K. Manella1, K. Macon2, L. Elizondo3, K. Kallus4, J. Sulzer2
1University of St. Augustine for Health Sciences, Doctor of Physical Therapy Program, Austin, United States, 2University of Texas at Austin, Mechanical Engineering, Austin, United States, 3Spero Rehab Clinics, Physical Therapy, Austin, United States, 4St. David's Rehabilitation Hospital, Outpatient Rehabilitation, Austin, United States
Background: In people with stroke, spinal cord injury, multiple sclerosis, and other upper motorneuron lesions, ankle clonus and quadriceps spasm may limit self-care and mobility, restricting independence and quality of life. Precise, reproducible measures of plantar flexor and quadriceps hyperreflexia are needed to assess effectiveness of interventions directed at normalizing reflex excitability. The ankle clonus drop test and quadriceps pendulum test provide valid and reliable measurement of plantar flexor and quadriceps reflex threshold angles (PFRTA and QRTA). However, PFRTA and QRTA measurement is limited to laboratory settings requiring expensive high fidelity motion capture system.
Purpose: We aimed to design an easy, inexpensive smartphone method to calculate RTAs during the ankle clonus drop test and quadriceps pendulum test in individuals with hyperreflexia. Intrarater, interrater, and test-retest reliability of smartphone recorded RTAs were investigated. We assessed accuracy and validity of smartphone RTA with synchronous 3-D inertial motion capture measurements.
Methods: We tested 22 impaired legs of 14 participants with ankle clonus or quadriceps hyperreflexia at four clinical facilities. Eight student physical therapists (SPT) and physical therapists (PT) performed tests during two test sessions scheduled 1 week apart. During test session 2, seven inertial motion unit (IMU) sensors were applied to both legs and sacrum for synchronous motion capture during each test. During each test session, four trials of the ankle clonus drop test and quadriceps pendulum test were performed. The SPT performed trials 1 and 2, the PT performed trials 3 and 4, with a 1-minute rest after each trial. Trial responses were recorded for 15 seconds with an iPhone. In the seated ankle clonus drop test, the participant’s leg is raised off a platform and released, causing the forefoot to impact the platform edge, providing a quick stretch to the plantar flexors. The quadriceps pendulum test is performed supine on a high table with lower legs dangling off the edge. The test leg forefoot is grasped and lifted until the knee is extended, the forefoot is released causing the knee to flex. Each trial video was processed using custom software (Reflex Tracker) to extract the RTA. Interclass Correlation Coefficients (ICCs) analyzed intrarater, interrater, and test-retest reliability, and interrater reliability between Reflex Tracker and IMU measurements. Bland Altman analysis assessed level of agreement.
Results: ICCs demonstrated good to excellent PFRTA reliability and excellent QRTA reliability. PFRTA ICCs were interrater 0.87 (0.75-0.93), intrarater 0.94 (0.91-0.96), and test-retest 0.82 (0.66-0.90). QRTA ICCS were interrater 0.95 (0.9-0.97), intrarater 0.99 (0.98-0.99), and test-retest 0.95 (0.88-0.97). Interrater reliability between Reflex Tracker and IMU was excellent. PFRTA ICC was 0.93 (0.89-0.96), agreement was good (β=0.06) with no fixed bias (p=0.46). QRTA ICC was 0.99 (0.99-1.00), agreement was good (β=-0.05) with no fixed bias (0.13).
Conclusion(s): The single-camera smartphone video and Reflex Tracker application provide valid and reliable measures of PFRTA and QRTA for assessment of plantar flexor hyperreflexia, elicited with the ankle clonus drop test, and quadriceps hyperreflexia, elicited with the quadriceps pendulum test.
Implications: The smartphone and Reflex Tracker application provide clinically useful outcome measures for assessing ankle clonus and quadriceps spasticity.
Funding, acknowledgements: University of St. Augustine for Health Sciences supported this research with internal grant funding.
Keywords: Hyperreflexia, Clinical Measurement, Mobile Application
Topic: Research methodology, knowledge translation & implementation science
Did this work require ethics approval? Yes
Institution: University of St. Augustine for Health Sciences
Committee: Institutional Review Board - University of St. Augustine for Health Sciences
Ethics number: UR-1005-298
All authors, affiliations and abstracts have been published as submitted.
