Three-dimensional analysis of ankle instability after tibiofibular syndesmosis injuries: a biomechanical experimental study

Radiological characteristics and injury mechanism of Logsplitter injury: a descriptive and retrospective study

BACKGROUND

Logsplitter Injury is a type of high-energy ankle fracture dislocation. The mechanism of injury has not been described in detail. A detailed understanding of the radiological features and pathological changes can further guide treatment.

METHODS

Between April 2009 and December 2018, a retrospective analysis was conducted on 62 patients with Logsplitter injury. The study analysed the characteristics of fibular injury, tibial injury, syndesmosis injury, medial injury and lateral ligament injury on preoperative X-ray and CT scans. The incidence of the different injury types was summarised. The correlation between Logsplitter injuries and the mechanisms causing them were analysed using the Lauge-Hansen classification of ankle fractures.

RESULTS

The study provides data on the types of fractures observed. Of the total fractures, 98.4% were open fractures. The fibula injuries were classified as no fracture (1.6%), transverse or short oblique fractures (61.3%), butterfly fragments (25.8%), and comminuted fractures (11.3%). The tibial injuries included compression of lateral articular surfaces (38.7%) and posterior compressions (6.5%). Medial injuries, including medial malleolar fractures, accounted for 87.1%, and deltoid ligament rupture accounted for 12.9%. The study found that injuries to the syndesmosis consisted of simple ligament ruptures (11.3%), Tillaux fractures (8.1%), Volkmann fractures (43.5%), and Tillaux and Volkmann fractures (37.1%). In 12.9% of cases, there was a complete rupture of the lateral collateral ligament. Based on the Lauge-Hansen classification, 87.1% of injuries were pronation-abduction injuries, while 8.1% were pronation and external rotation injuries, and 1.6% were supination external rotation injuries. Furthermore, 3.2% of cases could not be classified.

CONCLUSION

The pathoanatomic characteristics of Logsplitter injury are diverse, with some cases accompanied by collateral ligament injury. It is important to note that these evaluations are objective and based on current results. The most common injury mechanism is vertical violence combined with abduction, although in some cases, it may be a vertical combined external-rotation injury.

LEVEL OF EVIDENCE

(4) case series.

TRIAL REGISTRATION

This study has been approved by the ethical research committee of the Honghui Hospital of Xi'an Jiaotong University, under the code: 202,003,002.

Standardized analysis of syndesmosis stability in ankle trauma with an innovative syndesmosis-test-tool: a biomechanical study

When treating ankle fractures, the question of syndesmosis complex involvement often arises. So far, there is no standardized method to reliably detect syndesmosis injuries in the surgical treatment of ankle fractures. For this reason, an intraoperative syndesmosis-test-tool (STT) was developed and compared to the recommended and established hook-test (HT). Tests were performed on cadaveric lower legs (n = 20) and the diastasis was visualized by 3D camera. Tests were performed at 50, 80, and 100 N in native conditions and four instability levels. Instability was induced from anterior to posterior and the reverse on the opposite side. The impact on diastasis regarding the direction, the force level, the instability level, and the device used was checked using a general linear model for repeated measurement. The direction of the induced instability showed no influence on the diastasis during the stability tests. The diastasis measured with the STT increased from 0.5 to 3.0 mm depending on the instability, while the range was lower with the HT (1.1 to 2.3 mm). The results showed that the differentiation between the instability levels was statistically significantly better for the developed STT. The last level of maximum instability was significantly better differentiable with the STT compared to the HT. An average visualizable diastasis of more than 2 mm could only be achieved at maximum instability. In conclusion, the newly developed STT was superior to the commonly used HT to detect instability.

Association between the distal tibiofibular syndesmosis morphology classification and ankle osteoarthritis: a retrospective study

BACKGROUND

Syndesmosis injury is proposed to contribute to ankle stability and osteoarthritis (OA). However, whether distal tibiofibular syndesmosis structure is closely related to ankle OA is unclear. We hypothesized that different DTS morphology classifications would affect the biomechanics properties in ankle OA. The study aimed to determine the association between the distal tibiofibular syndesmosis (DTS) morphological classification and ankle OA.

METHODS

This is a retrospective study examining imaging data of 147 patients (87 males and 60 females) with ankle OA. Magnetic resonance imaging was used to access the DTS morphological classification, according to measuring various parameters. Joint space narrowing and osteophytes were measured using ankle weight-bearing radiography. The classification and parameters were analyzed to determine the relationship between the syndesmosis classification and the abnormality of ankle OA.

RESULTS

Five morphological classifications of the DTS, including Chevron (19.6%), Widow's peak (16.2%), Flat (22.3%), Trapezoid (32.0%), and Crescent (19.6%), were shown. There were statistical differences between DTS classification and tibial angle surface angle (TAS) (P = .009) and talar tilt angle (TTA) (P = .014). The TAS (degree) of the Crescent (86.47 ± 3.21) was less than Chevron (88.75 ± 2.72) (P = .006), Widow's peak (89.26 ± 3.15) (P = .001), Flat (88.83 ± 3.62) (P = .003) and Trapezoid (88.11 ± 2.62) (P = .041), respectively. The TTA (degree) of Crescent (86.83 ± 5.30) was less than Chevron (89.28 ± 2.46) and Widow's peak (89.82 ± 3.41). The men were greater than women for TAS (P = .008) and angle (P = .003), which are consistent with osteophyte (P = .019) and the modified Kellgren-Lawrence grades (P = .041) between gender.

CONCLUSIONS

DTS morphological classification might affect the biomechanics properties in TAS and TTA in ankle OA. In clinical practice, surgeons should pay attention to the effects of DTS on ankle OA.

LEVEL OF EVIDENCE

Level III, retrospective study.

Objective Assessment of Syndesmosis Stability Using the Hook Test

The hook test is a widely used intraoperative method for assessing syndesmosis stability. However, there are no recommendations regarding the force required to perform this test. Furthermore, the reliability of the test is unclear. Ten experienced surgeons performed hook tests on a cadaver bone model. The applied forces were recorded in a blinded manner. In addition, standardized hook tests with defined forces (50, 80, and 100 N) were performed on 10 pairs of cadaver lower legs and the syndesmosis was sequentially destabilized. Diastasis of the syndesmosis was recorded using an optical 3D camera system. A median force of 81 N (Range: 50 N-145 N) was applied. A proportion of 82% of the tests showed a force < 100 N. The data showed good intraraterreliability and poor interraterreliability. In the standardized investigation of the hook test on the cadaver bone model, both the force and the instability of the syndesmosis had a significant influence on the syndesmosis diastasis. Nevertheless, even with maximum instability of the syndesmosis, diastasis > 2 mm could only be measured in 12 of the 19 evaluable specimens. The widely used hook test shows a high variability when performed in practice. Even in a standardized manner, the hook test cannot detect a relevant syndesmosis injury.

Multidirectional Chronic Ankle Instability: What Is It?

Not all ankle sprains are the same and not all ankles behave the same way after an injury. Although we do not know the mechanisms behind an injury producing an unstable joint, we do know ankle sprains are highly underestimated. While some of the presumed lateral ligament lesions might eventually heal and produce minor symptoms, a substantial number of patients will not have the same outcome. The presence of associated injuries, such as additional medial chronic ankle instability, chronic syndesmotic instability, has been long discussed as a possible reason behind this. To explain multidirectional chronic ankle instability, this article aims to present the literature surrounding the condition and its importance nowadays.

