Traditional mobile arm supports (MAS) have been very functional, but they required specialized training and experience by the occupational therapist to both fit and adjust the numerous specialized parts for optimal user function. This has severely limited its widespread use. Also, it became very difficult to attach the traditional MAS system to the newer, varied wheelchair designs. The traditional MAS also protruded laterally, making it almost impossible to go through doorways in a standard house. The metallic appearance was not appealing to many users and families, especially children, teenagers, and young adults.

In the previous mobile arm support grant, the Rancho Rehabilitation Engineering Program designed a new MultiLink MAS System. Lateral protrusion is less, allowing better clearance through doorways. The MAS systems can be easily converted for right or left side usage which is a definite asset in a clinical evaluation setting. The new MAS mount attachment has been designed to more readily adapt to new wheelchair designs. Basic, initial set-up of the new MultiLink system can be done in 10 to 20 minutes. Only two sizes of hex wrenches and a flathead screwdriver is needed. Functional adjustments can easily be done without additional tools. Caretakers can be trained in basic adjustments because of its ease. The black anodized appearance has been acceptable to users as it blends in with most of the newer wheelchairs and is less obtrusive.

Potential MultiLink MAS users include persons with arm weakness, including those with muscle diseases, spinal cord injuries (with C-5 key muscles), arthrogryposis, Guillain-Barre, post-polio, polymyositis. The MultiLink has been useful for persons with other neurological disorders where weakness is the primary problem. In its current form, it is not recommended for persons with incoordination or hypertonicity problems.

The MultiLink system design was transferred to Jaeco Orthopedic in the Fall of 2002. They now manufacture and distribute the Jaeco/Rancho MultiLink Mobile Arm Support System. Over 125 units have been sold. Refer to their website: www.jaeco-orthopedic.com for ordering information or to download the Instruction Manual for Setup and Adjustment of the Jaeco/Rancho MultiLink Mobile Arm Support System, developed by NIDRR funding.

Current Project:

Need: To increase functional independence for disenfranchised users.
There are many persons who are too weak to successfully use the traditional MAS or the new MultiLink MAS, including those with Duchenne Muscular Dystrophy who become progressively weaker and unable to use their MAS system.

The target population for this project is children with muscle disease, especially those who have very weak shoulder and elbow muscles, but some functional strength in their hands.

Many of the children in this target group are able to operate their motorized wheelchair (W/C) joystick control without a MAS. In fact, because of their weak shoulder muscles, they demonstrate less control operating the joystick while using the MAS because the MAS allows the arm to move too freely. This is especially a problem when starting/stopping and going up/down inclines. They need the stability provided by resting their forearm on the W/C armrest which allows controlled movement of the joystick by fingers/hand and/or wrist motions.

The primary use of the MAS has traditionally been for self-feeding and tabletop activities. However, because of the difficulty controlling the W/C joystick with the MAS on, it is taken off for driving. Frequent need for putting on and taking off the MAS limits the functional wear and use time of the MAS.

Functional Objectives:
The objective of the current Active Mobile Arm Support project is to design power assist components to the existing MultiLink system in order to provide extended functional abilities to disenfranchised and potential MAS users.

The extended functions we are aiming for include ability to use the MultiLink MAS for wheelchair driving as well as for self-feeding and tabletop activities. The ultimate aim is for the user to have the ability to independently and easily switch between driving, feeding, and tabletop activities. An additional objective is to offer a low cost, quick and easy, manual option to be adjusted by a helper.

Progress:

Power Assist Height Adjustor:
It was determined that if stability could be provided for operating the W/C joystick while wearing the MAS, wear time and use would be improved and thus more functional. A powered assist prototype, using the new MultiLink MAS as the functional base, has been developed to allow the user to independently adjust the height of their MAS. Low position: W/C armrest level provides stability and a long term comfortable position. Mid position: The user can independently raise the MAS a couple of inches to allow clearance and movement for tabletop activities. High position: It can be raised 4 to 8 inches to allow hand to reach mouth or head for feeding, adjusting glasses/ hair, brushing teeth, etc.

Patient evaluations are presently being conducted with the power prototype.

Manual MAS Height Adjustor:
In conjunction with the Spinal Cord Injury Mobile Arm Support Project, a manual version of the MAS Height Adjustor has been developed. The Manual Height Adjustor is an add-on component to the current Jaeco/Rancho MultiLink Mobile Arm Support system. It requires the assistance of a helper or caretaker to adjust the MAS height needed for varied activities. Height adjustments are made in seconds by pressing a knob and raising or lowering the MAS. No tools are needed. The Manual Height Adjustor will be a cost effective add-on component which will allow improved functional use and wear time of the MAS. It will offer multiple height working levels for activities such as W/C operation, tabletop activities (computer keyboard/mouse use, games, writing, etc.), and hand to mouth/head reach.

The Manual MAS Height Adjustor will soon be commercially available, hopefully by summer, 2005.

Power Assist Retractor:
A power assist prototype has also been developed for retracting the proximal link of the MultiLink. This helps reduce lateral protrusion for improved doorway clearance as well as provide additional MAS stability while driving, including inclines. The power retraction also helps stabilize the MAS while reclining in the W/C for pressure relief; it prevents the arm from flinging out to the side and back when reclining.

To download a Mobile Arm Support Flyer, click here.

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Last modified: July 28, 2005