Do Syndesmotic Injury Patterns Influence Functional and Radiological Outcomes in Complex Ankle Fractures? A Retrospective Cohort Study

Category: Ankle; Trauma Introduction/Purpose: Syndesmosis injury can be of a varying magnitude; little information exists about the influence of degree of initial syndesmotic injury/instability on functional outcomes in ankle fractures, nor is there any correlation of this with follow up radiological parameters. Aims and Objectives: To identify and define morphological patterns of syndesmotic injury in ankle fractures according to a zone based evaluation, and correlate initial degree of instability with mid-term functional and radiological outcomes using validated scores Design: Retrospective cohort study, to review a prospective question. Methods: 40 complex ankle fractures out of 120 ankle fractures in our ankle registry met the inclusion criteria ie significant documented syndesmosis involvement needing stabilization, with all initial clinical and radiological records available. The patients were followed up between January 2020 to July 2021. Injury characteristics, fracture morphology of posterior malleolus, medial malleolus and fibula were noted and classified by validated classification systems based on x-rays and CT scan. The syndesmosis was analyzed on axial CT scan; it was divided into 3 zones, A,B,C from anterior to posterior, and degree of displacement and morphology was noted. Immediate post-operative radiographs were evaluated for fracture and syndesmosis reduction. The patients were evaluated at final follow up with both ankle specific scores (Olerud Molander score, Ankle-Hindfoot scale, Manchester-Oxford Foot questionnaire) and quality of life score (SF-12). Ankle Osteoarthritis grade was used to evaluate radiological outcomes. Results: Mean follow-up was 19 months. 22(55%) patients had syndesmotic widening on plain radiographs; however in pre- operative CT scan evaluation 40(100%) patients had syndesmotic injury based on the Zone evaluation of the syndesmosis. 22 patients had Zone A injury (widening, AITFL, Chaput, Wagstaff). 22 patients had widening of Zone B. Zone C was involved in 30 patients (PM fracture,PITFL involvement). At final follow up; the mean OMAS was 83.38±16.35, mean Ankle-Hindfoot scale= 88±9.98, mean Mox-FQ score=27.15±13.35 & mean SF-12 were (MCS=56.59±8.24, PCS=51.18±8.48). There was no significant difference in outcome scores based on fracture types, Posterior malleolus morphology, or based on zones of syndesmosis injury. Syndesmosis malreduction contributed to significantly poorer outcomes (SF-12, OMAS, MoxFQ) Conclusion: Despite a zonal classification of syndesmotic injury on CT and more clarity of injury patterns, we could not corelate the site and extent of syndesmotic injury with final functional and radiological outcomes. The one factor that has significant influence is initial accurate reduction of both the malleolar fractures and syndesmosis injury. In this the CT based axial classification may play a role

Talar Neck Malunions: Evaluation of Kinematics, Pedobarographic Changes and Patient Reported Outcome Measures

Category: Trauma; Hindfoot Introduction/Purpose: Malunion is a disabling complication of talar neck fractures and is prevalent in approximately 17% of cases. The impact of talar neck malunions (TNM) on foot biomechanics and functional outcomes is not well established. The available evidence is primarily derived from cadaveric studies which have demonstrated that TNMs result in reduced motion and significant alterations in contact characteristics of the subtalar joint. Owing to the paucity of literature on this subject, we conducted this study to evaluate the kinematic and pedobarographic changes and functional outcomes associated with TNMs. Methods: In this study, adult patients with talar neck malunions (TNM) without ankle arthrosis were prospectively enrolled over a 5-year period. The Rammelt and Zwipp classification was utilized to categorize the deformities. Demographic data and ankle and subtalar range of motion were assessed. Weight-bearing anteroposterior (AP), lateral, and long axial radiographs, as well as CT scans of both feet, were obtained. Dynamic pedobarography was performed to evaluate gait kinematics and plantar pressure distribution. Functional outcomes were evaluated using the Manchester Oxford Foot Questionnaire (MOxFQ), Visual Analog Score, and the EQ5D questionnaire. The t-test was utilized to compare the range of motion, pedobarographic and kinematic parameters between the normal and pathologic foot. Furthermore, correlation coefficients were calculated to determine the strength of the association between changes in talar neck geometry, plantar pressures, kinematics, and functional outcomes. Results: A total of 10 patients, 6 males, and 4 females, with a mean age of 32.4 years were enrolled. On the TNM side, significant increases were observed in step length and step time, while significant decreases were noted in the single limb support time and single limb support center of pressure line. Moreover, midfoot forces were significantly increased, whereas the forefoot and hindfoot forces were significantly decreased on the TNM side. A strong positive correlation was found between midfoot force and the talar torsion angle, and a moderate negative correlation was observed between hindfoot and midfoot forces and the inclination angle. A strong positive correlation was also noted between high midfoot pressures and VAS Scores, MOxFQ scores, and the EQ5D walking and usual activities domains. Conclusion: This study demonstrates that TNMs are associated with decreased single limb support time, increased step length and time, increased midfoot pressures, and decreased forefoot and hindfoot pressures. Additionally, an increase in talar neck torsion after TNM is linked with higher midfoot pressures, which can lead to higher levels of pain and poorer function. Our findings provide valuable insights into the altered foot biomechanics after TNMs, which can assist surgeons in offering optimal management strategies for these patients

