Estimating knee stability using inertial measurement units: insights from smoothness metrics
Sanchana Krishnakumar (EEMCS-BSS), Bert-Jan F. van Beijnum (EEMCS-BSS), Chris T. M. Baten (RRD), Peter H. Veltink (EEMCS-BSS), and Jaap H. Buurke (EEMCS-BSS)
Abstract
After an Anterior cruciate ligament (ACL) reconstruction, residual knee laxity often persists and causes a lack of knee stability. During rehabilitation, neuromusculoskeletal strengthening exercises are often performed to improve knee stability. However, no definitive quantitative metrics are currently available to assess the improvement in knee stability over time in a clinical setting. Our objective is to utilize inertial measurement units (IMUs) for the analysis of acceleration patterns, aiming to indirectly quantify knee stability through the assessment of smoothness metrics, specifically SPARC (Spectral Arc Length) and LDLJ (Log Dimensionless Jerk). Our research comprised nine healthy individuals and eight patients, engaging in various activities such as hopping, side hops and drop jump landings. These activities were segmented into sub-movements to enable a detailed analysis of distinct movement phases.
Preliminary findings suggest a notable reduction in movement smoothness during the stabilizing phase of these activities, which coincides with critical periods where knee stability is pivotal. Additionally, the research seeks to identify group-level differences in smoothness and compare outcomes between healthy individuals and patients.
This study underscores the importance of evaluating smoothness metrics to gain insights into knee stability. By employing these metrics, we aim to provide a practical and non-invasive method for assessing knee stability during rehabilitation in clinical settings. Furthermore, our findings have the potential to assist physiotherapists in making informed decisions and monitoring the progress of ACL patients throughout the rehabilitation process.