Intraoperative analysis of uncemented cup implantation

P. Messer, J. Bätz, M.M. Morlock, G. Campbell

Uncemented hip prostheses are well established as common surgical method in total hip arthroplasty (THA). Primary stability in theses implants is achieved by the principle of press-fit, whereby an oversized implant is inserted into an undersized reamed cavity.

Inaccuracies in the reaming of the acetabular cavity and malpositioning of the acetabular cup can lead to an insufficient seating and therefore to a reduced primary stability of the implanted cup. This may lead to a loosening of the implant which is a major cause for revision surgery.

A human cadaver study simulating a hip implantation was implemented to analyse impact forces, cavity preparation and variabilities in the surgical technique in order to investigate certain factors on a THA in a more realistic setting than in the laboratory. By using a portable 3D laser scanner system it is possible to non-invasive assess acetabular cup implantation intraoperatively. After implantation cup deformation, effective press-fit, the reamed acetabular cavity and the contact area at the bone-implant interface can be quantified by this method. With additional CT scans during the surgery the positon of the cup can be linked to the gained data as well as to the primary stability, which is measured by levering-out the implant.

These data are essential for monitoring the implantation procedure in order to understand and improve cup implantation and to prevent failures.

Publications:

Messer P., Bätz J., Lampe F., Püschel K., Klein A., Morlock M.M., Campbell M. G. (2016), A Non-tactile Method for Analyzing the Deformation and Press-fit of Uncemented Acetabular Cups, 22nd Congress of the European Society of Biomechanics

Messer P., Bätz J., Lampe F., Püschel K., Klein A., Morlock M.M., Campbell M. G. (2017), Contact Conditions of Acetabular Press-fit Cups and their Influence on the Restoration of the Hip Rotation Center, Annual Congress of the International Society for Technology in Arthroplasty (ISTA)