The Feasibility of Shoulder Motion Tracking During Activities of Daily Living Using Inertial Measurement Units

The team won the 2015 ISTA HAP Paul Award for the best paper on new developments in the field of Arthroplasty for the aforementioned study, “The Feasibility of Shoulder Motion Tracking During Activities of Daily Living Using Inertial Measurement Units.”

The study included placing APDM Opal sensors on 5 subjects, including a dental hygienist, a primary school teacher, a mechanical project engineer, an administrative assistant, and a retail associate. These subjects wore Opals on the sternum and upper arm for 4 hours while working, and 4 hours while off-work.

The findings from this study are valuable in a multitude of ways. For example, there are several conditions such as arthritis or traumatic injury that can cause joint pain and lead to disability. To avoid pain, individuals with joint injury may alter their joint mechanics during functional activities. Altered patterns of movement, characterized by a change in the joint range of motion, can have a profound effect on the progression of the injury.

In addition, current clinical practices for mobility assessment lack standardization. Often, clinical providers employ a brief, subjective, visual evaluation, or rely on patient-reported questionnaires regarding pain and physical functioning. Many clinicians and clinical researchers have recognized the need for standardized performance-based, objective measures of mobility that complement subject reports. In the past, APDM has helped conduct a few studies using Opal sensors to measure normal and abnormal shoulder, elbow, hip, knee and ankle movements during prescribed and daily activities.

“Initial data was very promising. There are some things we want to improve on in the future to see if we can quantitatively show how different patients can benefit rather than using self-reported questionnaires. Those questions can be interpreted a lot of ways, so it’s hard to get through the noise of that measurement technique the way the Opals and tracking technology can,” says Kirking.

Mahmoud El-Gohary states, “To our knowledge, this is one of the very first studies to characterize arm movement continuously for more than 5 hours during daily activities. Our preliminary results suggest that our innovative algorithm and the inertial system can accurately and reliably track human arm movement for extended periods during normal activities of daily living. The system can help in the diagnosis and design of interventions to prevent or delay development or progression of joint impairments.”

Co-Author Bryan Kirking is the Biomechanics and Testing Scientist at DJO Surgical. Kirking’s research focuses on the improvement of functional outcomes of total joint replacements by ways of numerical simulation and physical testing. He commented on the fact that APDM “brings new technologies that were not being utilized outside laboratory studies and simulations,” and are a huge help to his industry. He states, “We may not understand the true motions that people need or prefer to use their shoulders for, and when designing things like implants, we can’t rely on assumptions.”

When asked about his experience using the Opal sensor system, Kirking suggested he would “use it again in clinics and in the field to look at patients to get anatomical replacements and shoulder implants to see if they can function better.”