Gait analysis after bi-compartmental knee replacement.

BACKGROUND It is reported that a majority of the patients with knee osteoarthritis have cartilage degeneration in medial and patellofemoral compartments. A bi-compartmental knee replacement system was designed to treat osteoarthritis at medial and patellofemoral compartments. To date, there is very little information regarding the knee mechanics during gait after bi-compartmental knee replacement. The purpose of the study was to evaluate knee strength and mechanics during level walking after knee replacement. METHODS Ten healthy control subjects and eight patients with unilateral bi-compartmental knee replacement participated in the study. Maximal isokinetic concentric knee extension strength was evaluated. 3D kinematic and kinetic analyses were conducted for level walking. Paired Student t-test was used to determine difference between surgical and non-involved limbs. One way MANOVA was used to determine difference between surgical and control groups. FINDINGS The surgical knee exhibited less peak torque and initial abduction moment than both the non-involved and control limbs (P<0.05). The non-involved limb had less knee extension at stance and greater knee extensor moment during push-off than both the surgical and control limbs (P<0.05). No differences were found for other typical knee mechanics among the surgical, non-involved, and control limbs during walking (P>0.05). INTERPRETATIONS Patients with bi-compartmental knee replacement exhibited good frontal plane knee mechanics and were able to produce the same level of knee extensor moment as healthy control limbs during walking. While showing some compensatory patterns during walking, patients with bi-compartmental knee replacement largely exhibited normal gait patterns and knee mechanics.