Varying Distance Between Suture Buttons Does Not Improve Stability of the Transected Syndesmosis and Deltoid Ligament in a Motion-Tracking Cadaveric Model

Abstract

Background:

A growing body of evidence favors the use of dynamic fixation techniques such as suture button fixation over rigid screw fixation for syndesmotic injuries. However, specific dynamic fixation techniques have been poorly evaluated.

Purpose:

To compare single suture button (SEB) fixation to double fixation with suture buttons placed 1 cm apart (DSEB 1) and double fixation with suture buttons placed 3 cm apart (DSEB 3).

Study Design:

Controlled laboratory study.

Methods:

A total of 24 lower leg specimens from 12 cadavers were tested using a custom biaxial apparatus. Internal rotation, external rotation, and anterior and posterior translation of the tibia and fibula were examined using motion-tracking systems after transection of deltoid and syndesmotic ligaments to compare 3 syndesmotic repair techniques: (1) an SEB placed 1 cm above the joint line, (2) 2 suture buttons placed 2 and 3 cm above the joint line, and (3) 2 suture buttons placed 1 and 4 cm above the joint line.

Results:

All 3 button constructs improved the stability of the syndesmosis by reducing aberrant motion after transection. There was no clear superiority of SEB, DSEB 1, or DSEB 3. DSEB 3 and DSEB 1 showed equal median laxity for tibial internal rotation (2.7°; DSEB 1, 2.0° to 3.2°; DSEB 3, 2.3° to 2.8°), tibial external rotation (–0.2°; DSEB 1, –0.4° to 0.4°; DSEB 3, –0.4° to 0.3°), and fibular external rotation (–0.3°; DSEB 1, –0.7° to 0.3°; DSEB 3, –0.7° to 0.7°).

Conclusion:

We found that utilization of a second suture button does not contribute additional stability to the syndesmosis after transection of the major syndesmotic ligaments. Moreover, we found that wider spread of 2 buttons (1 cm vs 3 cm apart) also did not confer additional stability. Future research should build upon these findings to further investigate the optimal configuration of suture button constructs.

Clinical Relevance:

Our study provides a framework for clinicians to reconsider syndesmotic suture button repair techniques based on our finding that there appears to be no enhanced syndesmotic stability with additional buttons.

Keywords

syndesmosis cadaver button syndesmosis fixation

It is well established that distal tibiofibular syndesmotic injuries require surgical treatment,¹⁸ and a growing body of evidence supports the use of dynamic stabilization options such as suture buttons over rigid screw fixation.^5,8 While traditional management of syndesmotic injuries required reduction and stable fixation with a screw construct,¹⁷ maintenance of physiologic motion at the syndesmosis through use of dynamic fixation has been theorized to provide advantages, including lower rates of syndesmotic malreduction^{1,3,4,6,10,11,14,19} and decreased incidence of secondary procedures after screw breakage.⁹

Cadaveric external rotation torque modeling has revealed that suture button fixation compares favorably to screw fixation of the syndesmosis with regard to failure under load.¹⁶ However, a dearth of literature directly compares various suture endobutton techniques to one another. For example, Teramoto et al¹⁵ demonstrate inadequacy of both single and double fixation for the provision of multidirectional stabilization of the syndesmosis after transection of syndesmotic ligaments in a cadaver model. In contradiction, Schon et al¹³ show favorable syndesmosis volume reduction on 3-dimensional computed tomography (3DCT) scanning indicative of increased compression with the use of 2 suture buttons versus screw fixation.

In light of these conflicting data, we aimed to provide further evidence on whether there is benefit to the use of 2 suture buttons over single suture button fixation and, if 2 suture buttons are used, how far apart the buttons should be placed. Given the widespread use of suture button fixation for syndesmotic injuries, the answer to these questions has important implications for patient care. Accordingly, the purpose of this study was to compare single suture button (SEB) fixation versus double fixation with suture buttons placed 1 cm apart (DSEB 1) and double fixation with suture buttons placed 3 cm apart (DSEB 3). Our hypothesis was that double 3 cm would provide more restoration of anatomic motion at the distal tibiofibular syndesmosis in a cadaveric model compared with single fixation and double 1 cm after both syndesmosis and deltoid ligament transection.

Methods

Specimen Preparation

This study used 12 matched pairs of fresh-frozen cadaveric lower limbs (24 total lower limbs, 5 female, 7 male) with an equal distribution of right and left lower limbs and a mean age of 51 years (range, 18-66 years). All specimens were purchased from registered tissue banks receiving cadaveric donations for medical research and were deidentified for this study.

