objectsJosh Shiau

Mobiliti Compact Crutch

objectsJosh Shiau
Mobiliti Compact Crutch

Developed with a graduate team at MIT – 2015

The Mobiliti Compact Crutch began in the Product Design and Development Course at MIT. It was developed in 4 months working closely with graduate students from the School of Engineering and Sloan School of Management. I conducted user research, facilitated design thinking through the development of the product, and fabricated the final prototype.

 

Market Analysis

There are approximately 6.1M users of mobility products in the United States leading to a $320M annual market. The market is dominated by ‘traditional’ crutches that can be purchased for $20 retail. New entrants and niche products, such as hands–­free scooters, and forearm crutches fulfill many needs of the long–­term crutch users. The majority of users only require crutches for less than 1­2 weeks, incentivizing a highly disposable or reusable product. Other market-–based tensions include declining medical reimbursement rates for crutches and an insurance industry preference for the lightweight ‘traditional’ crutch type. Ultimately, there is niche market need for an improved crutch but the existing suite of products make an additional new product financially challenging. For a new product to succeed, it would have to address unmet user needs as well as innovate with a new business model that would allow it to deliver much higher quality without a huge price jump.

 

Understanding the User

Over the course of a 10 interviews with current and past users of crutches as well 2 physical therapists we found that though there were a variety of circumstances in which people needed to crutches, they correlated with 3 main types/timescales: 

Short-term users like sprains were often due to sports injuries and lasted usually for a few weeks. Prolonged users typically have undergone surgery and in some cases required physical therapy as well. These could last for several months. Permanent users could need crutches due to age or accidents.

Common sentiments across the users were mapped and synthesised for reference throughout the project.

Common sentiments across the users were mapped and synthesised for reference throughout the project.

Though on very different time scales, users faced similar physical and social constraints through their crutch experiences.

Though on very different time scales, users faced similar physical and social constraints through their crutch experiences.

 

Pain Points

We condensed our observations and user-voiced concerns into 3 main categories:
1. Stigma – Many users were concerned about their perception and the increased attention that crutches drew. Rattling height adjustment mechanisms, dirty grips, and the sterile medical aesthetic of the crutch were mentioned, with pity from others being by far the most uncomfortable feeling they encountered in their day to day.
2. Ease of Storage – Crutches were notoriously hard to store for students. Laying them down them under the desk meant inviting grime on the grips and presenting a potential tripping hazard, but leaning them against a wall was unstable and fairly inconvenient if the seat was not close to a call. 
3. Sanitary - Finally, users were frequently concerned about the hygene of their crutches. Germs on the grips accumulated over continued use or how they were stored were mentioned as concerns, especially when eating hand-held food.

 

Insights

Interestingly, we found a large cultural difference between America and the rest of the world in terms of use and perception. The short–term mobility product market is primarily separated into the traditional underarm (left) vs. the forearm (right) crutch, with underarm crutches being popular in the US market, and the forearm crutch the preferred crutch for Europe and much of the rest of the world. Though priced similarly (~$20 on Amazon) this inconsistency is often attributed to a stigma attached to forearm crutches – often seen as only for longer term or permanent disability, despite mounting evidence that underarm crutches can cause lasting muscle and nerve damage.

“One reason behind the lack of usage of forearm cruthches in the United States could stem from the permanent connotation associated with forearm crutches in comparison to the indicated temporary usage of axillary crutches…Several studies have shown that forarm crutches are less harmful to one’s body.”
“Repetitive loads on the hands, wrists, elbows, and shoulders have resulted in injuries secondary to crutch usage…Compressive neuropathies in the upper extremity have been well established with the use of the traditional crutch…An association between the development of carpal tunnel syndrome and the use of assistive devices by patients has been reported”
Traditional underarm crutch on left, forearm crutch on right.

Traditional underarm crutch on left, forearm crutch on right.

 

Ideation and Exploration

We came up with a number of concepts, many not even involving mechanical crutches but instead focusing on other specific parts of the user journey.

A self–standing crutch could allow for full freedom of motion for users while standing in place, making everyday actions like retriving a credit card from a wallet easy again.

