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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

Background

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

Methods

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

Results

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

Conclusion

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

Clinical Relevance

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

Level of Evidence

controlled laboratory study.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

High-Ankle Sprain and Syndesmotic Instability: How Far Have We Come with Diagnosis and Treatment?

Probably one of the most controversial subjects in the orthopedic field is the distal tibiofibular articulation. Even though its most primary knowledge can be a matter of enormous debate, it is in the diagnosis and treatment most of the disagreements reign. Distinguishing between injury and instability remains challenging as well as an optimal clinical decision regarding surgical intervention. The last years presented technology and that was able to bring body to an already well-developed scientifical rationale. In this review article, we aim to demonstrate the current data behind syndesmotic instability in the ligament scenario, whereas using few fracture concepts.

The Tibiofibular Line: A Reliable Method of Syndesmosis Assessment in Certain Fibula Morphologies

Background The tibiofibular line (TFL) technique was initially proposed to assess syndesmosis reduction. Clinical utility was limited by low observer reliability when applied to all fibulas. This study aimed to refine this technique by describing TFL's applicability to various fibula morphologies. Methods Three observers reviewed 52 ankle CT scans. Observer consistencies for TFL measurement, anterolateral fibula contact length, and fibula morphology were assessed using intraclass correlation (ICC) and Fleiss' Kappa. Results TFL measurement and fibula contact length intra-observer and inter-observer consistencies were excellent (minimum ICC, 0.87). Fibula shape categorization intra-observer consistency was substantial to almost perfect (Fleiss' Kappa, 0.73 to 0.97). Six to 10 mm of fibula contact length corresponded to excellent TFL distance consistency (ICC, 0.80 to 0.98). Conclusion The TFL technique appears best for patients with 6 mm to 10 mm of straight anterolateral fibula. Sixty-one percent (61%) of fibulas featured this morphology, indicating most patients may be amenable to this technique.

Is routine removal of syndesmotic screw justified? A meta-analysis

BACKGROUND

Syndesmosis injuries are common with rotational ankle injuries, and placement of a positional syndesmotic screw to maintain its reduction is used as the ligaments heal. There is no clear consensus on routine removal or retention of syndesmotic screw. This study aimed to appraise the current evidence both on removal and retention of syndesmotic screw and to conduct a meta-analysis comparing outcomes and rate of complications of syndesmotic screw removal and retention.

METHODS

Following PROSPERO registration, a systematic search using was performed using keywords ('Syndesmosis' OR 'Syndesmotic' OR 'Transsyndesmotic' OR 'distal tibiofibular') AND ('Screw') AND ('Removal' OR 'Retention') AND 'Outcome' in various databases. No language restrictions were applied and the meta-analysis incorporated the PRISMA statement. VAS (Visual analogue scale for pain), AOFAS (American Orthopaedic Foot And Ankle Society) scores expressed as mean ± SD, and both groups' complication rates were compared. Comparisons with a random-effects model were performed, and heterogeneity between the studies was calculated using the I2 statistic. T-test for two independent sample means was used to compare pooled mean and Z-test for two proportions to assess the difference in the proportion of complications.

RESULTS

A total of 7 studies with 522 patients were included in this review for analysis. Pooled analysis showed non-significant difference in AOFAS score (MD = -1.84; 95% CI: -4.33 to 0.66; p = 0.150) as well as for VAS score (MD = -0.48; 95% CI: -1.56 to 0.60; p = 0.390) between the two groups. The value of z and p-value for complication rates was 0.6021 and 0.5485, respectively, which was not significant.

CONCLUSION

There doesn't appear to be a difference in functional outcome, pain scores, and complication rates between patients who had their syndesmotic screws removed and those where screw was retained. The fear of inferior outcomes with retained screws is thus unfounded, and routine removal adds to morbidity and financial burden. In conclusion, present data does not support the routine removal of the intact syndesmosis screw, and a change in practice is needed to abandon routine syndesmotic screw removal.

The effect of the ankle syndesmosis reduction quality on the short-term functional outcome following ankle fractures

INTRODUCTION

A few radiographic techniques have been proposed to evaluate ankle syndesmosis reduction. The purpose of this study was to analyze post-operatively with CT-scanning the quality of ankle syndesmotic reduction. Moreover, to assess the impact of quality of syndesmotic reduction to functional outcome.

MATERIALS AND METHODS

A prospective cohort study focused on patients older than 17 years with lateral and medial malleolar fracture with verified syndesmotic disruption.

EXCLUSION CRITERIA

open fracture, concomitant injury, surgery delayed for more than 24 hours, additional posterior malleolar fracture, ASA score of ≥ 3, complication requiring revision surgery, articular step or gap of ≥ 2mm on the postoperative CT scans.

RESULTS

Out of 41 patients, 34 participants completed the follow-up. There was a male predominance (20 patients - 58.82%) and the mean age was 48.46±16.1 years (range (20-72 years). 22 patients (64.71%) have sustained type B fracture, while in 12 patients (35.29%) the fracture was of a type C. The reduction was classified as anatomical in 26 patients (76.50%), while in 8 patients (23.50%) the reduction of the syndesmosis was non-anatomical. In those 26 patients in whom the reduction was anatomical, 17 (65.39%) were males and there were 18 (66.67%) type B fractures. In the patients with non-anatomical reduction, 3 patients (37.5%) were of a male gender and there was the equal number of type B and C fractures. The statistical analysis showed significantly favorable scores for both AOFAS score and VAS scale for the patients with anatomical reduction.