Specimens had no obvious deformity or injury to the lower leg. Prior to dissection, specimens were thawed for 24 hours at room temperature. All skin and subcutaneous tissue overlying the proximal tibia and fibula to the midfoot was removed during dissection, with care taken to preserve the interosseous membrane and all ankle ligamentous structures, including the syndesmosis. To aid in anatomic digitization, drill holes were made in the medial and lateral tibial condyles, at the apex of the tibial tubercle, at the center of the medial and lateral malleoli, and one on the second metatarsal for each specimen.

Biomechanical Testing and Cycling

After dissection, the specimen was fixed in an upright position on a baseplate using a custom setup. The inferior portion of the specimen was fixed with 2 external fixation connecting rods drilled through the calcaneus (lateral to medial) and secured to a medial baseplate using washers. Superiorly, an axial-torsional actuator (E10000 Instron) was fixed to the tibia using another external fixation connecting rod drilled through the proximal tibia (anterior to posterior). Three cortical screws were used to provide additional medial stabilization for the tibia. A 3D Creator motion capture system (Boulder Innovation Group), with a positional and rotational accuracy of 0.1 mm and 0.2°, respectively, recorded the motion of the foot and fibula relative to the tibia throughout testing. Trackers for the motion capture system were placed on the foot and secured with 2 cortical bone screws at the distal tibia and fibula proximal to the syndesmosis. The position coordinates of the second metatarsal and tibial landmarks (tibial tubercle, medial tibial condyle, lateral tibial condyle, medial malleolus, lateral malleolus) were registered on the motion-tracking system prior to each test. The specimen was kept upright throughout testing, and a normal saline spray was used to prevent sample desiccation (Figure 1).

Figure 1.

Testing setup.

At each stage of testing, axial force and torque were applied to the proximal tibia. Specimens were axially loaded with 750 N of force, then cycled between 5 N·m of internal and external rotation for a total of 100 cycles, and the degree of rotation or translation was measured in degrees using rotational detectors positioned on the tibia and fibula. Motion trackers on the tibia and fibula recorded the resulting translation and rotation in degrees and millimeters to quantitatively compare internal rotation (IR) and external rotation (ER) across the testing conditions. Using the rotational and translational data recorded by the motion capture system and motion trackers attached to the tibia and fibula, the difference in IR and ER and their anterior translation (AT) and posterior translation (PT) were calculated for each testing condition. Specifically, the change in IR, ER, AT, and PT was calculated before and after syndesmosis and deltoid ligament transection and repair. The change in median rotational and translational motion was reported in degrees, where positive values indicate an increase in motion or rotation from the native state while negative values indicate smaller changes under the applied axial load relative to the native state.

Repair Conditions

Biomechanical testing was performed to evaluate the relative efficacy of 3 suture button fixation techniques (Knotless Syndesmosis TightRope; Arthrex) in the setting of syndesmotic and deltoid ligament repair. Testing began with specimens bilaterally in their native state to obtain a baseline measurement. Syndesmotic injury was then induced by sectioning the anteroinferior tibiofibular ligament, the posteroinferior tibiofibular ligament, and the interosseous membrane with a scalpel blade. The specimen was then cycled through biomechanical testing as described above. The deltoid ligament was then cut, the specimen was again cycled, and data were recorded.

After the induction of both syndesmotic and deltoid ligament tears, each specimen was randomly assigned to 1 of 3 repair groups for each ligament: a single suture button placed 1 cm above the joint line (SEB), 2 suture buttons placed 2 and 3 cm above the joint line (DSEB 1), and 2 suture buttons placed 1 and 4 cm above the joint line (DSEB 3). For each specimen, one of the lower leg syndesmotic injury models was repaired with one of the double suture button constructs. For syndesmosis repair, suture buttons were placed in accordance with the surgical technique provided by the device manufacturers, oriented parallel to the tibiofibular axial plane. The buttons were placed in an anatomic trajectory: posterior fibula to anterolateral tibia. For deltoid ligament repair, suture anchors were placed in the medial malleolus. Syndesmosis repair and biomechanical testing of the 3 groups was performed first, followed by deltoid ligament repair and testing in the custom apparatus.

