Electromechanical reshaping (EMR) provides a means of producing shape change in the cartilage by initiating oxidation–reduction reactions in mechanically deformed specimens. This paper evaluates the effect of voltage and application time on specimen shape change using needle electrodes. Rabbit septal cartilage specimens (20 mm × 8 mm × 1 mm, n = 200) were bent 90° in a precision-machined plastic jig. Optimal electrode placement and the range of applied voltages were estimated using numerical modeling of the initial electric field within the cartilage sample. A geometric configuration of three platinum needle electrodes 2 mm apart from each other and inserted 6 mm from the bend axis on opposite ends was selected. One row of electrodes served as the anode and the other as the cathode. Constant voltage was applied at 1, 2, 4, 6, and 8 V for 1, 2, and 4 min, followed by rehydration in phosphate buffered saline. Samples were then removed from the jig and bend angle was measured. In accordance with previous studies, bend angle increased with increasing voltage and application time. Below a voltage threshold of 4 V, 4 min, no clinically significant reshaping was observed. The maximum bend angle obtained was 35.7 ± 1.7° at 8 V, 4 min.

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.

An alternative to conventional "cut-and-sew" cartilage surgery,e lectromechanical reshaping (EMR) is am olecular-based modality in whicha na rrayo fn eedle electrodes is inserted into cartilage held under mechanical deformation by aj ig. Brief (ca. 2min) 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;t his matrix is highly permselective for cations.Our studies indicate that EMR results from electrochemical generation of localized, low-pH gradients within the tissue:f ixedn egative charges in the proteoglycan matrix are protonated, resulting in chemically induced stress relaxation of the tissue.R e-equilibration to physiological pH restores the fixednegative charges,and yields remodeled cartilage that retains anew shape approximated by the geometry of the reshaping jig.Hyaline cartilage forms underlying structural features of the head and neck, and serves acritical functional role in the upper airway.[1] Congenital defects,t rauma, and disease can damage cartilage tissue,necessitating surgical intervention to reshape (or replace) damaged (or missing) structures. [2] Conventional open surgery is characterized by long recovery times,s ignificant tissue morbidity,a nd high cost;r eshaping living tissue using less invasive techniques is thus the subject of active research. [3,4] Most alternative methods focus on modifying the bulk mechanical properties of cartilage,that is, by using laser or radiofrequency( RF) heat generation to denature and/or accelerate stress relaxation by exploiting the thermoviscoelesticity common to collagenous tissues.[5] Our work focuses instead on novel electrochemical modalities that transiently alter the chemical properties of tissue,p roviding amolecular-based alternative to the scalpel and sutures.Originally conceived as at hermal technique in which electrical current flow through cartilage would cause resistive heating, [6] "electromechanical reshaping" (EMR) was developed as al ow-cost technique for reshaping cartilage.E MR combines mechanical deformation with the application of electric fields:i natypical embodiment, cartilage is held in mechanical deformation by am old or jig, needle electrodes are inserted into the tissue,and aconstant voltage (e.g.,5V) is applied across the specimen for several minutes.Whenthe electrodes and mold are removed, the cartilage assumes anew shape that approximates the geometry of the mold (e.g.,a908 8 bend). [7] Although effective shape change has been demonstrated in several animal models, [8,9] the process often is accompanied by tissue injury near the electrode-insertion sites;m oreover, the relationship between shape change and the duration and magnitude of the applied voltage can be unpredictable.T he lack of detailed mechanistic insight into the molecular changes that occur during EMR has impeded its development as ap rac...