Biomechanical evaluation of syndesmotic screw position: a finite-element analysis

Do lateral ankle ligaments contribute to syndesmotic stability: a finite element analysis study

Whether the lateral ankle ligaments contribute to syndesmotic stability is still controversial and has been the subject of frequent research recently. In our study, we tried to elucidate this situation using the finite element analysis method. Intact model and thirteen different injury models were created to simulate injuries of the lateral ankle ligaments (ATFL, CFL, PTFL), injuries of the syndesmotic ligaments (AITFL, IOL, PITFL) and their combined injuries. The models were compared in terms of LFT, PFT and EFR. It was observed that 0.537 mm LFT, 0.626 mm PFT and 1.25° EFR occurred in the intact model (M#1), 0.539 mm LFT, 0.761 mm PFT and 2.31° EFR occurred in the isolated ATFL injury (M#2), 0.547 mm LFT, 0.791 mm PFT and 2.50° EFR occurred in the isolated AITFL injury (M#8). The LFT, PFT and EFR amounts were higher in the both M#2 and M#8 compared to the M#1. LFT, PFT and EFR amounts in M#2 and M#8 were found to be extremely close. In terms of LFT and PFT, when we compare models with (LFT: 0.650 mm, PFT: 1.104) and without (LFT: 0.457 mm, PFT: 1.150) IOL injury, it is seen that the amount of LFT increases and the amount of PFT decreases with IOL injury. We also observed that injuries to the CFL, PTFL and PITFL did not cause significant changes in fibular translations and PFT and EFR values show an almost linear correlation. Our results suggest that ATFL injury plays a crucial role in syndesmotic stability.

The clinical outcome comparison between trans-syndesmotic fixation and anatomic deltoid ligament repair in unstable ankle fractures with medial clear space widening: A systematic review and meta-analysis

BACKGROUND

Due to the variability in evidence supporting either trans-syndesmosis fixation or deltoid ligament repair in unstable ankle fractures with medical clear space (MCS) widening makes it unclear which surgical technique leads to the best patient outcomes. The goal of our systematic review and meta-analysis was to compare clinical outcomes of trans-syndesmotic fixation versus anatomic deltoid ligament repair in the management of unstable ankle fractures with MCS widening.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were utilized in this study. A comprehensive and systematic search was conducted using the PubMed, Embase, Web of Science and Cochrane Library databases. Outcomes investigated in this review included the rates of syndesmotic malreduction, removal of hardware, postoperative complications including wound issues, and functional/pain scores.

RESULTS

A total of five level-3 studies were selected in this review, with 280 unstable ankle fractures with MCS widening: 165 for the trans-syndesmotic fixation group and 115 for the anatomic deltoid ligament repair group. Three out of five studies evaluated syndesmotic malreduction using CT. Compared to the trans-syndesmosis fixation group, the deltoid repair group showed significant lower rates of syndesmotic malreduction rates and removal of hardware: 6.5 % (4/61) Vs. 27 % (16/59) (RR=0.26, 95 % CI=[0.10, 0.68]), and 2.6 % (3/115) Vs.54.5 % (90/165) (RR=0.06, CI=[0.02, 0.14]), respectively. No significant differences were found between the two groups in postoperative wound complications, reoperations, and functional scores including AOFAS and VAS pain score.

CONCLUSIONS

Based on our findings, anatomic deltoid ligament repair was associated with a lower rate of syndesmotic malreduction and the need for hardware removal while there was no significant difference in terms of postoperative wound complications, reoperation, AOFAS score, or VAS pain score. These results should be interpreted with caution due to limitations related to heterogeneity among the studies. Further high-level RCTs with larger sample sizes are necessary to establish a robust consensus.

Finite element analysis comparison of Type 42A2 fracture fixed with external titanium alloy locking plate and traditional external fixation frame

BACKGROUND

At present, not all Type AO/OTA 42A2 open fractures can be treated by external fixation brackets, not to mention the inconvenience of this technique in clinical practice. External titanium alloy locking plates, which are lightweight and easy-to-operate, can be used as an alternative treatment option for such patients. However, there are few reports of finite element biomechanical analysis on the titanium alloy locking plates and fixation brackets being placed on the medial side of the tibial fracture. In this study, the biomechanical properties of titanium alloy locking plates and fixation brackets for treating Type AO/OTA 42A2 fractures were compared by applying the finite element method, and the results provided data support for the clinical application of the external titanium alloy locking plate technique.

