Biomechanics comparison between endobutton fixation and syndesmotic screw fixation for syndesmotic injury ankle fracture; a finite element analysis and cadaveric validation study

Syndesmotic screws, unscrew them, or leave them? A systematic review and meta-analysis of randomized controlled trials

Background

Syndesmotic injuries are frequently stabilized using syndesmotic screws. Traditionally, these screws were routinely removed during the postoperative period, however recent literature has brought into question the necessity of routine removal, citing no change in functional outcomes and the inherent risks of a second surgery. Our study aimed to compare outcomes of patients undergoing routine syndesmotic screw removal versus those undergoing an on-demand approach to removal.

Methods

A systematic search of studies comparing routine syndesmotic screw removal to on-demand screw removal following an acute ankle fracture, or an isolated syndesmotic injury was conducted across seven databases. Only Prospective randomized controlled trials were eligible for inclusion. Data reported on by at least 2 studies was pooled for analysis.

Results

Three studies were identified that met inclusion and exclusion criteria. No significant difference in Olerud-Molander Ankle Score (MD -2.36, 95% CI -6.50 to 1.78, p = 0.26), American Orthopedic Foot and Ankle Hindfoot Score (MD -0.45, 95% CI -1.59 to .69, p = 0.44), or dorsiflexion (MD 2.20, 95% CI -0.50 to 4.89, p = 0.11) was found between the routine removal group and on-demand removal group at 1-year postoperatively. Routine removal was associated with a significantly higher rate of complications than on-demand removal (RR 3.02, 95% CI 1.64 to 5.54, p = 0.0004). None of the included studies found significant differences in pain scores or range of motion by 1-year postoperatively.

Conclusion

Given the increased risk of complications with routine syndesmotic screw removal and the comparable outcomes when screws are retained, an as-needed approach to syndesmotic screw removal should be considered.

Better outcomes using suture button compared to screw fixation in talofibular syndesmotic injuries of the ankle: a level I evidence-based meta-analysis

INTRODUCTION

The present meta-analysis evaluated current level I clinical trials which compared the use of a suture button (SB) versus syndesmotic screw (SS) fixation techniques for syndesmosis injuries of the ankle. The outcomes of interest were to compare patient-reported outcome measures (PROMs) and complications. It was hypothesised that SB might achieve better PROMs along with a lower rate of complications.

METHODS

This study was conducted according to the 2020 PRISMA statement. In August 2023, PubMed, Web of Science, Google Scholar, and Embase were accessed. All the randomised controlled trials (RCTs) which compared SB versus SS fixation for syndesmosis injuries of the ankle were accessed. Data concerning the American Orthopaedic Foot & Ankle Society (AOFAS), and Olerud-Molander score (OMS) were collected at baseline and at last follow-up. Data on implant failure, implant removal, and joint malreduction were also retrieved.

RESULTS

Data from seven RCTs (490 patients) were collected. 33% (161 of 490) were women. The mean length of the follow-up was 30.8 ± 27.4 months. The mean age of the patients was 41.1 ± 4.1 years. Between the two groups (SB and SS), comparability was found in the mean age, and men:women ratio. The SS group evidenced lower OMS (P = 0.0006) and lower AOFAS (P = 0.03). The SS group evidenced a greater rate of implant failure (P = 0.0003), implant removal (P = 0.0005), and malreduction (P = 0.04).

CONCLUSION

Suture button fixation might perform better than the syndesmotic screw fixation in syndesmotic injuries of the ankle.

A finite element method study of the effect of vibration on the dynamic biomechanical response of the lumbar spine

BACKGROUND

Studies focusing on lumbar spine biomechanics are very limited, and the mechanism of the effect of vibration on lumbar spine biodynamics is unclear. To provide guidance and reference for lumbar spine biodynamics research and vibration safety assessment, this study aims to investigate the effects of different vibrations on lumbar spine biodynamics.

METHODS

A validated finite element model of the lumbosacral spine was utilized. The model incorporated a 40 kg mass on the upper side and a 400 N follower preload. As a comparison, another model without a coupled mass was also employed. A sinusoidal acceleration with an amplitude of 1 m/s2 and a frequency of 5 Hz was applied to the upper and lower sides of the model respectively.

FINDINGS

When the coupled mass point is not introduced: in the case of upper-side excitation, the lumbar spine shows a significantly larger response in the x-direction than in the z-direction, while in the case of lower-side excitation, the lumbar spine experiences rigid body displacement in the z-direction without any movement, deformation, rotation, or stress changes in the x-direction. When the coupled mass point is introduced: both upper and lower-side excitations result in significant differences in z-directional displacement, with relatively small differences in vertebral rotation angle, disc deformation, and stress. Under upper excitation, low-frequency oscillations occur in the x-direction. In both types of excitations, the anterior-posterior deformation of the L2-L3 and L4-L5 intervertebral discs is greater than the vertical deformation. The peak (maximum) disc stress exceeds the average stress and stress amplitude across the entire disc. Regardless of the excitation type, the stress distribution within the disc at the moment of peak displacement remains nearly identical, with the maximum stress consistently localized on the anterior side of the L4-L5 disc.

INTERPRETATION

Accurately simulating lumbar spine biodynamics requires the inclusion of the upper body mass in the lumbosacral spine model. The physiological curvature of the lumbar spine could escalate the risk of lumbar spine vibration injuries. It is more instructive to apply local high stress in the disc as a lumbar spine vibration safety evaluation parameter.

Predictors of Hardware Removal in Orthopaedic Trauma Patients Undergoing Syndesmotic Ankle Fixation With Screws

Background

Indications for removal of syndesmotic screws are not fully elucidated. This study aimed to determine factors related to elective syndesmotic screw removal.

Methods

Patients who underwent fixation of ankle syndesmotic injuries were included. Screw removal was offered after a minimum of 12 weeks after surgery for pain, stiffness or patient desire to remove painful or broken hardware. Patient demographics, surgical data, distance of the syndesmotic screw from the joint, location of the screw at the physeal scar, and number of syndesmotic screws placed were collected for all patients. Bivariate and multivariate analyses were performed to determine the relationship between patient characteristics and screw removal and independent predictors of hardware removal.

Results

Of 160 patients, 60 patients (38%) with an average age of 36.1 (range: 18-84) years underwent elective syndesmotic screw removal at a mean of 7 (range, 3-47) months after initial fixation. The most common reason for screw removal (50/60 patients) was ankle stiffness and pain (83%). Patients who underwent screw removal were more likely to be younger (36.1 years ± 13.0 vs 46.6 years ± 18.2, P < .001) and have a lower ASA score (2 ± 0.8 vs 2.1 ± 0.7, P = .003) by bivariate analysis. Of patients who underwent screw removal, 21.7% (13/60) had a broken screw at the time of removal. Whether the screw was placed at the physeal scar was not significantly associated with patient decision for hardware removal (P = .80).

Conclusion

Younger and healthier patients were more likely to undergo elective removal of syndesmotic hardware. Screw distance from joint and screw placement at the physeal scar were not significantly associated with hardware removal.

Level of Evidence

Level III, retrospective cohort study.