Coordinated control of miniature magnetic pumps for liquid sampling and delivery in a knee implant

Total knee arthroplasty (TKA) is widely used to surgically treat knee arthritis; however, clinical results remain suboptimal, with issues such as infection, aseptic loosening, and implant failure often requiring invasive revision surgery. Existing implants also lack integrated sensing and drug-delivery capabilities due to the challenge of embedding wireless pumps within constrained spaces. Here, we report a next-generation TKA device that integrates miniature magnetic pumps and wireless sensors for closed-loop, on-demand liquid delivery. The pumps are independently actuated by external magnetic fields below 15 mT, enabling simultaneous biofluid sampling and therapeutic release. Joint biofluid properties are monitored continuously, and ~70 μL of liquid can be refilled and delivered via magnetically driven pumping. The implant withstands compressive stresses of ~26.7 MPa, exceeding physiological loads during daily activities. Closed-loop functionality is validated in an ex vivo porcine bone. This device enables continuous implant health monitoring and targeted anti-inflammatory therapy, advancing intelligent orthopedic implants.