METHODS

Type AO/OTA 42A2 fracture models were constructed using CT data of a male volunteer for two external fixation techniques, namely the external titanium alloy locking plate technique and the external fixation bracket technique, according to commonly-used clinical protocols. Then, the four-point bending, axial compression, clockwise rotation and counterclockwise rotation tests under the maximum load were simulated in finite element analysis software. The stress distribution, peak stress and overall tibial displacement data for the two different external fixation techniques were obtained and compared.

RESULTS

In the four different test conditions (i.e., four-point bending, axial compression, clockwise torsion, counterclockwise torsion) under the maximum load, the two external fixation techniques showed obvious von Mises stress concentration at the contacts between the screw and tibia, between the screw and titanium alloy locking plate, between the self-tapping self-drilling needle and tibia, between the self-tapping self-drilling needle and the external fixation device, as well as around the fracture end and around the cortical bone at the upper and lower ends of the tibia. The peak stress was ranged 26.67-558.77 MPa, all below the yield stress strength of titanium alloy. The peak tibial displacement of the external titanium alloy locking plate model was smaller than that of the fixation bracket model. In terms of structural stability, the external titanium alloy locking plate technique was superior to the external fixation bracket technique.

CONCLUSIONS

When fixing Type AO/OTA 42A2 fractures, external titanium alloy locking plates are not only lightweight and easy-to-operate, but also have better performance in terms of axial compression, bending and torsion resistance. According to the finite element biomechanical analysis, external titanium alloy locking plates are superior to traditional external fixation brackets in treating Type AO/OTA 42A2 fractures and can better meet the needs of clinical application.

Current concepts in ankle fractures

Ankle fractures are among the most common orthopaedic injuries. Operative management is performed in unstable ankle fracture patterns to restore the stability and native kinematics of the ankle mortise and minimize the risk of post-traumatic degenerative changes. In this study, we review current concepts in ankle fracture management, including posterior malleolus fixation, syndesmosis fixation, deltoid ligament repair, fibular nailing, and early weightbearing, from both a biomechanical and clinical perspective.

Biomechanical analysis of different internal fixation methods for special Maisonneuve fracture of the ankle joint based on finite element analysis

OBJECTIVE

The objective of this study was to evaluate the biomechanical properties of different internal fixation methods for Maisonneuve fractures under physiological loading conditions.

METHODS

Finite element analysis was used to numerically analyze various fixation methods. The study focused on high fibular fractures and included six groups of internal fixation: high fibular fracture without fixation + distal tibiofibular elastic fixation (group A), high fibular fracture without fixation + distal tibiofibular strong fixation (group B), high fibular fracture with 7-hole plate internal fixation + distal tibiofibular elastic fixation (group C), high fibular fracture with 7-hole plate internal fixation + distal tibiofibular strong fixation (group D), high fibular fracture with 5-hole plate internal fixation + distal tibiofibular elastic fixation (group E), and high fibular fracture with 5-hole plate internal fixation + distal tibiofibular strong fixation (group F). The finite element method was employed to simulate and analyze the different internal fixation models for the six groups, generating overall structural displacement and Von Mises stress distribution maps during slow walking and external rotation motions.

RESULTS

Group A demonstrated the best ankle stability under slow walking and external rotation, with reduced tibial and fibular stress after fibular fracture fixation. Group D had the least displacement and most stability, while group A had the largest displacement and least stability. Overall, high fibular fracture fixation improved ankle stability. In slow walking, groups D and A had the least and greatest interosseous membrane stress. Comparing 5-hole plate (E/F) and 7-hole plate (C/D) fixation, no significant differences were found in ankle strength or displacement under slow walking or external rotation.

