Biomechanical Analysis of the Individual Ligament Contributions to Syndesmotic Stability

Editorial Commentary: Cadaveric Biomechanical Orthopaedic Research Is Essential and Requires Quality and Validity Metrics

Evidence-based medicine is the commanding philosophy of patient care in the field of orthopaedic surgery, and analysis of clinical research is facilitated by instruments and scales developed for assessing methodologic quality and validity of conclusions. In contrast, little consideration has been given to developing metrics to assess the quality and validity of orthopaedic ex vivo and laboratory research. This is easier said than done because these studies may be heterogeneous and complex in design, and methodologic details may not be intuitive to (non-engineer) readers. The recently described Biomechanics Objective Basic Science Quality Assessment Tool (BOBQAT) represents a reliable means to assess cadaveric biomechanical studies. The BOBQAT emphasizes essential study elements including a clinically relevant, answerable purpose; detailed description of the specimens studied; thorough description of surgical technique; and careful consideration of loading conditions including clinically relevant cyclic loading. The BOBQAT provides a logical recipe for the design of future studies, a mechanism of quality assessment for systematic reviews, and a framework for readers to assess biomechanical research consistent with the ethos of evidence-based medicine.

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.

Bilateral External Torque CT Reliably Detects Syndesmotic Lesions in an Experimental Cadaveric Study

BACKGROUND

If tibiofibular syndesmotic injury is undetected, chronic instability may lead to persistent pain and osteoarthritis. So far, no reliable diagnostic method has been available. The primary objectives of this study were to determine whether defined lesions of the syndesmosis can be correlated with specific tibiofibular joint displacements caused by external rotational torque and to compare the performance of bilateral external torque computed tomography (BET-CT) and arthroscopy. Secondary objectives included an evaluation of the reliability of CT measurements and the suitability of the healthy contralateral ankle as a reference.

METHODS

Seven pairs of healthy, cadaveric lower legs were tested and assigned to 2 groups: (1) supination-external rotation (SER) and (2) pronation-external rotation (PER). In the intact state and after each surgical step, an ankle arthroscopy and 3 CT scans were performed. During the scans, the specimens were placed in an external torque device with 2.5, 5.0, and 7.5 Nm of torque applied.

RESULTS

The arthroscopic and CT parameters showed significant correlations in all pairwise comparisons. The receiver operating characteristic (ROC) curve analyses yielded the best prediction of syndesmotic instability with the anterior tibiofibular distance on CT, with a sensitivity of 84.1% and a specificity of 95.2% (area under the curve [AUC], 94.8%; 95% confidence interval [CI], 0.916 to 0.979; p < 0.0001) and with the middle tibiofibular distance on arthroscopy, with a sensitivity of 76.2% and specificity of 92.3% (AUC, 91.2%; 95% CI, 0.837 to 0.987; p < 0.0001). Higher torque amounts increased the rate of true-positive results.

CONCLUSIONS

BET-CT reliably detects experimental syndesmotic rotational instability, compared with the healthy side, with greater sensitivity and similar specificity compared with the arthroscopic lateral hook test. Translation of these experimental findings to clinical practice remains to be established.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Chronic syndesmotic instability - Current evidence on management

This review article discusses the current evidence on the management of chronic syndesmotic instability. Conservative treatment has a limited role, and surgical intervention is most commonly reported as the mainstay of treatment, however the literature consists of small case series and descriptions of operative techniques, and thus the evidence base for any treatment is weak. Surgical options include arthroscopic debridement alone, static fixation with cortical screws, dynamic fixation with suture-button devices, and ligamentous repair or augmentation.

Application of external torque enhances the detection of subtle syndesmotic ankle instability in a weight-bearing CT

PURPOSE

Acute syndesmotic ankle injuries continue to impose a diagnostic dilemma and it remains unclear whether weightbearing and/or external rotation should be added during the imaging process. Therefore, the aim of this study was to assess if combined weightbearing and external rotation increases the diagnostic sensitivity of syndesmotic ankle instability using weightbearing CT (WBCT) imaging, compared to isolated weightbearing.

METHODS

In this retrospective study, patients with an acute syndesmotic ankle injury were analysed using a WBCT (N = 21; Age = 31.6 ± 14.1 years old). Inclusion criteria were an MRI confirmed syndesmotic ligament injury imaged by a WBCT of the ankle during weightbearing and combined weightbearing-external rotation. Exclusion criteria consisted of fracture associated syndesmotic injuries. Three-dimensional (3D) models were generated from the CT slices. Tibiofibular displacement and talar rotation were quantified using automated 3D measurements (anterior tibiofibular distance (ATFD), Alpha angle, posterior Tibiofibular distance (PTFD) and Talar rotation (TR) angle in comparison to the contralateral non-injured ankle.

RESULTS

The difference in neutral-stressed Alpha angle and ATFD showed a significant difference between patients with a syndesmotic ankle lesion and contralateral control (P = 0.046 and P = 0.039, respectively). The difference in neutral-stressed PTFD and TR angle did not show a significant difference between patients with a syndesmotic ankle lesion and healthy ankles (n.s.).

CONCLUSION

Application of combined weightbearing-external rotation reveals an increased ATFD in patients with syndesmotic ligament injuries. This study provides the first insights based on 3D measurements to support the potential relevance of applying external rotation during WBCT imaging. In clinical practice, this could enhance the current diagnostic accuracy of subtle syndesmotic instability in a non-invasive manner. However, to what extent certain displacement patterns require operative treatment strategies has yet to be determined in future studies.

LEVEL OF EVIDENCE

Level III.

Dynamic syndesmotic stabilisation and reinforcement of the antero-inferior tibiofibular ligament with internal brace

PURPOSE

Syndesmotic injuries are associated with long recovery times and high morbidity. Systematic reviews show a trend toward better outcomes of suture buttons compared to screw fixation. The anteroinferior tibiofibular ligament (AITFL) confers the most significant component of translational and rotatory stability. Techniques have developed which reinforce the AITFL. This study aimed to assess results of syndesmotic stabilisation with dynamic stabilisation and reinforcement of the AITFL, with an early mobilisation program.

MATERIALS AND METHODS

Retrospective case series of 30 patients (mean age 31 years). Syndesmotic instability was confirmed with clinical examination, MRI and weightbearing-CT. Dynamic syndesmotic stabilisation with a single suture button was performed followed by the placement of an Internal Brace over the AITFL. A standardised postoperative rehabilitation protocol was established. Foot and Ankle Ability Measure (FAAM) scores were collected postoperatively.

RESULTS

The average follow-up was 13 months. The total FAAM score for ADL was 95 ± 4.9 % (range, 83 - 100 %) and for sport activities 87 ± 13.6 % (range, 50 - 100 %). The rating of mean postoperative function for ADL was 94 ± 5.5 % (range, 80 - 100 %) and 90 ± 13 % (range, 35 - 100 %) for sportv. The difference between acute and chronic injuries was statistically higher (p < 0.05) for daily activities and sport, but the rating of current level of sport activites as well as for daily activites did not show a significant difference (p = 0.9296 and p = 0.1615, respectively). Twenty-seven patients (90 %) rated their overall current level of function as normal or nearly normal.

CONCLUSION

This technique aims to directly stabilise the AITFL and the interosseous components of the syndesmosis, and allow early mobilisation and return to sport at 10 weeks. Early results show the procedure is safe, with comparable results to the literature. Acute injuries showed better results of the FAAM score than chronic injuries.

The Role of Ultrasound in the Management of Ankle Sprains and a Clinically Relevant Geisinger Ankle Sprain Sports Ultrasound Protocol

ABSTRACT

Ankle sprains are the most common lower extremity injury in physically active individuals. These injuries are classified as lateral, medial, and/or syndesmotic. Treatment may include functional rehabilitation, bracing, weight-bearing restriction, medications, injections, and surgery. While most sprains heal rapidly, permanent disability and pain may arise. Diagnostic ultrasound has been demonstrated to be accurate in diagnosing ligamentous injuries, but it is often excluded from management algorithms that rely on physical examination alone to diagnose significant injuries. This article proposes a comprehensive, evidence-based diagnostic ankle ultrasound protocol to implement in conjunction with thorough history and physical examination. We also review the current literature to describe where this protocol most improves diagnostic accuracy compared with physical examination alone.

