Overtightening of the ankle syndesmosis: is it really possible?

Which type of supra-syndesmal fractures Weber C or Equivalent Weber C have the best reduction of the distal tibio-fibular syndesmosis? A prospective CT-scan investigation on 60 ankles

INTRODUCTION

The reduction of the distal tibiofibular syndesmosis (SyTFd) is a crucial factor in the functional prognosis following a suprasyndesmotic ankle fracture. Few studies have compared, using computed tomography (CT), the quality of SyTFd reduction in Weber C ankle fractures (WebC) and Equivalent Weber C (EqWebC) fractures, where there is a medial ligament injury instead of a bony malleolar lesion. This CT-based study aimed to answer the following questions: (1) Do Weber C fractures allow for better reduction of the distal tibiofibular syndesmosis compared to Equivalent Weber C fractures? (2) Are the functional outcomes one year postoperatively better for Weber C fractures compared to Equivalent Weber C fractures?

HYPOTHESIS

The hypothesis was that WebC fractures would present better reduction of the SyTFd than EqWebC fractures due to the restoration of bone anatomy, considering the bony nature of the medial ligament involvement.

MATERIALS AND METHODS

Since December 2021, all patients presenting with an ankle fracture were included in a database. Suprasyndesmotic fractures were extracted, and between December 2021 and February 2022, 60 patients underwent surgery for a suprasyndesmotic fracture (28 WebC - 32 EqWebC). All patients were operated on using the same technique and underwent a postoperative bilateral CT scan in axial slices with both ankles in a neutral position (foot at 90 ° to the leg). An analysis of 8 measurements was performed under the same conditions. Each fractured ankle was compared to the healthy contralateral ankle, and a delta was obtained for each measurement. The follow-up was standardized. At one year, an AOFAS Score and a Maryland Foot Score (MFS) were recorded. Statistical differences between the two groups were measured using the Student's t-test and Chi-square test.

RESULTS

There was a significant difference between the WebC and EqWebC groups for clinical scores at one year postoperatively: AOFAS: 92.0 ± 6.3 [78-100] vs. 80.1 ± 5.4 [62-100], p < 0.05; MFS: 90.9 ± 6.4 [78-100] vs. 81.6 ± 5.2 [64-100], p < 0.05. CT scan analysis of the SyTFd reduction found significantly better reduction in the WebC group.

DISCUSSION

WebC fractures showed better clinical scores associated with better SyTFd reduction on postoperative CT scans. The anatomical reduction related to the bone reduction criteria during surgery could explain our findings.

LEVEL OF EVIDENCE

III; Case-Control Comparative Study.

A Cadaveric Study: Does Ankle Positioning Affect the Quality of Anatomic Syndesmosis Reduction?

OBJECTIVE

The objective of this study was to compare the quality of syndesmotic reduction with the ankle in maximal dorsiflexion versus neutral plantarflexion (normal resting position).

METHODS

Baseline computed tomography (CT) imaging of 10 cadaveric ankle specimens from 5 donors was obtained with the ankles placed in normal resting position. Two fellowship-trained orthopaedic surgeons disrupted the syndesmosis of each ankle specimen. All ankles were then placed in neutral plantarflexion and were subsequently reduced with thumb pressure under direct visualization through an anterolateral approach and stabilized with one 0.062-inch K-wire placed from lateral to medial in a quadricortical fashion across the syndesmosis. Postreduction CT scans were then obtained with the ankle in normal resting position. This process was repeated with the ankles placed in maximal dorsiflexion during reduction and stabilization. Postreduction CT scans were then obtained with the ankles placed in normal resting position. All postreduction CT scans were compared with baseline CT imaging using mixed-effects linear regression with significance set at P < 0.05.

RESULTS

Syndesmotic reduction and stabilization in maximal dorsiflexion led to increased external rotation of the fibula compared with baseline scans [13.0 ± 5.4 degrees (mean ± SD) vs. 7.5 ± 2.4 degrees, P = 0.002]. There was a tendency toward lateral translation of the fibula with the ankle reduced in maximal dorsiflexion (3.3 ± 1.0 vs. 2.7 ± 0.7 mm, P = 0.096). No other statistically significant differences between measurements of reduction with the ankle placed in neutral plantarflexion or maximal dorsiflexion compared with baseline were present (P > 0.05).

CONCLUSIONS

Reducing the syndesmosis with the ankle in maximal dorsiflexion may lead to malreduction with external rotation of the fibula. There was no statistically significant difference in reduction quality with the ankle placed in neutral plantarflexion compared with baseline. Future studies should assess the clinical implications of ankle positioning during syndesmotic fixation.

Effect of Distal Tibiofibular Destabilization and Syndesmosis Compression on the Flexibility Kinematics of the Ankle Bones: An In Vitro Human Cadaveric Model

Background

Overcompression of the distal tibiofibular syndesmosis during open reduction and internal fixation of ankle fracture may affect multidirectional flexibility of the ankle bones.

Methods

Ten cadaveric lower limbs (78.3±13.0 years, 4 female, 6 male) underwent biomechanical testing in sagittal, coronal, and axial rotation with degrees of motion quantified. The intact force (100%) was the force needed to compress the syndesmosis just beyond the intact position, and overcompression was defined as 150% of the intact force. After intact testing, the anterior inferior tibiofibular ligament (AITFL), interosseus membrane (IOM), and posterior inferior tibiofibular ligament (PITFL) were sectioned and testing was repeated. The IOM and AITFL were reconstructed in sequence and tested at 100% and 150% compression.

Results

Overcompression of the syndesmosis did not significantly reduce ROM of the ankle bones for any loading modality (P > .05). IOM+AITFL reconstruction restored distal tibiofibular axial rotation to the intact condition. Axial rotation motion was significantly lower with AITFL fixation compared with IOM fixation alone (P < .05). The proximal tibiofibular syndesmosis demonstrated significantly higher motion in axial rotation with all distal reconstruction conditions.

Conclusion

As assessed by direct visualization, overcompression of the distal tibiofibular syndesmosis did not reduce ROM of the ankle bones. Distal tibiofibular axial rotation was significantly lower with IOM+AITFL fixation compared with IOM augmentation alone. Distal tibiofibular axial rotation did not differ significantly from the intact condition after combined IOM+AITFL fixation. Dynamic fixation of the distal tibiofibular syndesmosis resulted in increased axial rotation at the proximal tibiofibular syndesmosis.

Clinical Relevance

These biomechanical data suggest that inadvertent overcompression of the distal tibiofibular syndesmosis when fixing ankle fractures does not restrict subsequent ankle bone ROM. The AITFL is an important stabilizer of the distal tibiofibular syndesmosis in external rotation.

Level of Evidence

controlled laboratory study.

