The rates for loosening and infection of the pins used in the halo
apparatus are unfortunately high. The commonly recommended amount of torque
to be used in applying the pins is 0.68 newton-meter (six inch-pounds).
Forty-two adult patients underwent application of a halo device for
immobilization of the cervical spine using an increased torque of 0.90
newton-meter (eight inch-pounds). The rate for loosening of the pins and
the rate for infection at the pin site dropped from 36 per cent to 7 per
cent and 20 per cent to 2 per cent, respectively.