Rancho Rehabilitation Engineering Program: Current Title

Rancho REP Logo2

Project 2: Engineering Solutions for Increasing Upper Extremity Function in Individuals with SCI

New Generation Mobile Arm Supports for Better Hands-on Activity

Project Staff:

Pierre Leung, MSME
Robert Waters, MD
Jane Baumgarten, OTR
Michal Atkins, MA, OTR/L
Lynn Yasuda, MSED, OTR/L, FAOTA
Roger Weber, CPO

Background Information:

Mobile Arm Supports (MAS) are mechanical linkages with low friction joints which provide support for the arms. They allow individuals with weal proximal musculature to maximize upper extremity function and participate in activities such as power wheelchair (WC) propulsion, self-feeding, hygiene and grooming activities, and desktop functions. Traditional MASs have been available for approximately 50 years, however maximal set-up and adjustment require specialized training and extensive experience by Occupational Therapists. Traditional MASs may also require frequent and ongoing adjustments following discharge from the hospital. This, in conjunction with shortened rehabilitation stays, has significantly limited their widespread use. As useful as MASs are to the spinal cord injured (SCI) population, they are not used by many individuals who could clearly benefit from them. In addition, the traditional "Jaeco" MAS also protruded 9-10 inches laterally from the WC making it difficult if not impossible to navigate through standard in-home doorways.

In a previous pediatric MAS grant, the Rancho Rehabilitation Engineering Department designed a new Multi-Link MAS system. This new design features decreased lateral protrusion, most compontents fabricated in black which is cosmetically appealing to the users, and the entire system can be used interchangeably for right or left side application. In addition, initial set-up can be accomplished in 10-20 minutes, fewer tools are needed, and further adjustments can frequently be made without tools. This design was transferred to Jaeco Orthopedic in 2002, and they currently manufacture and distribute the Jaeco/Rancho Multi-Link MAS. Further information can be obtained from their website at www.jaeco-orthopedic.com.

Current Project:

Overall Objectives

1) Conduct outcome surveys documenting current treatment practices with regard to MAS prescription and use at SCI treatment centers nationwide.

2) Evaluate the Jaeco/Rancho MAS with the adult SCI population in comparison to other devices.

3) Upgrade MAS technology by creating more user-friendly, functional, and adaptable supports for individuals with SCI.

4) Transfer new technology to the marketplace.

5) Create and evaluate a pilot training program for therapists to fit/adjust the MAS.

Progress to Date

Clinicial Survey

The survey showed a wide variance in MAS use by participating clinicians. The major reason for non-use by experienced clinicians include lack of patient psychological readiness during rehabilitation stay, shortened length of stay, and lack of payment sources. The major design limitations identified in the traditional Jaeco MAS include MAS hitting chair arm or work surface with attempted use, difficulty managing the arm when reclining for pressure relief, incompatibility between the mount and the WC, and doorway clearance due to increased WC width. The greatest issues related to training of professionals who fit and adjust the devices included the need for hands-on experience, training on how to apply to a variety of WCs, and information for caregivers regarding ongoing adjustment needs.

Evaluation of existing devices

A comparison between the traditional Jaeco MAS and the Jaeco/Rancho Multi-Link MAS revealed a 3”-4” decrease in overall WC width with the Multi-Link MAS. In addition 7/8 patients evaluated demonstrated greater horizontal range of motion (ROM) using the Multi-Link MAS (without training). The average increase in horizontal ROM was 60%. Subjective patient opinions favored the Multi-Link MAS.

Product Development

Multi-mount wedge:
A wedge was fabricated which can be inserted into the Multi-mount mounting bracket, and allows the MAS to be balanced for functional use for those SCI patients who sit in a semi-reclined position. The Multi-mount alone will only allow functional adjustments for users who are seated very close to the upright position. This device has been used for several patients, and can be easily discontinued when the user tolerates upright seating.

Power WC driving simulator:
A device for simulating joystick control was developed. It attaches to the commercially available MAS evaluation stand from Jaeco Orthopedics. This has been used successfully during project related patient evaluations, as well as by Occupational and Physical Therapists at Rancho to assess potential for power WC propulsion.

Manual Arm Height adjustor:
The manual Arm-Height Adjustor was developed in conjunction with the pediatric MAS project. This device provided unlimited adjustment of the multilink arm height, allowing the user immediate access to a variety of work surfaces such as the joystick WC control, the desktop, the computer, and capability of hand to mouth/face activities. It provides a smooth, fast and easy transition between functional activities. It has been used in single session evaluation with 5 SCI patients, and extended evaluation with one patient. All responses have been favorable. It requires the assistance of a helper or caretaker for use. It is inexpensive and will hopefully be commercially available in late 2005.

Power-assisted Arm-Height Adjustor:
A prototype for the power version of the arm-height adjustor has been developed, and is awaiting trial evaluation with an appropriate SCI MAS user. This device will allow independent arm-height adjustment of the Multi-Link MAS to access a variety of work surfaces and expand the number of activities that a user can engage in without assistance.

Manual Arm Retractor:
A manual arm retractor has been designed and a prototype fabricated that retracts the proximal and middle links in any position. This decreases the overall WC width for doorway clearance and stabilizes the arms when reclining for pressure relief, hence preventing flailing of the arms. This will enhance stability during driving in populations with distal motor control, but will require further development for use with the SCI population. As soon as development is complete this will be evaluated with the SCI population.

Power Assisted Retractor:
A power assisted prototype has also been developed to serve the same purposes as the manual arm retractor. This will allow independent arm retraction by the user, and will be evaluated as appropriate candidates are available.

Rancho REP || What's New? || About Us || Our Projects || REP Publications
Contact Us || Frequently Asked Questions || REP Links

Web Administrator

Last modified: April 06, 2006