scholarly journals Displacement of Sequential Syndesmotic Ankle Injuries Assessed by a 3D Weightbearing CT

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0012
Author(s):  
Arne Burssens ◽  
Nicola Krähenbühl ◽  
Hannes Vermue ◽  
Nathan Davidson ◽  
Maxwell Weinberg ◽  
...  
Keyword(s):  
External Rotation ◽  
Imaging Techniques ◽  
Pearson Correlation ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
3D Analysis ◽  
Anatomical Landmarks ◽  
Posterior Translation ◽  
2D Imaging ◽  
Weightbearing Ct

Category: Ankle Introduction/Purpose: Syndesmotic ankle injuries are challenging to diagnose, since current 2D imaging techniques try to quantify a 3D displacement. Therefore, our aim was two-fold: to determine displacement of sequential syndesmotic ankle injuries under various amounts of load using a 3D weightbearing CT (WBCT) and to assess the relation with current 2D imaging. Methods: Seven paired male cadaver specimens were included (tibia plateau to toe-tip) and mounted into a custom-built frame. WBCT scans were obtained after different patterns of load (0 kg or 85 kg) were combined with torque (0 Nm or 10 Nm external rotation). These conditions were repeated after each ligament condition: intact ligaments, sequential sectioning of the anterior inferior tibiofibular ligament (AITFL), deltoid ligament (DL), and interosseous membrane (IOM). CT images were segmented to obtain 3D models. These allowed quantification of displacement based on the position of computed anatomical landmarks in reference to the intact position of the fibula. A correlation analysis was performed between the 2D and 3D measurements. Results: The effect of torque caused significant displacements in all directions (P<0.05), except for shortening of the fibula (P>0.05). Weight caused a significant lateral (mean=-1.4 mm, SD=1.5) and posterior translation (mean=-0.6 mm, SD=1.8). The highest displacement consisted of external rotation (mean=-9.4°, SD=6.5) and posterior translation (mean=6.1 mm, SD=2.3) after IOL sectioning combined with torque (Fig. 1). Pearson correlation coefficients were moderate (range 0.31-0.51, P<0.05). Conclusion: Torque demonstrated superiority over weight in detecting syndesmotic ankle instability after 3D analysis. The clinical relevance of these findings can improve diagnosis by incorporating rotatory platforms during imaging and treatment strategies by providing appropriate stabilization against rotation.

Templating of Syndesmotic Ankle Lesions by Use of 3D Analysis in Weightbearing and Nonweightbearing CT

2018 ◽  
Vol 39 (12) ◽  
pp. 1487-1496 ◽  
Author(s):  
Arne Burssens ◽  
Hannes Vermue ◽  
Alexej Barg ◽  
Nicola Krähenbühl ◽  
Jan Victor ◽  
...  
Keyword(s):  
External Rotation ◽  
Imaging Techniques ◽  
Ankle Injuries ◽  
Control Group ◽  
3D Analysis ◽  
Anatomical Landmarks ◽  
Distal Fibula ◽  
Fracture Group ◽  
Significant Difference ◽  
The Mean

Background: Diagnosis and operative treatment of syndesmotic ankle injuries remain challenging due to the limitations of 2-dimensional imaging. The aim of this study was therefore to develop a reproducible method to quantify the displacement of a syndesmotic lesion based on 3-dimensional computed imaging techniques. Methods: Eighteen patients with a unilateral syndesmotic lesion were included. Bilateral imaging was performed with weightbearing cone-beam computed tomography (CT) in case of a high ankle sprain (n = 12) and by nonweightbearing CT in case of a fracture-associated syndesmotic lesion (n = 6). The healthy ankle was used as a template after being mirrored and superimposed on the contralateral ankle. The following anatomical landmarks of the distal fibula were computed: the most lateral aspect of the lateral malleolus and the anterior and posterior tubercle. The change in position of these landmarks relative to the stationary, healthy fibula was used to quantify the syndesmotic lesion. A control group of 7 studies was used. Results: The main clinical relevant findings demonstrated a statistically significant difference between the mean mediolateral diastasis of both the sprained (mean [SD], 1.6 [1.0] mm) and the fracture group (mean [SD], 1.7 [0.6] mm) compared to the control group ( P < .001). The mean external rotation was statistically different when comparing the sprained (mean [SD], 4.7 [2.7] degrees) and the fracture group (mean [SD], 7.0 [7.1] degrees) to the control group ( P < .05). Conclusion: This study evaluated an effective method for quantifying a unilateral syndesmotic lesion of the ankle. Applications in clinical practice could improve diagnostic accuracy and potentially aid in preoperative planning by determining which correction needs to be achieved to have the fibula correctly reduced in the syndesmosis. Level of Evidence: Level III, retrospective comparative study.

