DME

Blog posts of '2019' 'June'

The Weight is Not just Coming from the Frame

_______

 

We just finished last week’s blog talking about the differences between titanium and aluminium, one of those differences was the weight of each metal. In our continued discussion on shoulder preservation, we know that weight can be an important factor when propelling a manual wheelchair all day. Remember studies show that the average full-time manual wheelchair user completes 2,000 to 3,000 pushes every day! This is an enormous amount of work that we are asking the shoulders to complete. Therefore, weight is important. However, weight does not just come from the frame.

 

 

We can have the lightest wheelchair frame, but if we load it down with armrests, heavy cushions and backrests, solid tyres, etc… we just cancelled the weight we saved in choosing a lighter-weight frame. It is important we think about the components that we are putting on the wheelchair. With each component that we add onto the chair, we should ask ourselves, “What is the purpose/goal of this component?”. Let’s think about a few examples when it comes to an individual who is a full-time upper extremity propeller in a rigid manual wheelchair.

One of my favourite ways to decrease weight is to consider the armrests. What are the armrests doing for my client? Perhaps the end-user needs to have armrests to complete a functional activity, but more than often I see that the armrests are placed on the wheelchair for “comfort” reasons. How much weight does this comfort option add onto a wheelchair? It is not just the armrest itself, but also the large brackets required to mount these armrests to the wheelchair.

What about the wheels and tyres? This is another way that we can substantially increase the weight of a wheelchair. We often forget about how much a wheel and tyre can weigh. The position of the wheel and tyre is also a key. The further from the end-user the more impact the weight will have on propulsion. So, now if we think about the wheels and tyres and their location, we begin to understand the importance.

Does this mean that everyone who is a full-time manual wheelchair user should have pneumatic tyres and Spinergy Carbon Blade wheels? No, but it does mean that a discussion on goals and how this relates to the wheels and tyres is crucial. Therapists are often nervous about recommending pneumatic tyres for manual wheelchairs, but we want to help decrease this fear and will have a discussion in the upcoming blogs on the truths and myths of pneumatic tyres.

It is important to remember that even small changes can make a big difference. This should be considered in two ways. First, remember you can slowly start to work on decreasing the overall weight of the manual wheelchair, you don’t have to change the whole wheelchair in one day. This is also important for reason 2. Even the smallest changes could feel like a big change to the end-user. Everyone, whether you are the therapist, dealer, or end-user, has to remember that any change to the wheelchair will take time to get used to and may need further adjustments in the future.

As the therapist or end-user should you have to know all the different components available and their corresponding weight? No! You need to know your goals and/or the goals of the end-user. Then, it is the role of the dealer to help determine which products meet those goals and provide options. The dealer can help to discuss the options to decrease the overall weight of the wheelchair. The less weight on the chair, the less demand we place on the shoulders, right? This is absolutely true and should be considered for all individuals who are full-time upper extremity propellers, but if we don’t have the proper configuration, then even the lightest-weight wheelchair will be difficult to push.

Remember that if we all work together as a team, we can achieve the best results!

If you are interested in understanding more about this topic and how the weight distribution on the wheelchair matters, email me to set up your Materials Science for Manual Wheelchairs course.

Rachel

 

 

Materials Matters: Titanium verses Aluminium Manual Wheelchair Frames

____

 

Malcolm’s perspective:
Right from the get-go let me say, I love titanium! From my first ride in a titanium chair some 15 years ago I remain convinced it is the best material on earth for wheelchairs. The ride in a titanium chair feels different, it has a dampening effect on bumps. When I got my first titanium chair my wife would often get surprised when she realised, I was beside her – she could hear my aluminium chairs coming as they went over the tiles and floorboards, but not the titanium chair. This was because of the vibration dampening. Apart from the “ride”, I love the fact it does not have to be powder coated, which means it does not chip, or look scratched and old. As well as that, titanium is strong – the strongest weight to strength ratio of any metal – which suits my lifestyle which involves lots of travel. After 15 years of regular plane trips I have confidence that when I arrive my chair will be good to go despite the rough handling it gets. That peace of mind is really important to me.