Preoperative CT parameters to predict tibiofibular syndesmosis injury associated with ankle fracture: a propensity score-matched analysis

BACKGROUND

Untreated ankle fractures with concomitant tibiofibular syndesmosis injury often lead to postoperative pain and early traumatic arthritis. CT has advantages in the preoperative diagnosis of combined ankle injuries. However, a few studies have investigated the best preoperative CT parameters to predict tibiofibular syndesmosis injuries associated with ankle fractures. This study aimed to identify and evaluate the optimal preoperative CT parameters for predicting tibiofibular syndesmosis injuries associated with ankle fractures.

METHODS

We retrospectively analyzed 129 patients who underwent preoperative CT of an ankle fracture treated between January 2016 and April 2022 at a tertiary A hospital. All patients underwent open reduction and internal fixation and intraoperative stability testing. Based on the Cotton test, the patients were divided into the stable group (n = 83, 64.3%) and unstable group (n = 46, 35.7%). After 1:1 propensity score matching, the general conditions, anterior tibiofibular distance (TFD), posterior TFD, maximum TFD, tibiofibular syndesmosis area, sagittal fracture angle, Angle-A, and Angle-B were compared between the stable and unstable groups.

RESULTS

The propensity score-matched cohort comprised 82 patients. There were no significant differences between the stable and unstable groups in sex, age, affected side, operation interval, injury mechanism, Lauge-Hansen classification, sagittal fracture angle, and Angle-A (all P > 0.05). Compared with the stable group, the unstable group had a significantly greater aTFD, pTFD, maxTFD, and area (all P < 0.05). PTFD, maxTFD, and area were positively correlated with joint instability. Angle-B was smaller in the unstable group (57.13°) than the stable group (65.56°). ROC analysis showed that Area (AUC 0.711) and maxTFD (AUC 0.707) had the highest diagnostic efficacy.

CONCLUSION

MaxTFD and Area were the best predictive parameters; a larger Area was associated with a higher likelihood of instability of the tibiofibular syndesmosis after ankle fracture fixation.

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).

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.

Effect of Posterior Malleolar Fixation on Syndesmotic Stability

BACKGROUND

Transsyndesmotic fixation with suture buttons (SBs), posterior malleolar fixation with screws, and anterior inferior tibiofibular ligament (AITFL) augmentation using suture tape (ST) have all been suggested as potential treatments in the setting of a posterior malleolar fracture (PMF). However, there is no consensus on the optimal treatment for PMFs.

PURPOSE

To determine which combination of (1) transsyndesmotic SBs, (2) posterior malleolar screws, and (3) AITFL augmentation using ST best restored native tibiofibular and ankle joint kinematics after 25% and 50% PMF.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty cadaveric lower-leg specimens were divided into 2 groups (25% or 50% PMF) and underwent biomechanical testing using a 6 degrees of freedom robotic arm in 7 states: intact, syndesmosis injury with PMF, transsyndesmotic SBs, transsyndesmotic SBs + AITFL augmentation, transsyndesmotic SBs + AITFL augmentation + posterior malleolar screws, posterior malleolar screws + AITFL augmentation, and posterior malleolar screws. Four biomechanical tests were performed at neutral and 30° of plantarflexion: external rotation, internal rotation, posterior drawer, and lateral drawer. The position of the tibia, fibula, and talus were recorded using a 5-camera motion capture system.

RESULTS

With external rotation, posterior malleolar screws with AITFL augmentation resulted in best stability of the fibula and ankle joint. With internal rotation, all repairs that included posterior malleolar screws stabilized the fibula and ankle joint. Posterior and lateral drawer resulted in only small differences between the intact and injured states. No differences were found in the efficacy of treatments between 25% and 50% PMFs.

CONCLUSION

Posterior malleolar screws resulted in higher syndesmotic stability when compared with transsyndesmotic SBs. AITFL augmentation provided additional external rotational stability when combined with posterior malleolar screws. Transsyndesmotic SBs did not provide any additional stability and tended to translate the fibula medially.

CLINICAL RELEVANCE

Posterior malleolar fixation with AITFL augmentation using ST may be the preferred surgical method when treating patients with acute ankle injury involving an unstable syndesmosis and a PMF ≥25%.

Ultrasonography vıew for acute ankle ınjury: comparison of ultrasonography and magnetic resonance ımaging

INTRODUCTION

We aim to asses the diagnostic performance of ankle ultrasonography in patients presenting with acute ankle sprain injury, with comparison to MRI (Manyetik Rezonans İmaging).

MATERIALS AND METHODS

The study included patients who applied to the hospital within 48 h after an ankle sprain, and who presented with signs of pain, swelling, and tenderness in the ankle. Ankle ultrasonography examination was performed and an ankle MRI took place the same day.

RESULTS

30 patients were included in the study. 53.3% (n = 16) were female. The mean age was 30 ± 6.4 years. The ultrasonography examination determined 76.6% (n = 23) of the patients to have anterior talofibular ligament (ATFL) injury, 33.3% to have (n = 10) CFL injury, and 33.3% to have (n = 10) anterior inferior tibia-fibular ligament (AITFL) injury. The MRI of the patients determined 73.3% (n = 22) of the patients to have ATFL injury, 43.3% (n = 13) to have calcaneal fibular ligament (CFL) injury, and 33.3% to have (n = 10) AITFL injury. The ATFL, CFL, and AITFL injuries diagnosed on ultrasonography correlated with the MRI results (ICC = 0.875, ICC = 0.879, and ICC = 0.858). However, among the ATFL injuries observed on MRI, 26.6% (n = 8) were grade I, 26.6% (n = 8) were grade II, and 20% (n = 6) were grade III injuries. Of the ATFL injuries observed on ultrasonography, 46.6% (n = 14) were grade I, 8.6% (n = 2) were grade II, and 30.4% (n = 7) were grade III injuries.

CONCLUSIONS

Findings on all types of ATFL, CFL and AITFL appear to have a higher degree of correlation. Ultrasonography could have an added role as a triaging tool, to fast-track MRI.

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.

Robotic Technology in Foot and Ankle Surgery: A Comprehensive Review

Recent developments in robotic technologies in the field of orthopaedic surgery have largely been focused on higher volume arthroplasty procedures, with a paucity of attention paid to robotic potential for foot and ankle surgery. The aim of this paper is to summarize past and present developments foot and ankle robotics and describe outcomes associated with these interventions, with specific emphasis on the following topics: translational and preclinical utilization of robotics, deep learning and artificial intelligence modeling in foot and ankle, current applications for robotics in foot and ankle surgery, and therapeutic and orthotic-related utilizations of robotics related to the foot and ankle. Herein, we describe numerous recent robotic advancements across foot and ankle surgery, geared towards optimizing intra-operative performance, improving detection of foot and ankle pathology, understanding ankle kinematics, and rehabilitating post-surgically. Future research should work to incorporate robotics specifically into surgical procedures as other specialties within orthopaedics have done, and to further individualize machinery to patients, with the ultimate goal to improve perioperative and post-operative outcomes.

The role of the posterior malleolus in the treatment of unstable upper ankle joint injuries - A biomechanical study

BACKGROUND

This biomechanical study aimed to test if the fixation of the posterior malleolus (PM) only with screws inserted from posterior to anterior (PA) restores stability comparable with the natural condition. The extent of stability was also compared with that of anterior to posterior (AP) screw osteosynthesis (OS) with an additional syndesmotic screw (SS).

METHODS

First, the stability of the upper ankle joint in seven pairs of intact lower legs were examined. Subsequently, half of the lower legs were treated with PA screw fixation of a PM fracture without SS and the other half with AP screw fixation with additional tricortical SS.

RESULTS

PA OS without SS showed significantly more diastasis (p = 0.027). The AP OS with an SS revealed a diastasis that was comparable with the intact condition (p = 0.797). The use of SS led to significantly higher stability compared to OS without SS (p = 0.019).

