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Cochrane Database of Systematic Reviews Protocol - Intervention

Surgical versus non‐surgical interventions for treating ankle fractures in adults

Authors' declarations of interest

Version published: 12 October 2021 Version history

https://doi.org/10.1002/14651858.CD014930
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Abstract

Objectives

This is a protocol for a Cochrane Review (intervention). The objectives are as follows:

To assess the effects (benefits and harms) of surgical versus non‐surgical interventions for the treatment of ankle fractures in adults.

Background

Description of the condition

Ankle fractures are one of the most common fractures in adults. At an orthopaedic trauma unit in the UK, it was the fourth most frequent fracture type after wrist, hand and hip fractures (Court‐Brown 2006). Other epidemiological studies have shown that the incidence of ankle fractures is rising due to increasing numbers of older people in many populations (in the context of demographic change) (Court‐Brown 2018).

The ankle joint (‘articulatio talocruralis’) forms the flexible connection between the lower leg and the foot. It is composed of parts of the tibia (the larger of the two lower‐leg bones, i.e. the ‘shin bone’), the fibula (the smaller lower‐leg bone) and the talus (‘ankle bone’). The distal (lower) portions of the tibia and the fibula form the so‐called malleolar fork. In the middle is the medial malleolus (‘inner malleolus’) of the tibia and on the outer side of the fibula is the malleolus lateralis (‘outer malleolus’). Both malleoli flank the proximal (upper) articular surface and laterally enclose the trochlea of ​​the talus. Furthermore, the posterior tibial edge forms the posterior malleolus, which is situated at the back of the tibia. The upper ankle joint is a hinge joint and allows for lifting (‘dorsal extension’) and lowering (‘plantar flexion’) of the foot. The syndesmosis is a complex ligamentous apparatus that is situated just above the ankle joint. The syndesmosis stabilises the joint during movement, both medially and laterally.

Biomechanically, the tibia and fibula are linked to the movement of the hind foot. This is where loads are transferred from the leg to the foot. The tibia is the main load carrier, and it forms the largest part of the contact surface with the load‐bearing talus. The talus is firmly clamped for its task in the malleolar fork. This important mechanism is particularly at risk in ankle fractures as well as in ligament injuries (Falk 2017 ). A common type of trauma is supination trauma, in which the lateral ligaments are hyperextended when the foot is turned outwards. Ankle fractures occur when one or more parts of the distal tibia or fibula break. Often, this is associated with soft‐tissue injuries, particularly of the ankle ligaments.

The annual incidence of acute fractures varies in different studies, ranging from 71 per 100,000 to 187 per 100,000 (Barile 2017; Bengnér 1986; Court‐Brown 1998; Daly 1987; Elsoe 2018; Juto 2018; Thur 2012). In general, the incidence of ankle fractures is rising among older adults and in the female population (Court‐Brown 1998; Elsoe 2018; Kannus 2002;  Juto 2018; Sporer 2006; Thur 2012). Juto and colleagues also describe a rising incidence in females during their lives, mainly between the ages of 30 and 60 years (Juto 2018). This is in contrast to males, who have a much more evenly distributed incidence throughout their lives (Juto 2018).

Elsoe and colleagues report that the most common form of the ankle fracture across all age groups was the lateral malleolus fracture (55% of all cases) (Elsoe 2018), which is in line with the findings of other studies (Court‐Brown 1998; Daly 1987). Most of the ankle fractures are closed fractures; only around 5% are open fractures (Olson 2001). Commonly, fractures can be traced back to a low‐energy trauma (Juto 2018).

There are three common classification systems used for the categorisation of ankle fractures (Bonnaire 2010). The anatomical classification system of Danis‐Weber categorises fibular fractures into fractures below the syndesmosis (Weber A), at the level of the syndesmosis (Weber B) or above the syndesmosis (Weber C) (Weber 1966). The Lauge‐Hansen classification system is based on the biomechanics of the injury mechanism and the fracture morphology (Lauge‐Hansen 1950). The Müller AO classification system is a more detailed classification, based on the Weber‐Danis classification, that promotes an understanding of the pattern of the injury and the combinations of ligamentous and osseous (‘bony’) lesions (Müller 1990). Such classification systems can support therapeutic decision‐making, but other factors need to be considered for the management of these often complex fractures. These include patient‐independent factors such as soft‐tissue damage, existing resources and expertise of the surgical team; as well as patient‐dependent factors, such as age, comorbidity, functional demands, bone quality and patient needs and preferences.

