Methods: Participants, interventions, and outcomes
Study setting
All patients treated for calcaneus fracture (DS920* ‘Fraktur af hælben’ according to the Danish SKS-browser) at the University Hospital Odense are prospectively screened for eligibility and included in the trial, if they fulfil the inclusion criteria as listed below. The follow-up period is 6 months.
Eligibility criteria
In Denmark, the treatment of calcaneus fractures is regarded as highly specialized, wherefore both decision-making and operations are done for the whole Region of Southern Denmark in the Department of Orthopaedics and Traumatology at the University Hospital Odense. Therefore, patients are screened by consultants of the local trauma section.
Inclusion criteria:
- Fracture of the calcaneus, which is classifiable according to the Sanders’ classification (excludes avulsion fractures)
- Being able to understand Danish or English and answer the questionnaires
- Informed consent
- Age between 18 and 65 years
Exclusion criteria:
- Pathological fractures including fractures associated with a Charcot foot
- Immature skeletal system
- Other fractures with influence on weight-bearing
- A soft-tissue situation not allowing the equipment with a ‘Settner shoe’ within 3 weeks after treatment (either decision-making for non-operative therapy or open reduction and internal fixation)
Interventions
After operation or decision for non-operative therapy, the schedule for the 2 groups are defined as follows:
Group 1 (treatment without ‘Settner shoe’):
- mobilization without weight bearing for 6 weeks starting with the day of either decision-making for non-operative therapy or open reduction and internal fixation, if needed a cast or another kind of orthosis as a Static Walker are applied, then 4 weeks 15-20 kg, 2 weeks 35-45 kg, after that transition to full-weight bearing (always only if possible)
- X-ray after 6 and 12 weeks; depending on the results, the schedule for weight bearing may be adjusted to the need in case of delayed healing or complications related to implants
Group 2 (treatment with ‘Settner shoe’):
- mobilization with the custom-made heel-unloading orthosis (‘Settner shoe’) without pads for 6 weeks, then 2 weeks one pad, 2 weeks 2 pads, 2 weeks 3 pads, after that full-weight bearing without any support (always only if possible)
- X-ray after 6 and 12 weeks; depending on the results, the schedule for weight bearing may be adjusted to the need in case of delayed healing or complications related to implants
The patients of both groups are informed about the aftercare at the time point of inclusion.
Outcomes
Overview about assessments
The schedule of enrolment, interventions, and assessments for the different variables is summariyed in table 1.
Primary outcome criterion
The number of active minutes per day following 3 months after fracture or decision for non-operative treatment (time point 3) is the primary outcome criterion.
Secondary outcome criteria
- active minutes per day at time point 1
- portion of highly active periods per day at time point 1 and 3
- the EuroQol 5D-3L questionnaire (5) following 3 months (time point 3)
Explorative outcome criteria
- AOFAS (time point 3) (6)
- 3-dimensional gait analysis (time point 2 if possible, and 4)
- time point of return to work of patients between 18 and 60 years
- Range of motion (ROM): Pro- and supination (percent of healthy side or assumed normal mobility) are analyzed as part of the clinical examination.
- Pain: The evaluation includes the medication and a visual-analogue scale (VAS).
- Comparison between patients with and without operation
Patient characteristics beside outcome criteria
Epidemiology
- age
- sex
- body mass index
- ASA (American Society of Anesthesiologists) physical status classification system
Injury characteristics
- classification according to Sanders (7)
- classification of open/closed tissue damage (8)
- polytrauma (ISS≥16, multiple injuries, monotrauma)
- indication for operation (dislocation, broadening, flattening of Böhler angle etc.) or conservative therapy (comorbidity, smoking etc.)
- the time between the fracture occurred and operation or decision making for non-operative therapy
Healing and treatment characteristics
- bone healing after 3 months: union or delayed healing
The decision is made based on conventional radiographs including the clinical description of complains.
- weight bearing after 3 months
Is it possible or not?
- hindfoot axis (varus/valgus-deformity, Böhler angle, subtalar osteoarthritis)
The decision is made based on conventional radiographs and a clinical evaluation.
- type of operation (approach, fixation method, graft)
Complications
- infection (I)
- deep venous thrombosis (DVT)
- nerve paresis/palsy/disturbed sensibility (N)
- subtalar posttraumatic osteoarthritis (PTOA) assessed using the Kellgren Lawrence score (9)
- subtalar instability (SI), clinically assessed
- local mechanical irritation by plate/screws (LI)
- wound irritations (WI) as superficial healing problems or skin edge necrosis
- irritations associated to the use of the custom-made heel-unloading orthosis (‘Settner shoe’)
Participant timeline
An overview about the timeline is provided in table 1. The clinical and radiological controls correlate with the usual guidelines for treating calcaneus fractures at the Odense University Hospital.
Sample size and power analysis
The sample size calculation was based on a 33% difference in activity, correlating with a clinical relevant difference. Setting the power to 80% and the 2-sided confidence interval to 95% the calculation according to the method of Fleiss with continuity correction resulted in 25 patients per group.
Recruitment
All consultants of the trauma section of the Department of Orthopaedics and Traumatology at the University Hospital Odense are involved in the recruitment process of the study.
Methods: Assignment of interventions (for controlled trials)
Allocation
In the period between treatment (either decision-making for non-operative therapy or open reduction and internal fixation) and consolidation of the soft-tissue situation, the patients are randomized for the aftercare with or without the custom-made heel-unloading orthosis (‘Settner shoe’). As soon as the soft-tissue situation allows the adjustment, the patients are referred to an orthopaedic shoemaker, who equips the patient accordingly. The randomization is done using the tool provided by OPEN.