CONCLUSIONS

The Fixation of the PM alone without an additional syndesmotic screw cannot achieve intact upper ankle stability. Fixation of a PM fracture with an SS helps in nearly achieving the natural condition.

Comparison of Treatment Methods for Syndesmotic Injuries With Posterior Tibiofibular Ligament Ruptures: A Cadaveric Biomechanical Study

Background:

Studies on ankle syndesmosis have focused on anterior inferior tibiofibular ligament (AITFL) and interosseous membrane injuries; however, the characteristics of posterior inferior tibiofibular ligament (PITFL) ruptures remain unclear.

Purpose/Hypothesis:

This study evaluated the biomechanical characteristics of syndesmotic instability caused by PITFL injury and compared various treatment methods. We hypothesized that PITFL injury would lead to syndesmotic internal rotational instability and that the stability would be restored with suture tape (ST) PITFL augmentation.

Study Design:

Controlled laboratory study.

Methods:

Ten uninjured fresh-frozen cadaveric leg specimens were tested via forces applied to the external and internal rotation of the ankle joint. The fibular rotational angle (FRA) related to the tibia, anterior tibiofibular diastasis (aTFD), and posterior tibiofibular diastasis (pTFD) were measured using a magnetic tracking system. Six models were created: (1) intact, (2) AITFL injury; (3) AITFL + PITFL injury; (4) suture button (SB) fixation; (5) SB + anterior ST (aST) fixation; and (6) SB + aST + posterior ST fixation. The FRA, aTFD, and pTFD were statistically compared between the intact ankle and each injury or fixation model.

Results:

In the intact state, the changes in FRA and aTFD were 1.09° and 0.33 mm when external rotation force was applied and were 0.57° and 0.41 mm when internal rotation force was applied. In the AITFL injury model, the changes in FRA and aTFD were 2.38° and 1.51 mm when external rotation force was applied, which were significantly greater versus intact (P = .032 and .008, respectively). In the AITFL + PITFL injury model, the changes in FRA and pTFD were 2.12° and 1.02 mm when internal rotation force was applied, which were significantly greater versus intact (P = .007 and .003, respectively). In the SB fixation model, the change in FRA was 2.98° when external rotation force was applied, which was significantly higher compared with intact (P < .001). There were no significant differences between the SB + aST fixation model and the intact state on any measurement.

Conclusion:

PITFL injury significantly increased syndesmotic instability when internal rotation force was applied. SB + aST fixation was effective in restoring syndesmotic stability.

Clinical Relevance:

These results suggest that SB + aST fixation is sufficient for treating severe syndesmotic injury with PITFL rupture.

A systematic review of ankle fracture-dislocations: Recent update and future prospects

Background

Ankle fracture-dislocations are one of the most severe types of ankle injuries. Compared to the simple ankle fractures, ankle fracture-dislocations are usually more severely traumatized and can cause worse functional outcomes. The purpose of this study was to review the previous literatures to understand the anatomy, mechanisms, treatment, and functional outcomes associated with ankle fracture-dislocations.

Methods

The available literatures from January 1985 to December 2021 in three main medical databases were searched and analyzed. The detailed information was extracted for each article, such as researchers, age, gender, groups, type of study, type of center research, level of evidence, significant findings, study aim, cause of injury, time from injury to surgery, type of fracture, direction of dislocation, follow-up, postoperative complications and functional evaluation scores.

Results

A total of 15 studies (1,089 patients) met the inclusion criteria. Only one study was a prospective randomized trial. The top-ranked cause of injury was high-energy injury (21.3%). Moreover, the most frequent type of fracture in ankle dislocations was supination-external rotation (SER) ankle fracture (43.8%), while the most common directions of dislocation were lateral (50%) and posterior (38.9%).

Conclusions

Collectively, most ankle fracture-dislocations are caused by high-energy injuries and usually have poor functional outcomes. The mechanism of injury can be dissected by the ankle anatomy and Lauge-Hansen's classification. The treatment of ankle fracture-dislocations still requires more detailed and rational solutions due to the urgency of occurrence, the severity of injury, and the postoperative complications.

Unstable Rotational Ankle Fractures Treated With Anatomic Mortise Repair and Direct Posterior Malleolus Fixation

Introduction: The purpose of this study was to evaluate patient outcomes following a standardized algorithmic approach to ankle mortise stabilization, following rotational fracture, utilizing direct repair of the posterior malleolus in the prone position. Methods: Eighty consecutive patients with unstable rotational ankle fractures that involved the posterior malleolus were analyzed. All underwent direct repair of the posterior malleolus regardless of size through a posterolateral approach. Electronic records were retrospectively reviewed for demographic information, initial injury and operation details, healing status, and complications. Preoperative and postoperative radiographs were obtained to assess the initial injury and healing was determined both by radiographic and clinical progress at follow-up visits. Results: Average posterior malleolus fragment width was 8.1 ± 3.7 mm (range = 2.1-19.9 mm) and percentage of the articular surface was 23.6% (range = 7.1%-56.7%) on the lateral radiograph. Overall, 80/80 (100%) patients healed their ankle fractures by a mean 2.9 ± 1.1 months. Only 1 (1.3%) patient required transsyndesmotic fixation following posterior malleolus repair. Mean range of ankle motion was as follows: dorsiflexion 20° ± 10°, plantarflexion 34° ± 10°, inversion 8° ± 4°, and eversion 7° ± 4°. Seventy-nine patients (98.8%) had an anatomic mortise reduction. Nine patients (11.3%) had a superficial wound complication, 3 patients (3.8%) had dysesthesia in the sural nerve distribution, and 1 patient (1.3%) lost reduction of the medial malleolus. Conclusion: Patients who undergo direct repair of the posterior malleolus in the prone position can expect a high rate of healing with superficial wound breakdown being the biggest problem, which was associated with an ankle fracture dislocation. Posterior malleolus fixation may obviate the need of transsyndesmotic stabilization.Levels of Evidence: Retrospective Level IV.

Anterior Inferior Tibiofibular Ligament Suture Tape Augmentation for Isolated Syndesmotic Injuries

BACKGROUND

The best operative construct and technique for treatment of isolated syndesmotic injuries is highly debated. The purpose of this study was to determine whether the addition of anterior inferior tibiofibular ligament (AITFL) suture repair or suture tape (ST) augmentation provides any biomechanical advantage to the operative repair of an isolated syndesmotic injury.

METHODS

Twelve lower leg specimens underwent biomechanical testing in 6 states: (1) intact, (2) AITFL suture repair, (3) AITFL suture repair + transsyndesmotic suture button (SB), (4) AITFL suture repair + ST augmentation + SB, (5) AITFL suture repair + ST augmentation, and (6) complete syndesmotic injury. The ankle joint was subjected to 6 cycles of 5 Nm internal and external rotation torque under a constant axial load. The spatial relationship between the tibia, fibula, and talus was continuously recorded with a 5-camera motion capture system.

RESULTS

AITFL suture repair and AITFL suture repair + ST augmentation showed no statistically significant change in fibula kinematics compared to the intact state. Compared to native, AITFL suture repair + SB showed increased fibular external rotation (+2.32 degrees, P < .001), and decreased tibiofibular gap (overtightening) (-0.72 mm, P = .007). AITFL suture repair + ST augmentation + SB also showed increased fibular external rotation (+1.46 degrees, P = .013). Sagittal plane motion of the fibula was not significantly different between any states. None of the repairs restored intact state talus rotation; however, the repairs that used ST augmentation reduced the talus external rotation laxity compared to the complete syndesmotic injury.

CONCLUSION

AITFL suture repair and AITFL ST augmentation best restored the rotational kinematics and stability of the fibula and ankle joint in an isolated syndesmotic injury model.

CLINICAL RELEVANCE

AITFL suture repair with or without ST augmentation may be a good operative addition or alternative to SB fixation for isolated syndesmotic disruptions.

In Vivo Syndesmotic Motion After Rigid and Flexible Fixation Using 4-Dimensional Computerized Tomography

INTRODUCTION

Maintaining reduction after syndesmotic injury is crucial to patient function; however, malreduction remains common. Flexible suture button fixation may allow more physiologic motion of the syndesmosis compared with rigid screw fixation. Conventional syndesmotic imaging fails to account for physiologic syndesmotic motion with ankle range of motion (ROM), providing misleading results. Four-dimensional computerized tomography (4DCT) can image joints through a dynamic ROM. Our purpose was to compare syndesmotic motion after rigid and flexible fixation using 4DCT.

