The effects of anterior stabilization in Bi-cruciate stabilized and posterior stabilized total knee arthroplasty during a weight-bearing extension activity.

Abstract

Bi-Cruciate Stabilized (BCS) and Posterior-Stabilized (PS) are two common total knee arthroplasties (TKA), where the BCS TKA offers mechanical substitution of both cruciate ligaments, while the PS TKA only offers substitution of the Posterior Cruciate ligament (PCL). The purpose of this study is to quantify whether anterior stabilization in TKA affects full extension kinematics by evaluating the weight-bearing kinematics for PS and BCS TKAs during a weight-bearing extension activity. In-vivo 3D kinematics were determined for 81 subjects having a BCS (47) or PS (34) TKA implanted by two different surgeons. All subjects were asked to perform a weight-bearing step-up activity (SU) under fluoroscopic surveillance, and 3D-to-2D image registration was used to determine kinematics such as lateral anterior/posterior position, medial anterior/posterior position, axial rotation, and cam/post engagement. The BCS TKA subjects were able to reach greater hyperextension than the PS TKA subjects at full extension (p < 0.0001). The BCS TKA was also positioned statistically more anterior than its PS counterpart at full extension (p < 0.0001), and it also experienced more anterior motion of both condyles from maximum flexion to full extension than the PS TKA (p < 0.0001). The results in this study suggest that the BCS TKA design differences such as anterior stabilization could be beneficial for achieving more condylar motion and axial rotation near full extension, ultimately helping to recreate the native screw-home mechanism in TKA.