Range of Motion Quantification

A 3-dimensional coordinate system was established by digitizing anatomic landmarks using the motion capture system's digitizer. The rotation and translation of the system's motion markers were recorded in reference to this 3-dimensional coordinate system. The long axis of the tibia was defined using a line drawn through the midpoints between the medial and lateral malleoli and the medial and lateral borders of the tibial condyles. The origin of the fibula, located 5 mm superior to the joint line, was positioned midway between the anterior and posterior points on the fibula. An average of anteromedial, anterolateral, posteromedial, and posterolateral points was used to define a talar origin at 5 mm inferior to the joint line. Fibular motion relative to the tibia was used to define specimen laxity.

Statistical Analysis

Continuous variables were represented as medians and interquartile ranges.

Kruskal-Wallis tests were used to compare across all 3 suture button fixation conditions, and Mann-Whitney tests were further used to compare the conditions that used 2 suture buttons. Findings were considered statistically significant for P < .05.

Results

Syndesmotic Repair

When comparing specimen rotational and translational motion under axial load for the native state and after syndesmotic repair, there was no significant difference between repair types in median laxity or translational and rotational motion at 10 or 100 cycles. After 10 cycles, DSEB 1 showed the greatest median change for all tracked rotations and translations under axial loading, aside from fibular ER, where equal median values were observed in DSEB 1 and DSEB 3. Both the translational and rotational data, as well as the largest median rotational and translational changes after 10 cycles, are presented in Figure 2 and Table 1, respectively.

Figure 2.

The change in rotational (degrees) and translational (millimeters) motion after syndesmotic repair relative to the native state after 10 cycles of axial loading for different suture button fixation conditions. There were no statistically significant differences between fixation conditions.

Table 1

Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation After 10 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	DSEB 1	4.0	1.2 to 6.0
Fibular IR, deg	DSEB 1	−2.2	−3.8 to −0.8
Tibial ER, deg	DSEB 1	0.9	−0.3 to 2.9
Fibular ER, deg	DSEB 1/DSEB 3	−0.9	−1.8 to 0.4/–1.4 to −0.4
Lateral malleolus AT, mm	DSEB 1	0.8	0.1 to 1.3
Lateral malleolus PT, mm	DSEB 1	0.4	0.2 to 0.7

AT, anterior translation; DSEB 1, double fixation with suture buttons placed 1 cm apart; DSEB 3, double fixation with suture buttons placed 3 cm apart; ER, external rotation; IR, internal rotation; PT, posterior translation.

After 100 cycles, DSEB 1 again showed a larger median change in all tracked rotational and translational motion, except for fibular ER, where a larger median change was observed for DSEB 3. Both the translational and rotational data, as well as the largest median rotational and translational changes after 100 cycles, are shown in Figure 3 and Table 2, respectively.

Figure 3.

The change in rotational (degrees) and translational (millimeters) motion after syndesmotic repair relative to the native state after 100 cycles of axial loading for different suture button fixation conditions. There were no statistically significant differences between fixation conditions.

Table 2

Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation After 100 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	DSEB 1	6.6	3.1 to 8.8
Fibular IR, deg	DSEB 1	−3.1	−4.2 to −1.2
Tibial ER, deg	DSEB 1	0.6	−0.9 to 3.9
Fibular ER, deg	DSEB 3	−1.3	−1.8 to 0.3
Lateral malleolus AT, mm	DSEB 1	1.6	1.3 to 2.7
Lateral malleolus PT, mm	DSEB 1	−0.3	−0.3 to 0.03

Median laxity was also recorded for both the DSEB 3 and DSEB 1 suture button fixation conditions after 100 cycles of axial loading. DSEB 1 and DSEB 3 displayed identical median laxity for tibial IR and ER as well as fibular ER. DSEB displayed greater median laxity in lateral malleolus AT and PT, while DSEB 3 displayed greater median laxity in fibular IR. The median laxity values after 100 cycles of axial loading are displayed in Table 3.

Table 3

Change in Tibiofibular Laxity From the Native State to Syndesmotic Repair for Different Suture Button Fixation Conditions After 100 Cycles of Axial Loading ^a

Delta	DSEB 1		DSEB 3
Delta	Median	IQR	Median	IQR	P Value
Tibial IR, deg	2.7	2.0 to 3.2	2.7	2.3 to 2.8	.937
Fibular IR, deg	1.7	1.5 to 2.7	1.9	1.1 to 2.1	.818
Tibial ER, deg	−0.2	−0.4 to 0.4	−0.2	−0.4 to 0.3	>.999
Fibular ER, deg	−0.3	−0.7 to 0.3	−0.3	−0.7 to 0.7	.937
Lateral malleolus AT, mm	1.4	1.0 to 1.7	1.0	0.6 to 1.1	.240
Lateral malleolus PT, mm	−0.4	−0.9 to −0.4	−0.2	−0.4 to 0.2	.132

Deltoid Ligament Repair

When comparing DSEB 1 and DSEB at 10 cycles of axial loading, DSEB 1 displayed greater median translational and rotational motion in fibular IR and lateral malleolus AT and PT, while DSEB 3 displayed greater median rotational and translational motion in tibial IR and ER as well as fibular ER. Both the translational and rotational data, as well as the largest median rotational and translational changes after 10 cycles, are shown in Figure 4 and Table 4, respectively.