METHODS

We analyzed 13 patients with syndesmotic injury who were randomized to receive rigid (n = 7) or flexible (n = 6) fixation. Patients underwent bilateral ankle 4DCT while moving between ankle dorsiflexion and plantar flexion. Measures of syndesmotic position and rotation were extracted from 4DCT to determine syndesmotic motion as a function of ankle ROM.

RESULTS

Uninjured ankles demonstrated significant decreases in syndesmotic width of 1.0 mm with ankle plantar flexion (SD = 0.6 mm, P < 0.01). Initial rigid fixation demonstrated reduced motion compared with uninjured ankles in 4 of 5 measures (P < 0.01) despite all patients in the rigid fixation group having removed, loose, or broken screws by the time of imaging. Rigid fixation led to less motion than flexible fixation in 3 measures (P = 0.02-0.04). There were no observed differences in syndesmotic position or motion between flexible fixation and uninjured ankles.

CONCLUSION

Despite the loss of fixation in all subjects in the rigid fixation group, initial rigid fixation led to significantly reduced syndesmotic motion. Flexible fixation recreated more physiologic motion compared with rigid fixation and may be used to reduce rates of syndesmotic malreduction.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Evidence-Based Surgical Treatment Algorithm for Unstable Syndesmotic Injuries

Background: Surgical treatment of unstable syndesmotic injuries is not trivial, and there are no generally accepted treatment guidelines. The most common controversies regarding surgical treatment are related to screw fixation versus dynamic fixation, the use of reduction clamps, open versus closed reduction, and the role of the posterior malleolus and of the anterior inferior tibiofibular ligament (AITFL). Our aim was to draw important conclusions from the pertinent literature concerning surgical treatment of unstable syndesmotic injuries, to transform these conclusions into surgical principles supported by the literature, and finally to fuse these principles into an evidence-based surgical treatment algorithm. Methods: PubMed, Embase, Google Scholar, The Cochrane Database of Systematic Reviews, and the reference lists of systematic reviews of relevant studies dealing with the surgical treatment of unstable syndesmotic injuries were searched independently by two reviewers using specific terms and limits. Surgical principles supported by the literature were fused into an evidence-based surgical treatment algorithm. Results: A total of 171 articles were included for further considerations. Among them, 47 articles concerned syndesmotic screw fixation and 41 flexible dynamic fixations of the syndesmosis. Twenty-five studies compared screw fixation with dynamic fixations, and seven out of these comparisons were randomized controlled trials. Nineteen articles addressed the posterior malleolus, 14 the role of the AITFL, and eight the use of reduction clamps. Anatomic reduction is crucial to prevent posttraumatic osteoarthritis. Therefore, flexible dynamic stabilization techniques should be preferred whenever possible. An unstable AITFL should be repaired and augmented, as it represents an important stabilizer of external rotation of the distal fibula. Conclusions: The current literature provides sufficient arguments for the development of an evidence-based surgical treatment algorithm for unstable syndesmotic injuries.

Intraoperative chertsey test, is it a reliable alternative to computed tomography scan for diagnosing syndesmotic injuries of the ankle?

Background:

The present study aims to evaluate the diagnostic exactitude of the intraoperative Chertsey test in tibiofibular syndesmotic injuries in patients with malleolar fractures, in comparison with a computed tomography (CT) scan.

Materials and Methods:

In this study, patients with malleolar fractures operated between 2018 and 2020 were examined. Thirty-nine patients were enrolled in the study. A three-dimensional preoperative CT scan was obtained. The opposite unfractured ankle was also scanned and considered as the control group. The Chertsey test was performed during the operation to assess the syndesmosis injury. Then, patients were partitioned into two distinct groups, considering the condition of their ankle, namely the Chertsey positive (unstable syndesmosis) group and the Chertsey negative (stable syndesmosis) group.

Results:

The outcomes of the present survey illustrated that the Chertsey test was positive in 16 patients (41.03%) and negative in 23 patients (59.07%). The median of all CT scan parameters (anterior tibiofibular distances (TFD), middle TFD, posterior TFD, and maximal TFD and volume) before surgery in the group of patients with a positive Chertsey test was significantly higher, measured against the unfractured control group (P < 0.001 for all parameters). Furthermore, a comparison of CT scan parameters and syndesmosis space volume before surgery between the two groups of patients with positive and negative Chertsey test results showed that the measurement of parameters in Chertsey-positive patients was significantly higher than the Chertsey-negative patients (P < 0.001).

Conclusion:

Chertsey test could be used to diagnose syndesmosis injuries in patients with malleolar fractures due to its high importance in the outcome of patients.

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.

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.

Prognostic value of the Haraguchi classification in posterior malleolar fractures in A0 44-C type ankle fractures

BACKGROUND AND PURPOSE

Incidence of posterior malleolar fractures (PMFs) associated with ankle fractures is historically based on plain radiographs. Several classification systems for PMF are currently in use, but the reliability of the Haraguchi classification is not reported. The aim of this diagnostic cohort study was to assess incidence of PMF in patients with AO 44-C fractures, and test the reliability of the Haraguchi fracture classification based on CT. In addition, to evaluate the clinical outcome in patients with PMF.

METHODS

210 patients with an AO 44-C type fracture treated with syndesmotic fixation between 2011 and 2017 were included. Presence of PMF was registered, morphology was assessed and classified according to the Haraguchi classification. Interobserver agreement for the Haraguchi classification was evaluated. Patient assessment was conducted at 6 weeks, 6 months, 1 and 2 years. The American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score (AOFAS) was the primary outcome measure. Secondary outcome measures included presence of osteoarthritis.

RESULTS

125 of 210 patients (60%) had a PMF. 34% of the PMFs were missed on plain radiographs compared to CT. The interobserver agreement was 0.797, (95% CI: 0.705 to 0.889, p < 0.001), for the Haraguchi classification. The 2-year follow-up rate was 86%. Haraguchi type II fractures had a lower AOFAS compared with the no-fracture group at 6 weeks (mean difference -7.5 (95% CI; -15.0 to -0.2), p = 0.04) and 6 months (mean difference -8.4 (95% CI; -15.3 to -1.5), p = 0.01). Presence of osteoarthritis was higher in patients with Haraguchi type II PMF compared to the no PMF group, this finding was not significant (relative risk (RR) 1.6(95% CI 1.1 to 2.4, p = 0.059)).

CONCLUSIONS

Plain radiographs underestimated PMF. Patients with a Haraguchi type II fracture had a poorer outcome measured by the AOFAS score compared to no PMF up until 6 months. Classification of PMF according to the Haraguchi classification was reliable.

The Syndesmosis, Part II: Surgical Treatment Strategies

Syndesmotic injuries in the setting of ankle fracture are critically important to diagnosis and treat to restore an anatomic tibiotalar relationship. Physical examination and clinical suspicion remain critically important for diagnosis. Ultrasound examination and weight-bearing computed tomography scans are evolving to help diagnosis more subtle injuries. Although flexible syndesmotic fixation may decrease malreduction rates, the benefits over rigid fixation is the subject of ongoing study. Anatomic reduction remains critical regardless of fixation choice. Routine removal of rigid syndesmotic hardware does not seem to offer substantial clinical improvement in pain or range of motion; however, broken hardware may cause irritation.

Arthroscopic characterization of syndesmotic instability in the coronal plane: Exactly what measurement matters?

BACKGROUND

Although ankle arthroscopy is increasingly used to diagnose syndesmotic instability, precisely where in the incisura one should measure potential changes in tibiofibular space or how much tibiofibular space is indicative of instability, however, remains unclear. The purpose of this study was to determine where within the incisura one should assess coronal plane syndesmotic instability and what degree of tibiofibular space correlates with instability in purely ligamentous syndesmotic injuries under condition of lateral hook stress test (LHT) assessment.