Though not a comprehensive solution, we considered other simple ways to assist users. After observing the difficulty users had with slinging shoulder bags, accessing their phone, and carrying shopping bags, a system of attachments and bags provided an easy way to manage items. This was considered out of MVP for the initial prototype.

A pressure sensor applied on the walking boot/injured foot allowed the patient to be alerted when he puts too much weight, increasing the amount the weight that can be applied over time. This required integration with the walking boot, sensors when testing were hard to calibrate with differing gaits, and physical therapists were reluctant to give safe weight ranges while healing.

An app using the front facing camera on the smartphone could match the person with an idealized position onscreen to assist with the perscribed physical therapy exercises. Doctors could perscribe and review progress saved on the app.

With a smart crutch, sensors would allow the user to monitor load, wrist strain, and their gait. We tested a prototype with an accellerometer to map the walk to a potential healthy step. Though not very accurate in early testing, refining patterns of different gaits would allow for the crutch and accompanying app to identify how a user was walking and if it was conducsive to their healing. This would require a lot more training data to positively correlate gaits.

After some initial testing and exploration we were able gauge impact to the user and the cost to further explore each option. Though more than a few of the avenues were promicing, based on the niche market and reletively low price point of most crutches, we ranked and focused on the features that would be most crucial in an MVP.

 

Converging on a Design Proposal

We considered many form factors based on strength, ergonomics, and aesthetic appeal. Based on a wealth of studies, we decided our crutch would support the user under the forearm as opposed to under the shoulder. The reasons are numerous, but can be mostly summarized in 3 main categories.

Posture – Many first-time users of underarm crutches tend to slouch over their crutches, and this can be a hard habit to break, eventually leading to strain and muscle pain. Forearm crutches, however, encourage good posture in their users- the taller and straighter a person stands, the easier their crutches will be to use.

Coordination – Underarm crutches are generally easy to master, as they have one basic possible gait. Forearm crutches can be more difficult to coordinate, and often require the consultation of a physical therapist to fully master. However, forearm crutches allow for a greater variety of walking styles and gaits, and are more stable on rough or uneven terrain.

Comfort – Forearm crutches feature a cuff under the elbow which helps reduce strain and keeps some of the pressure off the wrist while in motion, making these crutches comfortable and easy to use. Underarm crutches, however, press against the side of the body when used, often leading to soreness and abrasions no matter how much padding they feature.  

Virtual models were built and stress-tested in solidworks. Meanwhile, we drafted a novel business model and go-to-market plan. I 3D printed various pieces to test for ergonomics. Lastly, we designed a novel vertical adjustment mechanism that allowed a nested tube to slide and lock at various intervals within another tube, which provided reinforcement. We were able to source components using only off-the-shelf parts.

In our final prototype, we used steel tubing that ran the length of the entire crutch outfitted with detatchable molded plastic and rubber components which provided a good balence of strength and easy maintenance at a relatively low cost.

 

Final Features

With its understated and thoughtful design, the crutch engages the stigma of disability with dignified grace.

A velcro strap ensured the crutches fit each user snugly and also allows for easy separation in the case of a fall.

A velcro strap ensured the crutches fit each user snugly and also allows for easy separation in the case of a fall.

A push-button mechanism allows the user to easily fold the crutches for easy storage.

A push-button mechanism allows the user to easily fold the crutches for easy storage.

A spring-loaded height adjustment mechanism also doubles a convinient method, allowing the user to brace it between any two surfaces (like a desk and floor).

A spring-loaded height adjustment mechanism also doubles a convinient method, allowing the user to brace it between any two surfaces (like a desk and floor).

The grip and armrest components have an anti-microbial coating and are easily detatchable for repair, while the elastic strap is machine washable.

 

Business Plan

By designing the crutch to be easily collapsible and modular, we could cheaply reship and refurbish them after use, making a renting model feasible. This allows us to invest more considerably more money into manufacturing a quality product that we can then reuse. By renting instead of selling, we would actually be selling a service instead of selling a product.