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

2020 ◽  
Vol 41 (10) ◽  
pp. 1256-1268 ◽  
Author(s):  
Arne Burssens ◽  
Nicola Krähenbühl ◽  
Maxwell M. Weinberg ◽  
Amy L. Lenz ◽  
Charles L. Saltzman ◽  
...  
Keyword(s):  
Axial Load ◽  
External Rotation ◽  
Pearson Correlation ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
Anatomical Landmarks ◽  
3 Dimensional ◽  
External Torque ◽  
Lateral Translation ◽  
Dimensional Measurements

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.

Finite Element Analysis of Fixed Medial Malleolar Fractures

2013 ◽  
Author(s):  
Ruchi D. Chande ◽  
John R. Owen ◽  
Robert S. Adelaar ◽  
Jennifer S. Wayne
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Performance ◽  
External Rotation ◽  
Weight Bearing ◽  
High Stress ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
Medial Malleolus ◽  
Element Analysis

The ankle joint, comprised of the distal ends of the tibia and fibula as well as talus, is key in permitting movement of the foot and restricting excessive motion during weight-bearing activities. Medial ankle injury occurs as a result of pronation-abduction or pronation-external rotation loading scenarios in which avulsion of the medial malleolus or rupture of the deltoid ligament can result if the force is sufficient [1]. If left untreated, the joint may experience more severe conditions like osteoarthritis [2]. To avoid such consequences, medial ankle injuries — specifically bony injuries — are treated with open reduction and internal fixation via the use of plates, screws, wires, or some combination thereof [1, 3–4]. In this investigation, the mechanical performance of two such devices was compared by creating a 3-dimensional model of an earlier cadaveric study [5], validating the model against the cadaveric data via finite element analysis (FEA), and comparing regions of high stress to regions of experimental failure.

scholarly journals Characterization of Ankle Kinematics and Constraint Following Ligament Rupture in a Cadaveric Model

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Bardiya Akhbari ◽  
Matthew H. Dickinson ◽  
Ednah G. Louie ◽  
Sami Shalhoub ◽  
Lorin P. Maletsky
Keyword(s):  
Internal Rotation ◽  
External Rotation ◽  
Training Data ◽  
Ankle Injuries ◽  
Ankle Sprains ◽  
Ligament Rupture ◽  
Ankle Kinematics ◽  
Posterior Translation ◽  
Ankle Mobility ◽  
And Inversion

Ankle sprains are a common injury that may need reconstruction and extensive physical therapy. The purpose of this study was to provide a description of the biomechanics of the ankle joint complex (AJC) after anterior talofibular (ATFL) and calcaneofibular (CFL) ligament rupture to better understand severe ankle injuries. The envelope of motion of ten cadaveric ankles was examined by manual manipulations that served as training data for a radial basis function used to interpolate ankle mobility at flexion angles under load and torque combinations. Moreover, ankle kinematics were examined, while tendons were loaded to identify how their performance is altered by ligament rupture. The increased force required to plantarflex the ankle following ligament rupture was measured by calculating the load through the Achilles. Following ATFL injury, the largest changes were internal rotation (5 deg) in deep plantarflexion and anterior translation (1.5 mm) in early plantarflexion. The combined ATFL and CFL rupture changed the internal/external rotation (3 deg), anterior/posterior translation (1 mm), and inversion (5 deg) throughout flexion relative to the isolated ATFL rupture. Moreover, the Achilles' load increased by 24% after the rupture of ligaments indicating a reduction in its efficiency. This study suggests that if patients demonstrate primarily an increased laxity in internal rotation, the damage has solely occurred to the ATFL; however, if the constraint is reduced across multiple motions, there is likely damage to both ligaments. Higher loads in the Achilles suggest that it is overloaded after the injury; hence, targeting the calf muscles in rehabilitation exercises may reduce patients' pain.