Ankle fractures lead to pain, reduced mobility, restrictions in everyday life, as well as sporting activity (McPhail 2012). Generally, fractures of the lower extremity have a significant impact on the quality of life of those affected, not just in terms of mobility and everyday activity, but also in terms of the development of anxiety and depression (McKeown 2019). Moreover, they contribute to increasing health care and societal costs that accompanies an ageing population, in particular the cost of managing fragility fractures (Murray 2011).

The diagnostic criteria for ankle fracture are generally as follows: fracture of the lateral malleolus (distal fibula, Weber A/B/C), the medial malleolus (distal tibia) or the posterior tibial edge. Ankle fractures are mostly diagnosed by X‐ray, computed tomography or magnetic resonance imaging.

Description of the intervention

Ankle fractures can be managed non‐surgically or surgically, depending on the extent and pattern of bone and ligament injury. In everyday clinical practice, displaced fibular fractures (Weber B and C), bimalleolar fractures, trimalleolar fractures, as well as open fractures and fractures with chondral impaction, are usually treated surgically. Distal fibular fractures (Weber A) are typically treated non‐surgically (Goost 2014). Nevertheless, there is no consensus among clinicians as to whether non‐surgical therapy should be preferred over surgical therapy for certain fractures, or depending on the patients and their preferences and comorbidities.

Non‐surgical therapy involves consistently immobilising the ankle joint for several weeks (usually six weeks). Depending on the dislocation of the fracture fragments, a closed reduction might be necessary before immobilisation. During the closed reduction, the fracture is reduced by manipulation of the fractured parts through the skin without surgery. Furthermore, the extent of soft tissue damage must also be taken into account. Various methods of fracture stabilisation via immobilisation for several weeks are available, commonly including below‐the‐knee casts (made of plaster or synthetic material), as well as ankle orthesis, functional braces and walking boots (Goost 2014).

Surgical treatment involves the open, minimally invasive or closed reduction (if displaced) of the fracture followed by fracture fixation via various devices such as metal plates, screws, tension bands, tightropes, intramedullary nails, isolated fibular nailing and external fixation. The aim is an anatomical restoration of the articular surfaces and immediate stabilisation, to achieve optimal function and to avoid post‐traumatic joint wear as a result of bony malposition of the joint, or functional incorrect loading of the cartilage. Additionally, this facilitates an earlier mobilisation.

The initial non‐surgical or surgical management of an ankle fracture aims to restore the anatomy and stability of the ankle. Several rehabilitation interventions are implemented to treat the consequences of ankle fractures and immobilisation. Usually, rehabilitation begins during the immobilisation period. Alternatively, rehabilitation could start after the immobilisation period. A Cochrane Review on the rehabilitation of ankle fractures included comparisons of the different methods, including passive or active exercises, early weight‐bearing and manual therapy (Lin 2012). Lin 2012 concluded that there was only poor evidence on rehabilitation after non‐surgical or surgical treatment of ankle fractures; this was found also by Keene 2014.

How the intervention might work

Both non‐surgical as well as surgical management of an ankle fracture aim at restoring the anatomy and stability of the ankle.

For non‐surgical treatment, immobilisation of the ankle is generally considered to be important for bone healing. Healing of the bone takes at least several weeks (on average six weeks). Nonetheless, a consistent immobilisation can cause side effects, such as muscle atrophy, cartilage degeneration, stiffness, pain and soft tissue damage. Additionally, non‐surgical therapy can lead to secondary dislocation of the fracture and non‐union of the bone, requiring delayed surgery and prolonged immobilisation (Dietrich 2002).