CONCLUSION

Combining internal fixation for high fibular fractures with elastic fixation of the lower tibia and fibula is optimal for orthopedic treatment. It yields superior outcomes compared to no fibular fracture fixation or strong fixation of the lower tibia and fibula, especially during slow walking and external rotation. To minimize nerve damage, a smaller plate is recommended. This study strongly advocates for the clinical use of 5-hole plate internal fixation for high fibular fractures with elastic fixation of the lower tibia and fibula (group E).

Biomechanical Sequelae of Syndesmosis Injury and Repair

This review characterizes fibula mechanics in the context of syndesmosis injury and repair. Through detailed understanding of fibula kinematics (the study of motion) and kinetics (the study of forces that cause motion), the full complexity of fibula motion can be appreciated. Although the magnitudes of fibula rotation and translation are inherently small, even slight alterations of fibula position or movement can substantially impact force propagation through the ankle and hindfoot joints. Accordingly, implications for clinical care are discussed.

Biomechanical Analysis of Tibiofibular Syndesmosis Injury Fixation Methods: A Finite Element Analysis

The optimal treatment strategy after syndesmotic injuries is still controversial. In our study, we aimed to evaluate ideal fixation method in syndesmotic injury by using finite element analysis method. A 3D SolidWorks model file was created by taking computed tomography (CT) images of the area from the right foot base to the knee joint level of a healthy adult male. The intact model, injury model, and 8 different fixation models were created that 3.5 mm screw and suture-button were used in. The models were compared in terms of lateral fibular translation, posterior fibular translation and external rotation of fibula compared to tibia and stress values occurred on screws and suture-buttons. In the hybrid-1 model, lateral fibular translation and external fibular rotation values were obtained as close to the intact model. Von Mises stresses occurred in the screw (435.7 MPa) and suture-button (424.7 MPa) that used in hybrid-1 model was more than single screw at 4 cm model (316.8 MPa) and single suture-button at 2 cm model (160.7 MPa). In the Hybrid-1 model, the screw compensates for posterior fibular translation and external fibular rotation, while the suture-button compensates for lateral fibular translation. Also, the effect of the distal suture-button preventing diastasis in case of proximal screw failure, it was concluded that the hybrid-1 model can be used as a good treatment alternative in the surgical treatment of distal tibiofibular syndesmotic injuries.

Does the Level of Syndesmotic Screw Insertion Affect Clinical Outcome after Ankle Fractures with Syndesmotic Instability?

OBJECTIVE

Ankle fractures are often combined with syndesmotic instability, requiring reduction and stabilization. However, the optimal level for syndesmotic screw positioning remains unclear. This study aims to evaluate the effect of different syndesmotic screw insertion levels on postoperative clinical outcomes and determine whether an optimal level exists.

METHODS

This retrospective study included data from 43 adult patients with acute closed ankle fractures combined with intraoperative evidence of unstable syndesmotic injuries who underwent open reduction internal fixation from January 1, 2017 to March 1, 2018 according to the inclusion and exclusion criteria. All 43 patients were divided into three groups based on the syndesmotic screw placement level: trans-syndesmotic group: screw level of 2-3 cm; inferior-syndesmotic group: screw level <2 cm; and supra-syndesmotic group: screw level >3 cm. Clinical outcomes were measured at the final follow-up, including the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Olerud-Molander Ankle Score (OMAS), short-form 36-item questionnaire (SF-36), visual analogue scale (VAS) score and restrictions in ankle range of motion (ROM). The relationships between screw placement level and clinical outcomes were analyzed with the Kruskal-Wallis H-test and Spearman correlation analysis.

RESULTS

The median follow-up duration was 15 months (range, 10-22 months). No patients developed fracture nonunion or malunion or experienced hardware failure. The outcome scoring systems showed an overall score for the entire group of 94.91 points for the AOFAS ankle-hindfoot score, 83.14 for the OMAS, 96.65 for the SF-36, 1.77 for the VAS, 9.14° for the restrictions in dorsiflexion, and 1.30° for the restrictions in plantarflexion. There were no significant differences among three groups in clinical outcomes (P > 0.05). Neither the AOFAS score nor OMAS had significant correlations with screw insertion level (P = 0.825 and P = 0.585, respectively). No postoperative arthritis or widening of the tibiofibular space was observed at the final follow-up.