METHODS

Ankle arthroscopy was performed on 22 cadaveric specimens, first with intact ankle ligaments and then after sequential sectioning of the syndesmotic and deltoid ligaments. At each step, a 100N lateral hook test was applied through a lateral incision 5 cm proximal to the ankle joint and the coronal plane tibiofibular space in the stressed and unstressed states were measured at both anterior and posterior third of the distal tibiofibular joint, using calibrated probes ranging from 0.1 to 6.0 mm, in 0.1 mm of increments. The anterior and posterior points of measurements were defined as the junction between the anterior and middle third, and junction between posterior and middle third of the incisura, respectively.

RESULTS

Anterior third tibiofibular space measurements did not correlate significantly with the degree of syndesmotic instability after transection of the ligaments, neither before nor after applying LHT at all the three groups of different sequences of ligament transection (P range 0.085-0.237). In contrast, posterior third tibiofibular space measurements correlated significantly with the degree of syndesmotic instability after transection of the ligaments, both with and without applying stress in all the groups of different ligament transection (P range <0.001-0.015). Stressed tibiofibular space measurements of the posterior third showed higher sensitivity and specificity when compared to the stressed anterior third measurements. Using 2.7 mm as a cut off for posterior third stressed measurements has both sensitivity and specificity about 70 %.

CONCLUSION

Syndesmotic ligament injury results in coronal plane instability of the distal tibiofibular articulation that is readily identified arthroscopically with LHT when measured in the posterior third of the incisura.

CLINICAL RELEVANCE

When applying LHT, tibiofibular space measurement for coronal plane instability along the anterior third of the incisura is less sensitive for identifying syndesmotic instability and may miss this diagnosis especially when subtle.

Anatomic Repair vs Closed Reduction of the Syndesmosis

BACKGROUND

The goal of the study was to compare radiographic and functional outcomes between conventional closed syndesmotic reduction and screw fixation with open reduction, direct repair of the anterior inferior tibiofibular ligament (AiTFL) and screw fixation. We hypothesized that open reduction with restoration of the AiTFL would provide an improved reduction with better radiographic and functional outcomes.

METHODS

Fifty consecutive patients with OTA 44-C ankle fractures were enrolled. Treatment was nonrandomized and based on surgeon preference. Patients were treated with either open reduction, suture-anchor AiTFL repair, and screw fixation (ART group), or conventional closed reduction of the syndesmosis followed by screw fixation (CR group). The primary outcome measure was anteroposterior (AP) displacement of the fibula on CT scan at 3 months postoperatively. Secondary outcome measures included the Maryland Foot Score, the American Orthopaedic Foot & Ankle Society (AOFAS) Ankle Hindfoot Score, and the Foot and Ankle Outcome Score (FAOS).

RESULTS

Mean AP difference between injured and noninjured ankles was decreased in the ART group compared with the CR group (0.7 ± 0.3 mm vs 1.5 ± 0.3 mm, P = .008). No differences were observed between groups in overall scores for secondary outcome measures. The ART group displayed a significant difference in Maryland Foot Shoe subscore at 12 months (ART = 9.5 vs CR = 8.3, P = .03) and FAOS Quality of Life subscore at 12 months (64.1 compared to 38.3, P = .04).

CONCLUSION

Open anatomic syndesmotic repair resulted in improved radiographic outcomes compared with closed reduction. Cosmesis was worse at 6 weeks compared to the CR group; however, quality of life and shoewear were improved in the ART group at 1 year postoperatively.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

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.

APKASS Consensus Statement on Chronic Syndesmosis Injury, Part 2: Indications for Surgical Treatment, Arthroscopic or Open Debridement, and Reconstruction Techniques of Suture Button and Screw Fixation

Background:

The indications for surgical treatment of chronic syndesmosis injury are challenging for many orthopaedic clinicians, as there is no international consensus on the optimal management of these injuries.

Purpose:

An international group of experts representing the field of sports injuries in the foot and ankle area was invited to collaboratively advance toward consensus opinions based on the best available evidence regarding chronic syndesmosis injury. All were members of the Asia-Pacific Knee, Arthroscopy and Sports Medicine Society (APKASS).

Study Design:

Consensus statement.

Methods:

From November to December 2020, a total of 111 international experts on sports medicine or ankle surgery participated in a 2-stage Delphi process that included an anonymous online survey and an online meeting. A total of 13 items with 38 statements were drafted by 13 core authors. Of these, 9 items with 17 clinical questions and statements were related to indications for surgical treatment, arthroscopic versus open debridement, and suture button versus screw fixation reconstruction techniques and are presented here. Each statement was individually presented and discussed, followed by a general vote. The strength of consensus was characterized as follows: consensus, 51% to 74%; strong consensus, 75% to 99%; and unanimous, 100%.

Results:

Of the 17 questions and statements, 4 achieved unanimous support, 11 reached strong consensus, and 2 reached consensus.

Conclusion:

This APKASS consensus statement, developed by international experts in the field, will assist surgeons and physical therapists with surgical indications and techniques for chronic syndesmosis injury.

Morphometric analysis of the incisura fibularis in patients with unstable high ankle sprains

OBJECTIVE

The role of the syndesmotic ankle ligaments as extrinsic stabilizers of the distal tibiofibular joint (DTFJ) has been studied extensively in patients with high ankle sprains (HAS). However, research concerning the fibular incisura as intrinsic stabilizer of the DTFJ has been obscured by a two-dimensional assessment of a three-dimensional structure. Therefore, we aimed to compare the morphometry of the incisura fibularis between patients with HAS and a control group using three-dimensional radiographic techniques.

MATERIALS AND METHODS

Fifteen patients with a mean age of 44 years (SD = 15.2) diagnosed with an unstable HAS and twenty-five control subjects with a mean age of 47.4 years (SD = 6.5) were analyzed in this retrospective comparative study. The obtained CT images were converted to three-dimensional models, and the following radiographic parameters of the incisura fibularis were determined using three-dimensional measurements: incisura width, incisura depth, incisura height, incisura angle, incisura width-depth ratio, and incisura-tibia ratio.

RESULTS

The mean incisura depth (M = 4.7 mm, SD = 1.1 mm), incisura height (M = 36.1 mm, SD = 5.3 mm), and incisura angle of the control group (M = 137.2°, SD = 7.9°) differed significantly from patients with a HAS (resp., M = 3.8 mm, SD = 1.1 mm; M = 31.9 mm, SD = 3.2 mm; M = 143.2°, SD = 8.3°) (P < 0.05). The incisura width, incisura width-depth ratio, and incisura-tibia ratio demonstrated no significant difference (P > 0.05).

CONCLUSION

Our three-dimensional comparative analysis has detected a shallower and shorter fibular incisura in patients with HAS. This distinct morphology could have repercussion on the intrinsic or osseous stability of the DTFJ. Future prospective radiographic assessment could determine to what extend the fibular incisura morphology contributes to syndesmotic ankle injuries caused by high ankle sprains.

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.

The anatomy of the anterior inferior tibiofibular ligament and its relationship with the Wagstaffe fracture

BACKGROUND

Our aim in this study was to identify the fibular footprint of the Anterior Inferior Tibiofibular Ligament (AITFL) and its relation to Wagstaffe fracture fragment size.

METHODS

We examined 25 cadaveric lower limbs which were carefully dissected to identify the lateral ankle ligaments. The AITFL anatomy was compared to 40 Wagstaffe fractures identified from our ankle fracture database.

RESULTS

The AITFL origin was from the anterior fibular tubercle with an average length of 21.61 mm (95% CI 20.22, 22.99). The average distance of the distal aspect of the AITFL footprint to the distal fibula margin was 11.60 mm (95% CI 10.49, 12.71). In the ankle fractures analyzed, the average length of the Wagstaffe fragment was 17.88 mm (95% CI 16.21, 19.54). The average distance from the distal tip of the fibula to the Wagstaffe fracture fragment was 21.40 mm (95% CI 19.78, 23.01). In total there were 22 syndesmosis injuries. There was no statistical difference in Wagstaffe fragment size between stable and unstable groups.