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.

Tibiofibular Space Widening Assessment With a Ball-Tipped Probe in a Syndesmosis Injury Model

Assessment of syndesmotic instability is not precise with existing evaluation methods. This study was conducted to investigate the use of a ball-tipped probe under arthroscopy for quantitative assessment of tibiofibular space widening in a syndesmosis injury model. The test specimens were 5 uninjured ankles from Thiel-fixed cadavers of 2 male subjects and 3 female subjects of mean age of 82.4 years at death. The ball-tipped probe consisted of a metal probe having a ball at each end with diameters ranging from of 1.5 mm to 5.0 mm, in increments of 0.5 mm. The tibiofibular joint was observed arthroscopically as the largest-diameter ball probe as possible was inserted into its anterior third, middle, or posterior third portion with the ankle in natural plantarflexion or under external rotational stress. These measurements were performed for the uninjured ankle and then performed following Bassett's ligament sectioning, anterior inferior tibiofibular ligament sectioning, interosseous membrane distal 15 cm sectioning, or deltoid ligament, and posterior inferior tibiofibular ligament sectioning, with the sections added in this sequence and each followed by a similar assessment. The results of quantitative assessment of tibiofibular space widening with the ball-tipped probe in the syndesmosis injury model under arthroscopy were that the maximum possible diameter of ball probe that could be inserted was 1.5 to 2.0 mm in the uninjured state, 3.0 to 3.5 mm in the sectioned anterior inferior tibiofibular ligament model, and 5.0 mm in the severe-state model. The ball probe can serve as an effective tool for quantitative assessment of the intraoperative instability in cases of syndesmosis injury.

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.

Tibial Plafond Attachment of the Posterior-Inferior Tibiofibular Ligament: A Cadaveric Study

Background:

Some recent studies have reported the role of the posterior malleolus as an attachment of the posterior-inferior tibiofibular ligament (PITFL) and suggested that even a small fragment should be fixed. However, there are few anatomic studies of the tibial plafond attachment of the PITFL.

Methods:

Seven Thiel-embalmed ankles were obtained. The margin of the distal tibial joint surface and the attachments of the superficial fiber of the PITFL (sPITFL) and the deep fiber (dPITFL) were identified. In the frontal view, the percentages of the attachments of the sPITFL and dPITFL of the mediolateral dimension of the posterior tibial plafond were measured. In the lateral view, the line that started from the proximal margin of the attachment of the sPITFL and parallel to the tibial axis was drawn, and the distance between that line and the posterior edge of the joint surface was measured (AP distance of the sPITFL). Then, the percentage of the AP distance of the sPITFL of the joint surface in the anteroposterior dimension of the tibial plafond was measured.

Results:

In the frontal view, the mediolateral distance of the attachment of the sPITFL was 5.0 mm, and that of the dPITFL was 19.5 mm. The percentage of the attachment of the sPITFL on the tibial plafond was 20.6%, and that of the dPITFL was 78.2%. In the lateral view, the average AP distance of the sPITFL was 0.5 mm, and the percentage in the anteroposterior dimension of the tibial plafond was 1.7%.

Conclusion:

The PITFL was attached to less than 10% of the anteroposterior dimension of the tibial plafond in most ankles. Conversely, the PITFL attached widely in the mediolateral dimension.

Clinical Relevance:

This study suggests that the size of the posterior malleolar fragment in the mediolateral dimension could help estimate how much of the PITFL attaches to the fragment which may have implications for ankle stability.

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.

Hybrid Fixation Restores Tibiofibular Kinematics for Early Weightbearing After Syndesmotic Injury

Background:

Disruption of the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), and interosseous membrane (IOM) is a predictive measure of residual symptoms after an ankle injury. Controversy remains regarding the ideal fixation technique for early return to sport, which requires restoration of tibiofibular kinematics with early weightbearing.

Purpose:

To quantify tibiofibular kinematics after syndesmotic fixation with different tricortical screw and suture button constructs during simulated weightbearing.

Study Design:

Controlled laboratory study.

Methods:

A 6 degrees of freedom robotic testing system was used to test 9 fresh-frozen human cadaveric specimens (mean age, 65.1 ± 17.3 years). A 200-N compressive load was applied to the ankle, while a 5-N·m external rotation and a 5-N·m inversion moment were applied independently to the ankle at 0° of flexion, 15° and 30° of plantarflexion, and 10° of dorsiflexion. Fibular medial-lateral translation, anterior-posterior translation, and internal-external rotation relative to the tibia were tracked by use of an optical tracking system in the following states: (1) intact ankle; (2) AITFL, PITFL, and IOM transected ankle; (3) single-screw fixation; (4) double-screw fixation; (5) hybrid fixation; (6) single suture button fixation; and (7) divergent suture button fixation. Repeated-measures analysis of variance with Bonferroni correction was performed for statistical analysis.

Results:

In response to the external rotation moment and axial compression, single tricortical screw fixation resulted in significantly higher lateral translation of the fibula compared with that of the intact ankle at 10° of dorsiflexion (P < .05). Suture button fixation resulted in significantly higher posterior translation of the fibula at 0° of flexion and 10° of dorsiflexion, whereas divergent suture button fixation resulted in higher posterior translation at only 0° of flexion (P < .05). In response to the inversion moment and axial compression, single tricortical screw and hybrid fixation significantly decreased lateral translation in plantarflexion, whereas double tricortical screw fixation and hybrid fixation significantly decreased external rotation of the fibula compared with that of the intact ankle at 15° of plantarflexion (P < .05).

Conclusion:

Based on the data in this study, hybrid fixation with 1 suture button and 1 tricortical screw may most appropriately restore tibiofibular kinematics for early weightbearing. However, overconstraint of motion during inversion may occur, which has unknown clinical significance.

Clinical Relevance:

Surgeons may consider this data when deciding on the best algorithm for syndesmosis repair and postoperative rehabilitation.

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.

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

Influence of population variability in ligament material properties on the mechanical behavior of ankle: a computational investigation

Biomechanical behavior of ankle ligaments varies among individuals, with the underlying mechanism at multiple scales remaining unquantified. The present probabilistic study investigated how population variability in ligament material properties would influence the joint mechanics. A previously developed finite element ankle model with parametric ligament properties was used. Taking the typical external rotation as example loading scenario, joint stability of the investigated population was consistently shared by specific ligaments within a narrow tolerance range, i.e. 62.8 ± 8.2 Nm under 36.1 ± 5.7° foot rotation. In parallel, the inherent material variability significantly alters the consequent injury patterns. Three most vulnerable ligaments and the consequent rupture sequences were identified, with the structural weak spot and the following progressive stability loss dominated by the relative stiffness among ligaments. This study demonstrated the feasibility of biofidelic models in investigating individual difference at the material level, and emphasized the importance of probabilistic description of individual difference when identifying the injury mechanism of a broad spectrum.