CONCLUSION

Different syndesmotic screw placement levels appear not to affect the clinical outcomes of ankle fractures with syndesmotic instability. No optimal level was observed in this study. Our findings suggest other clinically acceptable options apart from syndesmotic screw placement 2-3 cm above the ankle.

Predicting ankle joint syndesmotic screw lifetime using finite element and fatigue analysis

After recovery and loading on the patient’s leg, syndesmotic screws mounted on an injured ankle may fail. The main subject of this study is to estimate the lifetime of screws considering the patient’s weight and physical activity. Method: A 3D finite element model of the bone and implemented screws were provided assigning the mechanical properties of ligaments, bones, and screws. Considering axial and tangential physiological loads during the walking phase, the stress and fatigue analyses were performed. Results: The stress distribution had an identical pattern in the screws and all of them experienced the maximum stress during 60–70% of the walking phase. Conclusion: The results of analyses show that body weight has a significant effect on the mounted screw lifetime. Patients with a weight of more than [Formula: see text] kg should prevent applying body load on the operated leg. Conversely, no worry about a patient having less than [Formula: see text] kg body weight.

Syndesmotic Screw Breakage May Be More Problematic Than Previously Reported: Increased Rates of Hardware Removal Secondary to Pain With Intraosseous Screw Breakage

BACKGROUND

The majority of retained syndesmotic screws will either loosen or break once the patient resumes weight-bearing. While evidence is limited, anecdotal experience suggests that intraosseous screw breakage may be problematic for some patients due to painful bony erosion. This study seeks to identify the incidence of intraosseous screw breakage, variables that may predict intraosseous screw breakage, and whether intraosseous screw breakage is associated with higher rates of implant removal secondary to pain.

METHODS

Five hundred thirty-one patients undergoing syndesmotic stabilization were screened, of which 43 patients (with 58 screws) experiencing postoperative screw breakage met inclusion criteria. Patient charts were retrospectively reviewed for demographic data, comorbidities, time to screw breakage, location of screw breakage, and implant removal. Several radiographic parameters were evaluated for their potential to influence the site of screw breakage.

RESULTS

Intraosseous screw breakage occurred in 32 patients (74.4%). Screw breakage occurred exclusively in the tibiofibular clear space in the remaining 11 instances (25.6%). Intraosseous screw breakage was significantly associated with eventual implant removal after breakage (P = .034). Screws placed further from the tibiotalar joint were at less risk for intraosseous breakage (odds ratio 0.818, P = .002). Screws placed at a threshold height of 20 mm or greater were more likely to break in the clear space (odds ratio 12.1, P = .002).

CONCLUSION

Syndesmotic screw breakage may be more problematic than previously described. Intraosseous breakage was associated with higher rates of implant removal secondary to pain in this study. Placement of screws 20 mm or higher from the tibiotalar joint may decrease risk of intraosseous breakage.Levels of Evidence: Level III: Retrospective study.

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.

Anatomical reconstruction of the anterior inferior tibiofibular ligament in elite athletes using InternalBrace suture tape

AIMS

The ideal management of acute syndesmotic injuries in elite athletes is controversial. Among several treatment methods used to stabilize the syndesmosis and facilitate healing of the ligaments, the use of suture tape (InternalBrace) has previously been described. The purpose of this study was to analyze the functional outcome, including American Orthopaedic Foot & Ankle Society (AOFAS) scores, knee-to-wall measurements, and the time to return to play in days, of unstable syndesmotic injuries treated with the use of the InternalBrace in elite athletes.

METHODS

Data on a consecutive group of elite athletes who underwent isolated reconstruction of the anterior inferior tibiofibular ligament using the InternalBrace were collected prospectively. Our patient group consisted of 19 elite male athletes with a mean age of 24.5 years (17 to 52). Isolated injuries were seen in 12 patients while associated injuries were found in seven patients (fibular fracture, medial malleolus fracture, anterior talofibular ligament rupture, and posterior malleolus fracture). All patients had a minimum follow-up period of 17 months (mean 27 months (17 to 35)).