CONCLUSION

The AITFL fibular origin was both larger and more distal than the Wagstaffe fracture fragments seen in our institution. Therefore, this suggests that a ligamentous failure will also have to occur to result in syndesmotic instability. The size of fracture fragment also did not confer to syndesmotic instability on testing. Level of Evidence - 3.

Diagnosing instability of ligamentous syndesmotic injuries: A biomechanical perspective

BACKGROUND

High ankle sprains are insidious injuries associated with a long recovery period, functional impairment and long-term sequelae if mistreated. This systematic review investigates the biomechanical knowledge on the kinematic consequences of sequential syndesmotic ligamentous injuries, aiming to furnish an updated and objective contribution for the critical appraisal and further elaboration of current diagnostic algorithms for high ankle sprains.

METHODS

A systematic review was performed to identify human biomechanical studies evaluating the stabilizing role of the syndesmotic ligaments. Special attention was paid to identify the smallest lesion within the progressive simulated injuries able to provoke statistically significant changes of the syndesmotic kinematic on the specimen, the mechanical solicitation that provoked it, and the measurement methodology.

FINDINGS

Fourteen studies were included. In eight articles already an isolated injury to the anterior inferior tibiofibular ligament provoked significant changes of the syndesmotic kinematic, which was always depicted under an external rotation torque. In three articles an isolated deltoid ligament injury provoked significant changes of the syndesmotic kinematic. Four articles described a direct measure of the bony movements, whereas seven collected data through conventional radiography or CT-scan imaging and three via a 3D motion analysis tracking system.

INTERPRETATION

An isolated lesion of the anterior inferior tibiofibular ligament can provoke significant kinematic modifications in ex vivo syndesmotic models and may be responsible of subtle patterns of dynamic instability, regardless of further syndesmotic ligamentous injuries. The data observed support efforts to define reliable CT imaging parameters to improve non-invasive diagnostic of subtle forms of syndesmotic instability.

Fixation of anterolateral distal tibial fractures: the anterior malleolus

OBJECTIVE

The anterior tibial rim with the anterolateral tibial tubercle provides attachment to the anterior tibiofibular syndesmosis. It may be considered an anterior or "fourth" malleolus. Fixation of a displaced anterior tibial fragment in the treatment of malleolar fractures aims at providing a bone-to-bone fixation of the anterior tibiofibular ligament and restoring the integrity of the tibial incisura.

INDICATIONS

Displaced intra-articular fragments of the anterior tibia; fractures involving the tibial incisura; fractures with intercalary fragments; impaction of the anterior tibial plafond; syndesmotic avulsions producing instability or preventing reduction of the distal fibula into the tibial incisura.

CONTRAINDICATIONS

Critical local soft tissues preventing an anterolateral approach; missing consent to surgery by the patient; overall critical general condition preventing surgery to the extremities.

SURGICAL TECHNIQUE

Anterolateral approach over the tibial tubercle. Identification and mobilization of the anterior tibial fragment without dissecting the anterior syndesmosis. Reduction of the anterior tibial fragment with a pointed reduction clamp. Fixation of extra-articular avulsion fractures (type 1) with suture anchor. Screw fixation of larger fragments involving the joint surface and incisura (type 2). Disimpaction, realignment of the joint surface, bone grafting as needed and plate fixation of impaction fractures of the anterolateral tibial plafond (type 3).

POSTOPERATIVE MANAGEMENT

Mobilization with partial weight bearing (15-20 kg) in a special boot (ankle foot orthosis) or cast for 6-8 weeks depending on the overall malleolar fracture pattern, bone quality and patient compliance.

RESULTS

Few studies report the results of anterior tibial fractures in adults. Failure to fix displaced fragments frequently leads to nonunions. Overlooked Chaput fractures have been reported to result in malpositioning of the distal fibula in the tibial incisura leading to incongruity of the ankle mortise requiring revision surgery. Secondary avascular necrosis of the anterolateral tibial plafond may develop after joint impaction.

A standardized approach for exact CT-based three-dimensional position analysis in the distal tibiofibular joint

Background

Assessment of tibiofibular reduction presents an intra- and postoperative challenge. Numerous two-dimensional measurement methods have been described, most of them highly dependent on leg orientation and rater. Aim of the present work was to develop a standardized and orientation-independent 3D based method for the assessment of syndesmotic joint position.

Methods

In a retrospective single center study, 3D models of bilateral ankle joints, either after unilateral syndesmosis stabilization (operative group) or with no injury (native group) were superimposed (best fit matching) and aligned uniformly. Based on center of gravity calculations three orientation- and rater-independent parameters were determined: tibiofibular clears space (CS), vertical offset between both fibulae, and translation angle of the fibulae about tibia axis.

Results

Bilateral CT datasets of 57 native and 47 postoperative patients were analyzed. In the native group mean CS was 2.7 (SD, 0.8; range, 0.7–4.9) mm, mean CS side difference was 0.62 (SD, 0.45) mm and mean translation angle was 1.6 (SD, 1.4) degrees regarding absolute values. The operative group was found to show a significantly higher CS side difference of 0.88 (SD, 0.75) mm compared to native group (P = .046). Compared to the healthy contralateral side, operated fibulae showed mean proximal displacement of 0.56 (SD, 1.67) mm (P = .025), dorsal displacement of 1.5 (SD 4.1) degrees (P = .017).

Conclusion

By using 3D best fit matching, orientation- and rater-dependent errors can be minimized. Large interindividual and small intraindividual differences of uninjured couples support previous recommendations for bilateral imaging.

Trial registration: AZ 131/18-ek; AZ 361/19-ek

Level of evidence

Level III.

Fixation of Posterior Malleolar Fractures with Posterior Plating Through a Posterolateral Approach

BACKGROUND

We aimed to evaluate radiologic and clinical outcomes of ankle fractures involving posterior fragments that were fixed with a posterior plate by the posterolateral approach.

METHODS

Sixty-five patients who were followed for at least 12 months and were older than 18 years were included. The posterior malleolus fractures were classified according to the Haraguchi classification system with computed tomography (CT). The posterior malleolus fragments were fixed with a plate through a posterolateral approach. Intra-articular step-off, reduction of the posterior malleolar fragment, and fibular position in the incisura were evaluated by early postoperative CT. American Orthopaedic Foot and Ankle Society (AOFAS) score and visual analog scale pain score were used for clinical assessment.

RESULTS

The posterior malleolus fractures were classified as Haraguchi type 1 in 45 patients (69.2%), Haraguchi type 2 in 12 patients (18.5%), and Haraguchi type 3 in eight patients (12.3%). No patients showed signs of instability or loss of reduction on direct radiographs during follow-up. Postoperative CT showed no loss of reduction in the posterior malleolus and tibiofibular alignment. On evaluation, there was no intra-articular step-off (<1) in any of the patients. The mean AOFAS score was calculated to be 91.6. The mean visual analog scale score was 1.2.

CONCLUSIONS

We conclude that direct posterior fixation with the posterolateral approach can be a good option for ankle fractures involving posterior malleolar fragments.

[Fractures of the anterolateral tibial rim : The fourth malleolus]

The anterolateral tibial rim with the anterior tibial tubercle (Tubercule de Tillaux-Chaput) serves as an insertion site of the anterior inferior tibiofibular ligament (AITFL). It can also be termed the anterior malleolus or fourth malleolus. Fractures of the anterolateral tibial rim typically result from an external rotation or abduction mechanism of the talus within the ankle mortise. They are frequently overlooked in plain radiographs. Computed tomography (CT) is needed for an exact visualization of the fracture anatomy and treatment planning. A total of three main types can be differentiated: (1) extra-articular avulsion fracture of the AITFL, (2) fracture of the anterolateral distal tibia with involvement of the joint and tibial incisura and (3) impaction fracture of the anterolateral tibial plafond. Surgical fixation of displaced anterolateral distal tibial fractures aims at bone-to-bone stabilization of the anterior syndesmosis, restoration of the tibial incisura for the distal fibula and joint surface. Displaced extra-articular avulsion fractures (type 1) are fixed with a suture anchor or transosseal suture. Larger fragments involving the tibial incisura and plafond (type 2) are mostly fixed with screws. Impression fractures of the anterolateral tibial plafond (type 3) necessitate elevation with restoration of the joint surface, bone grafting of the impaction zone as needed and anterior buttress plating. Only a few studies have reported the treatment results of anterolateral tibial rim fractures in adults. Conservative treatment of dislocated fragments reportedly leads to non-union and malposition of the distal fibula with incongruence of the ankle mortise requiring revision. Impaction fractures (type 3) can lead to secondary avascular necrosis of the anterolateral tibial plafond.

