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.

Compatibility of Lauge-Hansen Classification Between Plain Radiographs and Magnetic Resonance Imaging in Ankle Fractures.

We evaluated the accuracy of the predictive injury sequences of the Lauge-Hansen (L-H) classification using magnetic resonance imaging (MRI) in patients with ankle fractures and determined the possible causes of mismatch. Sixty-five patients with ankle fractures who had a complete series of anteroposterior, lateral, and oblique radiographs and ankle MRI studies available were included. The fracture pattern was assigned by 2 senior orthopedic surgeons according to the L-H classification system. The syndesmotic ligaments, lateral collateral ligaments, and medial deltoid complex ligaments were evaluated on the preoperative MRI scans. Comparisons were performed between the predicted ankle ligamentous injury based on the radiographic L-H classification and preoperative MRI analysis. Of the 65 feet in 65 patients, 50 feet (76.9%) were classified as having a supination-external rotation (SER) fracture, 6 feet (9.2%) as having a pronation-external rotation fracture, 4 feet (6.2%) as having a supination adduction fracture, and 2 feet (3.1%) as having a pronation abduction fracture. The overall compatibility of the radiologic classification with the MRI classification was 66.1%. In the evaluation of 50 feet with the MRI SER designation, maximum compatibility was found for stage 4 (77.3%). The main cause for the discrepancy in the SER designation was missing the presence of deltoid ligament disruption on the plain radiographs, especially in the stage 2 and 3 SER fracture pattern. In the evaluation of deltoid complex injuries, all injuries were localized to the anterior part of the medial deltoid complex. The validity of the L-H classification system was low. A new classification system is needed to address the medial malleolus fracture or deltoid complex injuries without posterior injury. Also, stress radiographs could be added to standard radiographs for the classification to address deltoid complex injuries.