Morphology of Fibular Incisura is a Deciding Factor Between Posterior Malleolus Avulsion Fracture or Syndesmotic Ligament Injury in Ankle Fractures.

The bone anatomy of tibiofibular syndesmosis has been a topic of interest. Fibular incisura morphology has been analyzed on cadaver specimens, plain radiographs, or CT images. The aim of this study is to examine the effects of fibula incisura features and fibula morphology in ankle injuries, especially involving posterior malleolus and posteroinferior tibiofibular ligament injuries. From 2017 through 2022, A total of 59 patients with isolated lateral malleolar fracture, Mason-Malloy type 1 posterior malleolar fracture, syndesmosis injury in those without posterior malleolar fracture, supination external rotation type 3 injuries according to Lauge-Hansen classification, and preoperative bilateral ankle computed tomography images were included in the study. Fibula morphologies and syndesmosis measurements were made from preoperative computed tomography images using axial CT images from 1 cm proximal to the tibial plafond. The diagnosis of posterior malleolar fractures was made using the CT classification system of Mason and Malloy, and the diagnosis of syndesmosis injury was made with a cotton test during surgery. Age, gender, fractured side, incisura type, incisor depth, width, anterior and posterior facet lengths, incisor version (antevert-retrovert), the angle between the anterior and posterior facets, and fibula type were recorded. There was a statistically significant difference between the groups in posterior facet length and incisura width. Morphological features of fibular incisura may be the determinant of PITFL injury or PMA injury in fibular fractures caused by an external rotation mechanism.

Syndesmosis Injuries in Lateral Malleolar Fractures Accompanied by a Posterior Malleolar Fracture: A Nonfixed Posterior Fracture Fragment May Not Affect Postoperative Tibiofibular Joint Malreduction Rates.

BACKGROUND: The fact that lateral malleolar fracture is accompanied by posterior malleolar fracture may adversely affect syndesmosis malreduction rates. We aimed to compare syndesmosis malreduction rates determined on postoperative radiographs between isolated lateral malleolar fractures and lateral malleolar fractures accompanied by posterior malleolar fractures. METHODS: We retrospectively examined 128 operative patients: 73 with isolated lateral malleolar fractures (group L) and 55 with lateral + posterior malleolar fractures (group LP). In group LP, no patients received posterior fragment fixation. In both groups, indirect syndesmosis fixation was performed with a single screw after open reduction and internal fixation of the lateral malleolus. Patient age, sex, fracture side, fracture type (Lauge-Hansen and Danis-Weber classifications), Kellgren-Lawrence osteoarthritis classification, syndesmotic incongruency on postoperative radiographs, syndesmotic malreduction of postoperative fibula fracture, fracture union time, complication rates, accompanying injuries, and preoperative and postoperative radiographic syndesmotic measurements (tibiofibular overlap, tibiofibular clear space, medial clear space) were recorded, and the groups were compared. RESULTS: Mean ± SD age was 44.32 ± 15.66 years in group L and 48.93 ± 14.03 years in group LP (P = .087). There were no significant differences in preoperative and postoperative tibiofibular distance, tibiofibular overlap, and medial clear space values between groups (P > .05). The prevalence of grade 2 fractures according to the Kellgren-Lawrence classification was significantly higher in group LP (P = .047). Postoperative syndesmosis malreduction was detected in 12 patients in group L and in nine in group LP (P = .991). CONCLUSIONS: In lateral malleolar fractures accompanied by small-fragment posterolateral or avulsion-type posterior malleolar fractures, closed syndesmotic screw fixation does not cause syndesmosis malreduction.

The Effect of Syndesmotic Screw Level on Postoperative Syndesmosis Malreduction.

Tibiofibular injury repair of ankle fractures may result in over-compression when performed via a partially threaded screw depending on its placed level. We aimed to examine the relationship between the screw level relative to the tibiotalar joint and syndesmosis malreduction in postoperative radiographs of ankle fractures treated with partially threaded screws. We retrospectively analyzed 129 patients who underwent surgery due to lateral malleolar fractures between 2011 and 2019. We measured the distance between the screw and the tibiotalar joint and stratified the patients per their screw level as either trans-syndesmotic or suprasyndesmotic. According to Lauge-Hansen, 83 cases were supination-external rotation type (64.3%), and the remaining were pronation-external rotation type (35.7%) injuries. We found postoperative syndesmosis malreduction in 20 cases (15.5%). Eight (6.2%) cases had medial clear space mismatch. As the distance of the screw to the joint increased, postoperative medial clear space values increased (rho: 0.190, p = .031). The relationship between postoperative syndesmosis mismatch and the level of the syndesmotic screw was statistically significant (p = .044). In syndesmosis repair with a partially threaded screw, as the distance of the screw from the joint increases, the over-compression caused by the screw may cause an increase in postoperative syndesmotic malreduction rates.