Center-Center Surgical Technique With Dynamic Syndesmosis Fixation: A Cadaveric Pilot Study

The objective of this cadaveric biomechanical study was to evaluate if the center-center surgical technique is a reliable and repeatable method of achieving proper syndesmotic reduction when using dynamic syndesmotic fixation. Nine fresh frozen above-knee cadaveric lower extremities were used. Computerized tomography (CT) scans were first obtained for each intact specimen as the baseline for comparison. A simulated complete syndesmotic disruption was created by transection of all deltoid and syndesmotic ligaments. Instability of the ankle was confirmed with stress imaging using fluoroscopy. Each unstable specimen was repaired using the center-center surgical technique with dynamic syndesmosis fixation. A series of measurements from the axial CT images of intact and repaired specimens were used to determine the anatomic distal tibiofibular relationships for comparison of changes from intact to postfixation. All radiographic measurements were performed by 4 independent foot and ankle surgeons. The level of inter-rater reliability for all the measurements was found to be "moderate" to "excellent" agreement (ICC value: 0.865-0.983, 95% confidence interval: 0.634-0.996). There was no statistical difference found between rotational alignment of native and postfixation (a/b: p = .843; b-a: p = .125; θ: p = .062). There was a statistical difference detected for lateral alignment at the center of fibularis incisura between native and postfixation (average: -0.6 ± 0.8 mm, range: -2.3 to 1.2 mm, p < .001). There was no statistical difference found for the anteroposterior translation alignment between native and postfixation (d/e: p = .251; f: p = .377). This study demonstrated the use of the center-center surgical technique as a viable and repeatable method for achieving anatomical reduction of the tibiofibular syndesmosis when used with dynamic fixation modalities.

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.

Anterior Incisura Fibularis Corner Landmarks Can Safely Validate the Optimal Distal Tibiofibular Reduction in Malleolar Fractures-Prospective CT Study

BACKGROUND

Distal tibiofibular injuries are common in patients with malleolar fractures. Malreduction is frequently reported in the literature and is mainly caused by insufficient intraoperative radiological evaluation. In this direction, we performed a prospective observational study to validate the efficacy of the anatomical landmarks of the anterior incisura corner.

METHODS

Patients with malleolar fractures and syndesmotic instability were reduced according to specific anatomic landmarks and had a postoperative bilateral ankle CT. The quality of the reduction was compared to the healthy ankles.

RESULTS

None of the controlled parameters differed significantly between the operated and healthy ankles. Minor deviations were correlated to the normal incisura morphology rather than the reduction technique.

CONCLUSIONS

The anterior incisura anatomical landmarks can be an efficient way of reducing the distal tibiofibular joint without the need for intraoperative radiological evaluation.

Instability of the distal tibiofibular syndesmosis

The distal tibiofibular syndesmosis (DTFS) is more frequently injured than previously thought. Early diagnosis and appropriate treatment is essential to avoid long term complications like chronic instability, early osteoarthritis and residual pain. Management of these injuries require a complete understanding of the anatomy of DTFS, and the role played by the ligaments stabilizing the DTFS and ankle. High index of suspicion, appreciating the areas of focal tenderness and utilizing the provocative maneuvers help in early diagnosis. In pure ligamentous injuries radiographs with stress of weight bearing help to detect subtle instability. If these images are inconclusive, then further imaging with MRI, CT scan, stress examination under anesthesia, and arthroscopic examination facilitate diagnosis. An injury to syndesmosis frequently accompanies rotational fractures and all ankle fractures need to be stressed intra-operatively under fluoroscopy after fixation of the osseous components to detect syndesmotic instability. Non-operative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. Anatomic reduction of the syndesmosis is critical, and currently both trans-syndesmotic screws and suture button fixation are commonly used for syndesmotic stabilization. Chronic syndesmotic instability (CSI) requires debridement of syndesmosis, restoration of ankle mortise with or without syndesmotic stabilization. Arthrodesis of ankle is used a last resort in the presence of significant ankle arthritis. This article reviews anatomy and biomechanics of the syndesmosis, the mechanism of pure ligamentous injury and injury associated with ankle fractures, clinical, radiological and arthroscopic diagnosis and surgical treatment.

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.

Predisposing Factors for Posttraumatic Osteoarthritis After Malleolus Fracture Fixation in Patients Younger Than 50 Years

BACKGROUND

The purpose of this study was to identify the risk factors for posttraumatic osteoarthritis (OA) after surgery for ankle fractures in patients aged ≤50 years.

METHODS

We performed a retrospective review of consecutive patients who underwent surgery for ankle fractures and were followed up for a minimum period of 5 years. The patients were assigned to 2 groups according to the presence of advanced OA at the last follow-up. Binary logistic regression was used to model the correlation between risk factors and OA. Functional outcomes were assessed using the Foot and Ankle Outcome Score.

RESULTS

The data of 332 patients who met the inclusion criteria were included in the analysis. The overall rate of posttraumatic arthritis was 27.7% (nonarthritis group: 240 patients, arthritis group: 92 patients). The arthritic change was significantly affected by BMI (95% confidence interval [CI] 1.29-19.76; adjusted odds ratio [OR] ≥ 30, 6.56), fracture-dislocation injury (CI 1.66-11.57; adjusted OR, 4.06), posterior malleolus (PM) fracture (CI 1.92-12.73, adjusted OR > 25% of the articular surface, 5.72), and postoperative articular incongruence (CI 1.52-18.10; adjusted OR, 7.21). The mean scores of the arthritis group were lower than those in the nonarthritis group (P < .05).

CONCLUSION

Obesity, fracture-dislocation injury, concomitant large PM fracture, and articular incongruence were risk factors of posttraumatic OA after surgery for ankle fractures. Surgeons should be aware that accurate reduction is critical in patients with ankle fractures with associated large PM fractures, especially those with obesity or severe initial injuries such as fracture-dislocation.

LEVEL OF EVIDENCE

Level III, case control study.

Four-Dimensional CT Analysis of Normal Syndesmotic Motion

BACKGROUND

The syndesmosis ligament complex stabilizes the distal tibiofibular joint while allowing for small amounts of physiologic motion. When injured, malreduction of the syndesmosis is the most important factor that contributes to inferior functional outcomes. Syndesmotic reduction is a dynamic measure, which is not adequately captured by conventional computed tomography (CT). Four-dimensional CT (4DCT) can image joints as they move through range of motion (ROM). The aim of this study was to employ 4DCT to determine in vivo syndesmotic motion with ankle ROM in uninjured ankles.

METHODS

Uninjured ankles were analyzed in patients who had contralateral syndesmotic injuries, as well as a cohort of healthy volunteers with bilateral uninjured ankles. Bilateral ankle 4DCT scans were performed as participants moved their ankles between maximal dorsiflexion and plantarflexion. Multiple measures of syndesmotic width, as well as sagittal translation and fibular rotation, were automatically extracted from 4DCT using a custom program to determine the change in syndesmotic position with ankle ROM.

RESULTS

Fifty-eight ankles were analyzed. Measures of syndesmotic width decreased by 0.7 to 1.1 mm as the ankle moved from dorsiflexion to plantarflexion (P < .001 for each measure). The fibula externally rotated by 1.2 degrees with ankle ROM (P < .001), but there was no significant motion in the sagittal plane (P = .43). No participants with bilateral uninjured ankles had a side-to-side difference in syndesmotic width of 2 mm or greater.

