gms | German Medical Science

German Congress of Orthopaedics and Traumatology (DKOU 2015)

20.10. - 23.10.2015, Berlin

Patient-specific templates for total knee replacement. Analysis of the learning curve in an academic department

Meeting Abstract

Search Medline for

  • presenting/speaker Jean-Yves Jenny - Hôpitaux Universitaires de Strasbourg, CCOM, Illkirch, France
  • Marco de Gori - University Hospital Strasbourg, CCOM, Illkirch, France
  • Yann Diesinger - University Hospital Strasbourg, CCOM, Illkirch, France

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2015). Berlin, 20.-23.10.2015. Düsseldorf: German Medical Science GMS Publishing House; 2015. DocIN28-378

doi: 10.3205/15dkou010, urn:nbn:de:0183-15dkou0106

Published: October 5, 2015

© 2015 Jenny et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objectives: An appropriate positioning of a total knee replacement (TKR) is a prerequisite for a good functional outcome and a prolonged survival. Patient specific templates have been developed to achieve at least the same accuracy than conventional instruments at a lower cost. The learning curve of such systems has not yet been evaluated. We hypothesized that there was no learning curve at our academic department when using patient specific templates for TKR instead of the routinely used navigation system.

Methods: The first 20 patients operated on for TKR at our academic department using a patient specific template entered the study. All patients had a pre-operative CT-scan evaluation. The planning of the bone resections was defined by the operating surgeon on the CT-scan views with a dedicated software. The patient specific templates were positioned on the bone according to the best fit technique. The position of the templates was controlled at each step of the procedure by the navigation system, and eventually corrected according to the navigated measure to achieve the expected goal. The discrepancy between the initial and the final positioning was recorded for each direction of resection. The paired difference between each set of measurement was analyzed with appropriate statistical tests at a 0.05 level of significance.

Results: The mean difference between the initial positioning of the tibia template in the coronal plane was 1° ± 3° (p<0.01); 5/20 cases were off the expected range. The mean difference between the initial positioning of the tibia template in the sagittal plane was 1° ± 3° (p<0.001); 4/20 cases were off the expected range. The mean difference between the initial positioning of the femur template in the coronal plane was 1° ± 2° (p<0.01); 3/20 cases were off the expected range. The mean difference between the initial positioning of the tibia template in the sagittal plane was 2° ± 3° (p<0.01); 4/20 cases were off the expected range. After correction of the position according to the navigation system, all templates were placed in the expected range in all directions. There was a trend to improve the initial positioning of the templates at the end of the study, especially for the femoral template.

Discussion: The global accuracy of the system tested was less than optimal when compared to the navigated reference. The current system should not be used without extensive intra-operative control of the positioning of the templates. However, when the positioning of the templates was adequate, the orientation of the resection was correct. We conclude that the planning and manufacturing process may be adequate, but the question of the intra-operative positioning should be addressed. As the results about positioning improved during the time of the study, one might argue that one of the relevant question is the learning curve of the surgeon when using such templates. The present study is currently going on to further document this point.