INTRAMEDULLARY NAILING WITH COMPUTER ASSISTED SURGERY

Abstract

Orthopaedic surgeons are often found with critical procedures in trauma surgery that involve precise action on the underlying bony fragments without direct surgical access. This is exemplified by the intramedullary nailing technique, which is successfully used in many orthopaedic and trauma departments. Besides surgical actions on the surrounding soft tissues it involves fracture reduction as well as control of leg length and antetorsion angle. Distal locking of the inserted nail provides secure fixation to the bone fragments. To date accurate and safe performance of these steps remains a challenge in particular for the less experienced surgeon and can often only be achieved with extensive use of the image intensifier.

We have recently proposed a novel computer based technique, which was achieved combining intraoperative fluoroscopy based imaging using widely available C-arm technology with modern freehand surgical navigation. Modules were developed to automate digital X-ray image registration, which allows the real-time image interactive navigation of surgical tools based on one single registered X-ray image with no further image updates. Furthermore, the system allows the acquisition and real-time use of multiple registered images, which provides an advanced pseudo 3D control. Projection parameters were used effectively for intraoperative measurements on the patient’s anatomy, e.g. to determine bone axes, anatomic angles (e.g. femoral antetorsion), distances (e.g. leg length).

The system has been adapted to intramedullary nailing through the development of special stereotactic instruments and appropriate graphical user interfaces. A detailed validation of the prototype system was performed in laboratory settings and throughout early clinical trials. Currently the system is in routine use in various European clinics. Based on the resulting data the novel technique holds promises for improved accuracy and safety.