Abstract
Background
Kinematic patterns in total knee arthroplasty (TKA) can vary considerably from the native knee. No study has shown a relation between a given kinematic pattern and patient satisfaction yet.
Questions
The purpose of this study was to test whether the kinematical pattern, and more specifically the anteroposterior translation during (1) open kinetic chain flexion-extension, (2) closed kinetic chain chair rising and (3) squatting, is related to the level of patient satisfaction after TKA.
Methods
Thirty TKA patients were tested using single plane fluoroscopy. Tibiofemoral kinematics were analyzed for 3 activities of daily living (open chain flexion-extension (FE) and closed chain chair rising (CH) and squatting(SQ)). A two- step cluster analysis was performed which resulted in two clusters of patients based on the KOOS and KSS questionnaires. Cluster 1 (CL1) contained patients with good PROMs, cluster 2 (CL2) contained patients with poorer PROMs. Tibiofemoral kinematics were compared between and within both clusters.
Results
Significant worse PROMs were found in cluster 2 for all KOOS and KSS subscores (P<0.001).
Open chain movement: Concerning the open chain flexion extension no significant difference was found between the two clusters.
Closed chain movements: On the medial side, an initial anterior translation (femur relative to tibia) was found in cluster 1 during early flexion but in cluster 2 this translation was steeper and ran more anteriorly. In mid-flexion a stable medial compartment was found in cluster 1 where cluster 2 started moving posteriorly already. In deep flexion a posterior translation was evaluated in both clusters
Concerning the lateral side, a small initial anterior translation in early flexion was found followed by a posterior translation in mid flexion which continued in deep flexion Cluster 1 moved significantly more posterior in deep flexion.
Conclusion
This is one of the first studies to evaluate the influence of total knee kinematics on patient reported outcomes. We found that patients with poorer PROMs experience (1) a more pronounced paradoxical anterior motion on the medial side followed by (2) a less stable medial compartment in mid flexion and (3) less posterior translation in deep flexion on the lateral side.