scholarly journals Correlation of Shoulder and Elbow Kinetics With Ball Velocity in Collegiate Baseball Pitchers

2015 ◽  
Vol 50 (6) ◽  
pp. 629-633 ◽  
Author(s):  
Eric G. Post ◽  
Kevin G. Laudner ◽  
Todd A. McLoda ◽  
Regan Wong ◽  
Keith Meister
Keyword(s):  
External Rotation ◽  
Pearson Correlation ◽  
Anatomical Landmarks ◽  
Positive Correlation ◽  
Weak Positive Correlation ◽  
Ball Velocity ◽  
Collegiate Baseball ◽  
Shoulder External Rotation ◽  
Baseball Pitchers ◽  
Distraction Force

Context Throwing a baseball is a dynamic and violent act that places large magnitudes of stress on the shoulder and elbow. Specific injuries at the elbow and glenohumeral joints have been linked to several kinetic variables throughout the throwing motion. However, very little research has directly examined the relationship between these kinetic variables and ball velocity. Objective To examine the correlation of peak ball velocity with elbow-valgus torque, shoulder external-rotation torque, and shoulder-distraction force in a group of collegiate baseball pitchers. Design Cross-sectional study. Setting Motion-analysis laboratory. Patients or Other Participants Sixty-seven asymptomatic National Collegiate Athletic Association Division I baseball pitchers (age = 19.5 ± 1.2 years, height = 186.2 ± 5.7 cm, mass = 86.7 ± 7.0 kg; 48 right handed, 19 left handed). Main Outcome Measure(s) We measured peak ball velocity using a radar gun and shoulder and elbow kinetics of the throwing arm using 8 electronically synchronized, high-speed digital cameras. We placed 26 reflective markers on anatomical landmarks of each participant to track 3-dimensional coordinate data. The average data from the 3 highest-velocity fastballs thrown for strikes were used for data analysis. We calculated a Pearson correlation coefficient to determine the associations between ball velocity and peak elbow-valgus torque, shoulder-distraction force, and shoulder external-rotation torque (P &lt; .05). Results A weak positive correlation was found between ball velocity and shoulder-distraction force (r = 0.257; 95% confidence interval [CI] = 0.02, 0.47; r2 = 0.066; P = .018). However, no significant correlations were noted between ball velocity and elbow-valgus torque (r = 0.199; 95% CI = −0.043, 0.419; r2 = 0.040; P = .053) or shoulder external-rotation torque (r = 0.097; 95% CI = −0.147, 0.329; r2 = 0.009; P = .217). Conclusions Although a weak positive correlation was present between ball velocity and shoulder-distraction force, no significant association was seen between ball velocity and elbow-valgus torque or shoulder external-rotation torque. Therefore, other factors, such as improper pitching mechanics, may contribute more to increases in joint kinetics than peak ball velocity.

scholarly journals Restoration of Tibiofibular Kinematics with a Tricortical Screw or Suture Button Fixation After Syndesmotic Ankle Injuries

2017 ◽  
Vol 2 (3) ◽  
pp. 2473011417S0000
Author(s):  
Conor Murphy ◽  
Thomas Pfeiffer ◽  
Jason Zlotnicki ◽  
Volker Musahl ◽  
Richard Debski ◽  
...  
Keyword(s):  
Screw Fixation ◽  
External Rotation ◽  
Tracking System ◽  
Optical Tracking ◽  
Ankle Injuries ◽  
Suture Button ◽  
Tibiofibular Ligament ◽  
Cortical Screw ◽  
Significant Difference ◽  
Posterior Translation

