Background There is informal consensus that simple compression fractures of the body of the thoracolumbar vertebrae between the 10th thoracic vertebra and the second lumbar vertebra without neurological complications can be managed conservatively and that obvious unstable fractures require surgical fixation. However, there is a zone of uncertainty about whether surgical or conservative management is best for stable fractures. Objectives To assess the feasibility of a definitive randomised controlled trial comparing surgical fixation with initial conservative management of stable thoracolumbar fractures without spinal cord injury. Design External randomised feasibility study, qualitative study and national survey. Setting Three NHS hospitals. Methods A feasibility randomised controlled trial using block randomisation, stratified by centre and type of injury (high- or low-energy trauma) to allocate participants 1 : 1 to surgery or conservative treatment; a costing analysis; a national survey of spine surgeons; and a qualitative study with clinicians, recruiting staff and patients. Participants Adults aged ≥ 16 years with a high- or low-energy fracture of the body of a thoracolumbar vertebra between the 10th thoracic vertebra and the second lumbar vertebra, confirmed by radiography, computerised tomography or magnetic resonance imaging, with at least one of the following: kyphotic angle > 20° on weight-bearing radiographs or > 15° on a supine radiograph or on computerised tomography; reduction in vertebral body height of 25%; a fracture line propagating through the posterior wall of the vertebra; involvement of two contiguous vertebrae; or injury to the posterior longitudinal ligament or annulus in addition to the body fracture. Interventions Surgical fixation: open spinal surgery (with or without spinal fusion) or minimally invasive stabilisation surgery. Conservative management: mobilisation with or without a brace. Main outcome measure Recruitment rate (proportion of eligible participants randomised). Results Twelve patients were randomised (surgery, n = 8; conservative, n = 4). The proportion of eligible patients recruited was 0.43 (95% confidence interval 0.24 to 0.63) over a combined total of 30.7 recruitment months. Of 211 patients screened, 28 (13.3%) fulfilled the eligibility criteria. Patients in the qualitative study (n = 5) expressed strong preferences for surgical treatment, and identified provision of information about treatment and recovery and when and how they are approached for consent as important. Nineteen surgeons and site staff participated in the qualitative study. Key themes were the lack of clinical consensus regarding the implementation of the eligibility criteria in practice and what constitutes a stable fracture, alongside lack of equipoise regarding treatment. Based on the feasibility study eligibility criteria, 77% (50/65) and 70% (46/66) of surgeons participating in the survey were willing to randomise for high- and low-energy fractures, respectively. Limitations Owing to the small number of participants, there is substantial uncertainty around the recruitment rate. Conclusions A definitive trial is unlikely to be feasible currently, mainly because of the small number of patients meeting the eligibility criteria. The recruitment and follow-up rates were slightly lower than anticipated; however, there is room to increase these based on information gathered and the support within the surgical community for a future trial. Future work Development of consensus regarding the population of interest for a trial. Trial registration Current Controlled Trials ISRCTN12094890. Funding This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 62. See the NIHR Journals Library website for further project information.