Changes in the syndesmotic reduction after syndesmotic screw fixation for ankle malleolar fractures: One-year longitudinal evaluations using computer tomography

IntroductionTo evaluate time-dependent changes in the syndesmotic reduction after syndesmotic screw fixation and one year after screw removal for ankle malleolar fractures, and to assess whether the incidence of syndesmotic malreduction changes depending on the measurement method.MethodsWe assessed twenty patients who underwent syndesmotic screw fixation for ankle fractures. The syndesmotic screws were removed after six weeks of the fracture surgery. Syndesmotic reduction was assessed within two weeks of the fracture surgery and one year after the screw removal using the axial computer tomographic images. Side-to-side differences in the anterior and posterior tibiofibular distances, anteroposterior fibular translation, and fibular rotation were measured.ResultsThe mean anterior tibiofibular distance was 0.7 mm after syndesmotic fixation. It increased to 1.9 mm at one year after screw removal (p = 0.002). After syndesmotic fixation, four ankles had malreduction of the anterior tibiofibular distance, including three ankles with widening and one with overtightening. At one year, eight ankles had malreduction, all of whom had widening. The other measurement values did not change over time (0.1 mm vs. 0.6 mm for the posterior tibiofibular distance, 0.2 mm vs. 0.3 mm for the anteroposterior fibular translation, and 0.7 ° vs. 0 ° for the fibular rotation). The incidences of malreduction were significantly different depending on the definition of malreduction, ranging from 10% to 50% after syndesmotic fixation (p = 0.01) and from 20% to 60% at one year after screw removal (p = 0.02).ConclusionsThe anterior tibiofibular distance widened after one year of syndesmotic screw removal. The incidence of malreduction varied depending on the measurement method.     

The Clinical Efficacy of Suture-Button Fixation and Trans-Syndesmotic Screw Fixation in the Treatment of Ankle Fracture Combined With Distal Tibiofibular Syndesmosis Injury: A Retrospective Study

Twenty percent of ankle fractures present with concomitant syndesmosis injury which results in poor clinical outcomes. Surgical stabilization of the syndesmosis can be achieved with either trans-syndesmotic screws or a suture button device. The aim of this study is to investigate the clinical efficacy of suture button fixation and trans-syndesmotic screw fixation in the treatment of ankle fracture combined with distal tibiofibular syndesmosis injury. A retrospective analysis was conducted by enrolling 76 patients with ankle fractures combined with distal tibiofibular syndesmosis injury who were admitted in our trauma center from January 2018 to January 2019, including 34 cases of suture button group and 42 cases of the syndesmotic screw group with a mean follow-up period of 16 ± 7 (range 12-21) months. The demographic data included gender, age, injury mechanism, AO classification and the operation duration were recorded, the radiographic and clinical outcomes were determined by tibiofibular clear space, tibiofibular overlap distance, complications, and the Olerud-Molander Ankle Score at the last follow-up. All the indexes were compared between the 2 groups to discover the related statistical differences. With the numbers available, no significant difference could be detected in the surgical duration, tibiofibular clear space, tibiofibular overlap distance, total complication rate, and middle-term Olerud-Molander Ankle scores between the 2 groups. However, the suture button fixation group showed higher early stage Olerud-Molander Ankle scores (p = .027) and shorter full weightbearing time (p = .018) than that of syndesmotic screw fixation group. Considering the outcomes, we conclude that the suture button fixation not only shows equivalent efficacy to the traditional syndesmotic screw, but also has advantages of allowing early weightbearing, low requirements for routine removal.     

Ideal angle of syndesmotic screw fixation: A CT-based cross-sectional image analysis study

Without clear reference, the precision of syndesmotic screw placement cannot be guaranteed and malposition of these screws leads to poor results. Therefore, to prevent malpositioning of syndesmotic screws, an improved understanding of the orientation of tibiofibular syndesmosis is essential. We analyzed cross-sectional computed tomography (CT) scans of the foot and ankle to identify precise screw positions for the treatment of syndesmotic injuries. A total of 134 calcaneal fractures with intact tibiofibular syndesmosis were enrolled in this retrospective study. We measured the angle between the perpendicular line of the second proximal phalanx and the line start apex of the lateral cortex of the fibula bisecting the tibial incisura and crossing the center of the tibia in neutral ankle joints, with the second toe positioned anteriorly using a short leg splint. The second toe was used as the reference for clarity and applicability. The ideal angle of syndesmotic screw placement in cross-sectional CT images was 18.8 ± 5.6° (mean ± standard deviation) and did not differ according to independent variables (P > 0.05). In neutral ankle joints with the second toe positioned anteriorly, the ideal angle of syndesmotic screw placement is 18.8°, which is less than that currently in used in conventional methods.     

