what-when-how
In Depth Tutorials and Information
1
footwear available to manage the myriad foot problems that present to
clinicians.
The human foot and its precise behaviour during walking and other
activities remains one of the last mysteries of the musculoskeletal system.
While many texts claim to offer a complete description of foot bio-
mechanics and orthotic or other therapy solutions to foot and lower limb
injury, in truth there is much left to discover. With 26 bones, many
complex, multi-articular, non-hinge, non-ball and socket joints, over 100
ligaments, and complex layers of interlacing muscles, tendons and liga-
ments on the plantar surface, it is little wonder it continues to hold its
precise biomechanics function a secret. Here, we provide an overview of
what is known and can reasonably be extrapolated from the available
research and clinical experience.
the foot as a complex structure
One of the most important issues is the fact that while the foot is named
as a single anatomical entity, it comprises many individual and variable
mechanical parts. These function in an interdependent way because they
share many articulations, ligaments and muscles. That is to say that the
function of one joint or structure will influence the function of another
within the foot. It follows that when we discuss the overall biomechanical
function of the 'foot', we must do so in the context that how this
overall function is achieved can vary greatly. This is because the constitu-
ent parts of the foot are able to behave in different ways under different
biomechanical circumstances, and these vary between the feet of differ-
ent people. It also follows that when we refer to the foot it is intuitive to
think that the ankle, as the link between the foot and leg, is the joint where
foot biomechanics occurs. In fact, the ankle is simply one joint in a long
and complex series of joints connecting the ground to the leg, and we
must be mindful not to interpret 'foot' biomechanics as being those of
the ankle alone.
Both in the literature and clinical practice, there is emphasis on foot
structure and shape, since these are clearly important to foot orthosis
and footwear design and effectiveness; however, the foot is a highly
dynamic structure whose form or shape under static conditions (i.e., when
standing or lying) does not reflect the positions it adopts and the move-
ments it performs during activities such as walking and running. As such,
reference to foot shape or posture must reflect the limitations of what
shape can tell us about this complex and dynamic part of our muscu-
loskeletal system.
