Extracorporeally length-adjustable implant system, and length-adjustable implant component

An extracorporeally length-adjustable implant system comprising

• an implant component for an implantable prosthesis for attachment to a bone to be lengthened having an adjustment device comprising two fastening parts that are displaceable relative to one another, each of which is to be arranged on a part of the bone to be lengthened, wherein the adjustment device is designed to displace the two fastening parts, and comprises a drive element comprising a permanent magnet arranged rotationally movably, and a gearing mechanism to convert the rotational movement of the permanent magnet into a displaceable longitudinal movement of the adjustment device;
• and
• an extracorporeal drive unit for the drive element of the implant component, wherein
• the extracorporeal drive unit comprises a rotatably mounted extracorporeal magnet ring having an interior which is designed to receive the bone to be lengthened with the adjustment device, and an actuation device which is designed to rotate the extracorporeal magnet ring in its ring plane, wherein the extracorporeal magnet ring is designed as a permanent magnet structure and has, in its interior, a static magnetic field, which is stationary with respect to the ring, and the extracorporeal magnet ring is mechanically rotatable by the actuation device, wherein the magnet ring can be divided into at least two segments creating an openable and closable access for a body part provided with the implant component to the interior of the magnet ring, wherein the segments can be unfolded into an open position of the magnet ring.