High tibial osteotomy and additive manufacture can significantly reduce the climate impact of surgically treating knee osteoarthritis

Purpose: This study examines the climate impact of two surgical treatments for knee osteoarthritis, unicompartmental knee replacement (UKR) and high tibial osteotomy (HTO), also comparing conventional manufacturing (CM) with additive manufacturing (AM) for HTO. Factors beyond the implants themselves are considered that depend on the manufacturing method, such as surgical instruments and guides (jig), sterilisation, transport and anesthesia using data obtained first hand from manufacturers and a hospital. Method: The relevance of the comparative results are maximised beyond a specific manufacturer’s product by including uncertainty in the foreground and background life cycle inventories to represent uncertainty and variability of process characteristics, materials, and geographical location. The analysis is carried out in Brightway 2 using Ecoinvent inventory data and impacts are calculated across 18 mid-point categories. To consider possible improvement to the environmental impact of the surgical interventions, alternative electricity and surgical guide (jig) material scenarios are considered. Results: The climate change impact of UKR, 37.9 (36.8–38.9) kg CO2e, is highly significantly greater than that of the CM HTO, 10.7 (10.0–11.4) kg CO2e, and AM HTO, 13.4 (13.0–13.7) kg CO2e. The custom single-use surgical jig of the AM HTO and the use of potentially higher-carbon electricity leads to the AM HTO having an impact 1.25 (1.17–1.34) times higher than the CM HTO. But when low-carbon electricity is used and the surgical guide is made of stainless steel, this reduces to 0.78 (0.73–0.84). Initial screening of other lifecycle impact categories shows similar trends in most cases. Conclusions: This study concludes that HTO has highly significantly lower climate change impact than UKR. AM HTO has the potential to further reduce the climate impact compared to CM HTO given low-carbon energy supply and further improvements in material choice and design optimisation. Challenges include limited availability in design skill-set for optimisation and higher cost for healthcare providers compared to CM HTO, although still lower than the cost of UKR. Our study highlights policy implications: along with being a solution for early treatment and yielding improved correction accuracy compared to CM HTO, personalised AM HTO also offers environmental benefits if designed and manufactured well.