RESULTS

All patients returned to their pre-injury level of sports activities. One patient developed a delayed union of the medial malleolus. The mean return to play was 62 days (49 to 84) for isolated injuries, while the patients with concomitant injuries returned to play in a mean of 104 days (56 to 196). The AOFAS score returned to 100 postoperatively in all patients. Knee-to-wall measurements were the same as the contralateral side in 18 patients, while one patient lacked 2 cm compared to the contralateral side.

CONCLUSION

This study suggests the use of the InternalBrace in the management of unstable syndesmotic injuries offers an alternative method of stabilization, with good short-term results, including early return to sports in elite athletes. Cite this article: Bone Joint J 2022;104-B(1):68-75.

Diagnosis and Treatment of Syndesmotic Unstable Injuries: Where We Are Now and Where We Are Headed

Up to 10% of ankle sprains are considered "high ankle" sprains with associated syndesmotic injury. Initial diagnosis of syndesmotic injury is based on physical examination, but further evaluation of the distal tibiofibular joint in the sagittal, coronal, and rotational planes is necessary to determine instability. Imaging modalities including weight-bearing CT and ultrasonography allow a physiologic and dynamic assessment of the syndesmosis. These modalities in turn provide the clinician useful information in two and three dimensions to identify and consequently treat syndesmotic instability, especially when subtle. Because there is notable variability in the shape of the incisura between individuals, contralateral comparison with the uninjured ankle as an optimal internal control is advised. Once syndesmotic instability is identified, surgical treatment is recommended. Several fixation methods have been described, but the foremost aspect is to achieve an anatomic reduction. Identifying any associated injuries and characteristics of the syndesmotic instability will lead to the appropriate treatment that restores the anatomy and stability of the distal tibiofibular joint.

Biomechanical comparison of screw, tightrope and novel double endobutton in the treatment of tibiofibular syndesmotic injuries

BACKGROUND

Adequate reduction and stabilization of the syndesmosis are significant to prevent early degeneration of the ankle joint and get better clinical outcomes. However, the routine surgical methods have diffierent limitations. The purpose of this study was to develop a novel double Endobutton fixation to treat the distal tibiofibular syndesmotic injuries, and determine whether the novel double Endobutton fixation demonstrates a better biomechanical property compare with the intact syndesmosis, the screw fixation and the Tightrope fixation.

METHODS

Twenty-four normal fresh-frozen ankle specimens with a mean age of 42 ± 8 (range, 28-62) years were randomly divided equally into four groups: (1) the intact group, (2) the screw group, (3) the Tightrope group, (4) the Endobutton group. 3D printer technology was used to establish the personalized distal tibiofibular syndesmotic navigation modules to determine the accurate bone tunnel. Axial loading was applied in five ankle positions: neutral position, dorsiflexion, plantar flexion, varus and valgus. Rotation torque was applied in two ankle rotation of the neutral position: internal and external.

RESULTS

In most situations, the displacements of the intact group were larger than the screw group, the Tightrope group and the Endobutton group (P < .05), and the displacements of the screw group were smaller than other three groups (P < .05). The displacements of the double Endobutton group were slightly larger than the Tightrope group but no significant differences were found between these two groups except in the dorsiflexion position of axial loading experiments (P < .05). The novel double Endobutton fixation was steadier than intact syndesmosis and more micromotional than screw fixation.

CONCLUSION

Our study demonstrated that the novel double Endobutton can be considered as the better fixation in treatment of distal tibiofibular syndesmotic injuries.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Biomechanical evaluation of syndesmotic fixation techniques via finite element analysis: Screw vs. suture button

BACKGROUND AND OBJECTIVE

Tibiofibular syndesmotic injuries may cause degenerative changes, reduction in ankle function and compromising ankle stability. Different fixation techniques try to restore its functionality. Screw-fixation is the gold-standard. Recently, suture-button fixation has aroused the attention because it allows for physiologic micromotion while maintaining an accurate reduction. The aim of this study is to compare the biomechanical behaviour of both fixation techniques using the finite element method.

