Wireless knee joint monitoring using biodegradable single-ended pressure sensor in osteoarthritis management

Knee joint loading regulates cartilage regeneration and degeneration, influencing both healing and osteoarthritis (OA) progression. Although defining the optimal range of loading is essential, in vivo measurement remains challenging because current nonbiodegradable sensors require removal surgeries, and computational models provide only indirect estimates. Here, we report a fully biodegradable, implantable piezoelectric pressure sensor composed of biocompatible materials and designed with a single-ended configuration, consisting of only one electrode. This configuration maintained stable performance for more than 2 months, which, to our knowledge, is among the longest functional lifetimes reported for biodegradable pressure sensors. Ex vivo studies simulating the in vivo environment demonstrated accurate monitoring of intracranial pressure and knee movement, while in vivo implantation in a rabbit model confirmed both robust biocompatibility and reliable monitoring of joint loading during natural activities. This platform could enable feedback-guided, personalized rehabilitation regimes for OA management by identifying optimal joint loading conditions.