Gait Analysis Of Patients With A Unilateral Bi-compartmental Knee Replacement

Abstract

Total knee replacement is a common method of treating pain and dysfunction associated with knee osteoarthritis (OA). However, cartilage degeneration is often confined in the medial and patellofemoral compartments. The Journey Deuce system (Smith & Nephew Inc.) is a bi-compartmental knee replacement (BKR) system used to treat knee OA by replacing the medial and patellofemoral compartments while preserving the cruciate ligaments and lateral compartment. To date, there is very little information regarding functional outcomes after BKR surgery. PURPOSE: To compare frontal plane knee mechanics during level walking of the surgical and contra-lateral limbs of patients post BKR surgery and the limbs of healthy control subjects. METHODS: 10 healthy control subjects and 8 unilateral BKR patients (post-op: 14 ± 4 months) participated in the study. 3D kinematic and kinetic analyses were conducted during walking. The following variables were analyzed: peak initial external knee abduction moment, maximum knee adduction angle and peak external knee adduction moment during stance. Paired Student T tests were used to determine the differences in the BKR group (BKR vs. contra-lateral limbs). One way ANOVA was used to determine the differences between the BKR (both BKR and contra-lateral limbs) and control groups, a=0.05. RESULTS: The BKR limbs exhibited less initial peak knee abduction moment at touch-down than contra-lateral and control limbs (0.01 ± 0.06, -0.06 ± 0.08, and -0.06 ± 0.06 Nm/kg, respectively) (p < 0.05). No differences were found for peak knee adduction moment (0.53 ± 0.16, 0.42 ± 0.13, and 0.44 ± 0.14 Nm/kg) and knee adduction angle during stance (7 ± 4, 6 ± 4, and 7 ± 3 degrees) among the BKR, contra-lateral, and control limbs (p > 0.05). CONCLUSION: Individuals with knee OA typically exhibit increased peak knee adduction angle and external knee adduction moment when compared to non-OA subjects. In this study, no differences were found in peak knee adduction angle and external moment between the 3 groups. In addition, there was a reduction in the initial peak external knee abduction moment in the BKR surgical limb, which may indicate the absence of the typical pain avoidance compensatory pattern exhibited by individuals with knee OA. Typical knee OA frontal plane mechanics were not found in patients following BKR surgery.