Abstract
Orthopedics is a field of surgery that focuses on the musculoskeletal system. This includes procedures such as hip replacements and spinal fusions. Bone density is a critical property surgeons must consider when operating on a patient, as an accurate approximation of density helps inform crucial decisions during the procedure. Specifically, it influences the type of fixation screws needed and what their ideal location is. Current methods to approximate density are through external radiology technology such as CT scans or x-ray absorptiometry (Foreman, 2024). While this technology is reliable, it is still a relatively inaccurate measurement. Therefore, a more precise means to measure bone density would improve overall surgery success while lessening both costs and operation length.
My senior design project was to develop a device that provides an instantaneous density estimation. The device needed to accommodate varying drill bit sizes while also being compact and sterilizable. Since the density would be calculated by the change in torque, we first needed to relate these two properties. After some initial testing, we plotted our data on a torque vs density graph and added a line of best bit, providing us with this essential relationship. Following initial brainstorming, we decided the most optimal method to measure density would be by constructing a load cell that attaches to the drill chuck. The device would measure the micro changes in strain as a pilot hole was being drilled. After building the load cell, we could then apply an expected torque and measure the strain output. The relationship between torque and strain can then be plotted similarly to how it was for the torque and bone density. After determining typical strain ranges reached when drilling into different sections of bone, we programmed an LED to display different colors associated with each range. Ideally, when a surgeon drills into a dense enough section, the LED will shine green, indicating its quality. We then 3D-printed two plastic collars to hold the microcontroller and power source which can then slide onto our rod. The data can then be relayed from the microcontroller to a CSV file on a nearby computer that the surgeon can view.
The process of developing this medical device directly inspired my research question: how would a public healthcare system affect medical research and development in the United States? Healthcare in the United States is one of the world’s most complex, consisting of a predominantly private structure. As of 2022, Americans paid an average of $13,000 for their healthcare, over double the rate of other wealthy nations (PGPF, 2024). Furthermore, the average life expectancy in the United States is 76.4 years, nearly 6 years shorter when compared to other OECD nations (OECD, 2023). A frequent argument in favor of privatized health insurance is its contribution to medical research and development. The United States accounts for over 40% of medical development spending, investing over 245 billion dollars every year (Research America, 2023). This heavy investment in research and development has led to extraordinary results in the private sector. The United States develops the most new molecular entities (NMEs) in the world, which are drugs that contain an active ingredient not approved by the FDA. The U.S. accounted for 43.7% of all NMEs synthesized between 1992 and 2004 (Keyhani, 2010). The crux of the issue is whether the United States can still maintain its lead in medical innovation, while simultaneously improving its healthcare quality. Both domestic and international studies support a positive relationship between public health insurance and medical research and development. Most point to a complementary trend between public funding and private R&D. For example, an English study found that a 1% increase in the United Kingdom’s public sector expenditure is associated with a 0.81% increase in private sector expenditure (Sussex, 2016). Furthermore, a Chinese study found that the correlation between health insurance and pharmaceutical innovation is higher in countries with universal basic healthcare (r=0.473) when compared with the United States (r=0.236) (Fan, Song, and Li, 2023). My suggestion is that the United States model their healthcare system off a country like the United Kingdom, as it costs, on average, £2,892 ($3,836) per person. Despite this, the U.K. still has an active private sector that is a leader in medical research and development. When compared to the United States, they were more efficient in pharmaceutical innovation relative to their GDP contributions (Keyhani, 2010).
