Task Leader(s): Dan Ding, Ph.D.

Co-Investigator: Michael Boninger, MD., Annmarie Kelleher, MS

Other participants: TBN GSR

Rationale

Long-term use of the upper limbs for performing daily activities has led to an increase in the prevalence of musculoskeletal injuries and reports of pain. The Consortium for Spinal Cord Medicine recently published, Preservation of Upper Extremity Function Following Spinal Cord Injury: A Clinical Practice Guideline for Health Care Professionals. This monograph provides concise ergonomic and equipment recommendations based on review of relevant research.. The guidelines recommend reducing the frequency of repetitive upper limb tasks, minimizing forces required to complete tasks and minimizing extremes of wrist and shoulder motions. These guidelines also include specific recommendations related to wheelchair propulsion technique and transfer activities. The Clinical Practice Guideline is based on studies of objective measures of physical activities that were determined in laboratory and clinical settings.

The primary objective of this project is to develop and validate accelerometry-based field measures for wheelchair propulsion in the natural environment. We will examine the relationship between biomechanical variables and accelerometry measures during wheelchair propulsion in a laboratory setting. We will also assess the field utility of these measures to determine effectiveness of a wheelchair propulsion training program. The overall goal is to provide an effective tool to monitor actual upper extremity usage. This will enable us to more effectively evaluate propulsion interventions and understand of the etiology of upper extremity injuries and pain.

Specific Aims

This project will begin in the third year and will be utilize an unobtrusive wheelchair propulsion monitoring device (WPMD) capable of recognizing activities such as independent wheelchair propulsion, being pushed, driving, and other ADLs. The WPMD is being developed with support from the PVA Research Foundation for a two-year grant (Feb 2007-Jan 2009). WPMD will be able to recognize (and record) propulsion patterns including "semicircular," "looping over propulsion," and "arc." The WPMD will integrate three components. including a wearable 3-axis accelerometer (ACC) that monitors upper limb movements, a wheel rotation datalogger clipped onto the wheel and a vibration datalogger underneath the seat that monitors wheelchair motion. The proposed project is to further develop and validate ACC-based field measures that can capture wheelchair propulsion characteristics in terms of propulsion force, smoothness, cadence, and stroke length under free-living conditions based on the WPMD. The project will be implemented in two phases with the first phase focusing on the development of these measures and the second phase on validation of them. Figure 1 illustrates the various objectives of the PVA project, the proposed project, and future directions.

Subjects will propel a wheelchair on a computer-controlled dynamometer and along ADL courses, respectively, with a WPMD attached to the wheelchair and their upper limbs. Wheelchair propulsion biomechanics will be determined using the SmartWheel (Three Rivers Holdings, Mesa, AZ). We will evaluate a variety of data reduction strategies to determine how ACC-based measures can best represent wheelchair propulsion characteristics. The laboratory testing will also be followed by a 2-day field trial in the homes and community environments of the participants.

Aim 1: To validate the WPMD's performance in quantifying the amount of upper limb usage for wheelchair propulsion and further develop reliable ACC-based field measures for characterizing wheelchair propulsion in terms of propulsion force, smoothness, cadence, and stroke length.

Hypothesis 1a: The WPMD will be able to identify wheelchair propulsion episodes from a mix of ADLs with at least 90% accuracy during the laboratory trial.

Hypothesis 1b: ACC-based field measures collected by the WPMD will be able to predict greater than 60% of the variance of each wheelchair propulsion biomechanical variable (propulsion force, smoothness, cadence, stroke length).

Hypothesis 1c: The ACC-based field measures collected during the laboratory trial will be highly correlated (r>=0.8) with those collected during the home trial.

Aim 2: To examine the test-retest reliability of ACC-based field measures and the validity of the measures in assessing a wheelchair propulsion training program.

Hypothesis 2a: The test-retest reliability of ACC-based field measures indicated by the intraclass correlation coefficient (ICC) will be greater than 0.8 and there will be no significant difference between the test-retest data during Phase I and Phase II.

Hypothesis 2b: The ACC-based field measures collected during the laboratory trials before and after the training session will be significantly different if the training session is proved to be effective by the biomechanical variables.

Hypothesis 2c: There will be a significant change in the ACC-based field measures collected during the home trials in Phase I (before the training session) and Phase II (after the training session).

Aim 3: To quantify the amount of use and quality of upper limb movements in the home and community environment before and after the wheelchair propulsion training program.

Methodology

We will recruit 26 manual wheelchair users with SCI to participate in this study. Inclusion criteria include: 1) 18 years of age or greater; 2) use of a manual wheelchair for primary mobility (> 80% of ambulation); 3) SCI at T2 level or lower. Exclusion criteria include: 1) inability to tolerate sitting for 2 hours; and 2) presence of upper limb pain that limits mobility. The study will be implemented in two phases. Each subject will complete the protocol described in the table below.

Protocol

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Protocol Overview

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Phase I - Visit I

1. Consent form, demographics/wheelchair survey, pain questionnaires
2. WPMD attached to the wheelchair and the upper limb of the participant
3. Laboratory trial of wheelchair propulsion on a computer-controlled dynamometer
4. Laboratory trial along ADL courses
5. 2-day field trial at home and community environment

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Phase II - Visit II

1. Laboratory trial along ADL courses
2. Wheelchair propulsion training session
3. Laboratory trial along ADL courses
4. 2-day field trial at home and community environment

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Anticipated Findings and Implications of Future Research

We anticipate that the ACC-based field measures will enable us to accurately and reliably capture wheelchair propulsion characteristics. We also anticipate that the WPMD will become an accepted clinical tool for recording the amount and quality of functional upper-limb movements. This information will be useful to clinicians and researchers to evaluate training outcomes and understand the etiology of upper limb injuries and pain. We expect to learn how manual wheelchair users are using their wheelchairs and upper limbs during daily activities of living, and whether they will be able to apply what they learned during the training program to their everyday wheelchair propulsion activities.

Our primary priorities for future research include: 1) a multi-center evaluation project that expands the subject pool, refines and validates the ACC-based measures for characterizing wheelchair propulsion among individuals with SCI, and examines the carry-over effects of different training programs under free-living conditions; 2) a larger-scale study of the relationship between the amount and quality of upper-limb movements, and the upper-limb pain and injury among this population. Additional future directions may include investigation on the effectiveness of sensor combinations (e.g., accelerometer and EMG) to capture more propulsion characteristics, and improve the current WPMD to collect data for longer durations, provide coaching functions and prevent secondary musculoskeletal injuries related to wheelchair propulsion.

Figure 1 - Relationship between D3 activities, current, and future work