Ingrown nail correcting device using Cu-Al-Mn shape memory alloy

  Cu-based shape memory (SM) alloys are fascinating for industrial fields, however their brittleness due to the high degree of order has been one of the problems for practical applications.  For the past decade, we have investigated Cu-Al-Mn SM alloys and it was found that an excellent cold-workability and superelasticity can be obtained by controlling the degree of order and the microstructure.  Recently, we have developed a medical device for ingrown nail, which is one of the most common foot maladies, leading to significant pain in foot, using the Cu-Al-Mn SM alloy.  The new method to correct ingrown nails consists of clipping the device in the tip of an ingrown nail, keeping the curved nail straightened using the recovery force of the superelasticity.  This treatment is not invasive and the device has a clip-type shape to be removed easily by patients.  One of the important factors in the Cu-Al-Mn alloy is its good cold-workability necessary for forming the complicated shape of the device, and another characteristic feature is the low dependence of a shape recovery stress on temperature change, which means that the correcting force is less affected by temperatures.  The nail correction treatments using the device have been carried out, and it was found that the device has enough corrective force and that it produces a satisfactory therapeutic success quickly in most cases without any local pain.  Therefore, it is suggested that this simple technique be considered as a new method for ingrown nail treatment.