Effectiveness of suture button fixation versus screw fixation for the management of acute distal tibiofibular syndesmotic injuries: a systematic review protocol

Abstract

Objective: 

The aim of this review is to determine whether suture button fixation is more effective than traditional screw fixation for the management of acute distal tibiofibular syndesmotic injuries.

Introduction: 

Syndesmotic injuries are common and require surgical management to avoid chronic pain and instability, and to improve long-term functional outcomes. Screw fixation and suture button fixation are the 2 techniques of choice for treatment; however, there remains ongoing debate surrounding which treatment modality delivers the best outcomes, leading to significant variability in practice. The suture button is a relatively new technique; therefore, there is a need for an updated, high-quality systematic review to help guide best practice in syndesmosis injury management.

Inclusion criteria: 

This review will consider studies comparing suture button versus screw fixation of acute (<6 weeks) distal tibiofibular syndesmotic injuries. Patients aged 18 or over, with syndesmotic injuries requiring surgical stabilization, with or without an associated fracture, will be included. The primary outcome of interest will be composite functional ankle scores. Secondary outcomes will include range of motion, pain, joint malreduction, complications rates, re-operation rates, and return to work/sport.

Methods: 

This review will be conducted in accordance with the JBI guidelines for systematic reviews of effectiveness. The following electronic databases will be searched: PubMed, Embase, Scopus, The Cochrane Register of Controlled Trials, and Web of Science, in addition to gray literature databases. No publication date or language limits will be applied. Two independent reviewers will screen titles, abstracts, and full-text studies, assessing methodological quality using the JBI critical appraisal tools. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach will be used to assess certainty in the findings.

Systematic review registration number: 

PROSPERO CRD42022331211

Introduction

The ankle is the most commonly injured site of the lower limbs.¹ Syndesmotic injuries requiring surgical fixation are common, with injuries to the distal tibiofibular syndesmosis occurring in up to 10% of ankle sprains and 23% of ankle fractures,² with an overall incidence of 2.09 per 100,000 person-years.³ The importance of early diagnosis and surgical management of unstable syndesmotic injuries to avoid unwanted sequalae, including chronic pain, instability, functional impairment, and early osteoarthritis, has been firmly established.⁴ However, there remains ongoing debate surrounding the various fixation techniques and implant types that should be used.⁵

The distal tibiofibular syndesmosis is a syndesmotic joint compromised of the distal tibia, distal fibula, and 4 ligamentous structures. A syndesmosis is a fibrous joint in which 2 bones are connected by a strong membrane or ligaments. The ligaments are the anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, inferior transverse ligament, and interosseous ligament.⁶ The syndesmosis allows for motion in the coronal, sagittal, and transverse planes, with stability of this articulation integral to the proper functioning of the ankle. To facilitate this multi-dimensional movement, the syndesmosis is a dynamic structure that can naturally widen, which occurs throughout the transition from full plantarflexion to dorsiflexion.

Injuries to the syndesmosis usually occur due to external rotation and excessive dorsiflexion of the foot relative to the leg.⁷ This is commonly seen in sports such as football and rugby where there are twisting and cutting demands coupled with the risk of contact. Syndesmosis injuries are also commonly seen in sports requiring rigid immobilization in a boot (eg, ice hockey and skiing), which are prone to external rotation forces causing distal tibiofibular stress.

The syndesmosis can be injured in isolation or with accompanying bony or ligamentous injuries. The term “isolated” is commonly used to describe a syndesmotic injury without ankle fracture, but concomitant ligamentous, soft tissue injuries, and tibiofibular avulsion fractures may be present. However, true isolated rupture of the syndesmosis is rare.⁸

The importance of anatomical reduction and fixation of the syndesmosis has been firmly established as sequelae of untreated syndesmotic injuries, which include chronic pain, instability, and post-traumatic arthritis. An unstable syndesmosis is indication for surgical stabilization.⁴

Despite the importance of effective fixation of syndesmotic injuries, there remains ongoing debate among orthopedic surgeons as to the gold standard of care. The 2 most common methods of syndesmosis fixation involve the use of suture button and screw fixation. Following fixation of any associated fractures, and the subsequent reduction of the syndesmosis, the implant of choice is placed across the syndesmosis.

Screw fixation is the original method and involves either 1 or 2 3.5 mm or 4.5 mm screws placed between the fibula and the tibia, 15 mm to 20 mm proximal to the joint surface, penetrating either 3 or 4 cortices of bone.⁹ There is no consensus as to the optimal construct for screw fixation, with variability between institutions and individual surgeons. Methods of screw fixation remain a topic of much debate, with no consensus on factors, such as screw size, number of screws used, cortices, time to post-operative weight bearing, whether to electively remove the screw and, if so, at what time.^10,11 Screw fixation is associated with complications, such as implant irritation, loosening, and breakage, which has led to the development of alternative surgical modalities.

