Gait Cycle Essay

1.1 Gait Basics
Walking is essentially a cyclic activity, with both the legs undergoing the same motion, but with the cycle timings displaced. If it is assumed that the body is symmetric, describing one cycle for a single leg is sucient. It is important to consider the fact that every human being has a di erent gait and what is considered a normal gait for that person will depend upon his age, sex and body geometry among other factors.
The moment the foot makes contact with the ground is generally taken to be the start of the gait cycle. The gait cycle is divided into two phases: Stance phase, when the foot is in contact with the ground and the Swing phase, when the foot is in the air.
The initial contact marks the start of the stance phase, after which the

Literature Review 3 place during exion and extension. As the joint exes, the point of contact moves behind, while during extension it moves forward. This is achieved by theanterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The ACL is attached to the tibia anteriorly and the femur posteriorly, while the PCL to the tibia posteriorly and the femur anteriorly. These two ligaments with the two bones form a sort of four bar mechanism which facilitates this sort of motion[? ]. Quadriceps is the only muscle which is involved in extending of the knee. It includes four elements, three of which originate on the femur and one which originates on the pelvis, spanning both the knee and hip joints. The quadriceps tendon is formed from these four elements. It surrounds the patella and is joint to the tibula. A lot of muscles are involved in the exing of the knee, some of which span across the knee joint only, while some others are biarticualar spanning across the hip or ankle joints as well. Of particualar interest from the point of view of designing a transtibial prosthesis is the gastrocnemius, which spans across the knee and ankle joints, and is involved in exing the knee and