Designing a customized Outdoor Portable Knee Walker

Project Info


Our client requested us the industrial designing a customized Outdoor Portable Knee Walker. A knee walker or knee scooter is a medical mobility device used for below the knee injuries as an alternative to crutches. Knee walkers are specially used by people who have undergone ankle or leg surgery and is a replacement for the traditional clutches. These devices provide patients with good support as well as relief from pain.

The design was to be later patented for the production.


The main requirements were the followings:

  1. Stability during the movement
  2. Foldable to be easily carried and stored
  3. Adjustable in height and length
  4. Telescopic knee handle
  5. Adjustable seat
  6. Good safety and control


In order to satisfy the above requirements, the following steps were taken.

  1. To meet the stability requirements, there were several options. There are currently two types of knee walker designs, 3-wheel design as well as 4-wheel design with each of them having their own pros and coins. For example, due to the lack of an additional wheel, the 3-wheel design is more cost-effective while the 4-wheel design is more stable. In our design, we followed a 4-wheel design with the following additional features.
    1. Large tiers make its mobility easier in challenging terrain for users recovering from a foot injury
    2. Reliable break
    3. Having the distance between the two front wheels bigger than the back wheels.
  2. Regarding the requirement for the foldability of the design, a folding mechanism was used and the final design complied this condition and a handle was considered for its convenient carrying.
  3. In order to provide good safety and control, dual handbrakes were used. Also, similar to a car’s axle, the front wheels were driven by the handle via an axis connected to both front wheels. This mechanism provided higher stability once the rider wanted to turn to the left or right.
  4. In the new design, the wheels could be replaced by smaller wheels to also make it applicable to the indoor application.

The design took about 3 months to get completed and ready for the prototyping and patenting. The final design that was composed of 54 components met all the given requirements.
Some of the main features of the final product included the followings:
Height adjustable knee pad
1. Height adjustable handles
2. Adjustable body
3. Ergonomic seat
4. Telescopic handle
5. Dual handbrakes for safety and control
6. Steering system
7. Quick release folding mechanism
8. Made up of Aluminum with a weight of 5Kg
Also, while it was basically designed to be used as a knee walker, by changing the seat, which was designed for the knee, or leg, … it could be used for other applications by supporting more rest and convenience.

John Ward
January 31, 2019
Mechanical Engineering