CONCLUSION

Functional analysis showed a strong association with the CT observed reduction quality and both the AOFAS score and VAS scale. Further studies are desirable to provide further evidence in relation to the findings of this study.

Strategies to Avoid Syndesmosis Malreduction in Ankle Fractures

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

Acute and Chronic Syndesmotic Instability: Role of Surgical Stabilization

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

New landmarks for ideal positioning of syndesmotic screw: a computerised tomography based analysis and radiographic simulation

PURPOSE

A lack of specific intra-operative markers for accurate positioning of the syndesmotic screw can result in its malpositioning. Knowledge of the axial orientation of the syndesmosis can help in reducing this risk of malpositioning of the syndesmotic screw. In this CT-based study, we investigated the axial relationships of intact syndesmoses with various rigid bony landmarks around the ankle joint that were independent of foot and horizontal plane.

METHODS

We analyzed 126 CT-based studies of uninjured normal ankle joints and defined the following bony landmarks: posteromedial and posterolateral surface of the distal tibia, bimalleolar tips, and anterior and posterior extents of both malleoli. Axial differences between coronal plane through the central axis of syndesmosis and modified coronal planes through these bony landmarks were then measured. Software-based lateral radiographs were created with the reference coronal plane for each radiograph being kept perpendicular to the plane of the viewing screen.

RESULTS

The mean axial differences parting the syndesmotic axis from the modified coronal planes based on distal tibial posteromedial surface, distal tibial posterolateral surface, bimalleolar tips, anterior bimalleolar extents, and posterior bimalleolar extents were - 3.15°, 13.73°, 4.10°, 11.95°, and 12.24°, respectively. With the exception of the posterolateral surface of the distal tibia, all other bony landmarks were radiologically identifiable in the majority of cases.

CONCLUSION

Our study attempts to provide a solution to the issues related to malpositioning of the syndesmotic screw by providing new bony landmarks that can be clinically and fluoroscopically used for syndesmotic-screw positioning. The relationships of bimalleolar tips, anterior and posterior bimalleolar extents, and the posteromedial surface can be reliably used as landmarks for directing syndesmotic screws.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diagnosis and treatment of ankle syndesmosis injuries with associated interosseous membrane injury: a current concept review

BACKGROUND

Tibiofibular syndesmosis injury leads to ankle pain and dysfunction when ankle injuries are not treated properly. Despite several studies having been performed, many questions about diagnosis and treatment remain unanswered, especially in ankle syndesmosis injury with interosseous membrane injury. Therefore, the purpose of this study was to help guide best practice recommendations.

METHODS

This review explores the mechanism of injury, clinical features, diagnosis methods, and the treatment strategy for ankle syndesmosis injury with interosseous membrane injury to highlight the current evidence in terms of the controversies surrounding the management of these injuries.

RESULTS

Radiological and CT examination are an important basis for diagnosing ankle syndesmosis injury. Physical examination combined with MRI to determine the damage to the interosseous membrane is significant in guiding the treatment of ankle syndesmosis injury with interosseous membrane injury. In the past, inserting syndesmosis screws was the gold standard for treating ankle syndesmosis injury. However, there were increasingly more controversies regarding loss of reduction and broken nails, so elastic fixation has become more popular in recent years.

CONCLUSIONS

Anatomical reduction and effective fixation are the main aspects to be considered in the treatment of ankle syndesmosis injury with interosseous membrane injury and are the key to reducing postsurgery complications.

Anatomic Ligament Repairs of Syndesmotic Injuries

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

Effect of Syndesmotic Implant Removal on Dorsiflexion

BACKGROUND

There is limited evidence that syndesmotic implant removal (SIR) is beneficial. However, many surgeons advocate removal based on studies suggesting improved motion. Methodologic difficulties make the validity and applicability of previous works questionable. The purpose of this study was to examine the effect of ankle dorsiflexion after SIR using radiographically measured motion before and after screw removal utilizing a standardized load.

METHODS

All patients undergoing isolated SIR were candidates for inclusion. Dorsiflexion was measured radiographically: (1) immediately before implant removal intraoperatively, (2) immediately after removal intraoperatively, and (3) 3 months after removal. A standardized torque force was applied to the ankle and a perfect lateral radiograph of the ankle was obtained. Four reviewers independently measured dorsiflexion on randomized, deidentified images. A total of 29 patients met inclusion criteria. All syndesmotic injuries were associated with rotational ankle fractures. There were 11 men (38%) and 18 women (62%). The mean, and standard deviation, age was 50.3 ± 16.9 years (range 19-80).

RESULTS

The mean ankle dorsiflexion pre-operatively, post-operatively, and at a 3-month follow-up was 13.7 ± 6.6 degrees, 13.3 ± 7.3 degrees and 11.8 ± 11.3 degrees, respectively ( P = .466). For subsequent analysis, 5 patients were excluded because of the potential confounding effect of retained suture button devices. Analysis of the remaining 24 patients (and final analysis of 21 patients who had complete 3-month follow-up) demonstrated similar results with no statistically significant difference in ankle dorsiflexion at all 3 time points.

CONCLUSION

Removal of syndesmotic screws may not improve ankle dorsiflexion motion and should not be used as the sole indication for screw removal.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Is It Possible to Overcompress the Syndesmosis?

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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