PREOPERATIVE PLANNING FOR HIP AND KNEE REPLACEMENT ON A PC AS A FIRST STEP OF COMPUTER ASSISTED SURGERY

Abstract

Computer-based preoperative planning of orthopaedic interventions will gain increasing importance due to the following trends.

Digitalisation of x-ray equipment and installation of PACS in hospitals for electronic distribution and archiving of diagnostic images, corresponding need of planning procedures which directly process the digital images on a computer, forensic aspects within the scope of growing demands on documentation and quality assurance.

This paper presents the modiCAS software framework as an example which has been developed to meet these requirements. It is characterised by specific features that greatly enhance computer-based pre-operative planning of total hip and knee replacement procedures. The planning process can be compiled such that it is controllable by just three control buttons on the computer screen. Thus planning can be done very efficiently and does not demand more time than conventional film-based procedures on a light-box.

The software uses 3D-templates of the implants. It facilitates more informative planning even if standard 2D x-ray pictures are used, for example by showing the anteversion of the cup prosthesis in hip replacement. In case of accurate and patient-specific scaling of the x-ray images important parameters can be determined such as the required size of the implants, as well as offset and leg-length corrections. Future versions of the software will have a link to navigation systems and robotic assistance systems to support intra-operative realisation of the preoperative planning.

The modiCAS software is a manufacturer-independent solution which is not limited to certain implant or PACS producers. Its integrated DICOM interface facilitates data input from all compatible modalities, and the storage of the planning results at the end of the procedure. The library of available implant templates already comprises the most common implants and is continuously updated.