Suture button fixation is a fairly recent innovation utilizing a non-absorbable suture, which is passed through a 4 mm tunnel in the fibula and tibia, with the first case series on its use published in 2005.¹² The suture button is secured at both ends by metallic buttons, which are placed on the external surface of the outer cortices of both bones, providing physiologic stabilization of the ankle mortise. As the suture button technique provides less rigid fixation, it allows for maintenance of physiological motion of the syndesmosis and does not require routine implant removal.¹³

Clinical surveys have highlighted the discrepancy in practice, showing that among a cohort of 125 Australian orthopedic surgeons, 44% utilized suture buttons over screw fixation.¹⁰ Interestingly, 33% of the surgeons who commonly use screw fixation, stated that they would prefer a suture button if they personally sustained a syndesmotic injury. This figure is in contrast to a similar survey among 100 primarily European surgeons, where just 9% utilized the suture button technique.¹¹

The aim of this systematic review of randomized controlled trials (RCTs) is to determine whether suture button fixation is more effective than traditional screw fixation for the management of acute distal tibiofibular syndesmotic injuries.

A preliminary search for systematic reviews was conducted in PROSPERO, MEDLINE, the Cochrane Database of Systematic Reviews, and JBI Evidence Synthesis on March 19, 2022. A total of 12 systematic reviews examining clinical outcomes published between July 2017 and December 2021 was found, and these are summarized in Table 1.^14–25 Systematic reviews of biomechanical studies and cost analysis were not included. Five of the 12 reviews were limited solely to RCTs, while the remaining 7 included quasi-experimental and retrospective studies.

Table 1 - Summary of existing systematic reviews examining clinical outcomes on whether suture button fixation is more effective than traditional screw fixation for the management of acute distal tibiofibular syndesmotic injuries

Author	Journal name	Last literature search	First published	Number of trials	Design of included studies	GRADE	Subgroup	A priori protocol	Databases	Language
Chen et al.14	Foot and Ankle Surgery	March 2017	February 2019	9	3 RCTs, 6 non-RCTs	No	No	No	PubMed, Embase, Cochrane	No language restriction
Fan et al.15	Orthopaedic Surgery	November 2018	December 2019	10	3 RCTs, 7 non-RCTs	No	No	No	PubMed, Embase, Cochrane	No language restriction
Gan et al.16	Knee Surgery, Sports Traumatology, Arthroscopy	August 2018	August 2019	5	RCTs	No	No	No	PubMed, Embase, Cochrane	English only
Gerioba17	Not published in a journal: master’s thesis	April 2017	Submitted: February 21, 2018	53	24 descriptive, 19 cohort, 9 RCTs, 1 quasi-experimental	Yes	Yes	Yes	CINAHL, Cochrane, Embase, Libraries Australia, MedNar, OpenGrey, ProQuest, PubMed, Scopus, Web of Science	English only
Grassi et al.18	The American Journal of Sports Medicine	March 2018	June 2019	7	RCTs	Yes	Yes	No	PubMed, Embase, Cochrane, ClinicalTrials.gov	English only
McKenzie et al.19	The Journal of Foot and Ankle Surgery	October 2016	September 2019	6	2 RCTs, 4 non-RCTs	No	No	No	PubMed, Embase, Cochrane	Not specified
Onggo et al.20	Foot and Ankle Surgery	March 2018	January 2020	5	RCTs	No	No	No	PubMed, Embase, MEDLINE (Ovid)	English only
Ramadanov et al.21	Foot and Ankle Orthopaedics	June 2021	December 2021	8	RCTs	No	No	Yes	PubMed, Google Scholar	English only
Shimozono et al.22	The American Journal of Sports Medicine	January 2018	November 2018	5	RCTs	Yes	No	No	PubMed, Embase, Cochrane	English only
Xie et al.23	International Journal of Surgery	August 2018	December 2018	11	5 RCTs, 6 non-RCTs	No	No	No	PubMed, Embase, Cochrane	No language restriction
Xu et al.24	The Journal of Foot and Ankle Surgery	February 2020	May–June 2021	12	6 RCTs, 6 non-RCTs	No	No	No	PubMed, Embase, Cochrane, Web of Science	English only
Zhang et al.25	BMC Musculoskeletal Disorders	March 2017	July 2017	9	3 RCTs, 6 non-RCTs	No	No	No	PubMed, Embase, Cochrane, Web of Science	English only

RCTs, randomized controlled trials

Marasco et al.⁵ published a systematic review of overlapping meta-analyses comparing static versus dynamic fixation of the distal tibiofibular syndesmosis. Using A MeaSurement Tool to Assess systematic Reviews (AMSTAR), the review by Grassi et al.¹⁸ was the highest quality of the reviews limited only to RCTs; however, it only scored 9 out of a possible 11. It was also the only review to include gray literature; however, none of the studies provided a priori design or an included list of studies.

