Material-Intrinsic NIR-Fluorescence Enables Image-Guided Surgery for Ceramic Fracture Removal

Hip arthroplasty effectively treats advanced osteoarthritis and has therefore been entitled as 'operation of the 20th century.' With demographic shifts, the USA alone is projected to perform up to 850,000 arthroplasties annually by 2030. Many implants now feature a ceramic head, valued for strength and wear resistance. Nonetheless, a fraction, up to 0.03% may fracture during their lifespan, demanding complex removal procedures. To address this, a radiation-free, fluorescence-based image-guided surgical technique is proposed. The method uses ceramics' inherent fluorescence, demonstrated through chemical and optical analysis of prevalent implant types. Specifically, Biolox delta® implants exhibit strong fluorescence around 700 nm with a 74% photoluminescence quantum yield. We identified emission tails extending into the near-infrared (NIR-I) biological transparency range, forming a vital prerequisite for the label-free visualization of fragments. This ruby-like fluorescence can be attributed to Cr within the zirconia-toughened alumina matrix, enabling the detection of even deep-seated millimeter-sized fragments via camera-assisted techniques. Additionally, fluorescence microscopy detects μm-sized ceramic particles, enabling debris visualization in synovial fluid or histological samples. This label-free optical imaging approach employs readily accessible equipment and can seamlessly transition to clinical settings without significant regulatory barriers, thereby enhancing the safety, efficiency, and minimally invasive nature of fractured ceramic implant removal.