Diagnosis and treatment of tibiofibular syndesmosis lesions

The tibiofibular syndesmosis is a fibrous joint essential for ankle stability, whence the classical comparison with a mortise. Syndesmosis lesions are quite frequent in ankle trauma. This is a key element in ankle stability and lesions may cause pain or instability and, in the longer term, osteoarthritis. The lesions are often overlooked due to diagnostic difficulties, but collision sport with strong contact is the main culprit. Diagnosis, whether in the acute or the chronic phase, is founded on an association of clinical and paraclinical signs. Cross-sectional imaging such as MRI is fundamental to confirming clinical suspicion. Absence of tibiofibular diastasis no longer rules out the diagnosis. Stress CT and the introduction of weight-bearing CT are promising future diagnostic tools. Exhaustive osteo-ligamentous ankle assessment is necessary, as syndesmosis lesions may be just one component in more complex rotational instability. Therapeutically, arthroscopy and new fixation techniques, such as suture buttons, are opening up new perspectives, especially for chronic lesions (>6months). The present anatomic, epidemiological, diagnostic and therapeutic review does not preclude further clinical studies of rotational ankle instability with its strong risk of osteoarthritis.

Clinical Evidence for Treatment of Distal Tibiofibular Syndesmosis Injury: A Systematic Review of Clinical Studies

No consensus had been reached about the optimal treatment for syndesmotic fixation. We performed a review of randomized controlled trials (RCTs) to assist in clarifying many of the controversies that were debated for years despite new technology and options. PubMed, Embase, and the Cochrane Library were searched through specific terms and limits. Only RCTs were selected for final inclusion. Study screening and data extraction were performed independently by 2 reviewers. Thirteen RCTs, including 828 cases, met the inclusion criteria and are summarized in this review. Pooled results demonstrated that dynamic fixation had better functional outcomes as well as lower rates of malreduction and complications compared with syndesmotic screw fixation. Both absorbable screw and tricortical screw fixation showed similar results to quadricortical metallic screws. Therefore, dynamic fixation is recommended for the treatment of syndesmosis injuries.

In Vivo CT Analysis of Physiological Fibular Motion at the Level of the Ankle Syndesmosis During Plantigrade Weightbearing

Background. It is clear that motion at the syndesmosis occurs due to ranging of the ankle joint, but the influence of weightbearing with the foot in the plantigrade position is unclear. In vivo computed tomographic (CT) evaluation of the syndesmosis has not been previously described. The purpose of this study is to quantify physiological fibular motion at the level of the ankle syndesmosis in both weightbearing and nonweightbearing conditions with the foot in the plantigrade position. Methods. CT images were obtained from 9 normal healthy subjects using a weightbearing CT imaging system. The subjects were positioned in a nonweightbearing and weightbearing state with their foot in the plantigrade position. Fibular translation and rotation were measured from the axial CT images using previously validated techniques. Results. Both the average lateral and anteroposterior translation of the fibula between weightbearing and nonweightbearing states was minimal (0.3 mm and 0.2 mm, respectively). The largest difference in translation observed in either direction was 0.9 mm. An average of 0.5° was found for rotational differences of the fibula between weightbearing and nonweightbearing. Neither of the translational and rotational parameters reached statistical significance. Conclusion. In vivo CT analysis of the distal tibiofibular joint with an intact syndesmosis did not reveal statistically significant physiological motion between weightbearing and nonweightbearing conditions with the foot in plantigrade position. Our findings suggest that weightbearing accounts for little motion at the syndesmosis and supports further investigation into the role of early protected weightbearing after syndesmosis fixation. Levels of Evidence: Level III: Case-control study.

Tibiofibular relationships of the normal syndesmosis differ by age on axial computed tomography-Anterior fibular translation with age

INTRODUCTION

This study aimed to assess the tibiofibular relationships of normal syndesmosis on axial computed tomography (CT) images and evaluate the measurement differences by gender, age, and body sides.

PATIENTS AND METHODS

The cases of 120 volunteers who underwent bilateral ankle CT were retrospectively reviewed. Volunteers were divided into three groups of 40 (20 men and 20 women) as follows: 20-40, 40-60, and 60-80 years old. Radiographic evaluation included the anterior tibiofibular clear space (ATFCS), posterior tibiofibular clear space (PTFCS), anterior tibiofibular interval (ATFI), length of incisura (LI), depth of incisura (DI), and fibular width (FW). Each measured parameter was compared based on gender, age, and body sides. To calibrate anatomical variations among the volunteers, ATFCS, PTFCA, and ATFI were expressed as ratios of FW.

RESULTS

PTFCS and ATFI were significantly larger in the men (p = 0.001, 0.001). LI and FW were significantly smaller in the women (p <0.001, <0.001). Calibrated ATFCS, PTFCS, and ATFI did not differ between the genders. ATFCS, PTFCS, and ATFI were significantly different among the age groups (p = 0.001, 0.001, and <0.001, respectively). These calibrated parameters showed significant differences according to age (p = 0.009, 0.006, and <0.001, respectively). There were no significant differences between sides. All CT measurements, except DI, showed high intra- and inter-observer reliabilities.

CONCLUSIONS

Axial CT images of the normal syndesmosis showed significant differences according to gender and age, but not between sides. In light of the anatomical variation, narrowing of the syndesmotic joint due to anterior translation of the fibula following aging may represent the most significant finding.

LEVEL OF EVIDENCE

Level IV, case series.

Suture-button fixation and anterior inferior tibiofibular ligament augmentation with suture-tape for syndesmosis injury: A biomechanical cadaveric study

BACKGROUND

Suture-button (SB) fixation has been widely performed for syndesmosis injuries, but it has been reported unstable in some biomechanical studies. The purpose of this study was to evaluate the stability of the syndesmosis using SB fixation with anterior inferior tibiofibular ligament augmentation using suture-tape (ST).

METHODS

Eight normal fresh-frozen cadaveric legs were used. After initial tests of intact and injured models, SB fixation, SB fixation with ST augmentation, ST augmentation alone, and screw fixation were performed sequentially for each specimen. Loading tests stimulating dorsiflexion, inversion, and external rotation of the ankle joint were performed for each model. The tibiofibular diastasis (TFD) and the fibular rotational angle related to the tibia (FRA) were measured using a magnetic tracking system.

FINDINGS

In the injured model, both TFD and FRA increased significantly compared with the intact model in all directions (P < .05). In the SB fixation model, TFD and FRA generally showed significant increases (P < .05, except for TFD in external rotation). In the SB fixation with ST augmentation model and ST augmentation alone, TFD and FRA were not significantly different compared with the intact model (P > .05). In the screw fixation model, FRA with inversion force at the ankle was significantly decreased compared with the intact model (P = .027).

INTERPRETATION

SB fixation alone did not provide stability of the syndesmosis, and screw fixation became too rigid compared with the intact model. Using ST augmentation achieved dynamic stability similar to the intact model for syndesmotic injuries.

Suture-Button Fixation and Mini-Open Anterior Inferior Tibiofibular Ligament Augmentation Using Suture Tape for Tibiofibular Syndesmosis Injuries

Tibiofibular fixation using suture-button implants is an optional method for the surgical treatment of syndesmosis injuries. Although good clinical outcomes have been reported, inadequate stability between the tibia and fibula has also been documented. Thus, suture-button fixation is not considered the reference standard. For surgical treatment of lateral ligament injuries of the ankle, good treatment outcomes have also been reported with ligament augmentation using nonabsorbable suture tape. Ligament augmentation tape with suture-button fixation could also be promising for improved treatment outcomes in syndesmosis injuries. We describe suture-button fixation together with mini-open anterior inferior tibiofibular ligament augmentation using suture tape for treatment of syndesmosis injuries.