Figure 4.

The change in rotational (degrees) and translational (millimeters) motion after deltoid ligament and syndesmotic repair relative to the native state after 10 cycles of axial loading for different suture button fixation conditions (DSEB 1 vs DSEB 3). There were no statistically significant differences between fixation conditions. DSEB 1, double fixation with suture buttons placed 1 cm apart; DSEB 3, double fixation with suture buttons placed 3 cm apart.

Table 4

Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation After 10 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	DSEB 3	3.4	0.9 to 5.5
Fibular IR, deg	DSEB 1	−2.2	−3.3 to −0.6
Tibial ER, deg	DSEB 3	0.6	−0.4 to 0.9
Fibular ER, deg	DSEB 3	−0.9	−2.0 to 0.2
Lateral malleolus AT, mm	DSEB 1	0.6	−0.5 to 1.4
Lateral malleolus PT, mm	DSEB 1	0.3	−0.2 to 1.3

At 100 cycles, DSEB 1 displayed greater median rotational and translational motion in tibial and fibular IR as well as lateral malleolus AT and PT, while DSEB 3 displayed greater translational and rotational motion in tibial and fibular ER. Both the translational and rotational data, as well as the largest median rotational and translational changes after 100 cycles, are shown in Figure 5 and Table 5, respectively.

Figure 5.

The change in rotational (degrees) and translational (millimeters) motion after deltoid ligament and syndesmotic repair relative to the native state after 100 cycles of axial loading for different suture endobutton fixation conditions (DSEB 1 vs DSEB 3). There were no statistically significant differences between fixation conditions. DSEB 1, double fixation with suture buttons placed 1 cm apart; DSEB 3, double fixation with suture buttons placed 3 cm apart.

Table 5

Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation After 100 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	DSEB 1	5.0	1.8 to 8.7
Fibular IR, deg	DSEB 1	−2.6	−4.0 to −0.9
Tibial ER, deg	DSEB 3	0.8	−0.6 to 1.5
Fibular ER, deg	DSEB 3	−1.3	−2.4 to 0.3
Lateral malleolus AT, mm	DSEB 1	1.2	0.3 to 2.1
Lateral malleolus PT, mm	DSEB 1	0.3	−0.7 to 1.3

Median laxity was recorded for both the DSEB 3 and DSEB 1 suture button fixation conditions. After 100 cycles of axial loading, DSEB 1 displayed greater median laxity in tibial IR and ER as well as fibular IR and lateral malleolus AT. DSEB 3 displayed greater median laxity in fibular ER, while DSEB 3 and DSEB 1 displayed equal but opposite median laxities in lateral malleolus PT. The median laxity values after 100 cycles of axial loading are shown in Table 6.

Table 6

Change in Tibiofibular Laxity From the Native State to Deltoid Ligament and Syndesmotic Repair for Different Suture Button Fixation Conditions After 100 Cycles of Axial Loading ^a

Delta	DSEB 1		DSEB 3
Delta	Median	IQR	Median	IQR	P Value
Tibial IR, deg	1.6	1.0 to 2.0	1.4	1.1 to 1.8	.699
Fibular IR, deg	1.4	0.8 to 1.6	0.8	0.6 to 1.4	.818
Tibial ER, deg	0.2	−0.3 to 0.5	0.05	−0.01 to 0.3	>.999
Fibular ER, deg	0.0	−0.4 to 0.4	−0.2	−0.3 to 0.2	>.999
Lateral malleolus AT, mm	0.8	0.6 to 1.0	0.4	0.3 to 0.6	.132
Lateral malleolus PT, mm	−0.1	−0.3 to 0.03	0.1	−0.1 to 0.2	.240

When comparing SEB and DSEB 3 at 10 cycles, SEB displayed greater median rotational and translational motion in tibial IR, fibular IR and ER, and lateral malleolus AT. DSEB 3 displayed greater median rotational and translational motion in tibial ER, with equal median translational motion in lateral malleolus PT. Both the translational and rotation data, as well as the largest median rotational and translational changes after 10 cycles, are shown in Figure 6 and Table 7, respectively.

