Abstract
Aim of the study: Documentation of changes in retropa-tellar pressure, contact area and force after total knee arthroplasty in comparison with and without patella resurfacing devices.
Material and method: six cadaver specimen were examined after implantation of a total knee endoprosthesis (Genesis I type) with and without patella resurfacing implants of the sizes “small” und “medium”. Contact pressure and area measurements were done with Fuji Prescale Film (type super low) in a knee flexion angle of 60°.
Results: In comparison to the results without patella implants the implantation of the patella implant size “small” caused a significant decrease of retropatellar contact area (p=0.03) and force (p=0.03). Average and maximum pressure did not change significantly (p=0.6 and p=0.35) even though pressure increased slightly. For the „medium“ size maximum pressure (p=0.03) increased significantly and force decreased significantly (p=0,0277) whereas contact area and average pressure increased slightly.
Discussion: The significant reduction of contact area seen after implantation of both patellar implants may lead to non physiologic loading of the patella as well as to an unfavorable sliding behaviour of the femur.
Clinical relevance: Implantation of a patella resurfacing device can not significant change retropatellar pressure and the decrease of contact area is unfavorable because a small contact area can lead to accelerate wear debris and loosening. Implant size does not have a significant influence.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
