Walkers immobilise and stabilise the ankle during weightbearing.

HRQOL will be measured using the EuroQol five-dimension five-level questionnaire (ed-5d-5l)

is measured using the knee-to-wall test, which measures ankle mobility in degrees of motion in standing.

is measured using the heel rise test. Patients perform as many single-leg heel raises at a cadence of one per second until fatigue or a maximum of 50 is reached. The test is performed on both legs, and normal function is recovered if the difference in heel raises between legs is 10% or less.

Hospital Costs will be measured from a hospital perspective with a time horizon of three months and include cost of procedures and in-hospital activities.

Will be measured by asking patients what date they returned to work (full-time and part-time). Information on work-related physical requirements (e.g., blue-collar or white-collar workers) and usual employment status (e.g., retiree, unemployed, working) will also be collected.

The index score of the Manchester-Oxford Foot Questionnaire (MOXFQ) three months after randomisation is chosen as the primary outcome. Patients prefer MOXFQ, and it is a valid and reliable self-administered 16-item patient-reported outcome (PRO) divided into three dimensions (walking/standing seven items, pain five items and social interaction four items). MOXFQ will be summarised as an index score covering the most important dimensions patients indicated after ankle fracture (e.g. pain, function and social interaction). Response options consist of a 5-point Likert scale ranging from zero to four. The MOXFQ index score will be calculated by summing the raw scores of the 16 items of the MOXFQ to a index score ranging from a minimum of 0 to a maximum of 100, where 100 represents the most severe health state and analysed in subgroups: males 18-39, females 18-39, males 40-59, females 40-59, males 60+, females 60+ and in treatment groups (surgical and non-surgical)

Adverse events are undesirable experiences that may occur during brace use as: i) skin irritation, blisters, or pressure sores due to poor fit, friction, or prolonged use, ii) swelling or increased edema, iii) pain or discomfort resulting from tightness, misalignment, or mechanical pressure, iv) delayed fracture healing due to excessive joint movement, v) Muscle atrophy or joint stiffness from immobilization, vi) reduced range of motion (ROM) and vii) removal of material (e.g., screws) due to discomfort or healing complications. Serious adverse events are complications requiring hospitalisation, surgical intervention, or posing a significant risk to the patient as i) death (e.g., an unexpected cardiac event occurring during the study period) ii) hospitalisation due to falls resulting from brace-related instability, iii) wound infection requiring inpatient treatment, potentially related to brace-induced i

Physical activity will be measured in longer term using the short-form International Physical Activity Questionnaire (IPAQ-SF) and grouping patients into low, moderate and high physical activity levels.

Long term Health-related Quality Of Life (HRQOL) will be measured using the EuroQol five-dimension five-level questionnaire (ed-5d-5l)

The index score of the Manchester-Oxford Foot Questionnaire (MOXFQ) three months after randomisation is chosen as the primary outcome. Patients prefer MOXFQ, and it is a valid and reliable self-administered 16-item patient-reported outcome (PRO) divided into three dimensions (walking/standing seven items, pain five items and social interaction four items). MOXFQ will be summarised as an index score covering the most important dimensions patients indicated after ankle fracture (e.g. pain, function and social interaction). Response options consist of a 5-point Likert scale ranging from zero to four. The MOXFQ index score will be calculated by summing the raw scores of the 16 items of the MOXFQ to a index score ranging from a minimum of 0 to a maximum of 100, where 100 represents the most severe health state and analysed in subgroups: males 18-39, females 18-39, males 40-59, females 40-59, males 60+, females 60+ and in treatment groups (surgical and non-surgical)

cost-utility analysis will be completed alongside the clinical trial. Reporting will be from a societal perspective and with an one year timeframe. Utility will be measured in Quality Adjusted Life Years (QALY) by assigning values from the Danish eq-5d-5l reference set (i.e. each health state is assigned a value between -0.759 to 1.000 [40]. The follow-up period will be one year (t4). Costs will be collected from national registris. These, among others, include information on admissions, out-patient visits, home care services, contacts with general practitioners and other private healthcare professionals, prescription medication and welfare subsidies due to sick leave. Hours of informal care the last week patients receive from family and friends will be collected from patients at every follow-up (t1-t4). The reported amount will be assumed stable between time points. Valuation will based on the recommendations of the Health Technology Council and reported in euros (€) using the most

Carbon footprint of the BAF trial will be estimated by registrering activities associated with design, management and operation of the trial and summing the carbon of to estimate the overall carbon footprint (kgCO2e) using the Clinical Trial Carbon Calculator. Registered activities will be: cradle to gate estimate of ankle stirrups and foot-ankle braces, patients visits to hospital, mean of transportation to visits (car, public or bike, trial staff travel and mean of transportation to recruitments centers.

Adverse events are undesirable experiences that may occur during brace use as: i) skin irritation, blisters, or pressure sores due to poor fit, friction, or prolonged use, ii) swelling or increased edema, iii) pain or discomfort resulting from tightness, misalignment, or mechanical pressure, iv) delayed fracture healing due to excessive joint movement, v) Muscle atrophy or joint stiffness from immobilization, vi) reduced range of motion (ROM) and vii) removal of material (e.g., screws) due to discomfort or healing complications. Serious adverse events are complications requiring hospitalisation, surgical intervention, or posing a significant risk to the patient as i) death (e.g., an unexpected cardiac event occurring during the study period) ii) hospitalisation due to falls resulting from brace-related instability, iii) wound infection requiring inpatient treatment, potentially

A subgroup of patients will have their physical activity objectively evaluated using an accelerometer. The SENS Accelerometer is widely used and validated for young and older orthopedic patients. The accelerometer measures total accelerometer counts per day (a valid proxy for physical activity), rest time, standing time, active time (walking time, running, cycling), number of steps, movement intensity and sleep duration for four weeks. The total amount of accelerometer counts will be used to measure the level of physical activity between groups [39]. The accelerometer will be placed on the patients thigh at the day of randomization and followed for a minimum of 12 weeks.