Replicating a tissue with sound waves.

Tailoring implants to an individual's anatomy can offer better surgical outcomes and patient satisfaction. Traditionally, patient-specific artificial components, such as breast implants or hip joints, are sculpted outside of a body and inserted by open surgery. Additive manufacturing, or three-dimensional (3D) printing, offers an alternative to quickly build personalized implants with complex shapes (1–4). 3D printing using infrared light has enabled the patterning of complex shapes underneath submillimeter-thick skins or muscles (5). In this approach, irradiating tissue-embedded polymer inks with light triggers polymerization. However, considerable attenuation and scattering of light beams by intervening tissues limit direct printing of implants beneath millimeter-thick tissues. On page 616 of this issue, Davoodi et al. (6) report 3D printing using ultrasound rather than light to create complex structures underneath centimeterthick tissues inside an animal body. This process could potentially be combined with conventional ultrasound imaging to customize the shapes of implants on demand. [ABSTRACT FROM AUTHOR]