Surgical procedures aim to achieve anatomical restoration of the articular surface and to stabilise it by osteosynthesis. Accurate and rigid internal fixation of intra‐articular fractures aims at providing the best possible range of motion by allowing earlier mobilisation (in comparison with non‐surgical management) and optimising ankle joint mechanics. In doing so, surgery aims to speed recovery, return to everyday activities and back‐to‐work‐time. This in turn may reduce adverse effects following immobilisation. However, this may not be the case for older people with osteoporosis, because the porosity of their bones may increase the risk of fixation failure, and thus preclude early mobilisation (Salai 2000). Moreover, surgery is associated with an increased risk of complications such as bone infection, wound infection and fixation or implant failure (Zaghloul 2014), as well as amputation and reoperation in comparison to conservative treatment (SooHoo 2009).

Why it is important to do this review

Ankle fractures are one of the most common fractures in adults (Court‐Brown 2006; Court‐Brown 2015). Their incidence is rising, especially in older women (Juto 2018).

Recent literature suggests that non‐surgical treatment with casting in combination with regular check‐ups could lead to a functionally equivalent result, compared to surgical therapy. Additionally, non‐surgical treatment may be more cost‐effective, compared with surgical care (Abdelaal 2021; Keene 2014; Keene 2016) However,  this has not reflected current practice. For example, a recent analysis of admissions and treatment data in England showed that the rate of surgical treatments has remained relatively stable over the last decade (Scott 2020). It is therefore all the more important to review the latest evidence from randomised controlled trials (RCTs) to inform recommendations for everyday clinical practice in the treatment of ankle fractures.

A previous Cochrane Review, with searches conducted in February 2012, concluded that there was insufficient evidence to state the superiority of either surgical or non‐surgical treatments (Donken 2012). The authors included a total of four trials, involving 292 participants with ankle fractures. Since Donken 2012 was published, several relevant RCTs have been published, which again highlights the importance of performing this review. 

Objectives

To assess the effects (benefits and harms) of surgical versus non‐surgical interventions for the treatment of ankle fractures in adults.

Methods

Criteria for considering studies for this review

Types of studies

The review will include RCTs and quasi‐RCTs. Quasi‐RCTs are trials that use a quasi‐randomising technique for allocation, such as by date of birth or case record number (Higgins 2011).

Types of participants

We will include studies of adult participants (typically aged 18 years or over, and therefore with likely skeletal maturity) with acute ankle fractures (fracture of the lateral malleolus (distal fibula, Weber A/B/C), the medial malleolus (distal tibia) or the posterior tibial edge), who underwent a surgical or a non‐surgical intervention. We will include trials containing adults and children if the proportion of children was clearly small (under 5%), or if data for adults are reported separately. 

Exclusion criteria

  • Severe fractures of the last distal third of the tibia (pilon or plafond fractures).

  • Studies that include more than 5% of fractures with delayed presentation (unless separate data for acute ankle fractures can be obtained).

  • Studies that investigate revision surgery of displaced fractures.

Types of interventions

We will include studies that compare any kind of surgical fracture stabilisation with any kind of non‐surgical fracture stabilisation intervention. Possible surgical fracture stabilisation methods include, but are not limited to:

  • screw osteosynthesis (screw, lag screw, adjusting screw);

  • plate osteosynthesis (plate, bridge plate, double plate, locking plate, minimally invasive plate, angle‐stable plate);

  • wire osteosynthesis (Kirchner‐wire, K‐wire);

  • elastic stable intramedullary nailing (ESIN, intramedullary nail, rod);

  • tension band, tension belt;

  • external fixation;

  • internal fixation.

For the comparator, we will include any type of non‐surgical stabilisation method. These include but are not limited to the following: immobilisation with a plaster cast, a walking boot, a brace or any kind of removable stabilisation of the ankle that does not include the knee.

If a study includes multiple arms, we will include any arm that meets the inclusion criteria for this review.

Types of outcome measures

We will include studies provided they report at least one of our primary or secondary outcome measures. Those studies that do not meet this criterion will not be included, but we will provide some basic information on these should they otherwise be eligible. We will extract the following outcomes, using the methods and time points specified below.

