Project Background

The rope gripping device was born out of a very unique problem statement: To enable a C7 Quadriplegic para-athlete to effectively manage a solo sailboat by providing an optimal method of gripping sailing ropes. Our team has been in touch with an inspirational 'customer' for this concept, who will eventually use this device to improve his sailing. 

Quadriplegia (tetraplegia) is caused by damage to the cervical spinal cord segments at levels C1-C8. Damage to the spinal cord is usually secondary to an injury to the spinal vertebrae in the cervical section of the spinal column. The name arises out of the fact that all four limbs of the person are affected. The legs are completely paralyzed and the arms are partially affected depending on which segment of the neck received the injury as seen in the list below.  

C3,4 and 5 Supply the diaphragm (mostly C4)
C5 also supplies the shoulder muscles (deltoid) and the muscle that we use to bend our elbow (biceps).
C6 Bends the wrist back (extension), and externally rotates the arm (supinates).
C7 Straightens the elbow and wrist (triceps and wrist flexors) straightens fingers, pronates wrist.
C8 Bends the fingers (flexion).
Injury below the cervical spinal segments will result in paraplegia, since the arms would be fully functional, but the legs completely paralyzed. Source for Quadriplegia information: http://www.apparelyzed.com/quadriplegia-quadriplegic.html

So in the case of a C7 Quadriplegic, all the functions of C1-6 are normal. The functions of C7 are impaired to varying degrees, and those of C8 and below are usually completely impaired. To say that more simply, the movements of the arm are normal, and so is the ability to extend fingers as well as move the wrist. However, the flexing (or gripping movement) is almost absent. The only limited control here is a weak gripping movement of the thumb.

This means that a C7 Quadriplegic who is a sailing enthusiast or para-athlete would be strong enough to handle the ropes and maneuver a sailboat if only he were given an effective method of gripping ropes. In the specific case of our customer, the arms have enough strength to lift 50 pounds of weight if transmitted to the wrist, but the fingers would barely support a single pound. A simple rope gripping device would be able to fulfill this need allowing him full use of his arm's strength.

 Design Requirements and Theory ->