Category: Ankle, Sports, Trauma Introduction/Purpose: Anterior inferior tibiofibular ligament (AITFL), Posterior inferior tibiofibular ligament (PITFL) and Interosseous membrane (IOM) disruption is a predictive measure of residual symptoms after ankle injury. In unstable injuries, the syndesmosis is treated operatively with cortical screw fixation or a suture button apparatus. Biomechanical analyses of suture button versus cortical screw fixation methods show contradicting results regarding suture button integrity and maintenance of fixation. The objective of this study is to quantify tibiofibular joint motion in syndesmotic screw and suture button fixation models compared to the intact ankle. Methods: Five fresh-frozen human cadaveric specimens (mean age 58 yrs.; range 38-73 yrs.) were tested using a 6-degree-of- freedom robotic testing system. The tibia and calcaneus were rigidly fixed to the robotic manipulator and the subtalar joint was fused. The full fibular length was maintained and fibular motion was unconstrained. Fibular motion with respect to the tibia was tracked by a 3D optical tracking system. A 5 Nm external rotation moment and 5 Nm inversion moment were applied to the ankle at 0°, 15°, and 30° plantarflexion and 10° dorsiflexion. Outcome variables included fibular medial-lateral (ML) translation, anterior-posterior (AP) translation, and external rotation (ER) in the following states: 1) intact ankle, 2) AITFL transected, 3) PITFL and IOM transected, 4) 3.5 mm cannulated tricortical screw fixation, 5) suture button fixation. An ANOVA with a post-hoc Tukey analysis was performed for statistical analysis (*p<0.05). Results: Significant differences in fibular motion were only during the inversion moment. Fibular posterior translation was significantly higher with complete syndesmosis injury compared to the intact ankle at 0°, 15°, and 30° plantarflexion and the tricortical screw at 15° and 30°. Significantly higher fibular posterior translation was observed with the suture button compared to the intact ankle at 15° and 30 plantarflexion and to the tricortical screw at 15°. ER was significantly increased with complete injury compared to the tricortical screw at 0° and 30° plantarflexion. The suture button demonstrated significantly greater ER at 0° plantarflexion and 10° dorsiflexion compared to the intact ankle. The only significant difference in ML translation exists between the tricortical screw and complete injury at 30° plantarflexion. Conclusion: The suture button did not restore physiologic motion of the syndesmosis. It only restored fibular ML translation. Significant differences in AP translation and ER persisted compared to the intact ankle. The tricortical screw restored fibular motion in all planes. No significant differences were observed compared to the intact ankle. These findings are consistent with previous studies. This study utilized a novel setup to measure unconstrained motion in a full length, intact fibula. Physicians should evaluate AP translation and ER as critical fibular motions when reconstructing the syndesmosis with suture button fixation.

scholarly journals Bilateral Comparison of the Three-dimensional Configuration in the Normal Ankle Syndesmosis: A non-Weightbearing and Weightbearing CT-analysis

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0046
Author(s):  
Greg Tsarukian ◽  
Matthias Peiffer ◽  
Alexej Barg ◽  
Wouter Huysse ◽  
Yantarat Sripanich ◽  
...  
Keyword(s):  
Reference Values ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Ankle Injuries ◽  
Anatomical Landmarks ◽  
Ankle Trauma ◽  
Standard Deviations ◽  
Three Dimensional Configuration ◽  
The Right ◽  
Weightbearing Ct

Category: Ankle Introduction/Purpose: Syndesmotic ankle injuries can be present in up to one-fifth of all ankle trauma and may lead to syndesmotic instability or posttraumatic ankle osteoarthirtis on the long term. It remains challenging to distinguish syndesmotic ankle injuries from other types of ankle trauma. Currently, diagnosis is based on plain radiographs by comparing 2D measurements of the injured to the non-injured side. However, it is unclear to what extent the 3D configuration of the normal ankle syndesmosis is symmetrical during non- or weightbearing conditions. Therefore, our aim was two-fold (1) to establish reference values based on three-dimensional side-to-side comparison of the normal ankle syndesmosis imaged by a non-weightbearing (NWBCT) and weightbearing CT (WBCT) (2) to compare measurements obtained from a NWBCT with those of a WBCT. Methods: In this retrospective comparative cohort study, patients with a NWBCT (N=38; Mean age=51+-17.4 years) and WBCT (N=43; Mean age=48+-14.3 years) were analyzed. Inclusion criteria were a bilateral NWBCT or WBCT of the foot and ankle between January 2016 and December 2018. Exclusion criteria consisted of hindfoot pathology and an age <18 years or >75 years. CT images were segmented to obtain 3D models. Computer Aided Design (CAD) operations were used to mirror the left ankle and superimpose it over the right ankle (Fig. 1A). The apex of the lateral malleolus (AML), anterior tubercle (ATF) and posterior tubercle (PTF) were determined. The difference in the coordinates attached to these anatomical landmarks of the left distal fibula in the ankle syndesmosis with respect to the right were used to establish reference values within two standard deviations. The Mann-Whitney U-test was used to compare measurements from a NWBCT with a WBCT. Results: Reference values within two standard deviations are given for each 3D measurement derived from a NWBCT and WBCT-scan (Fig 1B). The highest difference in translation was detected in the anterior-posterior direction (Mean APNWBCT= 0.161mm; 2SD=3.212/ Mean APWBCT= -0.082mm; 2SD=2.374). The highest difference in rotation was detected in the external- internal direction (Mean EINWBCT= -0.484°; 2SD=8.720/ Mean EIWBCT= -0,326°; 2SD=5.370). None of these differences were statistically significant in the normal ankle syndesmosis when obtained from a NWBCT scan compared to a WBCT scan (P>0.05). Conclusion: This study provides reference values of the three-dimensional configuration in the normal ankle syndesmosis based on side-to-side comparison. It did not demonstrate significant differences in the normal ankle syndesmosis between NWBT and WBCT scans. These novel 3D data contribute relevantly to previously established bilateral 2D radiographic reference values. In clinical practice, they will aid in distinguishing if a patient with a syndesmotic ankle lesion differs from normal variance in syndesmotic ankle symmetry.

