The goal of this study is to set up a functional motion analysis test to examine effects of the anterior cruciate ligament in total knee arthroplasty (TKA) patients by comparing knee kinematics, kinetics, and muscle activation patterns during level and downhill walking for patients with posterior cruciate–retaining (PCR) and bicruciate-retaining (BiCR) TKAs.
Motion and electromyography (EMG) data were collected for 12 subjects (4/8 male/female, 64 ± 11 years, 31.3 ± 7.3 body mass index, 6/6 right/left) with BiCR TKAs and 15 subjects (6/9 male/female, 67 ± 7 years, 30.5 ± 5.1 body mass index, 4/11 right/left) with PCR TKAs during level and downhill walking using the point cluster marker set and surface electrodes placed on the vastus medialis obliquus, rectus femoris, biceps femoris, and semitendinosus muscles.
Level walking exhibited no significant differences in knee kinematics, kinetics, or EMG patterns. During downhill walking, BiCR subjects had significantly lower peak muscle activity in the vastus medialis obliquus and rectus femoris (P = .045 and .018, respectively), a trending higher peak knee flexion moment (2.0 ± 0.6% BW*HT vs 1.5 ± 0.6% BW*HT, P = .076), and significantly more knee flexion at heel strike (5.1° ± 4.7° vs 1.8° ± 2.8°, P = .044) compared with PCR subjects.
Anterior cruciate ligament retention led to altered muscle recruitment during downhill walking in BiCR subjects compared with PCR subjects; thus, BiCR TKAs may offer some neuromuscular benefits for stabilizing the knee joint. In conclusion, level and downhill walking knee kinematics and kinetics combined with corresponding quadriceps and hamstrings EMG signals begin to build an overall picture of implant functionality.