Overtightening of the syndesmosis revisited and the effect of syndesmotic malreduction on ankle dorsiflexion

BackgroundAnkle syndesmotic injuries are a significant source of morbidity and require anatomic reduction to optimize outcomes. Although a previous study concluded that maximal dorsiflexion during syndesmotic fixation was not required, methodologic weaknesses existed and several studies have demonstrated improved ankle dorsiflexion after removal of syndesmotic screws.The purposes of the current investigation are: (1) To assess the effect of compressive syndesmotic screw fixation on ankle dorsiflexion utilizing a controlled load and instrumentation allowing for precise measurement of motion. (2) To assess the effect of anterior & posterior syndesmotic malreduction after compressive syndesmotic screw fixation on ankle dorsiflexion.Material and methodsFifteen lower limb cadaveric leg specimens were utilized for the study. Ankle dorsiflexion was measured utilizing a precise micro-sensor system after application of a consistent load in the (1) intact state, (2) after compression fixation with a syndesmotic screw and (3) after anterior & (4) posterior malreduction of the syndesmosis.ResultsFollowing screw compression of the nondisplaced syndesmosis, dorsiflexion ROM was 99.7 ± 0.87% (mean ± standard error) of baseline ankle ROM. Anterior and posterior malreduction of the syndesmosis resulted in dorsiflexion ROM that was 99.1 ± 1.75% and 98.6 ± 1.56% of baseline ankle ROM, respectively. One-way ANOVA was performed showing no statistical significance between groups (p-value = 0.88).Two-way ANOVA comparing the groups with respect to both the reduction condition (intact, anatomic reduction, anterior displacement, posterior displacement) and the displacement order (anterior first, posterior first) did not demonstrate a statistically significant effect (p-value = 0.99).ConclusionMaximal dorsiflexion of the ankle is not required prior to syndesmotic fixation as no loss of motion was seen with compressive fixation in our cadaver model. Anterior or posterior syndesmotic malreduction following syndesmotic screw fixation had no effect on ankle dorsiflexion. Poor patient outcomes after syndesmotic malreduction may be due to other factors and not loss of dorsiflexion motion.Level of Evidence: IV     

Anterior-inferior tibiofibular ligament anatomical repair and augmentation versus trans-syndesmosis screw fixation for the syndesmotic instability in external-rotation type ankle fracture with posterior malleolus involvement: A prospective and comparative study

PurposeSyndesmosis injury is common in external-rotation type ankle fractures (ERAF). Trans-syndesmosis screw fixation, the gold-standard treatment, is currently controversial for its complications and biomechanical disadvantages. The purpose of this study was to introduce a new method of anatomically repairing the anterior-inferior tibiofibular ligament (AITFL) and augmentation with anchor rope system to treat the syndesmotic instability in ERAF with posterior malleolus involvement and to compare its clinical outcomes with that of trans-syndesmosis screw fixation.Methods53 ERAFs with posterior malleolus involvement received surgery, and the syndesmosis was still unstable after fracture fixation. They were randomised into screw fixation group and AITFL anatomical repair with augmentation group. Reduction quality, syndesmosis diastasis recurrence, pain (VAS score), time back to work, Olerud–Molander ankle score and range of motion (ROM) of ankle were investigated.ResultsOlerud–Molander score in AITFL repair group and screw group was 90.4 and 85.8 at 12-month follow-up (P > 0.05). Plantar flexion was 31.2° and 34.3° in repair and screw groups (P = 0.04). Mal-reduction happened in 5 cases (19.2%) in screw group while 2 cases (7.4%) in repair group. Postoperative syndesmosis re-diastasis occurred in 3 cases in screw group while zero in repair group (P > 0.05). Pain score was similar between the two groups (P > 0.05). Overall complication rate and back to work time were 26.9% and 3.7% (P = 0.04), 7.15 months and 5.26 months (P = 0.02) in screw group and repair group, respectively.ConclusionsFor syndesmotic instability in ERAF with posterior malleolus involvement, the method of AITFL anatomical repair and augmentation with anchor rope system had an equivalent functional outcome and reduction, earlier rehabilitation and less complication compared with screw fixation. It can be selected as an alternative.     

