How Can the Environmental Impact of Orthopaedic Surgery Be Measured and Reduced? Using Anterior Cruciate Ligament Reconstruction as a Test Case
Authors: Silva de Souza Lima Cano Nathalia , Engler Ian D. , Mohammadiziazi Rezvan , Geremicca Federica , Lawson Dylan , Drain Nicholas , Musahl Volker , Lesniak Bryson P. , Bilec Melissa M. 
Published: December 2024

Background
The healthcare sector in the United States has increased its greenhouse gas emissions by 6% since 2010 and today has the highest per capita greenhouse gas emissions globally. Assessing the environmental impact and material use through the methods of life cycle assessment (LCA) and material flow analysis (MFA) of healthcare procedures, products, and processes can aid in developing impactful strategies for reductions, yet such assessments have not been performed in orthopaedic surgery. We conducted an LCA and an MFA on an ACL reconstruction (ACLR). The ACLR served as a test case on the assumption that lessons learned would likely prove relevant to other orthopaedic procedures.

Questions/purposes
(1) What are the life cycle environmental impacts of ACLR? (2) What is the material flow and material circularity of ACLR? (3) What potential interventions would best address the life cycle environmental impacts and material circularity of ACLR?

Methods
First, we conducted an LCA according to International Organization for Standardization standards for quantifying a product’s environmental impact across its entire life cycle. One result of an LCA is global warming potential measured in carbon dioxide equivalent (CO2eq), or carbon footprint. Second, we conducted an MFA of ACLR. Material flow analyses are used to quantify the amount of material in a determined system by tracking the input, usage, and output of materials, allowing for the identification of where materials are consumed inefficiently or lost to the environment. To contextualize the MFA, we calculated the material circularity indicator (MCI) index. This is used to measure how materials are circulating in a system and to evaluate the extent to which materials are recovered, reused, and kept within the economic loop rather than disposed of as waste. These three methods are widely used in other fields, especially engineering, but are more limited in healthcare research. Data collection and observations of ACLRs were made during ACLRs at the University of Pittsburgh Medical Center Bethel Park Surgical Center in Pittsburgh, PA, USA, between 2022 and 2023. Three sessions of data collection and observations were needed due to complexity and scheduling, ranging from understanding the sterilization procedures to weighing individual items. Data encompassing electricity usage; surgical equipment type; the use of heating, ventilation, and air conditioning (HVAC) systems; the production and reuse of reusable instruments and gowns; and the production and disposal of single-use surgical products were collected. Following data collection, we conducted the LCA and the MFA and then calculated the MCI for a representation of a single ACLR. To identify strategies to reduce the environmental impact of ACLR, we modeled 11 possible sustainability interventions developed from prior work and compared those strategies against the impact of the baseline ACLR.

Results
Our results show that the ACLR generated an estimated life cycle greenhouse gas emissions of 47 kg of CO2eq, which is analogous to driving a typical gasoline-fueled passenger vehicle for 120 miles. The total mass of all products for one ACLR was estimated at 12.73 kg, including 7.55 kg for disposable materials and 5.19 kg for reusable materials. Concerning material circularity, ACLR had a baseline MCI index of 0.3. Employing LCA for the carbon footprint and the MCI for 11 sustainability interventions indicated the potential to reduce greenhouse gas emissions by up to 42%, along with an increase in circularity (how materials are recovered, reused, and kept within the economic loop rather than disposed of as waste) of up to 0.8 per ACLR. Among the most impactful interventions are the reduction in the utilization of surgical pack products, reutilization of cotton towels and surgical gowns, maximization of energy efficiency, and increasing aluminum and paper recycling.

Conclusion
ACLR has a substantial carbon footprint, which can meaningfully be reduced by creating a minimalist custom pack without material wastage, reusing cotton towels, and maximizing recycling. Combining LCA, MFA, and MCI can provide a thorough assessment of sustainability in orthopaedic surgery.

Clinical Relevance
Orthopaedic surgeons and staff can immediately reduce the environmental impact of orthopaedic procedures such as ACLR by opening fewer materials—via making minimalist packs and only opening what is needed in the operating room—and by incorporating more reusable materials such as towels. Larger scale medical center changes, such as implementing recycling programs and installing energy-efficient systems, also can make a meaningful difference in reducing environmental impact.