We were not able to find a core outcome set consistent with the 'Core Outcome Measures in Effectiveness Trials' (COMET) Initiative (COMET Initiative) that matches the objective, or could have been adapted to the objective, of our review. Further, we searched on the 'COnsensus‐based Standards for the selection of health Measurement INstruments' (COSMIN) database (COSMIN) for related systematic reviews of outcome measurements, but were not able to find a systematic review of outcome sets that could be used for ankle fractures. Finally, we based the selection of outcome measures on the related Cochrane Review (Donken 2012), on systematic reviews on outcome measures in ankle fractures (McKeown 2019; Ng 2018), and on general instruments to assess the function of the lower limbs (Darwich 2020); as well as on the clinical expertise of the review authors (primarily CJ).

Primary outcomes

We plan to evaluate the following critical outcomes, which will be presented in the ‘Summary of findings’ table.

  • Functional outcomes, using validated measured instruments, as rated by the patient, such as Olerud Molander Ankle Score (OMAS), the American Orthopaedic Foot and Ankle Society Ankle Hind‐Foot Scale (AOFAS) and the Lower Extremity Functional Scale (LEFS).

  • Health‐related quality of life as rated by the patient and measured by e.g. the Euroqol Quality of life questionnaire (EQ5D), the 12‐Item Short‐Form‐Health Survey (SF12) or the 36‐Item Short‐Form‐Health Survey (SF36).

  • Pain as assessed by the patient, such as with the Visual Analogue Scale (VAS).

  • Return to pre‐injury activities (number of patients returned pre‐injury activity level).

  • Treatment failure (major adverse events) at any follow‐up point after initial treatment and defined as any complication leading to any re‐operation such as:

    • loss of reduction

    • symptomatic malunion or non‐union

    • superficial or deep infection

    • compartment syndrome

    • symptomatic vascular or nerve injury

    • post‐traumatic arthritis

Secondary outcomes

Moreover, we will collect the following important outcomes.

Range of motion (ROM) standardised orthopaedic evaluations and documentation indexes for the mobility of joints measuring dorsal extension and plantar flexion of the upper ankle joint.

  • Other adverse events, including stiffness, swelling, muscle atrophy, walking difficulties or any other reported adverse events of included trials.

  • Radiological outcomes such as bony union, malunion, nonunion, signs of osteoarthritis.

  • Resource use such as duration of hospitalisation, numbers of operations, numbers of outpatient visits, other costs and findings of included trials reporting cost‐effectiveness analysis.

Timing of outcome measurement

We will analyse timing of outcomes as very short‐term (less than six weeks post injury), short‐term (six weeks to less than six months post‐injury), medium‐term (six months to less than 12 months post‐injury) and long‐term (12 months or longer post‐injury).

Search methods for identification of studies

Electronic searches

We will search for all relevant published and unpublished RCTs. The search strategies were developed by an experienced information specialist (MIM) and are provided in Appendix 1. A search alert will be created to monitor potential new studies for inclusion using the search strategy for Ovid MEDLINE. There will be no language, time or publication restrictions. We will not include Embase in our search because RCTs indexed in Embase are now prospectively added to CENTRAL via a highly sensitive screening process (Cochrane 2020).

We will identify published, unpublished and ongoing studies by searching the following databases from their inception.

  • MEDLINE Ovid (1946 to present).

  • Cochrane Central Register of Controlled Trials (CENTRAL) via Cochrane Register of Studies Online.

  • CINAHL (Cumulative Index to Nursing and Allied Health Literature).

  • PEDro (Physiotherapy Evidence Database).

  • ClinicalTrials.gov trials registry at the USA National Institutes of Health (ClinicalTrials.gov).

  • World Health Organization International Clinical Trials Registry Platform (ICTRP) (trialsearch.who.int).

As CENTRAL is kept fully up‐to‐date with all records from the BJMT Group’s Specialised Register, we do not plan to search this register separately.

Searching other resources

We will look for additional relevant trials by checking other sources such as the previous Cochrane Reviews (e.g. Donken 2012), bibliographies of included studies and any relevant systematic reviews.

