Upper Limb Rehabilitation Aids

The solution

The size of the tables that fit to a bed really defines the size of board that could be used- 400mm high x 550mm wide. On reviewing possible options, it was decided to develop two boards, one with low effort actions (e.g. micro manipulative skills) and one with moderate effort options (e.g. wrist rotation), as there was not enough room on a single board to fit all options.  The base of the MDF boards were fitted with anti-slip mats (clamps could be used if needed) to provide a positive fitting to the table.  All corners and edges were rounded.  Final paint finish: white bathroom satin washable.

Board 1 has 6 activities:

1. Yale lock mini door, with key on a chain. Also included on the mini door is a sliding safety lock.
2. Three lengths of cord (4 mm diameter) for plaiting and knot tying. Conventional cord could not be used because of difficulties in cleaning this material, so silicone rubber cord was sourced for this purpose.  Initially I was concerned that the cord may slip and not tie effectively.  However, it was found to work very well. An acetyl post (about 15 mm diameter) was attached to the board to allow hitches of different types to be tied.
3. Threaded plastic block with 3 sizes of bolt, with each attached to the board by a length of chain. Bolts (6, 10, 12mm diameter) were of nylon and fitted into a threaded Perspex block attached to the board.
4. A series of plastic strap clips (pinch action to open) of differing size. Again, conventional woven webbing could not be used because of concerns over microbial contamination.  Instead, lengths of silicone rubber sheet (1.5 mm thickness) were cut to the correct width and attached to the clips using brass rivets.  The set of straps was loosely held on the board with two vertical PVC bars with cut outs milled in position to allow the straps to slide along
5. A set of carabineers of differing size and spring strength were attached to a 5mm diameter aluminium rod supported between two posts attached to the board.
6. An analogue watch was attached to the board for patients to practice setting time and date (small scale manipulation skills).

A custom sheet was produced which included illustrations of a range of knots, and a table to allow Individuals to mark their progress with the tasks.  This sheet will be laminated by the OT staff, so that it can be readily cleaned, and reused.

Board 2 has 4 activities:

1. For wrist action, a rotating large (circa 80 mm diameter) plastic knob attached to a spring (see picture of spring below for view from rear showing mechanism) was used. The further the knob is rotated, the more the effort required. There is a coloured graduated scale with numbers to monitor progress. Note maximum torque required is about 0.8 Nm. The spring and rotation mechanism have a rear cover to prevent possible trapping of patient fingers.
2. Grip strength. As a commercial unit was not readily available, a simple device was built by connecting a pressure gauge (0-1 atmosphere) to a flexible rubber bulb by tubing. Squeezing the bulb gives a response on the gauge proportional to the hand pressure.
3. A series of 3 springs of increasing strength with attached chains for vertical pull practice. Positive latching was provided by a set of acrylic posts on the board.  Springs were contained in short lengths of plastic tube to help prevent any tangling.  Note that springs were vertical with any force used thus being directly down on the surface of the table.
4. A 3 mm diameter stainless-steel wire formed into a series of sharp bends going up and down and then left to right, with a connected handle and metal loop. This exercise is to practice upper limb movement.

Spring at Rear of Board

A board specific custom sheet was prepared, similar to that used for Board 1.

5.Effort and costs involved.

Costs are to be obtained from the NHS for this project

Consumables, travel and specific items (lock, paint, silicone rubber products, pressure gauge etc.) came to £106.75.  Additional minor items (screws etc.) were sourced from my workshop.

On average each activity took about 9 hours to design, prototype, test and finally manufacture, plus 3 hours for each of the two MDF boards (cutting, routing, construction and painting).  Discussions with the OT involved and her colleagues circa 6 hours.  Most trips to the hospital were by cycle, but travel costs for delivery of each board by car have been included in the.  Travel time was about 3h.

Thus, the total time taken on the project was about 105 hours.

Remap Member designing and manufacturing this project  ………………… Peter Statham

Further details on construction

Please read material on the Makeability site (makeability.org.uk) to obtain a full background to the project. The purpose of this note is to provide more detail on how I approached manufacture of key components of the boards.  if you plan to make these aids I suggest that you firstly discuss options with the client to ensure the detail is appropriate to their needs.  You may well have better ideas on how to make the components described here, so please use the material here as a guide only. Additional factors, such as the size of available components, may also necessitate some modifications to the dimensions shown here.

Two units were constructed (see Pictures  1 and 2), and each mounting board used the same dimensions and materials.   Below I focus on the more complicated components on each board, and details of simple racks and hooks are not given, but should be well within the ability of most home engineers.

1. Mounting Boards

These were constructed from 12 mm MDF, and dimensions are in Fig. 1.

Many items were sourced from a local DIY store or the web, with one or two items coming directly from China.

Fig. 1  Baseboard construction

The routed rebates, plus screw and glued joints ensures a strong structure.  Note that it is easier to decide on positioning of components, and in some cases drill and cut (e.g. mini door), prior to the gluing and screwing step.  The hand grip aperture was 100mm long and 25mm wide. The corners were rounded with a radius of about 25mm, and all edges were rounded over with a router and appropriate edge following bit.  During gluing and screwing, the base and upright boards were frequently checked that they were perpendicular to one another.

Before final fitting of components, I initially gave the MDF a coat of 50:50 PVA glue/ water, to ensure it was sealed, and then I then applied 2 coats of a high quality robust white satin paint.