Propagation of Syndesmotic Injuries During Forced External Rotation in Flexed Cadaveric Ankles

Background

Forced external rotation of the foot is a mechanism of ankle injuries. Clinical observations include combinations of ligament and osseous injuries, with unclear links between causation and injury patterns. By observing the propagation sequence of ankle injuries during controlled experiments, insight necessary to understand risk factors and potential mitigation measures may be gained.

Hypothesis

Ankle flexion will alter the propagation sequence of ankle injuries during forced external rotation of the foot.

Study Design

Controlled laboratory study.

Methods

Matched-pair lower limbs from 9 male cadaveric specimens (mean age, 47.0 ± 11.3 years; mean height, 178.1 ± 5.9 cm; mean weight, 94.4 ± 30.9 kg) were disarticulated at the knee. Specimens were mounted in a test device with the proximal tibia fixed, the fibula unconstrained, and foot translation permitted. After adjusting the initial ankle position (neutral, n = 9; dorsiflexed, n = 4; plantar flexed, n = 4) and applying a compressive preload to the tibia, external rotation was applied by rotating the tibia internally while either lubricated anteromedial and posterolateral plates or calcaneal fixation constrained foot rotation. The timing of osteoligamentous injuries was determined from acoustic sensors, strain gauges, force/moment readings, and 3-dimensional bony kinematics. Posttest necropsies were performed to document injury patterns.

Results

A syndesmotic injury was observed in 5 of 9 (56%) specimens tested in a neutral initial posture, in 100% of the dorsiflexed specimens, and in none of the plantar flexed specimens. Superficial deltoid injuries were observed in all test modes.

Conclusion

Plantar flexion decreased and dorsiflexion increased the incidence of syndesmotic injuries compared with neutral matched-pair ankles. Injury propagation was not identical in all ankles that sustained a syndesmotic injury, but a characteristic sequence initiated with injuries to the medial ligaments, particularly the superficial deltoid, followed by the propagation of injuries to either the syndesmotic or lateral ligaments (depending on ankle flexion), and finally to the interosseous membrane or the fibula.

Clinical Relevance

Superficial deltoid injuries may occur in any case of hyper-external rotation of the foot. A syndesmotic ankle injury is often concomitant with a superficial deltoid injury; however, based on the research detailed herein, a deep deltoid injury is then concomitant with a syndesmotic injury or offloads the syndesmosis altogether. A syndesmotic ankle injury more often occurs when external rotation is applied to a neutral or dorsiflexed ankle. Plantar flexion may shift the injury to other ankle ligaments, specifically lateral ligaments.

Syndesmotic stability: Is there a radiological normal?-A systematic review

BACKGROUND

Syndesmotic injury and instability poses a diagnostic challenge with unreliable clinical tests and inconsistent radiologic measures. Thus, used widely in clinical practice, there is huge debate pertaining to the reliability and validity of the radiologic parameters used for syndesmotic instability.

OBJECTIVE

Hence the purpose of the review was to explore the normal radiologic measures and morphometrics of distal tibiofibular syndesmosis and its relationships, which can aid in diagnosing syndesmotic instability.

METHOD

Computerised literature searches was performed for articles published in English using Pubmed, from inception through June 2016. All published articles reporting the normal anatomic and morphometric measures of distal tibiofibular syndesmosis with the use of any radiological modality individually or in combination, either in cadaveric or in live subjects were included. Studies done on or reporting of measures in healthy ankles or radiologically normal ankles were only included.

RESULTS

In this review wide anatomic and morphologic variability was observed amidst the landmarks used commonly for assessing syndesmotic instability and hence the normal measures. Further age and gender based variations were seen across the most commonly used radiologic measures for syndesmotic instability diagnosis, demanding the modification of existing radiologic criteria.

A novel method of using elastic bionic fixation device for distal tibiofibular syndesmosis injury

PURPOSE

To describe and evaluate the novel method of using elastic bionic fixation device in treating the distal tibiofibular syndesmosis (DTS) injury.

METHODS

From June 2013 to January 2014, 17 subjects with ankle fractures combined with DTS separation were treated by the elastic bionic fixation device. The syndesmotic parameters, healing, functional scores, and possible complications were recorded.

RESULTS

All patients had a mean follow-up of 23.35 ± 4.39 months (range, 15-28 months). Syndesmotic parameters returned to normal after surgery and remained normal throughout the follow-up period. X-ray examinations at 12 months follow-up showed no cable breakage of the elastic bionic fixation device or instrument invalidation compared to that of immediate post-operative X-ray films. Besides, no signs of articular degeneration and arthritis were observed. Furthermore, change in bone density near the fibular fixing button or tibial screw nut was also not detected. Primary wound healing was observed in 16 patients, while the remaining one showed redness and swelling of lateral ankle incision and got wound healing after seven to ten  days of antibiotic therapy and local radio frequency physiotherapy. All obtained excellent and good outcomes according to the AOFAS score at 12 months after surgery.

CONCLUSIONS

The use of elastic bionic fixation device appears to be a promising option in treating DTS injury because it can provide stable and reliable elastic fixation, good functional recovery, and relatively fewer complications.

Shapes of distal tibiofibular syndesmosis are associated with risk of recurrent lateral ankle sprains

Distal tibiofibular syndesmosis (DTS) has wide anatomic variability in depth of incisura fibularis and shape of tibial tubercles. We designed a 3-year prospective cohort study of 300 young physical training soldiers in an Army Physical Fitness School. Ankle computed tomography (CT) scans showed that 56% of the incisura fibularis were a "C" shape, 25% were a "1" shape, and 19% were a "Г" shape. Furthermore, we invited a randomly selected subcohort of 6 participants in each shape of DTS to undergo a three-dimensional (3D) laser scanning. The "1" shape group showed widest displacement range of the DTS in the y-axis, along with the range of motion (ROM) on the position more than 20° of the ankle dorsiflexion, inversion and eversion. During the 3-year study period, 23 participants experienced recurrent lateral ankle sprains. 7 cases of the incisura fibularis were "C" shape, 13 cases were "1" shape, and 3 cases were "Г" shape. The "1" shape showed highest risk among the three shapes in incident recurrent lateral ankle sprains. We propose that it is possible to classify shapes of DTS according to the shapes of incisura fibularis, and people with "1" shape may have more risk of recurrent lateral ankle sprains.

Is Incisura Fibularis a Reliable Landmark for Assessing Syndesmotic Stability? A Systematic Review of Morphometric Studies

Incisura fibularis (IF) is an important landmark in assessing syndesmotic stability radiologically postinjury. The purpose of this review was to explore the anatomy and morphometrics of this widely used anatomical landmark and to further the understanding of the same. A systematic review was conducted online using PubMed and Google Scholar, per PRISMA guidelines. Predefined eligibility criteria were applied, and the data thus compiled were analyzed. Wide variability in morphometrics and, thus, anatomy of IF were observed in the present review, which was influenced by gender. There was no side-to-side variability seen in this study. The study stresses the need to consider the anatomical and gender-based variability while assessing syndesmotic stability and further supports the recommendation of side-to-side comparison.

LEVELS OF EVIDENCE

Anatomical, Level V.

