Inertial sensors identified asymmetries in shank angular velocity at different gait speeds in individuals with anterior cruciate ligament reconstruction.

BACKGROUND:Inertial sensors can detect between-limb asymmetries in shank angular velocity (SAV) during loading response of walking in individuals with ACL reconstruction (ACLR), which may be indicative of abnormal knee joint loading. However, it is unknown whether these SAV asymmetries would exist up to 6 months post-ACLR and how they differ from SAV asymmetries in uninjured healthy subjects. RESEARCH QUESTION:To investigate whether patients with ACLR show significant and meaningful between-limb SAV asymmetries during walking and walking fast at 4 and 6 months post-surgery and to determine whether limb asymmetries are related across gait tasks and time. METHODS:Fifteen individuals with ACLR participated in this prospective study. Testing occurred in clinical settings. Participants were instructed to walk and walk fast while wearing one inertial sensor on each shank. The average of sagittal plane SAV peaks during loading response of gait was calculated bilaterally. The smallest meaningful between-limb difference for SAV was calculated from uninjured healthy subjects (n = 16) to define the limit of meaningful SAV asymmetries in patients with ACLR. RESULTS:At 4 and 6 months post-ACLR, the involved limb had significantly smaller peak SAV during walking (P < .01, d = 0.69-0.85) and walking fast (P < .005, d = 1.03-1.07) compared to the uninvolved limb. A significant main effect of gait task on SAV asymmetries was found (P = .006, ηp2 = 0.451). Further, patients with ACLR exhibited meaningful SAV asymmetries at both time points for both gait speeds. Limb SAV asymmetries correlated between gait tasks and across time (r = 0.760-0.860, P < .001). SIGNIFICANCE:Individuals with ACLR presented with significant and meaningful SAV asymmetries during walking and walking fast at 4 and 6 months post-surgery. Greater limb SAV asymmetries persisted across gait tasks and time, with greater asymmetry was observed at a faster walking speed. Thus, inertial sensors are feasible to be used in clinical settings to identify SAV asymmetry during gait post-ACLR.