CONCLUSION

4DCT allows accurate, in vivo syndesmotic measurements, which change with ankle ROM, confirming prior work that was limited to biomechanical studies. Side-to-side syndesmotic measurements are consistent within subjects, validating the method of templating syndesmotic reduction off the contralateral ankle, in a consistent ankle position, to achieve anatomic reduction of syndesmotic injury.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Predisposing factors for chronic syndesmotic instability following syndesmotic fixation in ankle fracture: Minimum 5-year follow-up outcomes

BACKGROUND

This study aimed to identify risk factors for chronic syndesmotic instability following syndesmotic fixation.

METHODS

We performed a retrospective review of consecutive patients who had sustained ankle fractures requiring syndesmotic fixation. Patients available for a minimum 5 years of follow-up were classified into 2 groups according to the presence of syndesmotic instability. Statistical binary logistic regression analyses were performed to investigate the significance of various risk factors. Functional outcomes were assessed using the FAOS.

RESULTS

In total, 166 patients who met the study inclusion criteria underwent analysis. The overall postoperative instability rate was 20.5%, which was significantly affected due to BMI (p = 0.018; OR 6.72), and concomitant posterior malleolar fracture (p = 0.032, OR 2.77). The mean scores in the syndesmotic instability (SI) group were significantly lower than those in the no syndesmotic instability (NSI) group (p = 0.021).

CONCLUSIONS

Obesity and concomitant posterior malleolar fracture were significant risk factors for postoperative syndesmotic instability.

Syndesmotic Ligament Allograft Reconstruction for Treatment of Chronic Diastasis

Chronic diastasis after a syndesmotic injury can lead to ankle joint instability and loss of joint congruence. Failure to restore the fibula into the proper anatomic position within the incisura increases the focal stress on the talus and can accelerate degenerative joint destruction. In the case of failed syndesmotic repair, fixation options are limited. If promptly diagnosed, the syndesmosis may be amenable to open debridement and subsequent fixation with 2 interosseous screws. If latent diastasis is found, however, syndesmotic fusion by bone block arthrodesis is recommended. We present a syndesmotic allograft repair technique for surgical reconstruction of chronic unstable syndesmotic ruptures.

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.

Acute syndesmotic injuries in ankle fractures: From diagnosis to treatment and current concepts

A stable and precise articulation of the distal tibiofibular syndesmosis maintains the tibiofibular relationship, and it is essential for normal motion of the ankle joint. The disruption of this joint is frequently accompanied by rotational ankle fracture, such as pronation-external rotation, and rarely occurs without ankle fracture. The diagnosis is not simple, and ideal management of the various presentations of syndesmotic injury remains controversial to this day. Anatomical restoration and stabilization of the disrupted tibiofibular syndesmosis is essential to improve functional outcomes. In such an injury, including inadequately treated, misdiagnosed and correctly diagnosed cases, a chronic pattern characterized by persistent ankle pain, function disability and early osteoarthritis can result. This paper reviews anatomical and biomechanical characteristics of this syndesmosis, the mechanism of its acute injury associated to fractures, radiological and arthroscopic diagnosis and surgical treatment.

Comparison of Different Magnitudes of Applied Syndesmotic Clamp Force: A Cadaveric Study

Overcompression of the ankle syndesmosis was once thought to be improbable. Recent studies using computerized tomography (CT) however, have demonstarted otherwise; raising pertinent questions regarding the factors associated with and consequences of syndesmotic overcompression. The purpose of the present study was to directly compare different magnitudes of applied clamp force on the coronal reduction of ankle syndesmosis. Eight through-the-knee cadaveric specimens were obtained. Fiducial cannulated screws were placed in the tibia and fibula to standardize placement of the reduction clamp's tines. CT scans were obtained as baseline controls, followed by destabilization of the syndesmosis. Reductions were then performed using a clamp equipped with an inline load cell, and objective forces (60, 80, 100, 120, 140, and 160 N) applied sequentially to each of the specimens. The syndesmosis was fixed with a single quadricortical screw, and CT were scans repeated. Applied clamp forces of 60 and 80 N resulted in lateral fibular displacement and undercompression (42.9% and 57.1%, respectively), whereas forces of 140 and 160 N resulted in medial fibular displacement (p = .011 and p = .001) and overcompression (100%). The smallest mediolateral displacements were observed with 100 and 120 N, respectively. Malreduction assessment with CT was superior to traditional radiographs [r(54) = 0.22; 95% confidence interval -0.04 to 0.45; p = .101]. In our cadaveric model, an applied clamp force of 100 N most effectively mitigated iatrogenic coronal syndesmotic malreduction from under- or overcompression. Although additional research is warranted, based on the data, inherent variabilities in the applied clamp force by surgeons appear to contribute to the unacceptably high coronal syndesmotic malreduction rate.

Strategies to Avoid Syndesmosis Malreduction in Ankle Fractures

Nearly half of surgically treated ankle fractures may have associated syndesmotic disruption, and the quality of reduction has been shown to affect functional outcomes. Malreduction ranges from 15% to 50% in the literature, and achieving anatomic reduction remains a significant challenge, even for experienced surgeons. Keys to success include having a stepwise plan and an understanding of reliable fluoroscopic parameters to help achieve reduction in both the coronal and sagittal planes. This article summarizes the literature on syndesmotic reduction and provides the authors' preferred technique using fluoroscopy.

A Radiological Study for Assessing Syndesmosis Malreduction: Its Validity and Limitation

This study assessed the diagnostic utility of different X-ray radiological methods on syndesmosis malreduction. Thirteen fresh ankle specimens were used to make a syndesmotic separation model. The specimen was fixed in the anatomic position and in malreduction positions, including internal rotation 10° (IR10°), IR20°, external rotation 10° (ER10°), and ER20°. The tibiofibular clear space (TCS), tibiofibular overlap (TFO) on the anteroposterior view, and anteroposterior ratio (A/P ratio) on the lateral view were measured. When the syndesmosis was fixed in IR20°, the sensitivity of the TCS, TFO, and A/P ratio for malreduction diagnosis was 92.3% (12/13), 69.2% (9/13), and 100%, respectively. When the syndesmosis was fixed in IR10° malreduction, the sensitivity of the TCS, TFO, and A/P ratio for malreduction diagnosis was 38.4% (5/13), 38.4% (5/13), and 84.6% (11/13); in ER10°, 30.7% (4/13), 76.9% (10/13), and 69.2% (9/13); and in ER20°, 92.3% (12/13), 100% and 92.3% (12/13). In the anatomic reduction, the false-positive rate of the TCF, TFO, and A/P ratio was 7.6% (1/13), 7.6% (1/13), and 0%, respectively. The TFO and A/P ratio exhibited differences between all malreduction groups and the anatomic group. However, the TCS measurements had no statistical difference between the anatomic position and IR10° malreduction (p = .109). On the AP view, the TCS and TFO measurements are not sensitive enough to detect the syndesmosis malreduction. The A/P ratio on the lateral view exhibits better diagnostic utility for syndesmosis malreduction.