We define grey literature as records detected in ClinicalTrials.gov, ICTRP or dissertations available via CINAHL as well as conference proceedings. We will search for conference proceedings in the Orthopaedic Proceedings (online.boneandjoint.org.uk/journal/procs). 

Additionally, we will contact the authors of included studies to obtain additional information on the retrieved studies, and to establish whether we may have missed further studies.

Data collection and analysis

We will use the Covidence software for screening and study selection, and for data extraction of the included trials (Covidence 2019).

Selection of studies

Two review authors (AN, CJ) will independently screen the title and abstract of every record retrieved by the literature searches. We will obtain the full text of all potentially relevant records. We will resolve disagreements through consensus or by recourse to a third review author (BR). If we cannot resolve a disagreement, we will categorise the study as 'Awaiting classification' and will contact the study authors for clarification. We will present an adapted PRISMA flow diagram to show the process of study selection (Liberati 2009). We will list all articles excluded after full‐text assessment in a 'Characteristics of excluded studies' table and will provide the reasons for exclusion. We will list all ongoing studies and those awaiting classification and will provide details of these in their respective 'Characteristics' tables.

Data extraction and management

We will design a data extraction form and will pilot this form on three studies. This final extraction form will be translated into a data extraction template in Covidence software, which will be used to extract the data from eligible studies. We will describe interventions according to the 'Template for Intervention Description and Replication' (TIDieR) checklist (Hoffmann 2014; Hoffmann 2017).

For studies that fulfil our inclusion criteria, two review authors (AN, CJ) will independently extract key information on study characteristics (e.g. study design, recruitment process, setting), participant characteristics (e.g. age, gender, disease characteristics), interventions and comparators (e.g. description of the interventions, description of co‐interventions), outcome measurement and data (e.g. definitions used in study, length of follow‐up, results of study analysis) as well as details on conflict of interest and financial disclosure. We will resolve disagreements by discussion or, if required, by consultation with a third review author (BR).

We will attempt to find the protocol for each included study and will report in a joint appendix, entitled 'Matrix of study endpoint (publications and trial documents)', the primary, secondary, and other outcomes from these protocols, alongside the data from the study publications.

We will email all authors of included studies to enquire whether they would be willing to answer questions regarding their studies. We will present the results of this survey in an appendix. We will thereafter seek relevant missing information on the study from the primary study author(s), if required.

Dealing with duplicate and companion publications

In the event of duplicate publications, companion documents, or multiple reports of a primary study, we will maximise the information yield by collating all available data, and we will use the most complete data set aggregated across all known publications. We will list duplicate publications, companion documents, multiple reports of a primary study, and trial documents of included trials (such as trial registry information) as secondary references under the study ID of the included study. We will also link together multiple reports of excluded studies, ongoing studies, and studies awaiting classification.

Assessment of risk of bias in included studies

Two review authors (AN, CJ) will independently assess the risk of bias for each included study. We will resolve disagreements by consensus or by consulting a third review author (BR). In the case of disagreement, we will consult the remainder of the review author team and make a judgement based on consensus. If adequate information is unavailable from the study publications, study protocols, or other sources, we will contact the study authors to request missing data on 'Risk of bias' items.

We will undertake ‘Risk of bias’ assessments according to Chapters 7 and 8 of the CochraneHandbook for Systematic Reviews of Interventions (Higgins 2021b). We will use the Cochrane 'Risk of bias 2' (RoB 2) tool (version 22, August 2019) (Sterne 2019).

We will focus on the assessment of the effect of assignment to the interventions at baseline. The effect will be analysed as the result of a comparison between interventions on a certain outcome at a specific time point. The RoB 2 tool evaluates the following domains.

  • Bias arising from the randomisation process.

  • Bias due to deviations from the intended interventions.

  • Bias due to missing outcome data.

  • Bias in measurement of the outcome.

  • Bias in selection of the reported results.

