Probe for locating holes in orthopaedic internal fixation devices

摘要

The necessity of the use, sometimes excessive, of an image intensifier in order to localize the holes for the screws in the internal fixation procedure with an interlocking nail implies an increase of the risks of radiation exposure involving the orthopaedic surgeon, the operation theatre personnel and the patient. The use is proposed of a magneto-resisting probe which looks for a signal produced by 2 microelectromagnets fixed to a rod which is introduced along the intramedullary nail: a high frequency alternating signal is produced by the two microelectromagnets and is recorded by the probe on the skin. The probe is made of 4 magneto-resistive sensors arranged on orthogonal axes for a more precise and straightforward location in the x and y directions. A screen with 4 arrows shows the direction one should follow for correct centering over the holes. A fourth possibility is represented by a small neodymium magnet, which can be inserted as a plug in the nail hole or fixed to a rod inserted into the canal of the nail, allowing a quick and precise localization of the hole and reducing the exposition time to radiation as well as the overall surgical procedure duration.