Only 3 reviews^17,18,22 used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.²⁶ These 3 papers were the highest quality of those published on this topic.However, more than 4 years have elapsed since the most recent literature searches, with the most recent search being by Grassi¹⁸ in March 2018, prior to publication in June 2019.

A search of PROSPERO identified only 1 registered review on the topic in the last 2 years, which has subsequently been published by Ramadanov et al.²¹ This paper has significant methodological flaws, as it only searched PubMed and Google Scholar. The presence of additional papers found from an unclear and non-reproducible Google Scholar search brings into question whether the entire body of literature was included, given that only 1 database was searched. Furthermore, the GRADE approach was not utilized in this review.

A high-quality systematic review is needed as the optimal fixation method remains unclear, which is confirmed by the large variability in practice. An umbrella review methodology was considered due to the large number of existing systematic reviews on the topic²⁷; however, these are considered outdated (a number of RCTs has since been published) and of poor methodological quality. Therefore, these reviews are unable to provide a clear result with recommendations to guide practice or focused on methods rather than the optimal fixation technique. As a result, a systematic review is recommended to address the gaps in research outlined here and in Table 1.^14–25 The aim is primarily to include more recent research and address the generally low methodological quality of the existing reviews, which reduces confidence in the recommendations.

Review question

Is suture button fixation more effective compared with screw fixation for the management of acute distal tibiofibular syndesmotic injuries?

Inclusion criteria

Participants

This review will evaluate studies involving adult patients, aged 18 years or over, with acute distal tibiofibular syndesmotic injuries requiring surgical stabilization, with or without an associated fracture.

The management of chronic syndesmotic injuries (>6 weeks since injury) will be excluded from this study as these are managed differently to acute injuries and have been shown to have worse functional outcomes.²⁸

Interventions

This review will consider studies that evaluate the use of suture button fixation for the surgical management of acute syndesmotic injuries. A suture button is a device consisting of a fibrous, suture-like material attached between 2 metallic buttons. The 2 most commonly used proprietary devices are the TightRope (Arthrex, Naples, FL, USA) and Biomet ZipTight (Biomet Sports Medicine, Warsaw, IN, USA); however, any suture button device will be considered.

Comparators

The comparator intervention is screw fixation, with either metal or bioabsorbable screws. This is the current gold standard, and involves the use of 1 or 2 3.5 mm (small fragment/small frag) or 4.5 mm (large fragment/large frag) diameter screws placed across the syndesmosis between the tibia and the fibula.

Outcomes

The primary outcome of interest will be composite functional ankle scores, such as the American Orthopaedic Foot and Ankle Society ankle-hindfoot score, Olerud–Molander Ankle Score, and the Foot and Ankle Disability Score. Where possible, all outcomes will be analyzed at 3, 6, 12, and 24 months. Should any studies be found with a follow-up period of >24 months, these later data points will also be included.

A number of secondary outcomes will be considered:

• Immediate: syndesmosis malreduction based on radiological measurements of the syndesmosis in the immediate post-operative period.
• Short term: time to return to work/sport.
• Medium and long term: range of motion (range of plantarflexion and dorsiflexion of the ankle joint) and pain (measured by visual-analogue scale or other metrics). Where possible, these outcomes will be analyzed at 3, 6, 12, and 24 months.
• All time points: re-operation rates (the incidence of revision operations due to either implant failure or syndesmosis malreduction) and complication rates (all complications will be considered; however, there will be a particular focus on infection and implant irritation).

Types of studies

This review will be limited to RCTs. Given the body of available evidence, the review will not consider non-RCTs, quasi-experimental, or epidemiological study designs, such as prospective and retrospective cohort studies, case series, individual case reports, or cross-sectional studies, with or without a control group.

Methods

The proposed systematic review will be conducted in accordance with the JBI methodology for systematic reviews of effectiveness.²⁹ The review title has been registered with PROSPERO (CRD42022331211).