Evaluation of an Electromagnetic 3D Navigation System to Facilitate Endovascular Tasks: A Feasibility Study

IntroductionWe describe a novel approach to arterial cannulation using the StealthStation^® Guidance System (Medtronic, USA). This uses electromagnetic technology to track the guidewire, displaying a 3D image of the vessel and guidewire.MethodsThe study was performed on a ‘bench top’ simulation model called the Cannulation Suite comprising of a silicone aortic arch model and simulated fluoroscopy. The accuracy of the StealthStation^® was assessed. 16 participants of varying experience in performing endovascular procedures (novices: 6 participants, ≤5 procedures performed; intermediate: 5 participants, 6–50 procedures performed; experts: 5 participants, >50 procedures performed) underwent a standardised training session in cannulating the left subclavian artery on the model with the conventional method (i.e. with fluoroscopy) and with the StealthStation^®. Each participant was then assessed on cannulating the left subclavian artery using the conventional method and with the StealthStation^®. Performance was video-recorded. The subjects then completed a structured questionnaire assessing the StealthStation^®.ResultsThe StealthStation^® was accurate to less than 1 mm [mean (SD) target registration error 0.56 mm (0.91)]. Every participant was able to complete the cannulation task with a significantly lower use of fluoroscopy with the navigation system compared with the conventional method [median 0 s (IQR 0–2) vs median 14 s (IQR 10–19), respectively; p = <0.001]. There was no significant difference between the StealthStation^® and conventional method for: total procedure time [median 17 s (IQR 9–53) vs median 21 s (IQR 11–32), respectively; p = 0.53]; total guidewire hits to the vessel wall [median 0 (IQR 0–1) vs median 0 (IQR 0–1), respectively; p = 0.86]; catheter hits to the vessel wall [median 0.5 (IQR 0–2) vs median 0.5 (IQR 0–1), respectively; p = 0.13]; and cannulation performance on the global rating scale [median score, 39/40 (IQR 28–39) vs 38/40 (IQR 33–40), respectively; p = 0.40]. The intra-class correlation coefficient for agreement between video-assessors for all scores was 0.99. 88% strongly agreed that the StealthStation^® can potentially decrease exposure of the patient to contrast and radiation.ConclusionArterial cannulation is feasible with the StealthStation^®.     

Biomechanical comparison of suture-button,bioabsorbable screw,and metal screw for ankle syndesmotic repair: A meta-analysis

BackgroundTo compare biomechanically metal screw fixation to suture-button or bioabsorbable screw fixation for ankle syndesmotic injuries.MethodsA literature search of the comparison studies in Pubmed and Google Scholar was conducted. The biomechanical outcomes of interest were syndesmotic stability in the coronal, sagittal, and axial planes as well as torque and rotation at failure.ResultsA total of 11 cadaveric studies were included. In the suture-button group, coronal displacement (MD 1.72 mm, p = 0.02) and sagittal displacement (MD 2.65 mm, p = 0.0003) were increased relative to the metal screw group. In contrast, no difference was found with axial rotation (MD 0.35 degrees, p = 0.57). Bioabsorbable screws exhibited equivalent failure torque (MD ?3.04 Nm, p = 0.53) and rotation at failure (MD 3.77 degrees, p = 0.48) in comparison to metal screws.ConclusionsSuture-button provide less rigidity when compared to metal screw fixation. They afford flexible syndesmotic micromotion which may more closely resemble a physiological state and be helpful for ligament healing. Bioabsorbable screws demonstrate similar mechanical strength properties to metal screws.     

