A Hybrid Discrete-Event and Agent-Based Simulation Approach to Model Circular Supply Chains in Healthcare: A Case Study of Laparoscopic Scissors

In the high-stakes environment of a modern hospital, a single pair of surgical scissors can determine the difference between a successful operation and a cancelled one. For decades, the standard practice has been simple: use a sharp, sterile instrument once, then throw it away. This linear approach is reliable and safe, but it generates a massive amount of waste and relies on a constant, energy-intensive supply of new products. As hospitals and governments look for ways to reduce their environmental footprint, a different path has emerged: the circular economy. This concept is not about recycling in the traditional sense of melting things down, but about keeping products in use for as long as possible through repair, cleaning, and reuse. However, shifting from a system of "use and discard" to one of "use and return" is incredibly complex. It introduces new uncertainties, such as how long it takes to clean an instrument, how often it breaks, and whether hospitals will have enough stock to keep surgeries running smoothly. Without a way to test these new systems before buying them, decision-makers risk either wasting money on equipment that never pays for itself or running out of tools during critical procedures.

To navigate this uncertainty, researchers at Nottingham Trent University, University College London, and Loughborough University turned to a powerful digital tool: a hybrid computer simulation. They chose a specific, widely used medical device, the laparoscopic scissors used in minimally invasive surgery, as their test subject. Instead of building physical prototypes or waiting years to see what happens in real hospitals, they constructed a virtual model of the entire supply chain. This model included the manufacturer, the distribution center, the hospitals, and the specialized facilities that clean and repair the instruments. The simulation acted as a risk-free laboratory where the team could run thousands of scenarios over a ten-year period, testing how different types of scissors would perform under real-world conditions of variability and delay.

The team compared the current standard—single-use scissors that are incinerated after one use—against three circular alternatives. The first option involved taking the single-use scissors, cleaning them, and remanufacturing them to look and function like new. The second option was a hybrid design, featuring a durable handle that could be reused many times but paired with a disposable blade that was thrown away after every surgery. The third option was a fully reusable instrument, where both the handle and the blade were designed to be cleaned, sterilized, and used again and again. The researchers ran these scenarios to see which approach would save the most money, reduce carbon emissions the most, and keep the hospitals running without interruption.

The results revealed that there is no single "best" solution; the right choice depends entirely on the specific goals and constraints of the hospital system. The study found that the most immediate and effective way to cut both costs and emissions was to simply start reusing the single-use scissors. When hospitals prioritized using these refurbished tools over buying new ones, the simulation showed a dramatic drop in expenses, saving nearly 41 percent of the total supply chain costs, while cutting carbon emissions by more than half. This approach worked because it reduced the need to manufacture new instruments from scratch, which is the most expensive and polluting part of the process.

However, the fully reusable scissors, while offering the greatest potential for environmental protection, came with a significant financial hurdle. These high-quality instruments are expensive to buy upfront. The simulation showed that a hospital would need to use the same pair of scissors between 45 and 50 times before the savings from not buying new ones would finally outweigh the initial investment. Once that point was passed, the system became cheaper than the traditional method, eventually saving about 19 percent over the long term. Yet, this long-term gain requires a hospital to commit to a system that demands rigorous cleaning, repair, and storage infrastructure, along with a dedicated staff to manage the flow of instruments.

The hybrid scissors presented a different kind of challenge. While they were environmentally friendly, becoming greener than the single-use option after just two uses, they failed to ever become financially viable in the simulation. The cost of the disposable blades remained too high, acting as a constant drain on the budget that the savings from reusing the handle could not overcome. Even if the handle lasted for 70 uses, the total cost remained 64 percent higher than the standard single-use system. This suggests that unless the price of the disposable blades drops significantly, this middle-ground option may not be a practical choice for hospitals trying to save money.

Beyond the financial and environmental numbers, the simulation highlighted a crucial operational reality: the speed of the cleaning process matters more than most people realize. When instruments are returned to the hospital, they must be decontaminated before they can be used again. The study showed that if this cleaning process is slow or unpredictable, hospitals must keep a much larger stock of spare scissors on hand to ensure they never run out. In scenarios where cleaning took a long time or varied wildly in duration, hospitals needed significantly more inventory to maintain a 100 percent success rate for surgeries. This finding provides a clear roadmap for hospital managers: adopting circular tools is not just about buying the right product, but also about investing in the speed and reliability of the cleaning and repair infrastructure.

Ultimately, this research suggests that the transition to a circular economy in healthcare is not a simple switch but a strategic balancing act. For hospitals looking to cut costs and emissions quickly, remanufacturing existing single-use tools offers the most immediate return. For those willing to invest in long-term sustainability and have the infrastructure to support it, fully reusable instruments offer the deepest environmental benefits, provided they can wait out the initial high costs. The hybrid approach, despite its intuitive appeal, appears to be a dead end under current market conditions. By mapping out these trade-offs, the study provides a clear guide for policymakers and hospital administrators, showing that the path to a greener healthcare system is paved with careful planning, realistic expectations, and a deep understanding of how every link in the supply chain affects the next.