Acute and Chronic Syndesmotic Instability: Role of Surgical Stabilization

Acute and chronic syndesmotic injuries significantly impact athletic function and activities of daily living. Patient history, examination, and judicious use of imaging modalities aid diagnosis. Surgical management should be used when frank diastasis, instability, and/or chronic pain and disability ensue. Screw and suture-button fixation remain the mainstay of treatment of acute injuries, but novel syndesmotic reconstruction techniques hold promise for treatment of acute and chronic injuries, especially for athletes. This article focuses on anatomy, mechanisms of injury, diagnosis, and surgical reduction and stabilization of acute and chronic syndesmotic instability. Fixation methods with a focus on considerations for athletes are discussed.

Validation of radiological reduction criteria with intraoperative cone beam CT in unstable syndesmotic injuries

Purpose

Acute unstable syndesmotic lesions are regularly treated with closed or open reduction and fixation with either a positioning screw or tight rope. Conventional fluoroscopy is limited to identify a malreduction of the ankle mortise. The aim of the study was to validate the reduction criteria of intraoperative cone beam CT in unstable syndesmotic injuries by analyzing the clinical outcome.

Methods

Acute unstable syndesmotic injuries were treated with a positioning screw fixation, and the reduction in the ankle mortise was evaluated with intraoperative cone beam CT. The patients were grouped postoperatively according to the radiological reduction criteria in the intraoperative 3D images. The reduction criteria were unknown to the surgeons. Malreduction was assumed if one or more reduction criteria were not fulfilled.

Results

Seventy-three of the 127 patients could be included in the study (follow-up rate 57.5%). For 41 patients (56.2%), a radiological optimal reduction was achieved (Group 1), and in 32 patients (43.8%) a radiological adverse reduction was found (Group 2). Group 1 scored significantly higher in the Olerud/Molander score (92.44 ± 10.73 vs. 65.47 ± 28.77) (p = 0.003), revealed a significantly higher range of motion (ROM) (53.44 vs. 24.17°) (p = 0.001) and a significantly reduced Kellgren/Lawrence osteoarthritis score (1.24 vs. 1.79) (p = 0.029). The linear regression analysis revealed a correlation for the two groups with the values scored in the Olerud/Molander score (p < 0.01).

Conclusion

The reduction criteria in intraoperative cone beam CT applied to unstable syndesmotic injuries could be validated. Patients with an anatomic reduced acute unstable syndesmotic injury according to the criteria have a significantly better clinical outcome.

Syndesmotic malreduction may decrease fixation stability: a biomechanical study

BACKGROUND

This study aims to investigate the malreduction of syndesmosis and its effects on stability.

METHODS

The biomechanical tests, including the three-dimensional (3D) displacement of the syndesmotic incisura, fibular rotation angle, and torque resistance, were performed on six cadaver legs. These specimens were first tested intact (intact group), then cut all the syndesmotic ligaments and fixed in anatomical position (anatomical model group) and test again. After that, syndesmosis was fixed in 1 cm malreduction (anterior and posterior displacement group) to do the same test.

RESULTS

In internal or external load, there were significant differences in torque resistance and fibular rotation angle (internal t = 2.412, P = 0.036; external t = 2.412, P = 0.039) between the intact and post-malreduction groups. In internal rotation load, there were significant differences in sagittal displacement between the intact and post-malreduction groups (P = 0.011), and between the anatomical and post-malreduction groups (P = 0.020). In external rotation load, significant differences existed between the intact and ant-malreduction group (P = 0.034) in sagittal (anterior-posterior) displacement. Significant differences also existed between the intact and post-malreduction groups (P = 0.013), and between the anatomical and post-malreduction groups (P = 0.038) in coronal (medial-lateral) displacement.

CONCLUSIONS

Malreduction in different conditions does affect the stability of the syndesmotic fixation. The result of the study may reveal the biomechanical mechanism of poor clinical outcome in syndesmosis malreduction patients and pathological displacement patterns of the ankle under syndesmotic malreduction conditions.

LEVEL OF EVIDENCE

III.

Comparison of three different reduction methods of the ankle mortise in unstable syndesmotic injuries

In order to achieve a clinically satisfying result and to prevent posttraumatic osteoarthritis in the treatment of unstable syndesmotic injuries, anatomically correct reduction is crucial. The objective of the study was to investigate three different reduction methods of the ankle mortise in unstable syndesmotic injuries. In a specimen model with 38 uninjured fresh-frozen lower legs, a complete syndesmotic dissection was performed. The ankle mortise was reduced with either a collinear reduction clamp, a conventional reduction forceps or manually with crossing K-wires. The reduction clamps and the K-wires were placed in a 0°-angle to the leg axis. The clamps were positioned on the posterolateral ridge of the fibula 20 mm proximal to the ankle joint line. A cone beam computed tomography was performed after dissection and after each reduction. Tibio-fibular distances and angles were determined. Despite significant differences in terms of overcompression (0.09–0.33 mm; p = 0.000–0.063) and the slight external rotation (0.29–0.47°; p = 0.014–0.07), the results show a satisfying reduction of the ankle mortise. There were no considerable differences between the reduction methods. It can therefore be concluded that the ankle mortise can be reduced with any of the methods used, but that the positioning and the contact pressure must be considered.

Screw fixation of the syndesmosis alters joint contact characteristics in an axially loaded cadaveric model

BACKGROUND

The purpose of this study was to quantify the effects of rigid syndesmotic fixation on functional talar position and cartilage contact mechanics.

METHODS

Twelve below-knee cadaveric specimens with an intact distal syndesmosis were mechanically loaded in four flexion positions (20° plantar flexion, 10° plantar flexion, neutral, 10° dorsiflexion) with zero, one, or two 3.5-mm syndesmotic screws. Rigid clusters of reflective markers were used to track bony movement and ankle-specific pressure sensors were used to measure talar dome and medial/lateral gutter contact mechanics.

RESULTS

Screw fixation caused negligible anterior and inferior shifts of the talus within the mortise. Relative to no fixation, mean peak contact pressure decreased by 6%-32% on the talar dome and increased 2.4- to 6.6-fold in the medial and lateral gutters, respectively, depending on ankle position and number of screws.

CONCLUSIONS

Two-way ANOVA indicated syndesmotic screw fixation significantly increased contact pressure in the medial/lateral gutters and decreased talar dome contact pressure while minimally altering talar position.

Anatomic Ligament Repairs of Syndesmotic Injuries

Poor clinical results are seen with syndesmotic injuries in the setting of ankle sprains and ankle fractures. The goal of syndesmosis repair is to restore the normal anatomic relationship of the distal tibiofibular joint and prevent ankle arthritis. Indications for surgical intervention for isolated syndesmotic injuries include frank syndesmosis diastasis, medial clear space widening on plain radiographs, significant radiographic syndesmosis diastasis during stress examination, or subtle syndesmotic diastasis detected by arthroscopic evaluation. Complications after syndesmosis repair include symptomatic hardware, malreduction, and arthritis. Anatomic reduction of the syndesmosis leads to better outcomes following surgery.