Figure 6.

The change in rotational (degrees) and translational (millimeters) motion after deltoid ligament and syndesmotic repair relative to the native state after 10 cycles of axial loading for different suture button fixation conditions (SEB vs DSEB 3). There were no statistically significant differences between fixation conditions. DSEB 3, double fixation with suture buttons placed 3 cm apart; SEB, single suture button.

Table 7

Suture Button Fixation Condition With Greatest Change in Rotation or Translation After 10 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	SEB	−3.2	−4.4 to −0.6
Fibular IR, deg	SEB	0.3	0.1 to 1.2
Tibial ER, deg	DSEB 3	−0.4	−1.2 to 0.1
Fibular ER, deg	SEB	−0.5	−0.9 to −0.3
Lateral malleolus AT, mm	SEB	−0.8	−1.0 to −0.7
Lateral malleolus PT, mm	SEB/DSEB 3	0.1	−0.04 to 0.4/–0.2 to 0.4

AT, anterior translation; DSEB 3, double fixation with suture buttons placed 3 cm apart; ER, external rotation; IR, internal rotation; PT, posterior translation; SEB, single suture button.

DSEB 3 displayed greater median laxity for tibial and fibular IR as well as lateral malleolus AT and PT. SEB displayed greater median laxity in fibular ER, while DSEB 3 and SEB displayed equal but opposite median laxities for tibial ER. The median laxity values after 10 cycles of axial loading are shown in Table 8.

Table 8

Change in Tibiofibular Laxity From the Native State to Deltoid Ligament and Syndesmotic Repair for Different Suture Button Fixation Conditions After 10 Cycles of Axial Loading ^a

Delta	SEB		DSEB 3
Delta	Median	IQR	Median	IQR	P Value
Tibial IR, deg	1.1	0.8 to 1.4	1.3	1.1 to 1.5	.310
Fibular IR, deg	1.0	0.8 to 1.4	1.3	1.0 to 1.5	.394
Tibial ER, deg	−0.2	−0.4 to 0.1	0.20	−0.2 to 0.3	.240
Fibular ER, deg	−0.5	−0.6 to −0.4	−0.3	−0.5 to 0.1	.394
Lateral malleolus AT, mm	0.5	0.5 to 0.5	0.6	0.5 to 0.8	.699
Lateral malleolus PT, mm	−0.3	−0.4 to −0.2	−0.4	−0.5 to −0.3	.310

AT, anterior translation; DSEB 3, double fixation with suture buttons placed 3 cm apart; ER, external rotation; IR, internal rotation; PT, posterior translation; SEB, single suture button.

At 100 cycles, SEB showed the greatest median change for all tracked rotations and translations under axial loading aside from tibial ER, where DSEB 3 displayed the greatest median value. Both the translational and rotational data, as well as the largest median rotational and translation changes after 100 cycles, are shown in Figure 7 and Table 9, respectively.

Figure 7.

The change in rotational (degrees) and translational (millimeters) motion after deltoid ligament and syndesmotic repair relative to the native state after 100 cycles of axial loading for different suture button fixation conditions (DSE vs DSEB 3). There were no statistically significant differences between fixation conditions. SEB, single; DSEB 1, double fixation with suture buttons placed 1 cm apart.

Table 9

Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation After 100 Cycles of Axial Loading ^a

Delta	Suture Button Fixation Condition With Greatest Median Change in Rotation or Translation	Median	IQR
Tibial IR, deg	SEB	−2.1	−3.6 to 0.7
Fibular IR, deg	SEB	0.2	−0.1 to 1.2
Tibial ER, deg	DSEB 3	−0.6	−0.9 to 0.1
Fibular ER, deg	SEB	−0.8	−1.2 to −0.6
Lateral malleolus AT, mm	SEB	−0.2	−0.5 to −0.03
Lateral malleolus PT, mm	SEB	0.3	−0.04 to 0.1

AT, anterior translation; DSEB 3, double fixation with suture buttons placed 3 cm apart; ER, external rotation; IR, internal rotation; PT, posterior translation; SEB, single suture button.

Discussion

The most important finding of the present study is that there was no clear superiority of SEB, DSEB 1, or DSEB 3 suture button fixation in terms of more closely replicating the native biomechanics of the ankle. Despite this finding, all 3 suture button constructs functioned to improve the stability of the syndesmosis by reducing aberrant motion noted after ligamentous transection.