Within each domain, signalling questions provide information about features of the study that are relevant to risk of bias. Possible answers to the signalling questions are 'Yes', 'Probably yes', 'Probably no', 'No' and 'No information'. After answering the signalling questions, we will make a 'Risk of bias' judgement, assigning one of three levels ('low risk of bias', 'some concerns', 'high risk of bias') to each domain.
For each specific outcome, we will establish an overall 'Risk of bias' judgement using the following criteria.

  • Low risk of bias: the study was judged to be at low risk of bias for all domains for this result.

  • Some concerns: the study was judged to raise some concern in at least one domain for this result, but not to be at high risk of bias for any domain.

  • High risk of bias: the study was either judged to be at high risk of bias in at least one domain for this result, or the study was judged to have some concerns for multiple domains in a way that substantially lowers confidence in the result.

We will distinguish among participant‐reported outcomes and observer‐reported outcomes that involve some judgement.

  • Participant‐reported outcomes: health‐related quality of life; functional outcomes; pain; non‐serious adverse events; time to return to work, time to return to sports and normal activities.

  • Observer‐reported: treatment failure, serious adverse events (SAEs), range of motion, radiological outcome.

Measures of treatment effect

We will express dichotomous data as risk ratios (RR) with 95% confidence intervals (CIs). For continuous outcomes measured on the same scale (e.g. weight loss in kg), we will estimate the intervention effect using the mean difference (MD) with 95% CIs. For continuous outcomes that measure the same underlying concept (e.g. health‐related quality of life) but use different measurement scales, we will calculate the standardised mean difference (SMD). We will express time‐to‐event data as a hazard ratio (HR) with 95% CIs. For continuous outcomes, we will present final scores in preference to change scores.

Unit of analysis issues

We anticipate that for individually randomised trials, the unit of analysis will be the participant, as bilateral ankle fractures are rare. However, should unit of analysis issues arise from the inclusion of many participants with bilateral ankle fractures, and where appropriate adjustments have not been made, we will conduct sensitivity analyses, where practical, to explore the potential effects of the incorrect analysis. We will be alert to unit of analysis issues relating to outcome reporting at different follow‐up times and the presentation of outcomes, such as total complications, by the number of outcomes, rather than by participants with these outcomes.

If more than one comparison from the same study is eligible for inclusion in the same meta‐analysis, we will either combine groups to create a single pairwise comparison, or we will appropriately reduce the sample size so that the same participants do not contribute data to the meta‐analysis more than once (splitting the 'shared' group into two or more groups). Although the latter approach offers some solution for adjusting the precision of the comparison, it does not account for correlation arising from inclusion of the same set of participants in multiple comparisons (Higgins 2021a).

Dealing with missing data

If possible, we will obtain missing data from the authors of included studies. We will carefully evaluate important numerical data such as screened, randomly assigned participants, as well as intention‐to‐treat and as‐treated and per‐protocol populations. We will investigate attrition rates (e.g. dropouts, losses to follow‐up and withdrawals) and we will critically appraise issues concerning missing data.

Where included studies do not report means and SDs for outcomes, and where we do not receive the requested information from study authors, we will calculate the missing SD from other data (standard errors, 95% CIs, exact P values) if these are available. We will not impute SDs. We will note any instances where data have been extracted from graphs.

Assessment of heterogeneity

In the event of substantial clinical or methodological heterogeneity, we will not report study results as the pooled effect estimate in a meta‐analysis. We will identify heterogeneity (inconsistency) by visually inspecting the forest plots and by using a standard Chi² test with a significance level of α = 0.1 (Deeks 2021). In view of the low power of this test, we will also consider the I² statistic ‐ which quantifies inconsistency across studies ‐ to assess the impact of heterogeneity on the meta‐analysis (Higgins 2002; Higgins 2003). We will base the interpretation of the I2 statistic results on those suggested by Deeks 2021 (Section: 10.10.2):  

  • 0% to 40%: might not be important;

  • 30% to 60%: may represent moderate heterogeneity;

  • 50% to 90%; may represent substantial heterogeneity; and

  • 75% to 100%: considerable (very substantial) heterogeneity.