Ankle Injuries During Excessive External Foot Rotation May Depend on Foot Constraint: Development of a Computational Model

2010 ◽  
Author(s):  
Feng Wei ◽  
John W. Powell ◽  
Roger C. Haut
Keyword(s):  
Computational Model ◽  
Bone Fracture ◽  
Clinical Studies ◽  
External Rotation ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
Calcaneofibular Ligament ◽  
Tibiofibular Ligament ◽  
Posterior Talofibular Ligament

Numerous studies on the mechanisms of ankle injury deal with injuries to the syndesmosis and anterior ligamentous structures, but previous sectioning and clinical studies also describe the important role of the posterior talofibular ligament (PTaFL) in the ankle’s resistance to external rotation of the foot. Foot constraint may influence subtalar motion and the movement of the bones in the foot, thereby influencing the mode of injury during external rotation [1]. Stiehl et al. [2] constrain the foot with fiberglass cast tape, externally rotate the foot 90°, and produce injury to the deltoid ligament and anterior tibiofibular ligament (ATiFL) with bone fracture. In contrast, Stormont et al. [3] fix the foot in a potting alloy and conclude the primary ligamentous restraints to external rotation are the PTaFL and calcaneofibular ligament (CaFL).

scholarly journals Syndesmotic Behavior after Sequential Sectioning: Simulation of Ligamentous Ankle Injuries in Vitro

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0001
Author(s):  
Robin P. Blom ◽  
Kaj S. Emanuel ◽  
Markus Knupp ◽  
Inger N. Sierevelt ◽  
Gino M.M.J. Kerkhoffs ◽  
...  
Keyword(s):  
External Rotation ◽  
Lower Limbs ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
Active Motion ◽  
Need For Treatment ◽  
Ligament Rupture ◽  
Fresh Frozen ◽  
Rotation Stress