Correction of Tibial Torsion in Children With Cerebral Palsy by Isolated Distal Tibia Rotation Osteotomy: A Short-term, In Vivo Anatomic Study

BACKGROUND

Excessive internal or external tibial torsion is frequently present in children with cerebral palsy. Several surgical techniques have been described to correct excessive tibial torsion, including isolated distal tibial rotation osteotomy (TRO). The anatomic changes surrounding this technique are poorly understood. The goal of the study was to examine the anatomic relationship between the tibia and fibula following isolated distal TRO in children with cerebral palsy.

METHODS

Twenty patients with 29 limbs were prospectively entered for study. CT scans of the proximal and distal tibiofibular (TF) articulations were obtained preoperatively, at 6 weeks, and 1 year postoperatively. Measurements of tibia and fibula torsion were performed at each interval. Qualitative assessments of proximal and distal TF joint congruency were also performed.

RESULTS

The subjects with internal tibia torsion (ITT, 19 limbs) showed significant torsional changes for the tibia between preoperative, postoperative, and 1 year time points (mean torsion 13.21, 31.05, 34.84 degrees, respectively). Measurement of fibular torsion in the ITT treatment group also showed significant differences between time points (mean -36.77, -26.77, -18.54 degrees, respectively). Proximal and distal TF joints remained congruent at all time points in the study.Subjects with external tibia torsion (ETT, 10 limbs) showed significant differences between preoperative and postoperative tibial torsion, but not between postoperative and 1 year (mean torsion 54, 19.3, 23.3 degrees, respectively). Measurement of fibular torsion in the ETT treatment group did not change significantly between preoperative and postoperative, but did change significantly between postoperative and 1 year (mean torsion -9.8,-16.9, -30.7 degrees, respectively). Nine of 10 proximal TF joints were found to be subluxated at 6 weeks postoperatively. At 1 year, all 9 of these joints had reduced.

CONCLUSIONS

Correction of ITT by isolated distal tibial external rotation osteotomy resulted in acute external fibular torsion. The fibular torsion alignment remodeled over time to accommodate the corrected tibial torsional alignment and reduce the strain associated with the plastic deformity of the fibula. Correction of ETT by isolated distal internal TRO resulted in acute subluxation of the proximal TF articulation in almost all cases. Subsequent torsional remodeling of the fibula resulted in correction of the TF subluxation in all cases. Acute correction of TT by isolated distal TRO occurs by distinct mechanisms, based upon the direction of rotational correction.

LEVEL OF EVIDENCE

Level II-Diagnostic.

Three-Dimensional Analysis of Fibular Motion After Fixation of Syndesmotic Injuries With a Screw or Suture-Button Construct

BACKGROUND

Suture-button constructs are an alternative to screw fixation for syndesmotic injuries, and proponents advocate that suture-button constructs may allow physiological motion of the syndesmosis. Recent biomechanical data suggest that fibular instability with syndesmotic injuries is greatest in the sagittal plane, but the design of a suture-button construct, being a rope and 2 retention washers, is most effective along the axis of the rope (in the coronal plane). Some studies report that suture-button constructs are able to constrain fibular motion in the coronal plane, but the ability of a tightrope to constrain sagittal fibular motion is unknown. The purpose of this study was to assess fibular motion in response to an external rotation stress test in a syndesmotic injury model after fixation with a screw or suture-button constructs.

METHODS

Eleven fresh-frozen cadaver whole legs with intact tibia-fibula articulations were secured to a custom fixture. Fibular motion (coronal, sagittal, and rotational planes) in response to a 6.5-Nm external rotation moment applied to the foot was recorded with fluoroscopy and a high-resolution motion capture system. Measures were taken for the following syndesmotic conditions: intact, complete lateral injury, complete lateral and deltoid injury, repair with a tetracortical 4.0-mm screw, and repair with a suture button construct (Tightrope; Arthrex, Naples, FL) aimed from the lateral fibula to the anterior medial malleolus.

RESULTS

The suture-button construct allowed significantly more sagittal plane motion than the syndesmotic screw. Measurements acquired with mortise imaging did not detect differences between the intact, lateral injury, and 2 repair conditions. External rotation of the fibula was significantly increased in both injury conditions and was not restored to intact levels with the screw or the suture-button construct.

CONCLUSION

A single suture-button placed from the lateral fibula to the anterior medial malleolus was unable to replicate the motion observed in the intact specimen when subjected to an external rotation stress test and allowed significantly more posterior motion of the fibula than when fixed with a screw in simulated highly unstable injuries.

CLINICAL RELEVANCE

Fixation of a syndesmotic injury with a single suture-button construct did not restore physiological fibular motion, which may have implications for postoperative care and clinical outcomes.

The use of TightRope fixation for ankle syndesmosis injuries: our experience

PURPOSE

Ten percentage of all ankle fractures sustain an associated syndesmotic injury. TightRope is a relatively new technique for syndesmosis fixation, characterized by a non-absorbable FibreWire held tight between two cortical metal buttons. The purpose of this study was to evaluate the results obtained with the use of this device.

METHODS

From January 2011 to December 2015, 54 patients with ankle diastases were treated. Eighteen patients were excluded from the study. Fractures of the fibula or tibia requiring fixation were internally fixed using standard AO techniques. Preoperative and the most recent postoperative ankle radiographs were reassessed for measurements of the tibiofibular clear space (TFCS), medial clear space (MCS) and tibiofibular overlap (TFO). Clinical outcomes were assessed at the time of follow-up using the American Orthopaedic Foot and Ankle Society (AOFAS) score, a self-administered Foot and Ankle Disability Index (FADI) score and patients satisfaction.

RESULTS

The mean follow-up was 28, 64 months. Mean values for MCS, TFCS and TFO were 1.51-1.53 and 0.25 cm, respectively. The mean AOFAS score was 93.11, and the mean FADI score was 130.11. Twenty-nine (80.6 %) patients reported their outcome as excellent or very good.

CONCLUSIONS

TightRope technique can achieve flexible fixation of the syndesmosis and permit full range of motion of the tibiofibular joint. Patients can start rehabilitation exercise at an early stage after operation. The results of this study indicate that TightRope fixation is a valid option for syndesmotic injuries.

Generalized Ligamentous Laxity Is an Independent Predictor of Poor Outcomes After the Modified Broström Procedure for Chronic Lateral Ankle Instability

BACKGROUND

The modified Broström procedure for chronic lateral ankle instability (CLAI) has presented outstanding clinical results. However, after the procedure, some patients with generalized ligamentous laxity have experienced a recurrence of ankle instability.

PURPOSE

To understand the effect of generalized ligamentous laxity on prognosis and risk of recurrence in a cohort of patients with CLAI after the modified Broström procedure.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 199 ankles from 188 patients underwent the modified Broström procedure for CLAI with a mean follow-up of 60.1 months (range, 48-108 months). Generalized ligamentous laxity was assessed in all patients. The Karlsson-Peterson ankle score (Karlsson score), talar tilt angle, and anterior displacement of the talus were used to evaluate clinical and radiological outcomes. Risk factors associated with clinical outcomes were evaluated using bivariate analysis and logistic regression analysis. Survival outcomes were compared using Kaplan-Meier analysis.