Is It Possible to Overcompress the Syndesmosis?

The case we present suggests that it might be possible to overcompress the syndesmosis, causing subluxation of the talus within the ankle mortise. A 26-year-old female patient had had a Weber Type C ankle fracture internally fixed with a lateral plate and syndesmosis screws. Despite the fibula appearing well reduced and computed tomography imaging showing a well-aligned fibula within the fibular notch, anteromedial subluxation of the talus was present in the ankle mortise. Examination with the patient under anesthesia revealed a stable syndesmosis fixation; however, talar malpositioning was not affected by the foot position. The syndesmosis fixation was revised sequentially. As the fixation was relaxed sequentially, the talus appeared to reduce within the ankle mortise, with restoration of the previously obliterated medial clear space. The syndesmosis was stabilized with a single 3.5-mm cortical screw in a reduced position. The patient had made a full recovery at the 12-month follow-up examination, having undergone elective syndesmosis screw removal at 12 weeks postoperatively. Several studies have suggested that it might not be possible to overcompress the syndesmosis and have even advocated the use of a lag screw technique for syndesmosis fixation. Based on the present case, we would advise a degree of caution with this approach, because it might be possible to overcompress the syndesmosis and cause significant subluxation of the tibiotalar articulation.

Operative Setup to Improve Sagittal Syndesmotic Reduction: Technical Tip

We analyzed the operative measures that may be used to reduce the likelihood of sagittal syndesmotic malreduction. Hence, we propose a simple technical tip to avoid sagittal plane malreduction of the fibula within the syndesmosis in ankle fractures. Supporting the leg under the heel should be avoided when performing syndesmotic reduction for unstable malleolar fractures, and support under the calf should be used instead. Our observations have been confirmed in 6 cadaver specimens. We observed that there was a significant anterior subluxation of the fibula when the leg was supported under the heel. No significant difference between the intact and unstable state was present when the leg was supported under the calf. In conclusion, during syndesmotic reduction and fixation in supine position, supporting the foot under the heel should be avoided.

Syndesmosis Fixation in Unstable Ankle Fractures Using a Partially Threaded 5.0-mm Cannulated Screw

The present study evaluated the radiographic outcomes of syndesmosis injuries treated with a partially threaded 5.0-mm cannulated screw. The present study included 58 consecutive patients with syndesmosis injuries concurrent with ankle fractures who had undergone operative fixation with a partially threaded 5.0-mm cannulated screw to repair the syndesmosis injury. Radiographic indexes, including the medial clear space, tibiofibular overlap, tibiofibular clear space, and fibular position on the lateral radiograph, were measured on the preoperative, immediate postoperative, and final follow-up radiographs. The measurements were compared between the injured and intact ankles. All preoperative radiographic indexes, including the medial clear space (p < .001), tibiofibular overlap (p < .001), tibiofibular clear space (p < .001), and fibular position on the lateral radiograph (p = .026), were significantly different between the injured and intact ankles. The medial clear space of the injured ankle was significantly wider than that of the intact ankle preoperatively (p < .001) and had become significantly narrower immediately postoperatively (p < .001). Finally, the medial clear space was not significantly different between the injured and intact ankles at the final follow-up examination (p = .522). No screw breakage or repeat fractures were observed. A 5.0-mm partially threaded cannulated screw effectively restored and maintained the normal relationship between the tibia and fibula within the ankle mortise with a low risk of complications. This appears to be an effective alternative technique to treat syndesmosis injuries concurrent with ankle fractures.

Comparison of Clamp Reduction and Manual Reduction of Syndesmosis in Rotational Ankle Fractures: A Prospective Randomized Trial

An optimal outcome of surgical treatment for a syndesmotic injury depends on accurate reduction and adequate fixation. It has been suggested that the use of a reduction clamp for reduction of the syndesmosis results in better reduction and a lower rate of redisplacement than manual reduction. However, these concepts have never been scientifically evaluated. We compared these 2 methods in a prospective randomized trial. A total of 85 acute ankle rotational fractures combined with syndesmotic injury were randomized to syndesmosis reduction with either a reduction clamp or manual manipulation. Reduction of the syndesmosis was assessed radiographically by measuring the tibiofibular clear space, tibiofibular overlap, and the medial clear space immediately postoperatively and at the final follow-up examination. Ankle joint range of motion, visual analog scale score, Olerud-Molander ankle scoring system, and complications were obtained at the last follow-up visit to assess the clinical outcomes. Of the 3 radiographic measurements, the tibiofibular clear space and tibiofibular overlap differed significantly between the 2 groups (p < .05). The clinical outcomes did not differ significantly between the 2 groups (p > .05). Although differences were found in the radiographic measurements, most syndesmoses in both groups were within the normal range at the final follow-up visit, and the 2 methods of syndesmosis reduction provided similar clinical outcomes. Accordingly, the results of the present study suggest that both of these methods are effective and reliable for reduction of the syndesmosis in rotational ankle fractures.

A Novel Indirect Reduction Technique in Ankle Syndesmotic Injuries: A Cadaveric Study

OBJECTIVE

To describe a novel technique using preoperative computed tomography (CT) to plan clamp tine placement along the trans-syndesmotic axis (TSA). We hypothesized that preoperative CT imaging provides a reliable template on which to plan optimal clamp tine positioning along the TSA, reducing malreduction rates compared with other described techniques.

METHODS

CT images of 48 cadaveric through-knee specimens were obtained, and the TSA was measured as well as the optimal position of the medial clamp tine. The syndesmosis was then fully destabilized. Indirect clamp reductions were performed with the medial clamp tine placed at positions 10 degrees anterior to the TSA, along the TSA, and at both 10 and 20 degrees posterior to the TSA. The specimens were then separately reduced using manual digital pressure and palpation alone. CT was performed after each clamp and manual reduction.

RESULTS

On average, reduction clamp tines were within 3 ± 2 degrees of the desired angle and within 5% ± 4% of the templated location along the tibial line for all clamp reduction attempts. Palpation and direct visualization produced the overall lowest malreduction rates in all measurements: 4.9% and 3.0%, respectively. Off-axis clamping 10 degrees anterior or 20 degrees posterior to the patient-specific TSA demonstrated an increased overall malreduction rate: 15.8% and 11.3%, respectively. Significantly more over-compression occurred when a reduction clamp was used versus manual digital reduction alone (8.6% vs. 0%).

CONCLUSIONS

Reduction clamp placement directly along an optimal clamping vector can be facilitated by preoperative CT measurements of the uninjured ankle. However, even in this setting, the use of reduction clamps increases the risk for syndesmotic malreduction and over-compression compared with manual digital reduction or direct visualization.

Effect of Ankle Position on Tibiotalar Motion With Screw Fixation of the Distal Tibiofibular Syndesmosis in a Fracture Model

BACKGROUND

Anatomic reduction and fixation of the syndesmosis in traumatic injuries is paramount in restoring function of the tibiotalar joint. While overcompression is a potential error, recent work has called into question whether ankle position during fixation really matters in this regard. Our study aimed to corroborate more recent findings using a fracture model that, to our knowledge, has not been previously tested.