Biomechanics of the Distal Tibiofibular Syndesmosis: A Systematic Review of Cadaveric Studies

Background:

This investigation’s purpose was to perform a systematic review of the literature examining the biomechanics of the ligaments comprising the distal tibiofibular syndesmosis with specific attention to their resistance to translational and rotational forces. Although current syndesmosis repair techniques can achieve an anatomic reduction, they may not reapproximate native ankle biomechanics, resulting in loss of reduction, joint overconstraint, or lack of external rotation resistance. Armed with a contemporary understanding of individual ligament biomechanics, future operative strategies can target key stabilizing structure(s), translating to a repair better equipped to resist anatomic displacing forces.

Study design:

Systematic review.

Methods:

A systematic review was conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines using a PRISMA checklist. Biomechanical studies testing cadaveric lower limb specimens in the intact and injured state measuring the distal tibiofibular syndesmosis resistance to translational and rotational forces were included in this review. Only studies that included numerical data were included in this review; studies that only reported figures and graphs were excluded.

Results:

Twelve studies met the inclusion and exclusion criteria. Two studies determined the mechanical properties of syndesmotic ligaments, finding superior strength and stiffness of the interosseous ligament (IOL), as compared to the anterior (AITFL) or posteroinferior tibiofibular ligament (PITFL). Four studies examined native ankle biomechanics establishing physiologic range of motion of the fibula relative to the tibia. Fibular range of motion was found to be up to 2.53 mm of posterior translation (Markolf et al), 1.00 mm lateral translation (Xenos et al), 3.6 degrees of external rotation (Burssens et al), and 1.4 degrees of internal rotation (Clanton et al). Four studies evaluated syndesmotic biomechanics under physiological loading and found that the AITFL, IOL, and PITFL provide the majority of resistance to external rotation, diastasis, and internal rotation, respectively. Two studies investigated the biomechanics of clinically and intraoperatively used tests for syndesmotic injuries and found increased sensitivity of sagittal plane posterior fibular translation, as opposed to coronal plane lateral fibular translation for unstable injuries.

Conclusions:

Study findings suggest that although the IOL is the strongest syndesmotic ligament, the AITFL has a dominant role stabilizing the distal tibiofibular syndesmosis to external rotation force. Because of these characteristics, operative repair of the AITFL along its native vector may provide a more biomechanically advantageous construct and should be investigated clinically. Additionally, evaluation of clinical stress tests revealed that the external rotation stress test is the most sensitive test to recognize an AITFL tear, and that a 3-ligament disruption is needed to cause diastasis greater than 2 mm.

[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.

Comparison of External Torque to Axial Loading in Detecting 3-Dimensional Displacement of Syndesmotic Ankle Injuries

BACKGROUND

Current imaging techniques try to quantify 3-dimensional displacement of syndesmotic ankle injuries using 2-dimensional measurements, which may obscure an exact diagnosis. Therefore, our aim was to determine 3-dimensional displacement of syndesmotic ankle injuries under load and torque using a weightbearing computed tomography (WBCT) and to assess the relation with previously established 2-dimensional measurements.

METHODS

Seven paired cadaver specimens were mounted into a radiolucent frame. WBCT scans were obtained to generate 3-dimensional models after different patterns of axial load (0 kg, 85 kg) combined with external torque (0, 10 Nm). Sequential imaging was repeated in ankles containing intact syndesmotic ligaments, sectioning of the anterior inferior tibiofibular ligament (AITFL; condition 1A), deltoid ligament (DL; condition 1B), combined AITFL+DL (condition 2), and AITFl+DL+interosseous membrane (condition 3). Reference anatomical landmarks were established relative to the intact position of the fibula to quantify displacement. A subsequent correlation analysis was performed between the obtained 2- and 3-dimensional measurements.

RESULTS

Axial load increased lateral translation (mean = -0.9 mm, 95% confidence interval [CI]: 1.3, -0.1) significantly in condition 2 relative to the intact ankle (P < .05) but did not demonstrate other significant displacements. External torque increased displacement significantly in all directions (P < .05), except for dorsal translation of the fibula (P > .05). The highest displacement could be detected when external torque was applied in condition 3 and consisted of posterior translation (mean = -3.1 mm; 95% CI: -4.8, -2.7) and external rotation (mean = -4.7 degrees; 95% CI: -5.6, -2.9). Pearson correlation coefficients between the 2-dimensional and 3-dimensional measurements were moderate and ranged from 0.31 to 0.56 (P < .05).

CONCLUSION

External torque demonstrated superiority over axial load in detecting syndesmotic ankle instability. Axial load increased lateral translation; however, differences were submillimeter in magnitude until torque was applied. A moderate correlation was found with previously established 2-dimensional measurements.

CLINICAL RELEVANCE

In clinical practice these findings substantiate application of external torque in current imaging modalities to improve detection of syndesmotic ankle injuries.

Pathoanatomy and Injury Mechanism of Typical Maisonneuve Fracture

OBJECTIVE

Maisonneuve fracture is a special type of injury which are rare in clinic. The manifestation of such fractures is variable. The aim of this study is to describe the pathoanatomical features of typical Maisonneuve fracture on the basis of radiographs, computed tomography (CT) scans, magnetic resonance imaging (MRI), and intraoperative exploration findings, and to investigate the injury mechanism of this variety.

METHODS

The data of 41 patients with Maisonneuve fracture from April 2014 to September 2019 were retrospectively analyzed. There were 32 males and nine females, the average age was 37.9 years (range, 18 to 61 years), the fractures occurred on the left side in 20 patients and on the right side in 21 patients. The cause of injuries were traffic accident in five patients, sprain injury in 20 patients, and falling injury from height in 16 patients. All patients underwent posteroanterior and lateral X-ray examinations of the ankle and calf. CT scan of the ankle was performed in 38 patients, including three-dimensional reconstruction in 33 patients. MRI examination of the ankle and calf was performed in 28 and five patients, respectively. Forty patients were treated with open reduction and internal fixation. The features of proximal fibular fracture, injuries of the medial and posterior structures of the ankle, injuries of the anterior inferior tibiofibular ligament and the interosseous membrane were recorded and analyzed.

RESULTS

Forty-one patients had proximal one-third fractures of the fibula including six patients with fracture involving the fibular neck, 30 with proximal one-third fractures of the fibular shaft, and five with proximal-medial one-third junction fracture of the fibular shaft. Thirty-five patients (35/41, 85.37%) with injury of posterior structures, 34 patients had posterior malleolar fracture (34/41, 82.93%), and one patient had posterior inferior tibiofibular ligament rupture (1/41, 2.44%). There were 20 patients with type I fracture, four patients with type II fracture, and 10 patients with type III fracture according to the Haraguchi classification of posterior malleolus fracture. The fracture of the medial malleolus was in 30 patients (30/41, 73.17%), rupture of the deltoid ligament was in 10 patients (10/41, 24.39%), and medial structures intact were in one patient (1/41, 2.44%). All 41 patients had injury of the anterior inferior tibiofibular ligament.

CONCLUSIONS

Maisonneuve fracture is characterized by fractures of the proximal fibula and the complete rupture of the anterior inferior tibiofibular ligament. Pronation-external rotation is the main injury mechanism. The manifestations of typical Maisonneuve fracture including that the fibular fracture located in proximal one-third diaphysis and the fracture line was from anterosuperior to posteroinferior.

Normal Kinematics of the Syndesmosis and Ankle Mortise During Dynamic Movements

Background:

Documenting the healthy articulation of the syndesmosis and talocrural joints, and measurement of 3D medial and lateral clear spaces may improve diagnostic and treatment guidelines for patients suffering from severe syndesmotic injury or chronic instability. This study aimed to define the range of motion (ROM) and displacement of the fibula and talus during static and dynamic activities, and measure the 3D movement in the tibiofibular (syndesmosis) and medial clear space.

