法医学バイオメカニクスジャーナル

概要

Handcuff Pressure and Risk of Superficial Radial Nerve Injury

Geoffrey T Desmoulin1

Background: A number of cases of handcuff neuropathy have been reported in the literature. Specifically, when handcuffs remain fastened around the wrists for a prolonged period there is a risk that function of the superficial radial nerve can be compromised. Although cases of median and ulnar nerve injury have also been reported, they are much less frequent and are usually accompanied by injury to the superficial radial nerve.

Methods: We hypothesized that the pressure applied to the superficial radial nerve by tightened handcuffs could readily exceed nerve injury thresholds. To test our hypothesis, we created a physical model of the wrist and superficial radial nerve which allowed us to measure the pressure applied by tightened handcuffs. We tested two handcuff designs and compared the measured pressures to pressures known to produce loss of function of the rat tibial nerve, a nerve which is similar in diameter to the human superficial radial nerve.

Findings: We found that relatively low levels of force applied by tightened handcuffs can produce pressures which exceed nerve injury thresholds if sustained for sufficiently long time periods.

Interpretation: Our results suggest that precautions must be taken by law enforcement officers, when fastening handcuffs, to ensure that the force produced by tightened handcuffs remains below nerve injury thresholds, that the double locking mechanism is engaged and that detainees should be made aware that movements which increase the force applied to the superficial radial nerve, even periodically, can increase the risk of nerve injury.