Movement Analysis Offers Quantification of the Benefit of Orthopaedic Interventions

By Erin M. Mannen, Ph.D., Assistant Professor of Orthopaedic Surgery and Director of Translational Orthopaedic Research at the University of Arkansas for Medical Sciences

Erin M. Mannen, Ph.D., Assistant Professor of Orthopaedic Surgery and Director of Translational Orthopaedic Research at the University of Arkansas for Medical Sciences

The goal of orthopaedic medicine is typically to relieve pain and restore function. People want to play with their grandkids without discomfort, socialize with friends during a walk, and enjoy the many benefits of pain-free movement. With the increasing pressure from payers to justify medical care, it is more important than ever to quantify the positive impact that orthopaedic surgery and therapy have on a patient’s quality of life. Current methods for evaluating the impact of clinical interventions include patient questionnaires, qualitative exams, and radiographic measurements. However, each of these have significant drawbacks. Patient-reported outcomes may be influenced by individual expectations and demeanor, fitness level, health literacy, and even the time of the day the patient completes the questionnaire. Qualitative exams have low repeatability which makes interpretation difficult. Radiographic measures provide only a static snapshot in time, and do not reflect dynamic activity that is so important to orthopaedic patients. It is also alarming to think that these qualitative and sometimes incomplete assessment tools heavily influence treatment decisions for patients. To advance the field and to provide quantitative assessment of the need for and the impact of orthopaedic interventions, movement analysis offers solutions to quantify function.

Movement analysis is a branch of biomechanics that focuses on understanding human movement. Specialized camera systems and force plates allow researchers to measure joint angles and loading during a variety of tasks, while muscle activity can be measured by electromyographic sensors. Walking, or gait, is the most commonly analyzed task, but activities can be customized to specific orthopaedic populations. For example, patients with knee or hip osteoarthritis often report difficulty rising from a chair, a common functional activity. While qualitative exams or questionnaires may address this task subjectively, motion analysis provides an objective measure of the improvement that total joint arthroplasty offers these patients in this specific task. Joint angles and loading, and muscles used to achieve a task can be quantified and compared to their pre-intervention state, justifying the positive impact on quality of life for orthopaedic patients.

The outcomes of movement analysis may also be useful to identify areas to improve via physical therapy. For instance, total knee arthroplasty patients often experience co-contraction of hamstrings and quadriceps muscle groups during loading. This abnormal muscle activity can prevent functional progress, but it is difficult or impossible to detect with traditional clinical assessments. Electromyography enables clinicians to identify patients who could benefit from physical therapy specifically focused on retraining muscle function to avoid co-contraction.

While movement analysis is becoming more common in the hip and knee fields, the research is lacking in other subspecialties. Opportunities to develop quantifiable diagnostic tools, to analyze movement changes due to orthopaedic intervention, and to develop patient-specific therapy interventions are needed for shoulder, elbow, spine, and more. Researchers and clinicians need to work collaboratively to develop movement analysis protocols to better quantify patient function in all orthopaedic areas.

Drawbacks of a typical movement analysis laboratory include the large space, expensive equipment, and technical personnel required to test and analyze the data. The clinician-researcher team is critical to design and implement clinical movement experiments in order to obtain meaningful results that benefit patients, but this relationship is often difficult to maintain, particularly in private practice outside of an academic setting. Fortunately, easier to use, stand-alone sensors and camera systems that will eventually be incorporated into clinical settings are being developed, offering medical professionals a quick and easy way to quantify function in orthopaedic patients.

Pain-free movement and the ability to fully participate in activities of daily living are the ultimate goals for orthopaedic interventions, but current qualitative outcome measures may not fully characterize functional changes. Quantifiable measures using common movement analysis techniques provide a unique way to objectively justify the benefit of orthopaedic surgery and therapy.

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