The CARBO CARBON Study
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Non-operative treatment, Surgical fixation.
- Who it may be relevant to
- Registry conditions: Metacarpal Shaft Fractures, Greenhouse Gas Emissions. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Sweden
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Official title
The CARBO CARBON Study: a Prospective Observational Comparative Cohort Study on Environmental Impact From Two Metacarpal Shaft Fracture Treatment Pathways
Overview
This study examines the environmental impact of two common treatment pathways for hand fractures (metacarpal shaft fractures): surgical and non-surgical management. Healthcare contributes significantly to climate change, and orthopedic surgery in particular generates substantial greenhouse gas emissions. Although surgical treatment is frequently favored for these fractures, it is not always superior to non-surgical treatment, and the difference in environmental impact between these options is not well understood. In this study, researchers will measure and compare the environmental impact of each treatment pathway, from inclusion to twelve months follow-up. This includes environmental impact related to single-use material, medical equipment, energy use, medications, and waste. A Life Cycle Assessment (LCA) will be performed and a mean difference in environmental impact between treatments pathways will be calculates. A Hotspot analysis will also be performed to highlight key sources of environmental impacts. The findings may help guide more sustainable healthcare practices without compromising patient care.
Detailed description
Healthcare contributes substantially to global greenhouse gas emissions, with orthopedic surgery representing a resource- and carbon-intensive part of the healthcare system. For metacarpal shaft fractures, surgical treatment is widely used despite limited evidence of superiority to non-operative management. The difference in environmental impact of the two treatment options remains unexplored.
This prospective multicenter observational comparative cohort study is conducted alongside a randomized controlled trial called the MetaCARpalBOne trial (The CARBO trial). Environmental impact will be estimated using LCA according to four standard phases: (1) goal and scope definition, (2) Life Cycle Inventory (LCI), (3) Life Cycle Impact Assessment (LCIA) and (4) interpretation including sensitivity and uncertainty analysis. All this will be based on detailed activity data for materials, energy use, pharmaceuticals and waste across the treatment pathway from inclusion in the study to 12 months post-treatment. Climate change impact will be calculated within defined system boundaries and expressed as kilograms of carbon dioxide equivalent (CO₂e) per treatment pathway. The primary outcome is the difference in mean CO₂e between treatment groups. Secondary outcomes include fine particulate matter formation, water consumption, weight of combustible waste and direct cost differences. Explorative outcomes will include all other environmental impact categories covered by the selected LCIA method and identification of major emission hotspots.
Appropriate parametric or non-parametric statistical tests will be applied to estimate the difference between treatment pathways. Normal distribution will be tested by Kolmogorov-Smirnov and Shapiro Wilk's test. If data is not normally distributed, we will present a median with a corresponding interquartile range and compare groups by Mann-Whitney U-test. To account for uncertainty both in the life cycle assessment (LCA) estimates and in the intervention effect, Monte Carlo-generated datasets will be analyzed using a linear mixed-effects modelling approach. The robustness of the results for the primary and secondary outcomes will be assessed using sensitivity analyses changing key assumptions regarding: energy mix, lifespan of products, allocations, and anesthesiology methods.
The study evaluates environmental impact and costs only and does not involve analysis of personal data. Ethical approval has been obtained from the Swedish Ethical Review Authority (DNR 2025-04413-01; amendment DNR 2025-07659-02). Results will be disseminated through peer-reviewed publications.
Interventions
- Procedure Non-operative treatment
Non-operative treatment through immediate unrestricted mobilization with optional buddy taping or removable splinting for comfort. - Procedure Surgical fixation
Open reduction and internal fixation with plate and screws or screws only, followed by postoperative imobilisation and rehabilitation.
Primary outcome measures
- Global warming potential [Time frame: 12 months]
Secondary outcome measures (4)
- Ambient air pollution [Time frame: 12 months]
- Water comsumption [Time frame: 12 months]
- Waste [Time frame: 12 months]
- Direct costs [Time frame: 12 months]
Eligibility criteria
Inclusion Criteria for the CARBO trial:
Age ≥18 years.
Access to a valid e-mail.
Injury within 10 days prior to inclusion.
Normal bilateral hand function prior to injury.
Ability and willingness to provide written informed consent
Single, displaced spiral or oblique diaphyseal fracture of the second to fifth metacarpals with definition of diaphysis as described by AO 2018 (AO/OTA as 77.2-5.2A) (Meinberg et al., 2018).
Fracture line length at least twice the diameter of the bone at the level of the fracture.
Fractures with at least 2 mm of radiological displacement and/or malrotation of injured finger compared to uninjured side regardless of fracture displacement.
Exclusion criteria
The patient is not expected to have difficulty adhering to the study protocol (e.g., due to insufficient language proficiency, dementia, substance abuse, or other reasons).
The patient does not have an open fracture (Gustilo-Anderson grade > I) or a pathological fracture.
The patient does not have an ipsilateral fracture of the upper extremity, polytrauma, or generalized joint dysfunction (e.g., rheumatoid arthritis).
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Observational model
- Cohort
Study locations
Sweden · 1 center
- Karolinska Institutet, Danderyd's hospital — Stockholm
Identifiers
NCT: NCT07521943 · 2025-07659-02