Abstract
The preservation of the posterior cruciate ligament in cruciate retaining (CR) total
knee arthroplasty (TKA) designs has the potential to restore healthy knee biomechanics;
however, concerns related to kinematic asymmetries during functional activities still
exist in unilateral TKA patients. As there is a limited data available regarding the
ability of the contemporary CR TKA design with concave medial and convex lateral tibial
polyethylene bearing components to restore healthy knee biomechanics, this study aimed
to investigate in vivo three-dimensional knee kinematics in CR TKA patients during
strenuous knee flexion activities and gait. Using a combined computer tomography and
dual fluoroscopic imaging system approach, in vivo kinematics of 15 unilateral CR
TKA patients (comparison of replaced and contralateral nonreplaced knee) were evaluated
during sit-to-stand, step-ups, single-leg deep lunge, and level walking. The patient
cohort was followed-up at an average of 24.5 months ( ± 12.6, range 13–42) from surgical
procedure. Significantly smaller internal knee rotation angles were observed for the
contemporary CR TKA design during step-ups (2.6 ± 5.8 vs. 6.3 ± 6.6 degrees, p < 0.05) and gait (0.6 ± 4.6 vs. 6.3 ± 6.8 degrees, p < 0.05). Significantly larger proximal and anterior femoral translations were measured
during sit-to-stand (34.7 ± 4.5 vs. 29.9 ± 3.1 mm, p < 0.05; –2.5 ± 2.9 vs. –8.1 ± 4.4 mm, p < 0.05) and step-ups (34.1 ± 4.5 vs. 30.8 ± 2.9 mm, p < 0.05; 2.2 ± 3.2 vs. –3.5 ± 4.5 mm, p < 0.05). Significantly smaller ranges of varus/valgus and internal/external rotation
range of motion were observed for CR TKA, when compared with the nonoperated nee,
during strenuous activities and gait. The preservation of the posterior cruciate ligament
in the contemporary asymmetric bearing geometry CR TKA design with concave medial
and convex lateral tibial polyethylene bearing components has the potential to restore
healthy knee biomechanics; however, the study findings demonstrate that native knee
kinematics were not fully restored in patients with unilateral asymmetric tibial polyethylene
bearing geometry CR TKA during functional activities.
Keywords
cruciate retaining total knee arthroplasty - in vivo 6DOF kinematics - sit-to-stand
- step-ups - single-leg deep lunge - gait