METHODS

Twenty cadaver leg specimens were obtained and prepared. Each was tested for tibiotalar motion under various conditions: intact syndesmosis, intact syndesmosis with lag screw compression, pronation external rotation type 4 (PER-4) ankle fracture with syndesmotic disruption, and single-screw syndesmotic fixation followed by plate and screw fracture and syndesmotic screw fixation. In each situation, the ankle was held in alternating plantarflexion and dorsiflexion when inserting the syndesmotic screw with the subsequent amount of maximal dorsiflexion being recorded following hand-tight lag screw fixation.

RESULTS

While ankle range of motion increased significantly with creation of the PER-4 injury, under no condition was there a statistically significant change in maximal dorsiflexion angle.

CONCLUSION

Ankle position during distal tibiofibular syndesmosis fixation did not limit dorsiflexion of the ankle joint.

CLINICAL RELEVANCE

Our findings suggest that maximal dorsiflexion during syndesmotic screw fixation may not be necessary.

Correlation of Incisura Anatomy With Syndesmotic Malreduction

BACKGROUND

The anatomy of the syndesmosis is variable, yet little is known on the correlation between differences in anatomy and syndesmosis reduction results. The aim of this study was to analyze the correlation between syndesmotic anatomy and the modes of syndesmotic malreduction.

METHODS

Bilateral postreduction ankle computed tomography (CT) scans of 72 patients treated for fractures with syndesmotic disruption were analyzed. Incisura depth, fibular engagement into the incisura, and incisura rotation were correlated with degree of syndesmotic malreduction in coronal and sagittal planes as well as rotational malreduction.

RESULTS

Clinically relevant malreduction in the coronal plane, sagittal plane, and rotation affected 8.3%, 27.8%, and 19.4% of syndesmoses, respectively. The syndesmoses with a deep incisura and the fibula not engaged into the tibial incisura were at risk of overcompression, anteverted incisuras at risk of anterior fibular translation, and retroverted incisuras at risk of posterior fibular translation.

CONCLUSIONS

Certain morphologic configurations of the tibial incisura increased the risk of specific syndesmotic malreduction patterns.

LEVEL OF EVIDENCE

Level III, comparative study.

Management of syndesmotic injuries of the ankle

Injuries to the tibioperoneal syndesmosis are more frequent than previously thought and their treatment is essential for the stability of the ankle mortise.

Recognition of these lesions is essential to avoid long-term morbidity.

Diagnosis often requires complete history, physical examination, weight-bearing radiographs and MRI.

Treatment-oriented classification is mandatory.

It is recommended that acute stable injuries are treated conservatively and unstable injuries surgically by syndesmotic screw fixation, suture-button dynamic fixation or direct repair of the anterior inferior tibiofibular ligament.

Subacute injuries may require ligamentoplasty and chronic lesions are best treated by syndesmotic fusion.

However, knowledge about syndesmotic injuries is still limited as recommendations for surgical treatment are only based on level IV and V evidence.

Cite this article: EFORT Open Rev 2017;2:403–409. DOI: 10.1302/2058-5241.2.160084

Acute syndesmotic instability in ankle fractures: A review

Ankle fractures are among the most common fracture types, and 10% of all ankle fractures lead to accessory syndesmotic injury. An injury that is challenging in every respect is syndesmotic instability. Since the range of diagnostic techniques and the therapeutic options is extensive, it still is a controversial subject, despite the abundance of literature. This review aimed to summarize the current knowledge on syndesmotic instability in ankle fractures and to formulate some recommendations for clinical practice. Chronic instability and the operative osseous treatment of ankle fractures are not part of this review.

Distal Tibiofibular Syndesmosis: Anatomy, Biomechanics, Injury and Management

A stable and precise articulation of the distal tibiofibular syndesmosis is essential for normal motion of the ankle joint. Injury to the syndesmosis occurs through rupture or bony avulsion of the syndesmotic ligament complex. External rotation of the talus has been identified as the major mechanism of syndesmotic injury. None of the syndesmotic stress tests was sensitive or specific; therefore the diagnosis of syndesmotic injury should not be made based on the medical history and physical examination alone. With the improvement in ankle arthroscopic technique, it can be used as a diagnostic and therapeutic tool in the management of distal tibiofibular syndesmosis injury.

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

BACKGROUND

Ankle 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 METHODS

Fifteen 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.

RESULTS

Following 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).

CONCLUSION

Maximal 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.

3D Model Analysis of Ankle Flexion on Anatomic Reduction of a Syndesmotic Injury

BACKGROUND

The effect of ankle positioning during suture-button fixation for syndesmosis repair on range of motion (ROM) and anatomic reduction has yet to be investigated. The purpose of this cadaveric study was to compare the effects of 3 different ankle positions during suture-button repair on volumetric reduction of the syndesmosis, fibular displacement, and ROM of the ankle using 3-dimensional computed tomography (CT) analysis. The null hypothesis was that ankle position during fixation would not affect syndesmotic volume restoration, fibular displacement, or ROM.

METHODS

Twelve matched pair (n = 24) human cadaveric specimens were used for this study. Prior to syndesmotic sectioning, ROM assessment and CT scans were performed. Following sectioning of the syndesmosis, specimens were repaired in plantarflexion, dorsiflexion, or neutral, and simulated postrepair ROM evaluations and CT scans were repeated. Least squares mean differences between repair groups and the preinjury state were compared by analysis of variance and Tukey's method.

RESULTS

There were no significant differences between repair groups for volumetric reduction ( P = .917), fibular displacement (anterior-posterior, P = .805; medial-lateral, P = .949), or dorsiflexion capacity ( P = .249). Among all specimens, compared with the preinjury state, there was a significant mean ± SD volume reduction of 337 ± 400 mm³ and medial displacement of 1.9 ± 1.5 mm.

CONCLUSION

This study failed to reject the null hypothesis and demonstrated that ankle flexion at the time of syndesmotic fixation with a suture-button construct had no significant in vitro effect on volume changes, fibular displacement, or dorsiflexion capacity. However, in comparison to the preinjured state, suture-button repair resulted in significant overcompression with respect to syndesmosis volume and medial displacement of the fibula.

CLINICAL RELEVANCE

Ankle position at the time of syndesmotic fixation did not affect overall ankle ROM when using a suture-button construct; however, overcompression was observed in all positions. The clinical impact of syndesmotic overcompression remains largely unknown.

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).

A 3-D CT Analysis of Screw and Suture-Button Fixation of the Syndesmosis

BACKGROUND

Historically, syndesmosis injuries have been repaired with screw fixation; however, some suggest that suture-button constructs may provide a more accurate anatomic and physiologic reduction. The purpose of this study was to compare changes in the volume of the syndesmotic space following screw or suture-button fixation using a preinjury and postoperative 3-D computed tomography (CT) model. The null hypothesis was that no difference would be observed among repair techniques.

