2015 ISAKOS Biennial Congress ePoster #1138
Medial Laxity Affects In Vivo Knee Kinematics
Shinichiro Nakamura, MD, PhD, Kyoto JAPAN
Hiromu Ito, MD, PhD, Kyoto JAPAN
Shinichi Kuriyama, MD, PhD, Kyoto JAPAN
Adrija Sharma, PhD, Knoxville, TN UNITED STATES
Richard D. Komistek, PhD, Knoxville, TN UNITED STATES
Shuichi Matsuda, MD, PhD, Kyoto JAPAN
University of Tennnesee, Knoxville, Tennessee, USA
FDA Status Cleared
Summary: The medial flexion gap had significant effects on in vivo knee kinematics compared with the lateral flexion gap during deep knee flexion and kneeling activities.
Soft-tissue balancing is quite important for the success of total knee arthrolasty (TKA). To make a rectangular gap in extension and in flexion is an important goal during surgery, and a well-balanced knee is correlated with excellent clinical results. However, it has been still unknown whether the flexion gap has significant effects on in vivo knee kinematics. The purpose of the current study was to examine the relationships between flexion gaps and in vivo knee kinematics during deep knee bend and kneeling activities.
Materials And Methods
Twenty two knees implanted with a tri-condylar TKA were included in this study. Fluoroscopy based in vivo femoro-tibial kinematics of the ceramic tri-condylar implant was assessed during deep knee bend and kneeling activities, using a three-dimensional model fitting approach. Each participant started kneeling from a non-weight bearing status to anterior tibia (before contact status (BC)) with the knee flexed, then set the lower leg on the box with loading (complete contact (CC)), and flexed to maximum flexion (MF). Subjects sat on a table with lower legs dependent, and axial radiographs of distal femur were obtained to analyze the medial and lateral flexion gaps. To examine the relationships between flexion gaps and in vivo knee kinematics, Pearson correlation coefficients were calculated.
In a deep knee bend activity, medial flexion gaps had significant correlations with a medial contact point and angular rotation, while lateral flexion gaps had a slight effect on kinematics. The implanted knees with medial laxity had anterior medial contact points and external angular rotation of femoral components at full extension and early flexion phase. In a kneeling activity, the number of factors correlated with flexion gaps was much more than in a deep knee bend activity. Medial flexion gaps had significant correlations with contact points at medial side as well as lateral side, angular rotation, and lift-off, while lateral flexion gaps had influences just on lift-off. The implanted knees with medial laxity had anterior contact points at CC after loading the weight to the anterior tibia, which was the reason for greater anterior translation of femoral component from BC to CC and greater posterior translation from CC to MF.
The medial flexion gap had significant effects on in vivo knee kinematics compared with the lateral flexion gap during deep knee flexion and kneeling activities. To coordinate the medial flexion gap properly is a quite important procedure for successful TKA.