Should all Small Shell Posterior Malleolar Fractures be Considered for Fixation? Results from a 3D Fracture Mapping Study

Category: Ankle; Trauma Introduction/Purpose: Approximately 10-15% of posterior malleolar fractures (PMFs) are "small shell," extra-articular fragments. Current classification systems present difficulties to perform a uniform typification of PMFs and contain no consensus on whether they should be fixed. Anatomical studies have identified two distinct components of the posterior inferior tibiofibular ligament (PITFL); the superficial band is thought to be more important than its deep counterpart in imparting syndesmotic stability. However, the involvement of one or both bands of the PITFL by small shell PMFs has not been evaluated so far. Hence, we conducted this study to perform 3D mapping of small shell PMFs and to determine whether surgeons should fix these routinely. Methods: Ankle fracture patients with a ‘small shell’ PMF (Haraguchi 3/Mason 1/Bartoníček 1 or 2) were included. Demographics, radiological features, treatment, and outcomes were recorded. 3D models of the fractured tibiae were generated from CT scans and superimposed on a statistical shape model of the right tibia, which served as a template. Fracture lines along with footprints of superficial and deep PITFL were marked on the template. 3D fracture heat maps were generated. Size of the fracture fragments and involvement of the superficial and deep PITFL footprints were quantified using a custom MATLAB script (Figure 1). Sparing of the footprint was defined as an overlap of < 1% between the fracture line and the footprint areas. Odds ratios (OR) with 95% confidence intervals (CI) were determined to determine which variables correlated with sparing of the PITFL footprint; P-values of < 0.05 were considered significant. Results: Thirty-nine patients were included. The superficial PITFL footprint was spared in 15 (38%), deep PITFL in 10 (26%), and both in 4 cases (10%). Males and Weber C fractures had a higher likelihood of sparing the superficial and deep PITFL footprints, respectively (P = 0.04). Supination external rotation (SER) patterns were less likely to demonstrate syndesmotic widening if either PITFL footprint was spared. Direct fixation of the PMF was done in 1 case; syndesmotic fixation in 25 cases and in 14 cases, no syndesmotic fixation was done. Of these, 11 were SER injuries where stability was achieved after fixation of medial and lateral malleoli. In 1 SER and pronation external rotation (PER) injury case, the syndesmosis was stable after fixation of a large Chaput fragment. Conclusion: This study demonstrated that 48% of small shell PMFs spare either the superficial or deep footprint of the PITFL; in 10% both PITFL footprints were spared. Hence, 58 % of small-shell PMFs may not benefit from direct fixation. Additionally, SER injuries with small shell PMFs that spare either PITFL footprint may not demonstrate radiographic instability and may not need direct or indirect fixation after addressing other components of the ankle fracture. However, given the fact that syndesmotic stability is not dictated by the PITFL alone, it remains prudent to stress the syndesmosis per-operatively to determine if syndesmotic fixation is needed