METHODS

A three-dimensional finite element model of the tibiofibular joint was reconstructed simulating the intact ankle and the injured syndesmosis. Then, different methods of syndesmosis fixation were analysed: screws (number of cortices, number of screws and distance between screws) and suture buttons (single, double parallel and double divergent with a sensitivity analysis on the pretension forces) configuration. Ligaments and cartilages were included and simulated as spring elements. Physiological loads during stance phase were simulated.

RESULTS

Syndesmosis widening and von Mises stresses were computed. Syndesmosis widening in the injured configuration compromised joint stability (2.06 mm), whereas using a single quadricortical screw (0.18 mm) stiffened the joint. Syndesmosis widening using suture-buttons were closer to syndesmosis widening of the intact ankle configuration (0.97 mm). Von Mises stresses were higher for the titanium screws than for the suture buttons.

CONCLUSIONS

A detailed biomechanical comparison among different syndesmotic fixation was performed. Suture buttons have advantages with regard to syndesmosis widening in comparison to screw fixation. This fact supports the good long-term clinical results obtained with suture buttons fixation. The proposed methodology could be an efficient tool for preoperative planning.

Ideal Angle of Upper and Lower Syndesmotic Fixation Based on Weightbearing Computed Tomographic Imaging in Uninjured Ankles

Syndesmotic fixation remains a controversial topic, however most authors recommend fixation of the disrupted syndesmotic complex in unstable ankle fractures. There is no clear reference for the angle of syndesmotic fixation, historically 30° has been cited but recently refuted, with new and current literature. It is common practice to place 2 points of transyndesmotic fixation one with fixation placed at around 2 cm above the ankle joint and the second point approximately 3.5 cm above the plafond. Our hypothesis is that the ideal angle of transyndesmotic fixation is less than 30° and that the ideal angle changes when you move proximal from the 2-cm level to 3.5-cm level. This is based on cross-sectional anatomy as seen on weightbearing computerized tomography imaging. It is imperative to achieve adequate reduction of the syndesmosis to prevent instability and a malaligned ankle joint, as this can result in refractory pain and early onset of degenerative changes. We reviewed 50 weightbearing computerized tomography scans of the foot and ankle to identify what we call the adjusted syndesmotic fixation angle. Our review found adjusted syndesmotic fixation angle to be 19.7° with ranges of (8°-31°) at 2 cm and 24.8° with ranges of (14°-38°) at 3.5 cm above the tibial plafond. These values were statistically significant when compared to historically cited 30°. Our research concludes that the historically cited 30° angle is frequently not the ideal angle for syndesmotic fixation and actually is less.

Can Syndesmosis Screws Displace the Distal Fibula?

Background. There has been historical debate as to whether the distal tibiofibular syndesmosis can be overtightened during operative fixation. We used finite-element analysis to determine if overtightening of syndesmotic screws can cause widening of the lateral gutter clear space in the ankle joint. Methods. A 3D finite-element model was constructed and analyzed using geometries from a computed tomography scan of a cadaveric lower leg. Starting 2 cm from the plafond, screw fixation was simulated at 5-mm increments to a distance of 5 cm from the plafond. The fibula was compressed 2 mm toward the tibia at each interval, and the change in distance between the lateral talus and distal fibula was measured. Results. Medial deflection of the fibula resulted in widening of the lateral clear space, which was proportional to the amount of deflection. The effect increased as screws were placed closer to the plafond, with 1.5 mm of widening at 2 cm (0.76 mm/mm) versus 0.7 mm at 5 cm (0.34 mm/mm). Conclusion. Our finite-element model demonstrated that overtightening of the distal tibiofibular syndesmosis with medial fibular displacement can cause widening of the lateral clear space. Clinical relevance. The results suggest that screws placed farther from the plafond widen the lateral clear space to a lesser degree, which may be advantageous during surgical fixation to prevent clear space widening and increased tibiotalar contact forces.Levels of Evidence: Level I.