1. Board 1 (low effort)

Silicone cord holder

The block was made of ABS, but other materials could be used (Fig 2). The Delrin post for tying hitches (25mm tall and 20mm diameter) had a groove machined along its length to aid securing the silicone cord. A simple knot was tied at the end of the piece (300mm), and the clear end is fed through the 5mm hole so that te cord hangs vertically

Holders for silicone rubber straps

A sheet of 1.5 mm silicone sheet was cut into strips of widths to suit the clip fittings used, and the rebates machined into the ABS mounting strips (Fig 3). A short length of the cut strip was glued (silicone rubber cement) at one end of each strip to prevent the silicone from sliding out.  The folds attaching the strips to the components of the clip were riveted together.   Materials were chosen to allow their easy and thorough cleaning.

Mini-door with Yale lock and safety latch.

The overall size of the door was 110 wide and 160 tall, with rounded corners; the door was offset form the right-hand edge by 50 mm. The door opened inwards, and an overlapping piece of MDF or similar material on the front of the board prevents the door swinging outwards.  To properly house the lock mechanism an extra thickness of MDF or wood was attached to the rear of the door and the 32 mm diameter hole was drilled through all layers.  Detailed instructions on fitting will be with the lock.   The key was attached to the board by an appropriate length of fine chain.  Having the door close to the edge of the main board means it can be readily closed with a hand around the rear of the board

The watch was a non-working unit that I donated to the project, on which the time and date could still be set.

1. Moderate effort board

Lateral and vertical motion

This exercise used a circa 1.3m length of 3mm diameter stainless steel, bent into a series of vertical and horizontal lengths (see photograph in Makeabiilty information).  For the handle that moved along the wire I used an M10 bolt with an eye at its end that was screwed into a circa 25mm diam. x 100mm threaded ABS handle.

I wanted the wire to have a good degree of rigidity so I did not anneal the stainless before bending the curves shown.  This was quite tough going, but I built a jig with vertical posts that significantly helped forming the bends.

Rotating effort dial for wrist action.
The rotating front dial is attached to a spring at the rear (see photo 2).  The further the dial is rotated, the greater the spring extension and effort needed. A variety of approaches could be taken for this build; the route I took is given below.

The main shaft was made of circa 12.5 mm diam. Delrin rod, carefully reduced in diameter on the lathe to give a tight push fit through a surface mounted 12 mm flange bearing unit (RS part 109-933) attached to the rear of the board. A 50mm length of stainless rod was attached at right angles through the main shaft to form a spring bar, and one end of the spring passed through an end hole in this rod.  The other end of the spring was attached to a post and screw directly above the shaft, such that with no rotation of the shaft, the spring was gently held in a vertical position. Rotation of the shaft (± 150˚) was limited by screws that met the spring bar (see Photo).

Obtaining an appropriate force to fully rotate the shaft is dependent on the strength of the spring.  There are several in depth articles about spring design and manufacture.  However, I took a more pragmatic approach and experimented with several strengths and dimensions, taking into consideration the length of the spring bar.   The experiments suggested a weight to extension ratio of about 70g/cm.  I had one spring in the workshop that met my specification, but for a later board I could not readily find a reasonably priced spring, so I wound a spring in the workshop.  Dimensions were 56 turns, giving 65 mm length and 14 mm diameter on relaxation. It was made from 1mm diameter music wire wrapped around a 9.5 mm diameter steel rod, whilst under tension.

There are a variety of ways in which the front knob can be made but the critical point is that it should be about 80 mm OD (i.e. similar to the diameter of a large jam jar).  One I constructed from scrap plastic components screwed together, and another I 3D printed.  A full-size copy of the dial scale is given at the end of this note.

Grip Strength exercise.

As a commercial unit was not readily available, a simple device was built by connecting a pressure gauge (0-1 atmosphere, Amazon) to a flexible rubber bulb by tubing. Squeezing the bulb gives a response on the gauge proportional to the hand pressure.

The rubber bulb came from a basting tube, but other sources might be an old pipette filler or old-fashioned blood pressure equipment.   A significant issue was ensuring strong enough connections at either end of the flexible connecting tube.   For the bulb to tube connection, I made a custom plastic connector on the lathe, and secured this with a jubilee clip.

Finger strength exercises

 A series of 3 springs of increasing strength with attached chains for vertical pull practice (see Fig. 4.   Positive latching was provided by a set of acrylic posts on the board.  Springs were contained in short lengths of plastic tube to help prevent any tangling. The tubes can be held in place by a purpose-built clamp or commercial pipe clips.   Note that springs were vertical with any force used thus being directly down on the surface of the table.

I used small extension springs (25 x 6.5 mm, 0.55mm wire diameter), and increased their number at each step (1, 2, 3) meaning an increasing force was needed at each step of the progression.   The bottom of the spring was attached to a short length of fine chain then a key ring, more chain and a final key ring that the patient can insert a finger to pull the spring(s) down until latched on the post by the upper ring.  See Fig. 4 for dimensions I used, but these may need modifying depending on the springs used.

Information and record sheets to accompany the boards

I put together some instructions (knot tying) and record sheets (effort dial) for patients to use.  The patient can then see how they are progressing through the exercise sequence. The intention is for them to be laminated by the OT staff so that they can be re-used.   These are appended at the end of the document:

1. Instructions and record sheet of knot tying and other exercises
2. Record sheet for the effort dial, and board 2 exercises
3. Full size image of effort dial scale. Check dimensions for your application!.