I therefore strongly advocate careful selection of the methods a patient should be treated with to accomplish functionality. For example, I very much question the need to fuse the vertebrae of a high-level quad's neck, which, on the other hand, reduces his chances for otherwise fuller functionality. The motion of the neck is a great asset for the rehabilitation of a C-4 quad. The more he or she can move the neck, the better he or she will be able to use a mouthstick. Surgeons, therefore, should re-consider before they fuse the cervical vertebrae of a broken neck.
Nobody knows what amount of exercise is best for anybody.
Likewise, the less a person exercises, the less chances he or she will have to live a long and healthy life. If a quad has only one functional muscle, he should exercise that muscle as much as possible. It is the condition of the heart which matters most, and the heart doesn't feel the difference whether it is one or 20 muscles being exercised. It only feels the overall intensity of the exercise, and the use of a mouthstick can be very intense, if it is used for everything. A mouthstick is also a simple tool, which is relatively cheap and does not break easily.