Cost analysis of ankle syndesmosis internal fixation

BackgroundUnstable ankle syndesmosis injuries are common, and the optimal surgical fixation is controversial. The two main options for stabilization of syndesmotic injuries are suture button fixation and screw fixation. Suture button fixation has a higher initial cost, but may have a lower hardware removal rate. The purpose of this study was to compare the costs of syndesmotic fixation.MethodsA cost analysis was performed at a single university-affiliated hospital. Variables included the number of suture buttons, the number and type of syndesmosis screws used, and the frequency of hardware removal and operative time required for hardware removal. There were four clinical scenarios evaluated: (A) one suture button versus one cortical screw; (B) two suture buttons versus two cortical screws; (C) one suture button versus one locking screw; (D) two suture buttons versus two locking screws. Suture button removal rate was assumed to be 0% in the analysis.ResultsCost equivalence was achieved at an 18 to 53% syndesmotic screw removal rate depending on the fixation construct used and the amount of time required for hardware removal. When the syndesmosis screws were removed 100% of the time, suture button fixation was more economical by $85,000–$194,656 per 100 ankles. When hardware was never removed, suture button fixation was more expensive by $169,844–$295,500 per 100 ankles.ConclusionThis study demonstrates that the costs associated with syndesmosis fixation are more dependent on the rate of hardware removal than the type of hardware utilized. Routine removal of syndesmosis screws is clearly less economical than suture button fixation.     

Simulating clamp placement across the trans-syndesmotic angle of the ankle to minimize malreduction: A radiological study

BackgroundAnkle fractures associated with syndesmotic injury have a poorer prognosis than those without such an injury. Anatomic reduction of the distal tibiofibular joint restores joint congruency and minimizes contact pressures, yet operative fixation of syndesmotic ankle injuries is frequently complicated by malreduction of the syndesmosis. Current methods of assessing reduction have been shown to be inadequate. As such, additional methods to judge the accuracy of syndesmotic reduction are required.Questions/PurposesThe purposes of our study were (1) to determine the anatomic axis of the syndesmosis, or the trans-syndesmotic angle (TSA), and (2) to describe the intraoperative fluoroscopic appearance of syndesmotic clamp reduction oriented along the anatomic syndesmotic angle.MethodsComputed tomography (CT) scans of 45 uninjured adult ankles were analyzed to measure the TSA, defined as the angle between the plane of a lateral ankle radiograph and a line drawn perpendicular to the fibular incisura. Three-dimensional reconstructions of CT scans were then used to demonstrate clamp placement collinear with the TSA as would be seen on an intraoperative lateral ankle radiograph.ResultsThe average TSA measured 21 ± 5° anterior to the plane of a lateral radiograph. When a simulated reduction clamp tine was placed on the fibular ridge and the clamp oriented along the TSA, the medial tine, as seen on a lateral radiograph, was within the anterior one-third of the tibia 93% of the time. It was, on average, 23 ± 7% of the distance from the anterior to the posterior tibial cortex, with tine placement occurring in this range in 73% of ankles. The medial tine rested 53 ± 17% of the distance between the anterior cortices of the tibia and fibula, with 71% of tines placed in this range.ConclusionsReduction clamp placement oriented along the TSA has a predictable appearance on lateral ankle imaging and can guide clamp positioning during syndesmotic reduction. With one tine placed on the fibular ridge, placing the medial clamp tine in the anterior third of the tibia, or halfway between the anterior cortices of the tibia and fibula is the most accurate position for reduction in line with the TSA.Level of evidence2 (Retrospective diagnostic).     

Motion of the fibula relative to the tibia and its alterations with syndesmosis screws: A cadaver study