RESULTS

Generalized ligamentous laxity was evident in 42 cases (21.1%). The average Karlsson score improved from 54.6 ± 7.1 preoperatively to 87.9 ± 7.2 at last follow-up (P < .001). The presence of generalized ligamentous laxity was significantly associated with poor clinical and radiological outcomes. The rates of clinical failure were 10.8% and 45.2% in the nonlaxity group and the laxity group, respectively (P < .001). According to bivariate analysis, generalized ligamentous laxity, syndesmosis widening, osteochondral lesion of the talus, high preoperative talar tilt angle (>15°), and high preoperative anterior displacement of the talus (>10 mm) were significantly associated with clinical failure. Multivariate logistic regression analysis revealed that generalized ligamentous laxity was the most important independent predictor of clinical failure after the modified Broström procedure. The cumulative success rates for the nonlaxity group were significantly superior to those for the laxity group in Kaplan-Meier curves (P < .001).

CONCLUSION

Generalized ligamentous laxity is an independent predictor of poor outcomes and a risk factor of recurrent instability following the modified Broström procedure for CLAI.

Real-time three-dimensional digital image correlation for biomedical applications

Digital image correlation (DIC) has been successfully applied for evaluating the mechanical behavior of biological tissues. A three-dimensional (3-D) DIC system has been developed and applied to examining the motion of bones in the human foot. To achieve accurate, real-time displacement measurements, an algorithm including matching between sequential images and image pairs has been developed. The system was used to monitor the movement of markers which were attached to a precisely motorized stage. The accuracy of the proposed technique for in-plane and out-of-plane measurements was found to be ?0.25% and 1.17%, respectively. Two biomedical applications were presented. In the experiment involving the foot arch, a human cadaver lower leg and foot specimen were subjected to vertical compressive loads up to 700 N at a rate of 10??N/s and the 3-D motions of bones in the foot were monitored in real time. In the experiment involving distal tibio fibular syndesmosis, a human cadaver lower leg and foot specimen were subjected to a monotonic rotational torque up to 5 Nm at a speed of 5 deg per min and the relative displacements of the tibia and fibula were monitored in real time. Results showed that the system could reach a frequency of up to 16 Hz with 6 points measured simultaneously. This technique sheds new lights on measuring 3-D motion of bones in biomechanical studies.

Rotational Dynamics of the Normal Distal Tibiofibular Joint With Weight-Bearing Computed Tomography

BACKGROUND

The normal distal tibiofibular joint is strongly stabilized by the syndesmosis, where previous cadaveric, biomechanical studies demonstrated only minimal widening and posterior translation of the fibula in external rotation of the ankle. However, little is known about normal rotational dynamics of the distal tibiofibular joint in upright weight-bearing conditions. The purpose of this study was to investigate the normal anatomy and rotational dynamics of the distal tibiofibular joint under physiological conditions on weight-bearing cone beam computed tomography (WBCT).

METHODS

In a cross-sectional study of 32 subjects, low-dose WBCT scans of uninjured bilateral ankles were performed. Normal intersubject and intrasubject variation in neutral position and changes in maximal internal and external rotation of the ankle were studied. Sagittal translation of the fibula, anterior and posterior widths of the distal tibiofibular syndesmosis, tibiofibular clear space (TFCS), and rotation of the fibula were measured.

RESULTS

In the neutrally loaded ankle, the fibula was located anteriorly in the tibial incisura in 88% of the subjects. When the ankle was rotated, mean anteroposterior motion was 1.5 mm and mean rotation of the fibula was 3 degrees. There was no significant change in TFCS between internal and external rotation. Large intersubject variation was detected, but intrasubject variation between ankles was less than 1 mm and 1 degree.

CONCLUSIONS

This study provides reference values to evaluate the dynamics of the normal distal tibiofibular joint. The internal control of the contralateral ankle seemed to be a better reference than the population-based normal values.

CLINICAL RELEVANCE

The current study provides the reference values to evaluate the rotational dynamics of a normal distal tibiofibular joint.

Effects of inferior tibiofibular syndesmosis injury and screw stabilization on motion of the ankle: a finite element study

PURPOSE

Traditional studies of syndesmosis injury and screw stabilization have been conducted in cadaveric models, which cannot yield sufficient and exact biomechanical data about the interior of the ankle. The purpose of this study was to evaluate the effects of inferior tibiofibular syndesmosis injury (ITSI) and screw stabilization on the motion of the ankle with finite element analysis.

METHODS

Three-dimensional models of the ankle complex were created with CT images of a volunteer's right ankle in three states: normal, post-ITSI, and stabilization with a screw 2.5 cm above (parallel to) the ankle. Simulated loads were applied under three conditions: neutral position with single foot standing, internal rotation, and external rotation of the ankle.

RESULTS

Compared with the normal state, ITSI increased the relative displacement between the lower extremes of the tibia and fibula in the anteroposterior and mediolateral directions and the angular motion of the tibia, fibula, and talus at internal and external rotations (ERs). However, when stabilized with syndesmotic screws, the range of motion (ROM) and all these parameters significantly decreased.

CONCLUSION

ITSI can lead to internal and ER instability of the ankle joint. Screw stabilization is effective in controlling the instability, but may reduce markedly the ROM of the ankle joint. Through this study, it can be proposed that the screws should be removed once the healing is gained in order to restore normal function of the ankle joint as soon as possible.

Three-dimensional motions of distal syndesmosis during walking

Introduction

The motion of the distal syndesmosis correlates highly with the instability, while an accurate kinematic description of the distal tibiofibular joint during normal gait has not previously been presented.

Material and methods

Sixteen healthy syndesmoses of sixteen living subjects (8 male and 8 female) were studied during stance phase of the normal gait. Data of CT scanning were collected first and used to create the 3D models of the distal tibia and fibula. The lateral X-ray images of the syndesmosis were captured by fluoroscopy when the subject was walking. Seven key-pose images were selected for subsequent 3D to 2D bone model registration and six degrees-of-freedom (DOF) motions of syndesmosis were then calculated. A validation experiment was also conducted to confirm the accuracy of the 3D/2D technique for the syndesmosis.

Results

During the stance phase, the distal tibiofibular joint exhibited with 2.98 ± 1.10° of dorsi/plantarflexion, 5.94 ± 1.52° of inversion/eversion, and 5.99 ± 2.00° of internal/external rotation; 2.63 ± 1.05 mm on medial/lateral, 3.86 ± 1.65 mm on anterior/posterior, and 4.12 ± 1.53 mm on superior/inferior translation. From heel strike to mid-stance, the syndesmosis demonstrated 1.69° of dorsiflexion, 3.61° of eversion, and 3.95° of external rotation. Likewise, from mid-stance to heel-off, the syndesmosis presented 1.04° of plantarflexion, 4.95° of inversion, and 5.13° of internal rotation.

Conclusion

During the stance phase of normal gait, internal/external rotation and vertical motion play dominant roles in terms of rotation and translation, respectively.

Deltoid Ligament and Tibiofibular Syndesmosis Injury in Chronic Lateral Ankle Instability: Magnetic Resonance Imaging Evaluation at 3T and Comparison with Arthroscopy

OBJECTIVE

To evaluate the prevalence of deltoid ligament and distal tibiofibular syndesmosis injury on 3T magnetic resonance imaging (MRI) in patients with chronic lateral ankle instability (CLAI).

MATERIALS AND METHODS

Fifty patients (mean age, 35 years) who had undergone preoperative 3T MRI and surgical treatment for CLAI were enrolled. The prevalence of deltoid ligament and syndesmosis injury were assessed. The complexity of lateral collateral ligament complex (LCLC) injury was correlated with prevalence of deltoid or syndesmosis injuries. The diagnostic accuracy of ankle ligament imaging at 3T MRI was analyzed using arthroscopy as a reference standard.

