Invention of the Wheelchair
True to its name, the original wheelchair prototype only had one wheel.

Several hospitals in March of 1910 agreed to use the prototype at their facilities to see how effective the wheelchair might be. After the conditions of all the 32 patients who used the prototype began to worsen dramatically, the hospital staff began to suspect their one-wheeled assistant - the wheelchair. Patients simply were not able to balance correctly if they were to have casts on one side of their body or if they were recovering from an amputation.
It wasn’t until 1932 when hospitals began to accept the wheelchair as we know it today.