BackgroundThe motion of the fibula in relation to the tibia is coupled on the motion of the talus in the ankle joint. Several authors investigated this motion with different methods. An injury of the elastic fixation of the fibula to the tibia and its treatment with the syndesmotic set screw has an impact on this motion.MethodsThe motion of the fibula relative to the tibia was measured in eight embalmed human above the knee amputated cadaver specimens using a 3D-motion analysis system. The relative motion was measured from 50° of plantar flexion to 30° of dorsiflexion. Experiments were performed in the following conditions: without fixation and intact ligaments, after sectioning of the four syndesmotic ligaments and the interosseous membrane, and application of either a tricortical screw, or a quadricortical screw or two quadricortical screws.ResultsConcordant movements of the lateral malleolus were a medial translation during plantar flexion, external rotation around the sagittal axis during plantar and dorsiflexion. The motion of the proximal fibula was smaller and more variable than in the distal part. After sectioning of the syndesmosis the range of motion, compared to the intact state increased, particularly in translation along the transversal (118%), sagittal (160%) and the longitudinal (136%) axis and in axial rotation (145%). Syndesmotic screws reduced the range of motion in transversal (p < 0.006) and sagittal translation (p < 0.011) and axial rotation.ConclusionThe small relative motion of the tibia and fibula is increased by syndesmotic injuries. Syndesmosis screws significantly limit this increased relative motion below physiologic values, which makes it necessary to remove the screws before flexion in the ankle joint is performed.     

Biomechanical analysis of endobutton versus screw fixation after Lisfranc ligament complex sectioning

BackgroundOur goal was to compare diastasis after endobutton and screw fixation after Lisfranc ligament complex sectioning.MethodsTwenty-four (12 pairs) fresh-frozen cadaveric feet were assigned to endobutton or screw fixation and loaded to 343 N. Displacement (first–second metatarsal bases) was measured in intact feet and after ligament sectioning (Lisfranc, medial–intermediate cuneiform ligaments), fixation, and 10,000 cycles.ResultsThe mean change in diastasis for endobutton and screw fixation under initial loading was 1.0 mm (95% CI, 0.2–1.9 mm) and 0.0 mm (95% CI, ?0.4 to 0.4 mm), respectively (p = 0.017). After cyclic loading, diastasis decreased (mean, ?0.7 mm, 95% CI, ?1.2 to ?0.1 mm) in the endobutton group but was unchanged in the screw group (p = 0.035).ConclusionsDiastasis after endobutton fixation was significantly greater than after screw fixation under initial loading but did not increase further after cyclic loading.     

Biomechanical Analysis of a Novel Syndesmotic Plate Compared With Traditional Screw and Suture Button Fixation

Many lateral malleolus fractures have been found to have syndesmosis injuries after anatomic reduction. The main methods for the treatment of syndesmosis injuries are screw fixation and suture-button flexible fixations. In pursuit of innovation, we have designed a novel syndesmotic plate (NSP) for simultaneous fixation of lateral malleolus fractures and distal tibiofibular syndesmosis injuries. The purpose of this study is to compare the biomechanical characteristics of the NSP to syndesmotic screw and suture-button fixations. Twelve adult cadaveric specimens were used in this experiment. Axial loading as well as rotation torque were applied in 3 different ankle positions: neutral, dorsiflexion, and plantarflexion. After the initial specimens were tested, they were made into a pronation-abduction III fracture model as described by Lauge-Hansen. Subsequently, the specimens were fixed sequentially using a distal fibular anatomic locking plate (DFALP) combined with syndesmotic screws, DFALP combined with suture button, and NSP. Then the above tests were repeated. The syndesmotic displacement and the strain of the tibia and fibula were recorded during the experiment. In most cases, the displacements and strains of the NSP group and the screw group were smaller than the suture button groups and the native (SBGAN) (p < .05), and the displacements and strains of the NSP group were also slightly smaller than the screw group in most cases, and there was no significant difference between the 2 groups. The NSP we developed has a fixed strength no less than the traditional syndesmotic screw fixation. This provides us a new idea for the treatment of distal tibiofibular syndesmosis injuries.     

Radiological assessment of ankle syndesmotic reduction

IntroductionThe intraoperative assessment of adequacy of syndesmotic reduction is challenging. The aim of this study was to develop a radiographic measure based on the lateral ankle view to assess both the normal and abnormal relationship between the tibia and fibula after simulated syndesmotic malreduction and to evaluate the effect on commonly used mortise measurements.MethodsMortise and talar dome lateral radiographs were obtained in eight fresh-frozen cadaveric specimens before and following syndesmosis division and posterior fibular displacement of 2 mm increments. Using the technique described, on the lateral radiograph the anterior fibular line ratio (AFL ratio) and posterior fibular line distance (PFL distance) were measured. Both measures were based on the anterior and posterior distal tibia articular margins and flat borders of the fibula.ResultsInter- and intraobserver reliability of the AFL ratio and PFL distance measured almost perfect agreement. In all uninjured specimens the AFL lay just anterior to the midpoint of the tibia and the PFL intersected the posterior tibia articular margin or lay just anterior to it, not posterior. At 2, 4 and 6 mm of posterior fibular displacement the decrease in AFL ratio and PFL distance showed significant differences between all pairwise comparisons.ConclusionThe proposed new measures of syndesmotic reduction are reproducible and capable of detecting from 2 mm of sagittal fibula displacement and can be useful adjuncts in the assessment of syndesmotic reduction.     