Methods:

Six healthy volunteers performed dynamic weightbearing motions on a single-leg: heel-rise, squat, torso twist, and box jump. Participants posed in a nonweightbearing neutral stance as well as weightbearing neutral standing, plantarflexion, and dorsiflexion. High-speed stereoradiography measured 3D rotation and translation of the fibula and talus throughout each task. Medial clear space and tibiofibular gap distances were measured under each condition.

Results:

Total ROM for the fibula was greatest in internal-external rotation (9.3 ± 3.5 degrees), and anteroposterior (3.3 ± 2.2 mm) and superior-inferior (2.5 ± 0.9 mm) translation, rather than lateral widening (1.7 ± 1.0 mm). The total rotational ROM of the talus was greatest in dorsiflexion-plantarflexion (34.7 ± 12.9 degrees) and internal-external rotation (15.0 ± 3.4 degrees). Single-leg squatting increased the lateral clear space (P = .045) and widened the medial tibiofibular joint, whereas single-leg heel-rises decreased the lateral clear space (P = .001) and widened the tibiotalar space. Gap spaces in the tibiofibular and medial clear spaces did not exceed 2.3 ± 0.9 mm and 2.7 ± 1.2 mm, respectively.

Conclusion:

These data support a potential shift in the clinical understanding of fibula displacements during dynamic activities and how implant device constructs might be developed to restore physiologic mechanics.

Clinical Relevance:

Syndesmosis stabilization and rehabilitation should consider restoration of normal physiologic rotation and translation of the fibula and ankle mortise rather than focusing solely on the restriction of lateral translation.

Syndesmosis Injury From Diagnosis to Repair: Physical Examination, Diagnosis, and Arthroscopic-assisted Reduction

Injuries to the tibio-fibular syndesmotic ligaments are different than ankle collateral ligament injuries and occur in isolation or combination with malleolar fractures. Syndesmotic ligament injury can lead to prolonged functional limitations and ultimately long-term ankle dysfunction if not identified and treated appropriately. The syndesmosis complex is a relatively simple construct of well-documented ligaments, but the dynamic kinematics and the effects of disruption have been a point of contention in diagnosis and treatment. Syndesmotic ligament injuries are sometimes referred to as "high ankle sprains" because the syndesmotic ligaments are more proximal than the collateral ligaments of the ankle joint. Rotational injuries to the ankle often result in malleolar fractures, which can be combined with ankle joint or syndesmotic ligament injuries. Most of the orthopaedic literature to this point has addressed syndesmosis ligament injuries in combination with fractures and not isolated syndesmotic ligament injuries. Thus, we propose a simplified general video guide to do the diagnostic examinations and arthroscopic-assisted reduction based on current evidence-based medicine.

Kinematic Analysis of Combined Suture-Button and Suture Anchor Augment Constructs for Ankle Syndesmosis Injuries

BACKGROUND

Syndesmosis injuries are common, with up to 25% of all ankle injuries being reported to involve an associated syndesmosis injury. These injuries are typically treated with cortical screw fixation or suture-button implants when indicated, but the addition of a suture anchor augment implant has yet to be evaluated. The purpose of this study was to evaluate the ability of a suture anchor augment to add sagittal plane translational and transverse plane rotational constraint to suture-button constructs with syndesmosis injuries. We hypothesized that the suture anchor augment oriented in parallel with the fibers of an injured anterior-inferior tibiofibular ligament (AITFL) in addition to a suture-button construct would achieve physiological motion and stability at the syndesmosis through increased rotational and translational constraint of the fibula.

METHODS

Eleven fresh-frozen cadaver ankles were stressed in external rotation using a custom-made ankle rig. Each ankle had simultaneous recording of ultrasound video, 6 degrees-of-freedom kinematics of the fibula and tibia, and torque as the ankle was stressed by an examiner. The ankles were tested in 6 different states: native uninjured; injured with interosseous ligament and AITFL sectioned; 1× suture button; 2× suture buttons, divergent; 1× suture anchor augment with 2× suture buttons, divergent; and 1× suture anchor augment with 1× suture buttons.

RESULTS

Only the suture anchor augment + 2× suture buttons and suture anchor augment + 1× suture-button constructs were found to be significantly different from the injured state (P = .0003, P = .002) with mean external rotation of the fibula.

CONCLUSION

Overall, the most important finding of this study was that the addition of a suture anchor augment to suture-button constructs provided a mechanism to increase external rotational constraint of the fibula.

CLINICAL RELEVANCE

This study provides a mechanistic understanding of how the combined suture-button and suture anchor augment construct provides an anatomically similar reconstruction of constraints found in the native ankle. However, none of the constructs examined in this study were able to fully restore physiologic motion.

Sagittal instability with inversion is important to evaluate after syndesmosis injury and repair: a cadaveric robotic study

PURPOSE

Disruption of the syndesmosis, the anterior-inferior tibiofibular ligament (AITFL), the posterior-inferior tibiofibular ligament (PITFL), and the interosseous membrane (IOM), leads to residual symptoms after an ankle injury. The objective of this study was to quantify tibiofibular joint motion with isolated AITFL- and complete syndesmotic injury and with syndesmotic screw vs. suture button repair compared to the intact ankle.

METHODS

Nine fresh-frozen human cadaveric specimens (mean age 60 yrs.; range 38-73 yrs.) were tested using a six degree-of-freedom robotic testing system and three-dimensional tibiofibular motion was quantified using an optical tracking system. A 5 Nm inversion moment was applied to the ankle at 0°, 15°, and 30° plantarflexion, and 10° dorsiflexion. Outcome measures included fibular medial-lateral translation, anterior-posterior translation, and external rotation in each ankle state: 1) intact ankle, 2) AITFL transected (isolated AITFL injury), 3) AITFL, PITFL, and IOM transected (complete injury), 4) tricortical screw fixation, and 5) suture button repair.

RESULTS

Both isolated AITFL and complete injury caused significant increases in fibular posterior translation at 15° and 30° plantarflexion compared to the intact ankle (p < 0.05). Tricortical screw fixation restored the intact ankle tibiofibular kinematics in all planes. Suture button repair resulted in 3.7 mm, 3.8 mm, and 2.9 mm more posterior translation of the fibula compared to the intact ankle at 30° and 15° plantarflexion and 0° flexion, respectively (p < 0.05).

CONCLUSION

Ankle instability is similar after both isolated AITFL and complete syndesmosis injury and persists after suture button fixation in the sagittal plane in response an inversion stress. Sagittal instability with ankle inversion should be considered when treating patients with isolated AITFL syndesmosis injuries and after suture button fixation.

LEVEL OF EVIDENCE

Controlled laboratory study, Level V.

Ankle stability in ankle fracture

Restoration of normal ankle kinematics should be the all-encompassing ethos in the approach to management of ankle fractures. To do this, the ligamentous stabilisers must also form part of its assessment and definitive management and be considered during index fracture fixation surgery. This article is a review of the anatomy, mechanics and clinical testing of instability in ankle fractures.

MRI of the distal tibiofibular joint

The distal tibiofibular joint is a fibrous joint that plays a crucial role in the stability of the ankle joint. It is stabilized by three main ligaments: the anterior inferior tibiofibular ligament, the posterior inferior tibiofibular ligament, and the interosseous tibiofibular ligament, which are well delineated on magnetic resonance imaging. Pathology of the distal tibiofibular joint is mostly related to trauma and the longer-term complications of trauma, such as soft tissue impingement, heterotopic ossification, and synostosis. This review article outlines the MRI anatomy and pathology of this joint.

Anatomy, Classification, and Management of Ankle Fractures Involving the Posterior Malleolar Fragment: A Literature Review

The posterior malleolar fragment is frequently involved in rotational ankle fractures, but diagnosis and definitive management remains controversial. Ankle fractures with a posterior malleolar component that are not identified and treated in a timely manner may contribute significantly to future comorbidities, including continued pain, instability, and the development of arthritis. This article highlights the anatomic features of posterior malleolar ankle fractures, the classification schemes used, and discusses the various nonsurgical and surgical methods currently used.