Blinding (masking)
The allocation is not blinded, because it will be obvious to the patient, whether a special shoe is worn or not. Furthermore, the treating trauma surgeon needs to initiate the prescription.
Methods: Data collection, management, and analysis
Management and collection
REDCap™ (Research Electronic Data Capture), a secure application for online surveys and databases, facilitates data management. The University Hospital Odense is an institutional partner of REDCap™, which was especially designed for biomedical research and fulfills all necessary safety features. This is supported by the OPEN initiative (Odense Patient data Explorative Network). REDCap™ used with the OPEN-platform supports also a randomization function, which is used for the study. This agreement was approved by OPEN (project nr. 656, 18/29801).
Statistical methods
Normally distributed numeric data sets are compared using the paired Student’s t–test. Otherwise or in case of non-numeric data, nonparametric tests such as the Mann-Whitney U-test for two and the Kruskal-Wallis H-test for multiple variables determine the significance of difference. For correlations, Spearman ρ is calculated. Incidences are compared using the chi square test. For the binary outcomes, a logistic regression is calculated at least including the a-priori confounders age and sex. For continuous variables, a multiple regression is used, while both regression analyses include confounders identified by dichotomous calculations. The analysis will be done using the Intention-to-treat approach., which means that the patients are considered as using the orthosis when they were randomized in this group.
Methods: Monitoring
Data monitoring
After exception from OPEN, a data manager was assigned to the study, who supports the data coherence. Furthermore, a yearly data monitoring will be done by a study nurse, who is assigned to the project.
Harms
Any adverse or severe adverse events will be registered during the trial. Expected are especially local mechanical irritations, which are listed in the chapter for registration of patient characteristics beside outcome criteria.
Ethics and dissemination
Ethics
The study was approved by the ethical board of the Region of Southern Denmark (https://komite.regionsyddanmark.dk/wm258128, S-20170219).
Patient law/privacy
All data collected from patients are protected by the Act on Processing of Personal Data and Health Act according to Danish Data Protection Agency. The project was reported to the local data safety authorities (Datatilsynet under “Regionens Paraply 2012-58-0018”, 17/44501). The database was established with OPEN, however, other possible related files are stored in a secure Sharepoint (https://secure.regionsyddanmark.dk/projektrum/ProTibExPla/SitePages/Startside.aspx).
Publication
Reporting will be conducted according to Consolidated Standards of Reporting Trials (CONSORT guidelines (http://www.consort-statement.org/) and published in a peer reviewed journal. The authorships are granted according to the ICMJE (International Committee of Medical Journal Editors) guidelines.
Trial registration
The project was registered and approved by the Ethical Board Region Southern Denmark (Project-ID S-20170219). Furthermore, the project was approved according to the Act on Processing of Personal Data (Journal no. 17/44501). Moreover, the trial was registered at Clinicaltrials.gov (Identifier NCT03572816).
Access to data
The final analysis is done by LP and HS, who will have access to the final trial dataset. This is monitored by the assigned data manager (OPEN). The access to the data is regulated by the contract with OPEN.
Appendices
Measurement of physical activity
For monitoring of activity, the patients are equipped with an Axivity™ AX3 (Newcastle upon Tyne, UK) at the lateral femur of the unaffected side. If there is a fracture at both sides, the trackers are attached to the side with the less complicated fracture. The wear time is 7 days. At day 7±14 (discharge, time point 1) and after 3±1 months (time point 3) patients are equipped, and activity signals are analyzed by calculating the mean of all acquired 24-hour-data during these two periods. Regarding the Axivity™ AX3, the portion of highly active periods per day and the number of active minutes, correlating with walking activity, have shown to be most discriminating in the validation study (10). Therefore, these parameters are selected. Reliability is checked using a wear-time analysis based on change of signal vector magnitudes and temperature monitoring. Correlating with these two data points, the EuroQol 5D-3L questionnaire (5) and the AOFAS (6) are monitored.
Orthosis
The heel-unloading orthosis (‘Settner shoe’ (4)) can be used for conservative treatment and aftercare following surgery. It needs to be assembled out of pre-formed and size-adjusted parts. This is done by an orthopaedic shoemaker. The increase of weight bearing is achieved by pads. The first 6 weeks the shoe is worn without pads. Then, the first pad is applied. Every 2 weeks a further pad is put in the shoe, which is removed after 3 months. Preliminary data suggest that this heel-unloading orthosis reduce days of inability to work.
3-dimensional gait analysis
All outcome calculations will be based on measurements taken during gait using a 3D Vicon MX movement analysis system with eight cameras operating at 100 Hz (Vicon, Oxford, UK) and two AMTI force-plates (AMTI, OR6-7, Watertown, MA, USA) embedded at floor level, operating at 1,000 Hz. A technician experienced in gait analysis and the Vicon system will attach reflective markers that reflect infrared light according to the Vicon Plug-in-Gait marker set and model (11).
Patient involvement
The patients give feedback about the actual use of the orthosis including the possible benefit associate with its application. Furthermore, activity measurements provide objective data about patient mobility during early aftercare and signals feedback to the patient. By this, the patients themselves can control their postoperatively increasing activity. This includes a scientifically supported evaluation by the study investigators at the defined follow-up time points at 6 weeks and 3 months after therapy start.
Consent form
The consent form used during the trial is provided as supplementary material.