Suture button versus syndesmosis screw constructs for acute ankle diastasis injuries: A meta-analysis and systematic review of randomised controlled trials

BackgroundAnkle syndesmotic injuries can be surgically managed with syndesmosis screws (SS) or suture button (SB) fixation. We performed a meta-analysis of randomized controlled trials (RCTs) aiming to compare the clinical and complication profiles of both modalities.MethodsA multi-database search up to 4th of March 2018 was performed according to PRISMA guidelines. All RCTs comparing both techniques and published in English were included.ResultsFive RCTs with a total of 280 patients (140 SB, 140 SS) were included for analysis. SB had a statistically significant higher AOFAS score at 1 year (mean difference = 5.46, 95% CI = 0.40–10.51, p = 0.03) and lower implant failure rate (OR = 0.03, 95% CI = 0.01–0.15, p < 0.001). Infection and wound issues were marginally higher with SB (OR = 1.4, 95% CI = 0.4–4.85, p = 0.60). No other parameters showed statistically significant difference.ConclusionsBoth constructs yielded similar clinical outcomes. The 1 year AOFAS score was higher in SB but clinical significance is unlikely. SB had significantly fewer implant failures.Level of evidence: Level I.     

Investigating the Radiological Outcomes of Syndesmosis Injuries in Ankle Fracture Patients After Suture Button Fixation

Concomitant syndesmotic injury occurs in 10% of ankle fractures. Anatomic reduction and maintenance of this reduction is critical in ensuring ankle stability and preventing long-term complications. This is a retrospective cohort study aimed at evaluating the mid-term radiological outcomes of syndesmotic injuries in ankle fracture patients after surgical fixation with suture button device. The study group included 33 patients. Plain radiographs including anteroposterior, lateral and mortise views of the affected ankle were performed preoperatively, postoperatively and at 3-month follow-up. Anteroposterior views were used to measure the amount of tibiofibular overlap and tibiofibular clear space. Paired Student's t test and linear model regression were performed. Between the immediate postoperative and 3-month follow-up period, there was a mean decrease in tibiofibular overlap of 0.841 (±2.07) mm (p = .0259). There was a mean increase in tibiofibular clear space of 0.621 (±1.46) mm (p = .0201). In addition, we found significant correlation between fracture type and change in tibiofibular clear space (p = .047). Our study showed that there is statistically significant widening of the syndesmosis after suture button fixation at 3-month follow-up as evidenced by reduced tibiofibular overlap and increase in tibiofibular clear space. However, they remain within the maximum threshold for acceptable syndesmotic widening of 1.5 mm. Further correlation between radiological outcomes and patient function is needed to determine clinical significance of these changes.     

Randomized trial comparing suture button with single 3.5 mm syndesmotic screw for ankle syndesmosis injury: similar results at 2 years

