Modelling Micromotion of Implants in the Rat Femur: A rat femoral knee prosthesis to simulate aseptic loosening

Background: Aseptic loosening [AL] of cementless implants is causing approximately 60% of total knee and total hip arthroplasty revisions. AL is caused among other factors by micromotion. The result is that the bone around the prosthesis is replaced by a fibrous membrane. This fibrous membrane allows for more micromotion and we thus enter a...

Inducible Displacement of a Knee Implant: A finite element study and validation of a loose and fixed tibial component

Introduction. Aseptic loosening is indicated as the main cause of knee implant failure. Despite all currently used techniques, it remains challenging to diagnose an aseptic loose knee implant. A promising technique to reveal aseptic loose related implant motions is inducible displacement (ID). ID measurements are used to detect implant motion...

Prevention of pin tract infections in external fixation by an electric current

Pin tract infection is a prevalent complication in treatments with external fixation. This study focused on the external fixation utilized for the knee joint distraction treatment. In a previous study initiated by the UMC Utrecht 85% of the patients got at least one pin tract infection during this treatment. A pin tract infection is caused by...

A Configurable Guide for Knee Arthroplasty

In total knee arthroplasty (TKA) the contact surfaces of the knee are replaced with prosthetic components. In order to fit the prosthetic components, the bones are shaped by making bone cuts. Patient specific surgical guides (PSSGs) are guides made from CT or MRI images to fit the patient’s anatomy. They guide the bone cuts. When bone deviations...

Structural and mechanical characterization of the peri-prosthetic fibrous membrane

In this pilot study, we obtained the peri-prosthetic fibrous membrane of eleven patients undergoing hip revision surgery due to aseptic loosening. We investigated the molecular content of the tissue by real-time PCR (RT-PCR) and the structural properties by histology and confocal microscopy. Atomic force microscopy (AFM) and nanoindentation were...

Control of cement penetration in TKA

Design project with the aim to improve cement penetration in the proximal tibia during total knee arthroplasty. A cement application guide was designed to facilitate procedure reproducibility and increase effective cement pressure.

A New Approach to Reduce Positional Errors of Surgical Guides for Arthroplasty

Orthopaedic surgeons can be assisted by Patient Specific Surgical Guides (PSSGs) during the determination of prostheses’ alignment in joint replacement surgeries. These guides are designed preoperatively – using Magnetic Resonance Imaging (MRI) or Computer Tomography (CT) – to have a matching contact surface with the patient’s bone. This enables...

Inherently safe water jet dissector

Aseptic loosening is the major failure mode for hip prostheses. Currently, loosened prostheses are revised during open surgery. Because of a high complication rate, this demanding procedure cannot be performed in patients with a poor general health. We are developing an alternative minimally invasive refixation procedure that leaves the...

Design of High Viscosity Cement Gun for Vertebroplasty

Vertebroplasty is a minimally invasive procedure for treating spine. Cement leakage is problem occurring from usage of low viscosity bone cements. High viscosity bone cements are difficult to inject with current design of cement gun due to very high injection forces. A new design of cement gun is developed for injection of high viscosity bone...