Quadruped robots are ground mobile platforms with great capabilities to navigate on challenging surfaces, like on natural ground and unstructured environments. The key element behind such great capabilities is the level of adaptation that each single leg can provide with respect to the terrain surfaces and obstacle sizes. In this perspective, an effective leg design exploits as much as possible the range of motion of every joint to allow the robot torso to reach extreme postures during the navigation. During the locomotion, the lower limb of a leg (the shin) is the robot link that has higher chances to make undesired contacts with the environment.