Background and purpose — Better outcomes are reported for suture button (SB) compared with syndesmotic screws (SS) in patients treated for an acute ankle syndesmotic injury. One reason could be that screws are more rigid than an SB. A single tricortical 3.5 mm syndesmotic screw (TS) is the most dynamic screw option. Our hypothesis is that 1 SB and 1 TS provide similar results. Therefore, in randomized controlled trial, we compared the results between SB and TS for syndesmotic stabilization in patients with acute syndesmosis injury.Patients and methods — 113 patients with acute syndesmotic injury were randomized to SB (n = 55) or TS (n = 58). The American Orthopedic Foot & Ankle Society (AOFAS) Ankle–Hindfoot Score was the primary outcome measure. Secondary outcome measures included Manchester Oxford Foot Questionnaire (MOXFQ), Olerud–Molander Ankle score (OMA), visual analogue scale (VAS), EuroQol- 5D (EQ-5D), radiologic results, range of motion, complications, and reoperations (no implants were routinely removed). CT scans of both ankles were obtained after surgery, and after 1 and 2 years.Results — The 2-year follow-up rate was 84%. At 2 years, median AOFAS score was 97 in both groups (IQR SB 87–100, IQR TS 90–100, p = 0.7), median MOXFQ index was 5 in the SB group and 3 in the TS group (IQR 0–18 vs. 0–8, p = 0.2), and median OMA score was 90 in the SB group and 100 in the TS group (IQR 75–100 vs. 83–100, p = 0.2). The syndesmotic reduction was similar 2 years after surgery; 19/55 patients in the SB group and 13/58 in the TS group had a difference in anterior syndesmotic width ≥ 2 mm (p = 0.3). 0 patients in the SB group and 5 patients in the TS group had complete tibiofibular synostosis (p = 0.03). At 2 years, 10 TS were broken. Complications and reoperations were similar between the groups.Interpretation — We found no clinically relevant differences regarding outcome scores between the groups. TS is an inexpensive alternative to SB.

Since 2018, several meta-analyses have been published evaluating treatment of acute ankle syndesmotic injury, reporting better outcomes for suture button (SB) fixation compared with syndesmotic screw (SS) (Shimozono et al. 2018, McKenzie et al. 2019). Shimozono concluded that the SB technique resulted in improved outcome and lower rates of joint malreduction. These results are based on heterogenous studies: different fracture types were compared; different numbers of implants were used and different diameters and cortices were engaged for SS fixation (Shimozono et al. 2018). Andersen et al. (2018) reported superior results for SB compared with a quadricortical 4.5 mm SS. A quadricortical SS necessitates routine screw removal, with a 5–9% reported risk of wound infection (Schepers et al. 2011, Andersen et al. 2015) and potential loss of reduction after implant removal (Laflamme et al. 2015). A quadricortical SS is a rigid fixation, inhibiting tibiofibular movement throughout the gait cycle (Riedel et al. 2017, Ramsey et al. 2018). The SB has a higher implant cost compared with SS (Ramsey et al. 2018), may not be sufficient to maintain fibular length in Maisonneuve fractures (Riedel et al. 2017), and has an implant removal rate of 6%, mainly due to irritation from the lateral knot (Andersen et al. 2018). The single tricortical 3.5 mm syndesmotic screw (TS) allows for some tibiofibular movement (Clanton et al. 2017), making the TS an inexpensive alternative, without need for routine implant removal. In this study we compare outcomes between a knotless SB and TS. Our hypothesis was that there is no difference in outcomes in patients treated with SB and a 3.5 mm TS.     

Radiographic parameters in gravity stress view of the ankle: Normative data

BackgroundIn rotational ankle injury with isolated fibular fracture, deltoid integrity is important for determining stability of ankle. Medial clear space and superior clear space in gravity stress view are parameters widely used to predict deltoid ligament tear. The purpose of this study is to report radiographic parameters in gravity stress view in normal population.Methods120 persons were enrolled. Non weight-bearing ankle mortise and gravity stress view were obtained. Radiographic measurements were made by 2 investigators, including medial clear space (MCS), superior clear space (SCS), tibiofibular overlaps, tibiofibular clear space and talocrural angle. Statistical analysis included mean, mean difference, SD, 95%CI, paired T-test were calculated and subgroup analysis by foot length. Intraclass correlation coefficients were used to determine intra/interobserver reliability of measurement.ResultsMean MCS in gravity stress view was 3.19 mm (95%CI 3.1–3.31). This compared to mean MCS of 3.01 mm (95%CI 2.9–3.12) in mortise view which was statistically significant (P = 0.02). Mean difference was 0.18 mm (95%CI 0.07–0.3). SCS in gravity stress view was 3.29 mm (95%CI 3.19–3.39) and when compared to MCS in gravity stress view, no statistical significance was found (P = 0.158). Mean difference was 0.1 mm (95%CI 0.03–0.21). In subgroup analysis by foot length, no significant difference was found in any parameters.ConclusionsThis study provides normative radiographic data for a gravity stress radiograph and supports that if measurable MCS >4 mm on gravity stress view, it should be aware of an unstable ankle in supination-external rotation injury.     

