.4 months after surgery, with a standard deviation of 20.5 months. Radiographic measurements included the tibiotalar tilt angle (TT) on varus stress view, anterior translation of the talus (AT) on the anterior drawer view, and the medial clear space (MC) and tibiotalar tilt angle on the valgus stress view. These measurements were compared between the injured and the noninjured contralateral ankle for all patients as well as in a subgroup of 19 patients with concomitant deltoid and syndesmosis injuries. There were no significant differences in Varus TT (p = .675, p = .394), AT (p = .516, p = .967), Valgus MC (p = .190, p = 0.498), and Valgus TT (p = .173, p = .442) between the injured and noninjured ankles in the whole group of patients as well as in the subgroup of patients with concomitant deltoid and syndesmosis injuries. Patients with displaced ankle fractures exhibited radiographically stable ankles postoperatively. Syndesmosis fixation without deltoid ligament repair is a viable treatment option for achieving ankle stability postoperatively in fractures with both ligament injuries.

The Biomechanical Role of the Deltoid Ligament on Ankle Stability: Injury, Repair, and Augmentation

BACKGROUND

Deltoid ligament injuries occur in isolation as well as with ankle fractures and other ligament injuries. Both operative treatment and nonoperative treatment are used, but debate on optimal treatment continues. Likewise, the best method of surgical repair of the deltoid ligament remains unclear.

PURPOSE

To determine the biomechanical role of native anterior and posterior components of the deltoid ligament in ankle stability and to determine the efficacy of simple suture versus augmented repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

Ten cadaveric ankles (mean age, 51 years; age range, 34-64 years; all male specimens) were mounted on a 6 degrees of freedom robotic arm. Each specimen underwent biomechanical testing in 8 states: (1) intact, (2) anterior deltoid cut, (3) anterior repair, (4) tibiocalcaneal augmentation, (5) deep anterior tibiotalar augmentation, (6) posterior deltoid cut, (7) posterior repair, and (8) complete deltoid cut. Testing consisted of anterior drawer, eversion, and external rotation (ER), each performed at neutral and 25° of plantarflexion. A 1-factor, random-intercepts, linear mixed-effect model was created, and all pairwise comparisons were made between testing states.

RESULTS

Cutting the anterior deltoid introduced ER (+2.1°; P = .009) and eversion laxity (+6.2° of eversion; P < .001) at 25 degrees of plantarflexion. Anterior deltoid repair restored native ER but not eversion. Tibiocalcaneal augmentation reduced eversion laxity, but tibiotalar augmentation provided no additional benefit. The posterior deltoid tear showed no increase in laxity. Complete tear introduced significant anterior translation, ER, and eversion laxity (+7.6 mm of anterior translation, +13.8° ER and +33.6° of eversion; P < .001).

CONCLUSION

A complete deltoid tear caused severe instability of the ankle joint. Augmented anterior repair was sufficient to stabilize the complete tear, and no additional benefit was provided by posterior repair. For isolated anterior tear, repair with tibiocalcaneal augmentation was the optimal treatment.

CLINICAL RELEVANCE

Deltoid repair with augmentation may reduce or avoid the need for prolonged postoperative immobilization and encourage accelerated rehabilitation, preventing stiffness and promoting earlier return to preinjury activity.