Anatomical Study of the Interosseous Ligament of the Tibiofibular Syndesmosis: An Analysis of Osseous Morphology and Attaching Interposing Structures

BACKGROUND

The morphological features of the interosseous tibiofibular area in relation to the tensile stress of the interosseous ligament (IOL) have rarely been discussed. The purpose of the present study was to investigate the IOL on the basis of osseous surface morphology and macroscopic and histological anatomy. We hypothesized that the osseous surface of the interosseous tibiofibular area has a specific feature corresponding to the fibrous structure in the IOL.

METHODS

Eighteen ankles from 15 cadavers were analyzed. Micro-computed tomography (micro-CT) images were obtained for all specimens to observe the osseous surface in the syndesmosis and to visualize the distribution of cortical bone thickness. Fifteen ankles were macroscopically analyzed, and the other 3 ankles were histologically analyzed.

RESULTS

Micro-CT imaging revealed the osseous prominence on the medial side of the fibula. Cortical thickness mapping showed that the thickness of the cortical bone on the medial side of the fibula proximal to the prominence (mean and standard deviation, 1.4 ± 0.5 mm; p < 0.001) was greater in comparison with the other quadrants, namely, the proximal part of the tibia (0.8 ± 0.2), distal part of the fibula (0.7 ± 0.2), and distal part of the tibia (0.5 ± 0.1). Macroscopic analysis indicated that the perforating branch of the fibular artery ran through the proximal top of the IOL, which formed a thickened fiber and was attached to the fibular prominence. Histological analysis revealed that the thickened fibrous part of the IOL attached to the fibula via the fibrocartilaginous insertion. At the middle of the IOL, thin and fatty-like tissue was interposed between the tibia and the fibula.

CONCLUSIONS

We observed that the osseous prominence of the fibula corresponded to the proximal thickened part of the IOL via the fibrocartilaginous attachment. The thickened proximal part of the IOL was consistently found in this location; we believe that this finding was related to the fact that the fibular artery perforated the adjacent distal part of the interosseous membrane (IOM).

CLINICAL RELEVANCE

The location of the prominence on the medial aspect of the fibula could be a helpful clue as to the ideal location of syndesmotic fixation.

[Research progress in diagnosis and treatment of distal tibiofibular syndesmosis injury]

Objective

To review the research progress in the diagnosis and treatment of distal tibiofibular syndesmosis injury.

Methods

The recent literature about distal tibiofibular syndesmosis injury was reviewed and analyzed.

Results

Distal tibiofibular syndesmosis injury is commonly seen in ankle joint injury, the anatomical complexities make diagnosis and treatment difficult. Preoperative physical examination, radiologic evaluation, and intraoperative stress-testing are important for the diagnosis. Aggressive treatment is also recommended for these injuries to prevent long-term chronic instability. Internal fixation is the main treatment, including metal screw, degradable screw, elastic fixation, and hybrid techniques. Metal screw fixation is still the current mainstream, but elastic fixation represented by Suture-button is more in line with the physiological characteristics of ankle joint, and the rate of secondary operation is low while the clinical outcome is satisfactory. The application prospect of elastic fixation is worthy of expectation.

Conclusion

It's crucial for patient with ankle fracture to repair the distal tibiofibular syndesmosis injury. How to diagnose the injury more accurately and simply, how to increase the success rate of reduction, and how to reduce the complications of surgery are still worthy for further exploration.

Optimal Screw Fixation of Syndesmosis Using a Targeting Drill Guide: A Technical Note

Optimal screw fixation of the syndesmosis is difficult. We introduce a novel technique using a targeting drill guide for centroidal screw fixation of a syndesmosis to ensure a reproducible and optimal screw trajectory for syndesmosis fixation. By using a drill guide for anterior cruciate ligament surgery and intraoperative fluoroscopy, syndesmosis fixation enables reproducible fixation along an individual centroidal axis.