Category: Ankle, Trauma, Distal Tibiofibular Joint Introduction/Purpose: Ankle fractures are often associated with ligamentous injuries of the distal tibiofibular syndesmosis and the deltoid ligament. These injuries may predispose to instability, early joint degeneration and long-term ankle dysfunction. In the classic article of Boden it was made clear that injuries of the syndesmotic ligaments were of no importance in absence of a deltoid ligament rupture. Even in the presence of a deltoid ligament rupture, the interosseous membrane withstood lateralization of the talus in fixated fibula fractures up to 4.5 mm above the ankle joint. However, detection of ligamentous injuries and the need for treatment remain subject of ongoing debate. Syndesmotic injuries are often treated operatively by temporary fixation performed with positioning screws. But do isolated syndesmotic injuries need to be treated operatively at all? Methods: Ten fresh-frozen, exarticulated through the knee, human cadaveric lower limbs were tested under axial compressive loads of 50 and 700 N, simulating non-weightbearing and weightbearing conditions. All specimens were tested with different foot positions (plantigrade, dorsiflexion, inversion, eversion, and 10 Nm external rotational torque) during sequential sectioning of the syndesmotic ligaments and the deltoid ligament. We triangulated Boden’s classic findings with an active motion capture system (0.1 mm accuracy) to track the translations and rotations of the fibula relative to the tibia. Results: Isolated sectioning of the AITFL resulted in an increase of external fibula rotation up to 8.9 degrees (doubling the physiological 4.0 degrees) with an external rotation stress of 10 Nm in non-weightbearing conditions. However, weightbearing appeared somewhat protective, reducing the external rotation to 7.9 degrees. Sectioning of all syndesmotic ligaments with an intact deltoid ligament resulted in a syndesmotic widening of 0.9 mm in weightbearing conditions with a plantigrade foot. Dorsiflexion of the foot resulted in a significant increase of syndesmotic widening for all conditions of the syndesmotic ligaments. Sectioning of the deltoid ligament resulted in a significant increase of all fibula translations in all foot positions during weightbearing conditions. Conclusion: The results of our study have implications for common ligamentous ankle injuries and their treatment. In isolated syndesmotic injuries with a plantigrade foot, weightbearing seemed protective and limiting syndesmotic widening probably due to the saddle shape of the tibiotalar surface. Conservative treatment in a cast seems justifiable. External rotation stress causes the “open-book-phenomenon” in isolated AITFL injuries, especially in non-weightbearing conditions. Protection with cast or surgery is necessary. The deltoid ligament prevents lateralization of the talus but allows increased syndesmotic widening and external rotation of the fibula in dorsiflexion and external rotation stress due to the shape of the talus.

3D Talar Kinematics During External Rotation Stress Testing in Hindfoot Varus and Valgus Using a Model of Syndesmotic and Deep Deltoid Instability

2019 ◽  
Vol 40 (7) ◽  
pp. 826-835 ◽  
Author(s):  
Jessica E. Goetz ◽  
Tanawat Vaseenon ◽  
Yuki Tochigi ◽  
Annunziato Amendola ◽  
John E. Femino
Keyword(s):  
Ankle Instability ◽  
External Rotation ◽  
Ankle Injuries ◽  
Deltoid Ligament ◽  
Starting Position ◽  
Coronal Rotation ◽  
Ligamentous Instability ◽  
Ligament Disruption ◽  
Rotation Stress ◽  
Fixed Center

Background: External rotation stress (ERS) identifies ankle instability after fibular reduction of rotational ankle injuries. Combined hindfoot and ankle motions and an inconsistent starting position could mask differing degrees of instability resulting from syndesmotic and/or deltoid ligament disruption. The goal of this work was to use full 3D talar kinematics to evaluate the effects of hindfoot orientation and foot starting position during ERS on the ability to detect instability caused by ligament disruptions. Methods: Six cadaveric ankles with metallic fiducial markers were CT scanned in neutral and 3 stress positions: varus hindfoot internal rotation stress (IRS-var), valgus hindfoot ERS (ERS-val), and varus hindfoot ERS (ERS-var). Scans were obtained in stress positions after transecting the deep deltoid ligament (tDDL) and then the syndesmotic ligaments (tDDL+Syn). Talar rotations and translations were computed in the axial, coronal, and sagittal planes in each stress position. Changes in a fixed center of rotation (CoR) relative to the intact sequence were calculated. Results: Axial plane rotation beginning from IRS-var increased significantly for each level of ligamentous instability ( P < .05 for all conditions) (10.9 degrees, intact; 14.1 degrees, tDDL; 22.7 degrees, tDDL+Syn during ERS-val; and 16.4 degrees, intact; 23.1 degrees, tDDL; 29.9 degrees, tDDL+Syn during ERS-var). With ERS-val, the talar CoR moved medially (3.6-5.4 mm) and posteriorly (0.5-5.2 mm); ERS-var moved anterior/laterally or posterior/medially depending on the specific ligamentous instability. With tDDL+Syn the ankle became grossly unstable and there were no clear trends in sagittal/coronal rotation or translation. Conclusion: An ERS test from internal to external rotation consistently differentiates between normal, tDDL, and tDDL+Syn. Talar CoR moved outside the mortise with ligamentous instability. Clinical Relevance: Significant residual deep deltoid instability is likely underrecognized with current practice. The most discriminatory test for detecting such instability in our laboratory was an ERS test performed by internally rotating the foot to a hard, bony endpoint, positioning the hindfoot in varus, and then performing the entire external rotation maneuver while maintaining the varus hindfoot position.

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