RESULTS

On MRI, deltoid ligament injury was identified in 18 (36%) patients as follows: superficial ligament alone, 9 (50%); deep ligament alone 2 (11%); and both ligaments 7 (39%). Syndesmosis abnormality was found in 21 (42%) patients as follows: anterior inferior tibiofibular ligament (AITFL) alone, 19 (90%); and AITFL and interosseous ligament, 2 (10%). There was no correlation between LCLC injury complexity and the prevalence of an accompanying deltoid or syndesmosis injury on both MRI and arthroscopic findings. MRI sensitivity and specificity for detection of deltoid ligament injury were 84% and 93.5%, and those for detection of syndesmosis injury were 91% and 100%, respectively.

CONCLUSION

Deltoid ligament or syndesmosis injuries were common in patients undergoing surgery for CLAI, regardless of the LCLC injury complexity. 3T MRI is helpful for the detection of all types of ankle ligament injury. Therefore, careful interpretation of pre-operative MRI is essential.

Histological analysis of the structural composition of ankle ligaments

BACKGROUND

Various ankle ligaments have different structural composition. The aim of this study was to analyze the morphological structure of ankle ligaments to further understand their function in ankle stability.

METHODS

One hundred forty ligaments from 10 fresh-frozen cadaver ankle joints were dissected: the calcaneofibular, anterior, and posterior talofibular ligaments; the inferior extensor retinaculum, the talocalcaneal oblique ligament, the canalis tarsi ligament; the deltoid ligament; and the anterior tibiofibular ligament. Hematoxylin-eosin and Elastica van Gieson stains were used for determination of tissue morphology.

RESULTS

Three different morphological compositions were identified: dense, mixed, and interlaced compositions. Densely packed ligaments, characterized by parallel bundles of collagen, were primarily seen in the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments. Ligaments with mixed tight and loose parallel bundles of collagenous connective tissue were mainly found in the inferior extensor retinaculum and talocalcaneal oblique ligament. Densely packed and fiber-rich interlacing collagen was primarily seen in the areas of ligament insertion into bone of the deltoid ligament.

CONCLUSIONS

Ligaments of the lateral region, the canalis tarsi, and the anterior tibiofibular ligaments have tightly packed, parallel collagen bundles and thus can resist high tensile forces. The mixed tight and loose, parallel oriented collagenous connective tissue of the inferior extensor retinaculum and the talocalcaneal oblique ligament support the dynamic positioning of the foot on the ground. The interlacing collagen bundles seen at the insertion of the deltoid ligament suggest that these insertion areas are susceptible to tension in a multitude of directions.

CLINICAL RELEVANCE

The morphology and mechanical properties of ankle ligaments may provide an understanding of their response to the loads to which they are subjected.

An update on the evaluation and treatment of syndesmotic injuries

INTRODUCTION

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

METHODS

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

RESULTS/COMPLICATIONS

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

CONCLUSION

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

Fibular malalignment in individuals with chronic ankle instability

STUDY DESIGN

Case series.

OBJECTIVES

To determine whether abnormal fibular alignment is present in individuals with chronic ankle instability (CAI) using 3-D analysis of computed tomography (CT)-based bone models.

BACKGROUND

A positional difference of the distal fibula in individuals with unilateral CAI, when compared to the contralateral side, has been suggested. However, previous studies report no consistent pattern of fibular malalignment in the anteroposterior direction and, to our knowledge, no study has investigated mediolateral malalignment.

METHODS

Seventeen males with unilateral CAI (mean ± SD age, 21.0 ± 2.4 years) and no history of injury in the contralateral side were enrolled. Geometric bone models of the tibia and fibula were created from non-weight-bearing CT images, and anatomical coordinate systems were embedded in the tibia model. Bilateral tibiae were superimposed using a best-fit algorithm that moved the tibia to the position of best congruity, and the amount of side-to-side difference in position of the fibulae was measured. The anteroposterior and mediolateral positional difference of the fibula of the ankle with CAI relative to the contralateral ankle, for the distal 10 cm of the fibula length, was determined using a color-coded map.

RESULTS

The fibula of the ankle with CAI was significantly more lateral (0.57-0.68 mm) than that of the contralateral healthy ankle at all reference points from distal 10 cm to the lateral malleolus. There was no significant difference in anteroposterior position between the healthy ankles and those with CAI.

CONCLUSION

This study detected malalignment of the distal fibula in ankles with CAI in a non-weight-bearing position. The fibula of the ankles with CAI had a significantly more lateral position than that of the healthy ankles, which may contribute to recurrent lateral ankle sprain or giving-way episodes.

Radiological morphology of peritalar instability in varus and valgus tilted ankles

BACKGROUND

Varus and valgus talar tilt in weight-bearing ankles can be explained by loss of peritalar stability allowing the talus to shift and rotate on the calcaneal and navicular surfaces. Little is known about the underlying destabilization process or the resulting talar malpositions. The purpose of this study was to determine talar position in 3 radiographic planes of varus and valgus tilted ankles.

METHODS

Standard weight-bearing radiographs of 126 varus ankles (118 patients [mean age 62 ± 12 years]) and 81 valgus ankles (75 patients [mean age 65 ± 10 years]) were retrospectively evaluated. The tibiotalar surface angle, sagittal talocalcaneal inclination angle, and horizontal talometatarsal I angle were used to determine the frontal, sagittal, and horizontal position of the talus. A control group was used for comparison.

RESULTS

Isolated talar varus malposition was found in 33.3% of the ankles (42/126), and malposition in 1 or both additional planes was found in 49.2% (62/126) and 17.5% (22/126), respectively. In valgus ankles, the percentages were 52% (42/81), 43% (35/81), and 5% (4/81), respectively. Seven out of 9 possible varus and 5 out of 9 possible valgus talar malposition configurations were found. The 4 predominant varus malposition configurations (89.7%, or 113/126) were dorsiflexion or neutral (sagittal plane) combined with neutral/external rotation and neutral/internal rotation (horizontal plane), respectively. The 3 predominant valgus malposition configurations (95%, or 77/81) were neutral or plantar flexion (sagittal plane) combined with neutral/external rotation and neutral (horizontal plane), respectively.

CONCLUSION

In varus and valgus tilted ankles, talar frontal plane alignment does not predict talar sagittal and horizontal position, indicating that peritalar instability leads to various talar malpositions. Prior to operative treatment of varus and valgus tilted ankles, thorough 3-dimensional analysis of talar position may minimize failure in properly balancing the talus within the ankle mortise.

LEVEL OF EVIDENCE

Level III, retrospective comparative series.

Posterior translation of the fibula may indicate malreduction: CT study of normal variation in uninjured ankles

OBJECTIVES

The aim of our study was to assess the intersubject and intrasubject variations of distal tibiofibular syndesmosis on computed tomography (CT) scans and to define standardized measures to verify syndesmosis reduction.

DESIGN

A retrospective study of 107 CT scans of ankles with normal tibiofibular syndesmosis.

SETTING

Main trauma center, university teaching hospital.

PATIENTS

The CT scans of 64 patients were reviewed by 2 musculoskeletal radiologists.