A computed tomography evaluation of two hundred normal ankles,to ascertain what anatomical landmarks to use when compressing or placing an ankle syndesmosis screw

Classical AO teaching recommends that a syndesmosis screw should be inserted at 25–30 degrees to the coronal plane of the ankle. Accurately judging the 25/30 degree angle can be difficult, resulting in poor operative reduction of syndesmosis injuries.The CT scans of 200 normal ankles were retrospectively examined. The centroid of the fibula and tibia in the axial plane 15 mm proximal to the talar dome was calculated. A force vector between the centroid of the fibula and the tibia in the axial plane should not displace the fibula relative to the tibia when surfaces are parallel. Therefore, a line connecting the two centroids was postulated to be the ideal syndesmosis line. This line was shown to pass through the fibula within 2.5 mm of the lateral cortical apex of the fibula and the anterior half of the medial malleolus in 100% of the ankles studied.The results support the concept that in the operatively reduced syndesmosis, the anterior half of the medial malleolus can be used as a reliable guide for aiming the syndesmosis drill hole, provided that the fibular entry point is at/or adjacent to the lateral fibular apex. The screw should also remain parallel to the tibial plafond in the coronal plane.     

Syndesmosis reduction by computer-assisted orthopaedic surgery with navigation: Feasibility and accuracy in a cadaveric study

IntroductionSyndesmotic disruption may be difficult to reduce and fix, and malreduction is associated with inferior outcomes. Intraoperative computed tomography (CT) can provide accurate assessment of syndesmotic reduction. We hypothesized that three-dimensional (3-D) computer-assisted orthopaedic surgery (CAOS) with navigation of syndesmotic reduction could avoid malreduction. Our goal was to assess feasibility and accuracy of such a technic in a cadaveric study.MethodEleven through-the-knee cadaveric specimens were used. Ankle CT as control was obtained prior to intervention. The syndesmosis was destabilized by sectioning the tibiofibular ligaments, producing a malreduction temporarily fixed with a Kirschner wire (K-wire). With reference base fixed to the tibia an acquisition scan was made. A K-wire was fixed to the fibula. The K-wire holding the syndesmosis malreduced was removed. The fibula was reduced within the syndesmosis under 3-D CAOS using a navigated K-wire. Once optimal position was obtained by referencing control images, the syndesmosis was fixed with a 3.5 mm screw. A CT scan was performed to assess quality of reduction.ResultsPosition of the fibula in control and post-reduction CT scans showed a mean anterior-posterior displacement of 0.74 (±0.62)mm. The medial-lateral position measured a mean displacement of 0.68 (±0.76)mm. Rotation of the fibula revealed a mean difference of 0.99° (± 0.73).ConclusionIn this cadaveric study, CAOS with navigation allowed for very accurate syndesmosis reduction. This appears to be a promising technique to be confirmed by clinical study.     

A Modified Technique for Fixation of Chronic Instability of the Distal Tibiofibular Syndesmosis Using a Wire and Button

Distal tibiofibular syndesmosis injury accounts for 1% to 11% of soft tissue injuries of the ankle. Some acute syndesmotic injuries will fail to heal effectively owing to inadequate treatment or misdiagnosis, eventually resulting in chronic instability, which can destroy the stability of the ankle joint. Various surgical techniques have been described for fixation of the syndesmosis. Among the existing methods, the suture button has the advantage of allowing for physiologic micromotion at the syndesmosis by maintaining the reduction and preventing the risk of screw breakage. However, the “relatively” long suture between buttons can gradually relax under continuous loading, resulting in fixation failure, which we have termed electric wire phenomenon. In the present report, we have described a modified technique for flexible fixation using the Endobutton CL ULTRA fixation device by tricortical fixation, instead of quadricortical fixation, to allow for robust and reliable fixation of the distal tibiofibular syndesmosis. The modified technique is devoid of the concern regarding the use of screw fixation and can reduce the risk of displacement or elongation and skin irritation associated with the suture button.