Controlled-Potential Electromechanical Reshaping of Cartilage

An alternative to conventional “cut‐and‐sew” cartilage surgery, electromechanical reshaping (EMR) is a molecular‐based modality in which an array of needle electrodes is inserted into cartilage held under mechanical deformation by a jig. Brief (ca. 2 min) application of an electrochemical potential at the water‐oxidation limit results in permanent reshaping of the specimen. Highly sulfated glycosaminoglycans within the cartilage matrix provide structural rigidity to the tissue through extensive ionic‐bonding networks; this matrix is highly permselective for cations. Our studies indicate that EMR results from electrochemical generation of localized, low‐pH gradients within the tissue: fixed negative charges in the proteoglycan matrix are protonated, resulting in chemically induced stress relaxation of the tissue. Re‐equilibration to physiological pH restores the fixed negative charges, and yields remodeled cartilage that retains a new shape approximated by the geometry of the reshaping jig. Changing shape: In a molecular‐based alternative to “cut‐and‐suture” cartilage surgery, electrodes are inserted into tissues held under mechanical deformation. Electrolysis at the water‐oxidation limit generates highly localized regions of low pH that chemically relax the stressed tissue. Re‐equilibration to physiological pH yields cartilage permanently remodeled to the new shape of the jig.