Abstract
INTRODUCTION
We wanted to assess the possible correlation between the intra-operative kinematics of the knee and the clinical results after total knee replacement (TKR).
MATERIAL
187 cases of TKR implanted with help of a navigation system for end-stage osteoarthritis have been prospectively analyzed. There were 127 women and 60 men, with a mean age of 71.4 years. Indication for TKR was osteoarthritis in 161 cases and inflammatory arthritis in 26 cases.
METHODS
A floating platform, PCL preserving, cemented TKR was implanted in all cases. A non-image based navigation system was used in all cases to help for accuracy of bone resections and ligamentous balancing. The standard navigation system was modified to allow recording the three-dimensional tibio-femoral movement during passive knee flexion during the surgical procedure. Two sets of records have been performed: before any intra-articular procedure and after final implantation. Only antero-posterior femoral translation (in mm) and internal-external femoral rotation (in degrees) have been recorded. Kinematic data have been analyzed in a quantitative manner (total amount of displacement) and in a qualitative manner (restoration of the physiological posterior femoral translation and femoral external rotation during knee flexion). Clinical and functional results have been analyzed according to the Knee Society scoring system with a minimal follow-up of one year. Statistical links between kinematic data and Knee Society scores have been analyzed with an ANOVA test and a Spearman correlation test at a 0.05 level of significance.
RESULTS
101 knees had a posterior femoral translation during flexion before and after TKR. 18 knees had a paradoxical anterior femoral translation during flexion before and after TKR. 51 knees had the pre-TKR paradoxical anterior femoral translation corrected to posterior femoral translation after TKR. 14 knees had the pre-TKR posterior femoral translation modified to a paradoxical anterior femoral translation after TKR.
91 knees had a femoral external rotation during flexion before and after TKR. 34 knees had a paradoxical femoral internal rotation during flexion before and after TKR. 50 knees had the pre-TKR paradoxical femoral internal rotation corrected to a femoral external rotation after TKR. 9 knees had the pre-TKR femoral external rotation modified to a paradoxical femoral internal rotation after TKR.
There was a moderate statistical link between the reconstruction of a physiological kinematics after TKR and the Knee Society scores, with higher scores in the group of physiological kinematics after reconstruction. There was no correlation between the quantitative data and the Knee Society scores.
DISCUSSION
To record the knee kinematics during TKR is feasible. This information might help the surgeon choosing the optimal reconstruction compromise. However, it is not well defined how to influence final kinematics during knee replacement. The exact influence of the quality of the kinematic reconstruction measured during surgery on the clinical and functional results has to be investigated more extensively.
SUMMARY
There is a statistical relationship between the intra-operative knee kinematics and the clinical and functional results.
