If displacement exists but isn't suitable to practical outcome (eg, humeral shaft fracture exactly where the shoulder and elbow motion can compensate for residual angulation) The many muscles that preserve your body in this posture are pressured to react on the oscillating movements provided by the device.31 Mechanical masses are https://www.theorthopaedicandpainpractice.com/i-have-a-broken-bone-what-should-i-do/