Identification of Surgical Plan for Syndesmotic Fixation Procedure Based on Finite Element Method

Syndesmosis injuries account for approximately 20% of ankle fractures that require surgery. Although multiple surgical options are available, all of them are based on metal screws. Serious complications that arise when applying metal screws include screw loosening or breakage. To prevent such complications, we applied a simulation method using a finite element (FE) analysis. We created a 3D FE model of an ankle joint and conducted an FE analysis focusing on syndesmosis in terms of the level, material, and diameter of the syndesmotic screw and the number of penetrated cortical bones. The magnitude and direction of the force applied to the tibia in the midstance state were considered for simulating the model. The maximum von-Mises stress and syndesmosis widening were analyzed in terms of different biomechanical parameters. We identified the characteristics of the most biomechanically stable syndesmotic screw and its fixation point on the basis of the two parameters. We demonstrated that the ideal syndesmotic screw fixation should be fixed at a level 20 to 25 mm above the ankle using a 4.5 mm titanium screw.

Diagnosis and treatment of ankle syndesmosis injuries with associated interosseous membrane injury: a current concept review

BACKGROUND

Tibiofibular syndesmosis injury leads to ankle pain and dysfunction when ankle injuries are not treated properly. Despite several studies having been performed, many questions about diagnosis and treatment remain unanswered, especially in ankle syndesmosis injury with interosseous membrane injury. Therefore, the purpose of this study was to help guide best practice recommendations.

METHODS

This review explores the mechanism of injury, clinical features, diagnosis methods, and the treatment strategy for ankle syndesmosis injury with interosseous membrane injury to highlight the current evidence in terms of the controversies surrounding the management of these injuries.

RESULTS

Radiological and CT examination are an important basis for diagnosing ankle syndesmosis injury. Physical examination combined with MRI to determine the damage to the interosseous membrane is significant in guiding the treatment of ankle syndesmosis injury with interosseous membrane injury. In the past, inserting syndesmosis screws was the gold standard for treating ankle syndesmosis injury. However, there were increasingly more controversies regarding loss of reduction and broken nails, so elastic fixation has become more popular in recent years.

CONCLUSIONS

Anatomical reduction and effective fixation are the main aspects to be considered in the treatment of ankle syndesmosis injury with interosseous membrane injury and are the key to reducing postsurgery complications.

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

BACKGROUND

Ankle 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/PURPOSES

The 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.

METHODS

Computed 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.

RESULTS

The 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.

CONCLUSIONS

Reduction 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 EVIDENCE

2 (Retrospective diagnostic).

Current trends in the diagnosis and management of syndesmotic injury

Ideal management of the various presentations of syndesmotic injury remains controversial to this day. High quality evidentiary science on this topic is rare, and numerous existing studies continue to contradict one another. The primary reasons for these discrepancies are that previous studies have failed to (1) properly distinguish between isolated (non-fractured) and non-isolated injuries, (2) accurately define stable from unstable injuries, and (3) sufficiently differentiate between acute and chronic injuries. The purpose of this review is to summarize today's body of literature regarding diagnosis and management of syndesmotic injury and discuss current trends and important future directions to optimize care of this very heterogeneous population.

An update on the evaluation and treatment of syndesmotic injuries

INTRODUCTION

Injuries to the distal tibiofibular syndesmosis are frequent and continue to generate controversy.

METHODS

The majority of purely ligamentous injuries ("high ankle sprains") is not sassociated with a latent or frank tibiofibular diastasis and may be treated with an extended protocol of physical therapy. Relevant instability of the syndesmosis with diastasis results from rupture of two or more ligaments that require surgical stabilization. Syndesmosis disruptions are commonly associated with bony avulsions or malleolar fractures. Treatment consists in anatomic reduction of the distal fibula into the corresponding incisura of the distal tibia and stable fixation. Proposed means of fixation are refixation of bony syndesmotic avulsions, one or two tibiofibular screws and suture button. There is no consensus on how long to maintain fixation. Both syndesmotic screws and suture buttons need to be removed if symptomatic.

RESULTS/COMPLICATIONS

The most frequent complication is syndesmotic malreduction and may be minimized with open reduction and intraoperative 3D scanning. Other complications include hardware failure, heterotopic ossification, tibiofibular synostosis, chronic instability and posttraumatic arthritis.

CONCLUSION

The single most important prognostic factor is anatomic reduction of the distal fibula into the tibial incisura.