 

 

My chair is also ultra-light, especially with a non-folding back. With the configuration I have it is slightly under 8kg with the wheels on, about 4.5kgs with them off.
A couple of things to note, not all titanium is the same, so the type of titanium and the thickness of the tubing will impact on how the chair rides and how heavy it is. Also, my chair frame is made from titanium, but I have carbon fibre components such as side guard, wheels and backrest. Some of the parts are aluminium, such as front forks and camber clamps, so it is really a titanium frame with hybrid components.

Rachel’s thoughts:
Mal just gave a great insight into his preference. Now, let’s look at the materials and why Mal has preference for titanium versus aluminium. We have been able to learn a lot about the materials we use in manual wheelchairs through other industries, one of the big ones being the biking industry. We will start with aluminium. All types of aluminium have specific strength, low density, and resistance to corrosion. There are lots of different types of aluminium, but most manual wheelchairs are made of either 6000 or 7000 series aluminium. Many people believe that 7000 series is the best, just like how the iPhone 10 is better than the iPhone 8, but this is not true. The type that is best depends on how each manufacturer wants to use the aluminium. TiLite uses 6000 series as this allows for the aluminium to be weldable and for the greatest amount of customisability while still having a high strength. The 7000 series has a slightly higher tensile strength, but it is heat treated and therefore is harder to machine and less customisable. The difference in strengths of aluminium is minimal as compared to the difference in strength of aluminium to titanium. You can see the difference in the chart below. The chart on the left showers the ultimate strength of 6000 series aluminium, 7000 series aluminium, and then titanium. The chart on the right shows the strength-to-weight ratio.

 

 

Titanium has the highest strength to weight ratio of any metal on Earth. This gives the end-user a light weight and strong frame. Titanium is virtually immune to corrosion and is easily machined. From its ability to be easily machined and its strength to weight ratio, and vibration dampening properties, Titanium can allow us to achieve that ultimate fit. This ultimate fit along with the design of the frame of the chair leads to the optimal ride for our end-user. Although titanium has many benefits, it is a more expensive metal, and therefore the base price for a titanium frame will be more than an aluminium frame.
When deciding what type of material is right for you or your client, it is important to assess each person individually and consider the environments in which the chair will be used. It is also important to keep in mind the amount of time that will be spent in the wheelchair. We know that vibration has negative impacts on our health, and we know titanium through its material properties, design of the frame, and being easy to machine, will help to limit some of these vibrations, therefore providing the highest performance and ride for the end-user that is in the wheelchair throughout the day. We also know that strength is important as we want the frame to be able to withstand the environment that it is taken through. Finally, we want to think about the weight of the overall chair and how we can keep the weight low. This will help reduce the amount of work that we are asking the shoulders to do with every push. This is where are shoulder preservation comes back in! We want to make sure we can keep the chair as light as possible. This doesn’t just include the frame! We also need to think about what we are putting on this frame. All of the seating components, accessories, tyres, wheels, etc… have an impact on the weight of the wheelchair. Besides what goes on the wheelchair, we will also have to consider how the frame design impacts the ride, strength, and way that the wheelchair is built. We will continue this discussion next week.

Shoulder Preservation: An End-User Perspective – Mal’s Story

 __________

 

In 1980, when I acquired my SCI, there was very little talk about preservation of shoulders. The focus was on strength, lots of weights and pushing. The adage “if you don’t use it you lose it” was strongly endorsed. In those days, I thought that shoulder pain was a good thing, it meant I had been working my shoulders and therefore strengthening them. In my mind it was “a badge of honour” to have sore shoulders. I didn’t know the difference between “good” pain and “bad” pain. In the early 1990s, I started playing competitive wheelchair basketball. Here I began to learn more about how to look after my shoulders – resistance bands, stretching, warming up, warming down, backwards pushing rotator cuff strengthening, etc… I also started handcycling and concentrated on the “pull” of the hand cranks to work the back of my shoulders. But, to tell the truth, my focus was so much on being competitive I often played with injuries, which I am sure has caused problems for me now. Hindsight is a great thing, and I wish I had of thought more about the long-term impact of the stresses I put on my shoulders, elbows, and wrists. Pain, loss of strength, loss of range and carpal tunnel syndrome are things I have experienced and continue to work against. At 39 years post injury, I am still mobile, and the past several years I have put into place strategies to maintain and improve the health of my upper limbs.