MAIN OUTCOME MEASUREMENTS

Bilateral variation was estimated. The intra- and interobserver reliabilities were calculated using standardized measurement points. CT measurements included the length of the tibial incisura (LI), A width and P width of the incisura (PW), depth of the incisura, narrowest part of the incisura, and sagittal translation of the fibula.

RESULTS

In 97% of normal cases, the fibula is situated either centrally or anteriorly in the tibial incisura. There were significant differences in PW and LI between genders, and the difference between the PW and A width was significantly larger in males (2.7 mm, SD 2.1) than in females (1.9 mm, SD 1.6, P = 0.023, t test). Significant asymmetry was not detected between ankles in single subjects. All CT measurements demonstrated good inter- and intraobserver reliabilities.

CONCLUSIONS

If P translation of the fibula is present, malreduction should be considered. Sagittal translation measurements are not affected by the size of the joint or the gender of the patient, in contrast to traditionally used cross-sectional measurement methods.

Analysis of the stress and displacement distribution of inferior tibiofibular syndesmosis injuries repaired with screw fixation: a finite element study

BACKGROUND

Studies of syndesmosis injuries have concentrated on cadaver models. However, they are unable to obtain exact data regarding the stress and displacement distribution of various tissues, and it is difficult to compare models. We investigated the biomechanical effects of inferior tibiofibular syndesmosis injuries (ITSIs) and screw fixation on the ankle using the finite element (FE) method.

METHODOLOGY/PRINCIPAL FINDINGS

A three-dimensional model of a healthy ankle complex was developed using computed tomography (CT) images. We established models of an ITSI and of screw fixation at the plane 2.5 cm above and parallel to the tibiotalar joint surface of the injured syndesmosis. Simulated loads were applied under three conditions: neutral position with single-foot standing and internal and external rotation of the ankle. ITSI reduced contact forces between the talus and fibula, helped periarticular ankle ligaments withstand more load-resisting movement, and increased the magnitude of displacement at the lower extreme of the tibia and fibula. ITSI fixation with a syndesmotic screw reduced contact forces in all joints, decreased the magnitude of displacement at the lower extreme of the tibia and fibula, and increased crural interosseous membrane stress.

CONCLUSIONS/SIGNIFICANCE

Severe syndesmosis injuries cause stress and displacement distribution of the ankle to change multidirectional ankle instability and should be treated by internal fixation. Though the transverse syndesmotic screw effectively stabilizes syndesmotic diastasis, it also changes stress distribution around the ankle and decreases the joint's range of motion (ROM). Therefore, fixation should not be performed for a long period of time because it is not physiologically suitable for the ankle joint.

Isolated posterior high ankle sprain: a report of three cases

High ankle sprains are difficult to diagnose and account for 10% of all ankle sprains. A high index of suspicion is essential for diagnosis. High ankle sprains are managed symptomatically, with prolonged rehabilitation. The posterior inferior tibiofibular ligament is the strongest syndesmotic ligament; isolated injury of it is rare. We present 3 cases of isolated posterior high ankle sprain and discuss the relevant anatomy, mechanism of injury, and management.

Consensus in chronic ankle instability: aetiology, assessment, surgical indications and place for arthroscopy

Ankle sprains are the most common injuries sustained during sports activities. Most ankle sprains recover fully with non-operative treatment but 20-30% develop chronic ankle instability. Predicting which patients who sustain an ankle sprain will develop instability is difficult. This paper summarises a consensus on identifying which patients may require surgery, the optimal surgical intervention along with treatment of concomitant pathology given the evidence available today. It also discusses the role of arthroscopic treatment and the anatomical basis for individual procedures.

Flexible fixation of syndesmotic diastasis using the assembled bolt-tightrope system

Background

Syndesmotic diastasis is a common injury. Syndesmotic bolt and tightrope are two of the commonly used methods for the fixation of syndesmotic diastasis. Syndesmotic bolt can be used to reduce and maintain the syndesmosis. However, it cannot permit the normal range of motion of distal tibiofibular joint, especially the rotation of the fibula. Tightrope technique can be used to provide flexible fixation of the syndesmosis. However, it lacks the ability of reducing the syndesmotic diastasis. To combine the advantages of both syndemostic bolt and tightrope techniques and simultaneously avoid the potential disadvantages of both techniques, we designed the assembled bolt-tightrope system (ABTS). The purpose of this study was to evaluate the primary effectiveness of ABTS in treating syndesmotic diastasis.

Methods

From October 2010 to June 2011, patients with syndesmotic diastasis met the inclusion criteria were enrolled into this study and treated with ABTS. Patients were followed up at 2, 6 weeks and 6, 12 months after operation. The functional outcomes were assessed according to the American Orthopedic Foot and Ankle Society (AOFAS) scores at 12 months follow-up. Patients’ satisfaction was evaluated based upon short form-12 (SF-12) health survey questionnaire. The anteroposterior radiographs of the injured ankles were taken, and the medial clear space (MCS), tibiofibular overlap (TFOL), and tibiofibular clear space (TFCS) were measured. All hardwares were routinely removed at 12-month postoperatively. Follow-ups continued. The functional and radiographic assessments were done again at the latest follow-up.

Results

Twelve patients were enrolled into this study, including 8 males and 4 females with a mean age of 39.5 years (range, 26 to 56 years). All patients also sustained ankle fractures. At 12 months follow-up, the mean AOFAS score was 95.4 (range, 85 to 100), and all patients were satisfied with the functional recoveries. The radiographic MCS, TFOL, and TFCS were within the normal range in all patients. After hardware removal, follow-up continued. At the latest follow-up (28 months on average, (range, 25 to 33 months) from internal fixation), the mean AOFAS score was 96.3 (range, 85 to 100), without significant difference with those assessed at 12 months after fixation operations. No syndesmotic diastasis reoccurred based upon the latest radiographic assessment.

Conclusions

ABTS can be used to reduce the syndesmotic diastasis and provide flexible fixation in a minimally invasive fashion. It seems to be an effective alternative technique to treat syndesmotic diastasis.

Operative exploration and reduction of syndesmosis in Weber type C ankle injury

OBJECTIVE:

To investigate the surgical methods in treating Weber type C ankle injury and estimate the necessity of syndesmosis operative exploration.

METHODS:

Forty three patients of Weber type C ankle injury were treated with open reduction and internal fixation from October 2004 to December 2009. Twenty nine patients were treated with routine procedure by open reduction and internal fixation, syndesmosis exploration and repair were performed in addition in the others. Thirty four patients were followed during an average time of 31.2 months (range 18 to 50 months), amomg them 22 patients were treated with routine procedures and 12 were treated with additional syndesmosis surgical exploration.

RESULTS:

All the fractures were reunited in an average time of 13.1 weeks (range 10 to 18 weeks) and full weight bearing began. The mean ankle and hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS) score was 79.86(range 65 to 98) in the routine procedures group and 86.67 (range 78 to 100) in the syndesmosis exploration group and Olerud-Molander score was 77.27 (range 55 to 100) and 86.67 (range 75 to 100) respectively. Statistically significant difference was found between the two groups (P<0.05).

CONCLUSION:

Syndesmosis surgical exploration is an essential treatment in some Weber type C ankle injuries, which make debridement and direct reduction of the syndesmosis possible, providing thus a more stabilized ankle joint. Level of Evidence III, Retrospective Comparative Study