Measuring the length and thickness of limb:
A tape ruler is usually used for measuring the length and thickness of limb, which is then compared with those of the healthy side.
 
Significance
The affected limb is longer than the healthy one:
This is usually a sign of dislocation. It is commonly seen in anterior or inferior dislocation of shoulder or hip joint; and also seen in length-wise separation and displacement of fracture.

The affected limb is shorter than the healthy one:
This is often seen in overlapped displacement of fracture or in posterior dislocation of hip and elbow joints.

The affected limb is thicker than the healthy one:
This is commonly seen in the serious case of fracture or dislocation, or in the case of swelling caused by injury of tendons and muscles if there is no fracture and dislocation.
 
The affected limb is thinner than the healthy one:
This is often caused by atrophy of muscles in the old trauma, or paralysis of limb with injury.