 

 

Apart from the obvious negative of pain, why is upper limb health so important to me? There are many reasons, but for the sake of this blog here are three of my main ones

Independence: A friend of mine often says that “if it goes without saying, it is worth saying”. My shoulders are fundamental to my independence. Being able to push my wheelchair, transfer, lift my chair in and out of the car, kayak, complete pressure reliefs – just about every activity of daily living (ADL) I do requires my shoulders.

Wellbeing: Being able to do all the things I can do independently has a huge impact on my        wellbeing. My SCI has cost me a lot of independence as it is, so I treasure every bit I have. Loss of independence is, quite frankly, depressing! As well as that, pain is a stressful thing, so minimising pain is really important.

Pressure Care: My shoulders are directly linked to my pressure care. In the past 39 years I have had only 2 pressure injuries which caused me to spend time in bed. One was post operation, the second was a stage 2 pressure injury caused by a bad transfer. The better my shoulders are the better my transfers are, and the less risk I have of a pressure injury.

So, as I race into my sixties and hopefully beyond, what are my strategies for looking after my shoulders? Here are some of the things I have done, and am now doing

My wheelchair is super light-weight and custom built around me. I have minimal adjustment and folding parts in my chair. After 39 years I pretty much know what I want out of my wheelchair, so a fixed back and fixed front to rear height is my preference. Even these simple things shave a noticeable amount of weight off my chair. I have the rear wheels as far forward as I feel safe with which makes it easier to push.

I restrict my pushing to areas that do not cause a lot of shoulder pain. I have been using a power assist device, the SmartDrive, for many years now and love it. I use it for any steep hills or really long pushes. I still push, but not as much and on less challenging slopes.

I have a set of strengthening and stretching exercises that I do regularly. Most of these involve resistance bands or a medicine ball, and are low weight with higher reps. The important thing is for me to concentrate on technique! They are exercises recommended by        my physiotherapist. As part of my NDIS Capacity Building, I have linked my goals of maintaining independence and function to the cost of the physiotherapist.

For cardio exercise, I rely on kayaking and handcycling. Both these activities allow me to focus on working the back of my shoulders, in the “pull” stroke.

I have been using an ergonomic hand rim for about 15 years now. These significantly improved my carpal tunnel issues. There are a number of these available, including the  Natural Fit™ and the Flex Rim™ (my favourite).

This is a little left field, but it has been an important change for me. Up until about 10 years ago I did not have wheel locks on my chair. With the improvement in design, specifically scissor locks, I finally decided to try them. It amazed me how much easier my transfers became!

 

The conversations I have with a lot of my peers these days centre around what we are doing to maintain shoulder strength and the impact long-term wheelchair propulsion is having on us now. If I could have a chat with my 20 year old self I would stress the importance of looking after his shoulders (not that he would have listened). In my mind the old adage of “use it or lose it” has been changed to “use it, don’t abuse it”. There is a lot of great Assistive Technology and resources to help wheelchair users maintain upper limb health, so why not take advantage of it all!

 

Malcolm Turnbull

 

Shoulder Preservation Part 4: The Recommendations for Shoulder Preservation with Manual Wheelchair Propulsion

_________

 

Let’s continue our conversation on propulsion with a manual wheelchair. Last week, we briefly looked at 7 of the recommendations based on clinical practice guidelines.  Today, we will begin our dive into those recommendations.  Let’s start at the top.

Provide manual wheelchair users with SCI a high-strength, fully customisable manual wheelchair made of the lightest possible material.

What does this mean?  We need to break this down into several parts.

High strength: This means that we need the chair frame to be strong enough for the individual using the chair and the environment the chair will encounter.  We can think about 3 of the popular manual wheelchair materials aluminium, titanium, and carbon fibre.

Each material has different properties and will give a different ride experience to the user. We must consider not only the material of the frame itself, but also how this frame is designed. The shape of the frame can greatly impact the ride experience for the user. Next week we will go into a discussion on these common frame materials and how we might choose one over the other based on each individual and their goals.