METHODS

Twelve pairs of cadaveric specimens were dissected to identify the syndesmotic ligaments. Specimens were imaged with CT prior to the creation of a complete syndesmosis injury and were subsequently repaired using 1 of 3 randomly assigned techniques: (a) one 3.5-mm cortical screw, (b) 1 suture-button, and (c) 2 suture-buttons. Specimens were imaged postoperatively with CT. 3-D models of all scans and tibiofibular joint space volumes were calculated to assess restoration of the native syndesmosis. Analysis of variance and Tukey's method were used to compare least squares mean differences from the intact syndesmosis among repair techniques.

RESULTS

For each of the 3 fixation methods, the total postoperative syndesmosis volume was significantly decreased relative to the intact state. The total mean decreases in volume compared with the intact state for the 1-suture-button construct, 2-suture-button construct, and syndesmotic screw were -561 mm³ (95% CI, -878 to -244), -964 mm³ (95% CI, -1281 to -647) and -377 mm³ (95% CI, -694 to -60), respectively.

CONCLUSION

All repairs notably reduced the volume of the syndesmosis beyond the intact state. Fixation with 1 suture-button was not significantly different from screw or 2-suture-button fixation; however, fixation with 2 suture-buttons resulted in significantly decreased volume compared with screw fixation.

CLINICAL RELEVANCE

The results of this study suggest that the 1-suture-button repair technique and the screw fixation repair technique were comparable for reduction of syndesmosis injuries, although both may overcompress the syndesmosis.

MRI Quantification of the Impact of Ankle Position on Syndesmosis Anatomy

BACKGROUND

Despite the common occurrence of syndesmotic injuries in ankle trauma, the distal tibiofibular relationship remains poorly understood. The aim of this study was to evaluate the anatomical impact of ankle sagittal positioning on the tibiofibular relationship in intact ankles by using a validated magnetic resonance imaging (MRI)-based measurement system.

METHODS

In this radiologic study, 34 healthy volunteers underwent a series of ankle MRIs with the ankle stabilized in 3 positions: neutral position (NP), dorsiflexion (DF), and plantarflexion (PF). Using a previously validated measurement system, 6 fixed translational measurements and 2 fixed angles were recorded on each MRI and compared using paired t tests.

RESULTS

When comparing PF to DF, the anterior distance between the tibial incisura and the fibula varied from 2.5 mm to 3.9 mm ( P < .001), respectively. The middle distance between the tibial incisura and the fibula varied from 1.5 mm to 2.6 mm ( P < .001). Fibular angle varied from 8.7 degrees to 7.8 degrees of internal rotation ( P = .046), respectively. When comparing NP to DF, only the anterior distance was found to be significantly different, varying 0.4 mm ( P < .002).

CONCLUSIONS

Ankle dorsiflexion leads to an increase in external rotation and lateral translation of the fibula. These changes could be measured on MRI using a validated measurement system. Ankle motion did have an impact on the distal tibiofibular relationship and should be considered in studies pertaining to syndesmosis imaging.

CLINICAL RELEVANCE

This is the first in vivo study demonstrating the impact of sagittal ankle position on the distal tibiofibular relationship in an uninjured ankle. Our findings also support the practice of placing the ankle in dorsiflexion when fixing a disrupted syndesmosis.

LEVEL OF EVIDENCE

Level III, comparative study.

The Effect of Varying Tension of a Suture Button Construct in Fixation of the Tibiofibular Syndesmosis-Evaluation Using Stress Computed Tomography

BACKGROUND/PURPOSE

There have been no studies assessing the optimal biomechanical tension of suture button constructs. The purpose of this study was to assess optimal tensioning of suture button fixation and its ability to maintain reduction under loaded conditions using a stress computed tomography (CT) model.

METHODS

Ten cadaveric lower limbs disarticulated at the knee were used. The limbs were placed in a modified ankle load frame that allowed for the application of sustained torsional axial or combined torsional/axial loads. The syndesmosis and the deep deltoid ligaments complex were sectioned and the limbs were randomized to receive a suture button construct tightened at 4, 8, or 12 kg. The specimens were loaded under the 3 loading scenarios with CT scans performed after each and at the conclusion of testing. Multiple measurements of translation and rotation were compared with baseline CT scan taken before sectioning.

RESULTS

Significant lateral (maximum 5.26 mm) and posterior translation (maximum 6.42 mm) and external rotation (maximum 11.71 degrees) was noted with the 4 kg repair. Significant translation was also seen with both the 8 and the 12 kg repairs; however, the incidence was less than with the 4 kg repair. Significant overcompression (ML = 1.69 mm, B = 2.69 mm) was noted with the 12 kg repair and also with the 8 kg repair (B = 2.01 mm).

CONCLUSION

Suture button constructs must be appropriately tensioned to maintain reduction and re-approximate the degree of physiological motion at the distal tibiofibular joint. These constructs also demonstrate overcompression of the syndesmosis; however, the clinical effect of this remains to be determined.

Management of sports injuries of the foot and ankle

Sporting injuries around the ankle vary from simple sprains that will resolve spontaneously within a few days to severe injuries which may never fully recover and may threaten the career of a professional athlete. Some of these injuries can be easily overlooked altogether or misdiagnosed with potentially devastating effects on future performance. In this review article, we cover some of the common and important sporting injuries involving the ankle including updates on their management and outcomes.

Cite this article: Bone Joint J 2016;98-B:874–83.

Conservative and surgical management of acute isolated syndesmotic injuries: ESSKA-AFAS consensus and guidelines

PURPOSE

Correct management of syndesmotic injuries is mandatory to avoid scar tissue impingement, chronic instability, heterotopic ossification, or deformity of the ankle. The aim of the present study was to perform a systematic review of the current treatments of these injuries to identify the best non-surgical and surgical management for patients with acute isolated syndesmotic injuries.

METHODS

A review of the literature was performed according to the PRISMA guidelines. A comprehensive search of PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases was performed using the following keywords: "ankle injury", "syndesmotic injury", "chronic", "acute", "treatment", "conservative", "non-operative" "operative", "fixation", "osteosynthesis", "screw", "synostosis", "ligamentoplasties" over the years 1962-2015.

RESULTS

The literature search and cross-referencing resulted in a total of 345 references, of which 283 were rejected due to off-topic abstract and/or failure to fulfil the inclusion criteria. After reading the remaining full-text articles, we included four studies, describing non-surgical management, and only two studies investigating surgical management of acute isolated injuries.

CONCLUSIONS

The ESSKA-AFAS consensus panel provided recommendations to improve the management of patients with isolated acute syndesmotic injury in clinical practice. Non-surgical management is recommended for stable ankle lesions and includes: 3-week non-weight bearing, a below-the-knee cast, rest and ice, followed by proprioceptive exercises. Surgery is recommended for unstable lesions. Syndesmotic screw is recommended to achieve a temporary fixation of the mortise. Suture-button device can be considered a viable alternative to a positioning screw. Partial weight bearing is allowed 6 weeks after surgery.

LEVEL OF EVIDENCE

IV.