Search strategy

The search strategy will aim to locate both published and unpublished studies. A 3-step search strategy will be utilized in this review. First an initial limited search of MEDLINE (PubMed) and CINAHL (EBSCO) was undertaken to identify articles on the topic. The text words contained in the titles and abstracts of relevant articles, and the index terms used to describe the articles, were used to develop a full search strategy (Appendix I). The keywords utilized were “syndesmosis,” “syndesmotic,” “distal tibiofibular joint,” “ankle diastasis,” and “high ankle sprain.” A second search using all identified keywords and index terms will then be undertaken across all included databases. Thirdly, the reference lists of all identified reports and articles (including all pre-existing systematic reviews) will be searched for additional eligible studies. Studies published in any language and of any publication date will be considered for inclusion in this review.

The databases to be searched will include MEDLINE (PubMed and Ovid), Embase (Elsevier), Scopus, the Cochrane Register of Controlled Trials (CENTRAL), and Web of Science. The search for unpublished studies will include Scirus, MedNar, ProQuest Dissertations and Theses, Grey Source, Index to Theses, and Libraries Australia.

Study selection

Following the search, all identified citations will be collated and uploaded into EndNote v.X9 (Clarivate Analytics, PA, USA) and duplicates removed. Following a pilot test, titles and abstracts will be screened independently using Covidence (Veritas Health Innovation, Melbourne, Australia) by 2 or more reviewers against the inclusion criteria for the review. Potentially relevant studies will be retrieved in full, and their citation details imported into the JBI System for the Unified Management, Assessment and Review of Information (JBI SUMARI; JBI, Adelaide, Australia).³⁰

The full text of selected citations will be assessed in detail against the inclusion criteria by 2 or more independent reviewers. Reasons for exclusion of papers at full text that do not meet the inclusion criteria will be recorded and reported in the systematic review. If disagreements arise between the reviewers at any stage of the selection process, this will be resolved through discussion, and if no consensus is reached, by an additional senior reviewer. The results of the search and the study inclusion process will be reported in full in the final systematic review and presented in a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.³¹

Assessment of methodological quality

Eligible studies will be critically appraised by 2 independent reviewers at the study level for methodological quality in the review using standardized JBI critical appraisal instruments.²⁹ The results of critical appraisal will be reported in a table with an accompanying narrative. All studies, regardless of the results of their methodological quality, will undergo data extraction and synthesis (where possible).

Data extraction

Data will be extracted from studies included in the review by 2 independent reviewers using a modified version of a JBI data extraction tool.²⁹ The data extracted will include specific details about the participants, study methods, interventions, and outcomes of significance to the review question.

Any disagreements that arise between the reviewers will be resolved through discussion or with a third reviewer. Authors of papers will be contacted to request any missing or additional data, where required.

Data synthesis

Studies will, where possible, be pooled using statistical meta-analysis in JBI SUMARI.³⁰ Effect sizes will be expressed as either odds ratios (for dichotomous data) or weighted (or standardized) final post-intervention mean differences (for continuous data), and their 95% CI will be calculated for analysis. Heterogeneity will be assessed statistically using the standard χ² and I². A random effects model will be used for the meta-analysis.

Subgroup analyses will be conducted where there are sufficient data to investigate.

The subgroups will include fracture versus isolated syndesmotic injury, 1 or 2 tightropes used in the construct (suture button fixation only), various types of screw fixation (metal vs. bioabsorbable), screw diameter, number of screws, number of cortices engaged, location relative to syndesmosis, screw removal versus retention, and age.

The Cochrane Risk of Bias 2 Tool will be utilized to assess the risk of bias in the studies. Should an included study have a high risk of bias across multiple domains compared with other included studies, a sensitivity analysis will be performed. Outcomes will be re-calculated excluding these studies to assess their impact. A funnel plot will be generated to assess publication bias if there are 10 or more studies included in a meta-analysis.

Assessing certainty in the findings

The GRADE approach for grading the certainty of evidence will be followed and a Summary of Findings will be created using GRADEpro GDT (McMaster University, ON, Canada). This will be undertaken by 2 independent reviewers at the outcome level. Any disagreements that arise between the reviewers will be resolved through discussion or with a third reviewer. Authors of papers will be contacted to request missing or additional data for clarification, where required.

The Summary of Findings will present the following information, where appropriate: absolute risks for treatment and control, estimates of relative risk, and a ranking of the quality of the evidence based on the risk of bias, directness, heterogeneity, precision, and risk of publication bias of the review results. The outcomes reported in the Summary of Findings will be composite functional ankle score, range of motion, pain, joint malreduction, complication rates, re-operation rates, and return to work/sport.