Fully Customisable: What does fully customisable mean? Does that mean that we can change the cushion and the backrest options? Or does that mean more?  Here is a great video where Josh Anderson discusses the importance of the fit of a wheelchair:

 

 

 

Think about fitting the wheelchair like a prosthetic.  This means fitting it across dimensions to get that perfect fit. If we think about this idea of prosthetics, we can understand the importance of the perfect fit. What happens to an individual when their prosthetic leg for example does not fit properly? Pain, skin breakdown, inefficient mobility, etc… Does this sound familiar for when we have a client with a manual wheelchair that is poorly fitted? We can all think about the hospital wheelchairs as an example. These wheelchairs are designed to fit everyone and for the hospital staff to get a client from point A to point B. Hopefully you have all attempted to propel this wheelchair and you remember how hard it is to even reach the wheels. This is an extreme example of a poor fit, but important for us to consider just how important the fit is for that full-time manual wheelchair user. We will dedicate another upcoming blog to getting this ultimate fit and what that truly means.

Lightest Material Possible: The key word there is possible. We must keep in mind the client’s environment and goals when deciding on the material. We will go into the weights of the main 3 materials next week but, what else do we need to consider? What if I choose the lightest material possible for the frame of the wheelchair for my client and then I give them every accessory they may every need on that chair?

It is crucial for us to not just consider the material of the frame, but to consider every component that goes onto that frame. This includes wheels, tyres, backrests, and armrests which is some of the areas that we often see a lot of weight being added to the wheelchair. Make sure when you are deciding on these components that you consider the client’s safety first along with their goals and then look into the weight of the different components.

 

 

 

 Rachel

Shoulder Preservation Part 3: The Recommendations for Shoulder Preservation with Manual Wheelchair Propulsion

_________

 

Did you know that the average number of pushes per day for a full-time manual wheelchair user is 2,000 to 3,000! Take a second and let this number sink in: 2,000 to 3,000 pushes every day. Now, go ahead and use that great technique we talked about last week and just take your arms and shoulders through 10 pushes. That was 10 pushes and without any bodyweight, weight of the wheelchair, friction of the chair across the ground, etc…. If we are not ourselves a wheelchair user, we cannot fully understand how our shoulders would feel propelling every day, but we can gain an understanding on the amount of work that the shoulders go through on a daily basis and what steps we can take to help in preserving the shoulder long term.

As a therapist, we cannot learn everything in our university, so it is important that we are always continuing the learning process and relying on researchers and experts in our field to guide us in our clinical practice. I often refer to our clinical best practice guidelines and today I want to talk about one of my favourites for shoulder preservation:
 
Preservation of upper limb function following spinal cord injury: A clinical practice guideline for health-care professionals. I highly recommend, if you haven’t already, downloading a copy. In reading the clinical practice guidelines there are 35 recommendations based on evidence-based research to promote preservation of the upper extremity. We will not cover all 35 recommendations, but over the next several blogs we will slowly be covering a few recommendations listed below:
 
1. Provide manual wheelchair users with SCI a high-strength, fully customisable manual wheelchair made of the lightest possible material.

2. Adjust the rear axle as far forward as possible without compromising the stability of the user.

3. Position the rear axle so that when the hand is placed at the top dead-centre position on the pushrim, the angle between the upper arm and forearm is between 100 and 120 degrees.

4. Educate the patient to:
    a. Use long, smooth strokes that limit high impacts on the pushrim.
    b. Allow the hand to drift down naturally, keeping it below the pushrim when not in actual contact with that part of               the wheelchair.

5. Promote an appropriate seated posture and stabilization relative to balance and stability needs.

6. Incorporate flexibility exercises into an overall fitness program sufficient to maintain normal glenohumeral motion and pectoral muscle mobility.

7. Incorporate resistance training as an integral part of an adult fitness program. The training should be individualized and progressive, should be of sufficient intensity to enhance strength and muscular endurance, and should provide stimulus to exercise all the major muscle groups to pain-free fatigue.
 
Hopefully as you read through all of these recommendations at least one or two makes sense already. Today, we are going to end with two videos from the extremely talented Madison de Rozario. Madison is an Australian Paralympic athlete and has helped create a few videos on the importance of shoulder health. In these videos you can see Madison touch on many of the above listed recommendations.
 

 

  

 

Next week, we will continue our discussion on shoulder preservation and deep dive into the recommendations.
Rachel

References:
Preservation of upper limb function following spinal cord injury: A clinical practice guideline for health-care professionals. J Spinal Cord Med. 2005; 28 5: 434–470.