Assessment of reporting biases

If we include 10 studies or more that investigate a particular outcome, we will use funnel plots to assess small‐study effects. Several explanations may account for funnel plot asymmetry, including true heterogeneity of effect with respect to study size, poor methodological design (and hence, bias of small studies), and selective non‐reporting (Kirkham 2010). Therefore, we will interpret the results carefully (Sterne 2011).

Data synthesis

Where appropriate, we will pool results of comparable studies using both fixed‐effect and random‐effects models. We will decide on the choice of the model to report by careful consideration of the extent of heterogeneity and whether it can be explained, in addition to other factors, such as the number and size of included studies. We will use 95% CIs throughout. We will consider not pooling data where there is considerable heterogeneity (I² statistic value greater than 75%) that cannot be explained by the diversity of methodological or clinical features among trials. Where it is inappropriate to pool data, we will present trial data in the analyses or tables for illustrative purposes, and report these in the text.

Subgroup analysis and investigation of heterogeneity

We expect the following characteristics to introduce clinical heterogeneity, and we plan to carry out subgroup analyses for these, including investigation of interactions (Altman 2003).

  • Sex (male and female).

  • Age (18 to 60 years; older than 60 years).

  • Fracture morphology (fibula fracture Weber A, fibula fracture Weber B, fibula fracture Weber C, bimalleolar fracture, trimalleolar fracture; displaced, non‐displaced fractures).

  • Comorbidities (diabetic versus non‐diabetic participants).

  • Main types of surgery (e.g. screws versus all other interventions) and conservative intervention (early mobilisation versus immobilisation).

Differences between subgroups will be assessed using the formal test for subgroup differences in Review Manager 5 (Review Manager 2020).

Sensitivity analysis

When applicable, we plan to explore the influence of important factors on effect sizes, by performing sensitivity analyses in which we restrict the analyses to the following.

  • Published studies.

  • Very long follow‐up (more than 5 years of follow‐up) or large studies, to establish the extent to which they dominate the results.

  • Impact of borderline decisions such as for studies included through discussion or a third author.

Furthermore, we plan to explore what influence studies with a high risk of bias (as specified in the Assessment of risk of bias in included studies section) have on the results. We will use the following filters, if applicable: language of publication (English versus other languages), source of funding (industry versus other), or country (depending on data). We will also test the robustness of results by repeating the analyses using different measures of effect size (RR, odds ratio (OR), etc.) and different statistical models (fixed‐effect and random‐effects models).

Summary of findings and assessment of the certainty of the evidence

We will present the overall certainty of the evidence for each outcome specified below, according to the GRADE approach, which takes into account issues related to internal validity (risk of bias, inconsistency, imprecision, publication bias) and external validity (indirectness of results) (Schünemann 2013). Two review authors (AN, CJ) will independently rate the certainty of evidence for each outcome. We will resolve any differences in assessment by discussion or by consultation with a third review author (BR).

We will include an appendix entitled 'Checklist to aid consistency and reproducibility of GRADE assessments', to help with standardisation of the 'Summary of findings' tables (Meader 2014).  If meta‐analysis is not possible, we will present the results in a narrative format in the 'Summary of findings' table. We will justify all decisions to downgrade the certainty of the evidence by using footnotes, and we will make comments to aid the reader's understanding of the Cochrane Review when necessary (Schünemann 2013).

'Summary of findings' table

We will present a summary of the evidence in a 'Summary of findings' table as displayed in Appendix 2. This will provide key information about the best estimate of the magnitude of effect, in relative terms and as absolute differences for each relevant comparison of alternative management strategies; the numbers of participants and studies addressing each important outcome; and a rating of overall confidence in effect estimates for each outcome. We will create the 'Summary of findings' table using the methods described in the Cochrane Handbook (Schünemann 2021).

We will present the results for each primary outcome. We will present functional outcomes at medium‐ and long‐term follow‐up, health‐related quality of life at long‐term follow‐up and treatment failure at short‐ and medium‐term follow‐up. The outcome of 'pain' will be presented at very short‐term and short‐term follow‐up. The outcome of 'return to pre‐injury activity level' will be presented at medium‐term follow‐up.