The CARBO CARBON Study: a Prospective Observational Comparative Cohort Study on CO2 Emissions From Metacarpal Shaft Fracture Treatment

Overview

This study examines the environmental impact of two common treatments for hand fractures (metacarpal shaft fractures): surgery and non-surgical care. Healthcare contributes significantly to climate change, and orthopedic surgery in particular can generate substantial greenhouse gas emissions. Although surgery is frequently used for these fractures, it is not always clearly more effective than 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 carbon footprint of each treatment pathway, from injury through one year of follow-up. This includes emissions related to medical equipment, energy use, medications, and waste. The goal is to calculate the difference in environmental impact between treatments and to highlight key sources of emissions. The findings may help guide more sustainable healthcare practices without compromising patient care.

Healthcare contributes substantially to global greenhouse gas emissions, with orthopaedic 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 over non-operative management. The difference in environmental impact of the two treatment options remains unexplored. This prospective multicentre observational comparative cohort study is conducted alongside a randomized controlled trial (The CARBO trial). Carbon emissions will be estimated using mainly a carbon foot printing bottom-up approach based on detailed activity data for materials, energy use, pharmaceuticals and waste across the treatment pathway from injury to 12 months post-treatment. Where a bottom-up approach is unavailable, an environmentally extended input-output (EEIO) model will be applied. Emissions will be calculated within defined system boundaries within Scopes 2 and 3 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 waste generation, emission hotspots and direct cost differences. Appropriate parametric or non-parametric statistical tests will be applied to estimate the differences between treatments. The robustness of the primary outcome (CO₂e emissions) will be evaluated using one-way sensitivity analyses and scenario analyses in which key model parameters are varied. The study evaluates environmental impact 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.