Arthroscopic Evaluation of Syndesmotic Instability in a Cadaveric Model

BACKGROUND

Ankle fractures are among the most common lower extremity injuries. Proper care requires evaluation for syndesmotic ligament disruption. Ankle arthroscopy has been proposed as an intraoperative tool that can evaluate stability. Our focus was to evaluate the amount of displacement produced in the coronal, sagittal, and transverse planes visualized through ankle arthroscopy in a cadaveric model.

METHODS

Seven below-knee specimens were mounted in a traction tower. Four groups were evaluated: no ligamentous disruption; anterior inferior tibiofibular ligament and interosseous ligament disruption; above plus anterior talofibular ligament and calcaneofibular ligament disruption; and posterior inferior tibiofibular ligament and transverse ligament disruption. Force was applied and measured using a digital scale. The amount of displacement of the fibula in relation to the center of the incisura was measured under arthroscopic evaluation using a calibrated probe.

RESULTS

An intact syndesmosis and lateral ankle ligaments provided multiplanar stability. In group 2, syndesmosis diastasis was appreciated in the transverse-external rotation plane with as little as 6 lb of force. In group 3, a greater amount of displacement was appreciated with less force. Multiplane instability was visible in every specimen with as little as 2 lb of force. Group 4 specimens were completely disrupted and so grossly unstable that testing was impossible.

CONCLUSION

Ankle arthroscopy has the potential to evaluate even partial disruption of the syndesmotic ligament complex. Instability in the sagittal and transverse planes was encountered early in the spectrum of disruption. Traditional evaluation methods have poor sensitivity for instability in these planes.

CLINICAL RELEVANCE

Arthroscopic evaluation of subtle displacement in multiple planes may assist the surgeon in understanding the extent of the syndesmotic injury. Further studies are necessary to determine to what extent instability requires fixation as well as the role for arthroscopy in assessing anatomic reduction of the syndesmosis after fixation is performed.

Long-term Results After Ankle Syndesmosis Injuries

Syndesmotic disruption occurs in more than 10% of ankle fractures. Operative treatment with syndesmosis screw fixation has been successfully performed for decades and is considered the gold standard of treatment. Few studies have reported the long-term outcomes of syndesmosis injuries. This study investigated long-term patient-reported, radiographic, and functional outcomes of syndesmosis injuries treated with screw fixation and subsequent timed screw removal. A retrospective cohort study was carried out at a Level I trauma center. The study group included 43 patients who were treated for ankle fractures with associated syndesmotic disruptions between December 2001 and May 2011. The study included case file reviews, self-reported questionnaires, radiologic reviews, and clinical assessments. At 5.1 (±1.76) years after injury, 60% of participants had pain, 26% had degenerative changes, 51% had loss of tibiofibular overlap, and 33% showed medial clear space widening. Retained syndesmotic positions on radiographs were linked to better self-reported outcomes. There is an inversely proportional relation between age at the time of injury and satisfaction with the outcome of the ankle fracture as well as a directly proportional relation between age at the time of injury and pain compared with the preinjury state. Optimal restoration and preservation of the syndesmosis is crucial. Syndesmotic disruption is associated with poor long-term outcomes after ankle fracture. Greater age is a risk factor for chronic pain and dissatisfaction with the outcome of ankle fracture and syndesmosis injury. Therefore, patient education to facilitate realistic expectations about recovery is vital, especially in older patients.

Over-Tightening of the Syndesmosis After Ankle Fracture: A Case Report

CASE

An eighteen-year-old patient sustained a fracture-dislocation of the left ankle while playing rugby. The fracture was treated in the emergency department with closed reduction and splinting, followed by open reduction and internal fixation. Subsequently, increased tibiotalar clear space was noted radiographically. Coronal computed tomography images confirmed distal distraction of the talus. This was determined to have resulted from "over-tightening" the syndesmosis. Our surgical treatment consisted of minute manual repositioning of the talus.

CONCLUSION

We advise meticulous scrutiny of intraoperative radiographs to evaluate potential talar distraction. Additionally, comparison radiographs of the contralateral ankle can be an essential component of preoperative and intraoperative assessment of ankle fractures with syndesmotic disruption.

In Vivo Syndesmotic Overcompression After Fixation of Ankle Fractures With a Syndesmotic Injury

OBJECTIVES

The goals of this study were to assess syndesmotic reductions using computerized tomography and to determine whether malreductions are associated with certain injury types or reduction forceps.

DESIGN

Prospective cohort.

SETTING

Urban level 1 trauma center.

PATIENTS

Twenty-seven patients with operatively treated syndesmotic injuries were recruited prospectively.

INTERVENTION

Patients underwent postoperative bilateral computerized tomography of the ankle and hindfoot to assess syndesmotic reduction. The uninjured extremity was used as a control.

MAIN OUTCOME MEASUREMENT

Side-to-side differences of the fibular position within the tibial incisura were measured at several anatomic points and analyzed based on injury type, the presence of posterior malleolar injury, level of fracture, and type of reduction forceps used.

RESULTS

On average, operatively treated syndesmotic injuries were overcompressed (fibular medialization) by 1 mm (P < 0.001) and externally rotated by 5° (P = 0.002) when compared with the uninjured extremity. The absence of a posterior malleolar injury and Weber B (OTA 44-B) fractures seemed to have a protective effect against malrotation, but not against overcompression. There was no difference in malreduction based on the type of the clamp used.

CONCLUSIONS

It is possible, and highly likely based on these data, to overcompress the syndesmosis when using reduction forceps. Care should be taken to avoid overcompression, as this may affect the ankle motion and functional outcomes. To our knowledge, this is the first in vivo series of syndesmotic overcompression.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Maintenance of reduction with suture button fixation devices for ankle syndesmosis repair

BACKGROUND

Malreduction of the syndesmosis can lead to increased peak pressures and subsequent arthritis. The purpose of this study was to evaluate the initial syndesmotic reduction and radiographic maintenance when using a knotless suture button fixation device for treatment of syndesmotic injury.

METHODS

A retrospective chart and radiographic review was performed to identify patients who underwent open reduction internal fixation of ankle syndesmosis ruptures treated with a knotless, suture button fixation system. Radiographic measurements included medial clear space, tibiofibular overlap, tibiofibular clear space, and the distance between buttons. Fifty-six patients underwent repair of an ankle fracture with syndesmotic rupture over a 3-year period, with a mean follow-up of 160.9 days.

RESULTS

The tibiofibular clear space and tibiofibular overlap significantly improved from pre- to first postoperative, but also demonstrated some loss of fixation at final follow-up (P < .001). The distance between the buttons increased on average 1.1 mm from immediate postoperative to final follow-up, demonstrating some postoperative creep and loss of fixation in the system. A low complication rate and need for a revision operation was found in our patient cohort. Some loss of reduction did occur postoperatively, although this did not correlate to adverse patient outcomes.

CONCLUSION

Syndesmotic stabilization, using a knotless suture button fixation device demonstrated adequate initial syndesmotic reduction, but also exhibited an increase in the tibiofibular clear space and tibiofibular overlap, relative to initial postfixation position, at short-term follow-up.

LEVEL OF EVIDENCE

Level IV, retrospective case series.