Changes in Movement Patterns during Stair Climbing from Two to Eight Years after ACL Reconstruction are Associated with Patient-Reported Outcomes

Abnormal joint loading and motion during walking have been observed in patients with anterior cruciate ligament (ACL) injury and reconstruction (ACLR), and may contribute to accelerated development of post-traumatic knee osteoarthritis (OA) in this population. A commonly observed functional deficit after ACLR is a reduction in knee flexion moment (KFM), an indication of quadriceps function inhibition. In particular, the analysis of more biomechanically demanding tasks, such as stair ascent, which produces larger joint angles and moments than level walking, has provided greater sensitivity in detecting KFM differences between ACLR and control knees two years after reconstruction. While knee mechanics during stair climbing have been shown to be altered at a single time point after ACLR, few studies have investigated changes longitudinally, and it is unknown if gait mechanics during a mechanically challenging activity, such as stair climbing, change with time past surgery. Further, prior work in an OA population demonstrated a distinctive compensatory pattern of movement of increased forward trunk lean which was correlated with reduced KFM in patients with severe knee OA during stair climbing, and analysis of changes in the sagittal plane trunk motion in the ACLR population is of interest. Trunk lean during stair climbing could provide a useful method to evaluate quadriceps function after ACLR without the need for full gait analysis. Thus, the purpose of this study was to determine whether movement pattern changes during stair ascent in patients from 2 to 8 years after ACLR are associated with changes in quadriceps function and patient-reported outcomes (PRO). We hypothesized that there will be changes in (1) peak KFM and (2) peak forward trunk flexion angle during stair ascent from baseline to follow-up. Further, we hypothesized that (3) the change in peak trunk flexion angle over the follow-up period will be correlated with the change in peak KFM and (4) that changes in peak KFM and trunk flexion angle during stair ascent from 2 to 8 years will be associated with changes in PRO over time.