While we expected a greater difference in conferred stability between the DSEB 1 and DSEB 3 repair groups, there was no statistically significant difference between use of a single suture button and either of the double suture button techniques. These data are consistent with prior literature, such as biomechanical work by Clanton et al² and Parker et al¹² demonstrating no added benefit with the addition of a second button 12 to 15 mm distally or with varying placement strategies (parallel vs divergent). Our finding, in conjunction with the growing body of evidence indicating no biomechanical advantage with the addition of a second suture button, may support widespread adoption of the use of only a single device, conferring a time- and cost-saving advantage. Moreover, in cases where significant fibular comminution precludes placement of a second suture button, we hypothesize that these data may serve to assuage doubts about the quality of single-button fixation. One potential benefit of using 2 suture buttons is to provide a backup in the event that one device fails. Additional research is indicated to evaluate failure rates of suture buttons to assess whether provisional use of backup fixation is cost-effective.

We also determined that modulation of distance between suture button devices appears to confer no additional stability to the syndesmosis across all planes of testing. This finding contradicts our hypothesis, as we theorized that increased spacing between suture buttons would allow for an increased working length of the construct and provide additional stability across more motion planes. These data build on previous cadaver work aimed at defining the optimal suture button configuration to more closely replicate anatomic motion of the syndesmosis.

Parker et al¹² compared 1 suture button to 2 buttons, placed either in parallel fashion or divergent fashion in the axial plane. In line with our results, these authors determined that while suture button placement did confer stability to the syndesmosis, neither the addition of a second button nor placement of the buttons in a divergent fashion provided additional stability to the syndesmosis. In another biomechanical study aimed at determining the optimal technique for suture button placement, Teramoto et al¹⁵ sought to evaluate the effect of anatomically oriented suture button placement. Anatomic placement of the button directed from the posterior cortex of the fibula to the anterolateral edge of the tibia provided enhanced fixation over nonanatomic button placement. The addition of a second suture button, however, did not confer additional stability to the construct. Finally, Schon et al¹³ demonstrate increased syndesmosis compression as determined by syndesmotic volume reduction on 3DCT with the use of 2 suture buttons versus screw fixation. In concordance with the above results, however, in the same study, these authors note that 2 suture buttons did not outperform 1 suture button with regard to syndesmotic volume reduction. This literature, taken in summation and considered with the results of our present study, indicates that to date, no optimal biomechanical configuration of suture buttons has been identified.

Strengths and Limitations

Our study includes certain strengths over other cadaveric syndesmosis modeling techniques described in the literature.⁷ These strengths include stepwise transection of syndesmotic ligaments to more accurately represent the complex nature of syndesmotic injuries, which do not always occur as an all-or-none phenomenon. Moreover, we attempt to simulate the postoperative period by including repeated-cycle modeling. We also used a motion-tracking device that allowed for measurements of fibular motion with 6 separate degrees of freedom, allowing for calculation of any abnormal motion of the fibula relative to the tibia while also permitting quantification of abnormal tibial and fibular translation.

The study is not without several limitations, including those inherent to cadaveric biomechanical studies. Given the nature of this study, the current results are applicable only to a time-zero postoperative scenario and to 10 and 100 cycles. It may take more than 100 cycles for settling to occur for suture button configurations, and 2-button constructs with 3 cm of spacing may outperform single constructs at higher numbers of cycles. Moreover, our study fails to replicate a typical clinical scenario where immobilization would occur after surgery, allowing for tissue healing prior to the initiation of cyclical loading. As a final limitation, despite a power analysis, our study may have been insufficiently powered to determine differences between the groups.

Conclusion

We observed that utilization of a second suture button does not contribute additional stability to the syndesmosis after transection of the major syndesmotic ligaments. Moreover, we found that wider spread of 2 buttons (1 cm vs 3 cm apart) also did not confer additional stability. Future research should build on these findings to further investigate the optimal configuration of suture button constructs.

Footnotes

Final revision submitted December 18, 2025; accepted December 20, 2025.

One or more of the authors has declared the following potential conflict of interest or source of funding: B.L. has received funds from Cytek, Miach, and New Clip. D.O. is a member of the AOFAS and a paid consultant for Stryker and Synthes.

Ethical approval for this study was exempt from the Institutional Review Board at Stanford University because the cadaveric specimens were deidentified.

ORCID iD

Taylor Stauffer

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