Before you attempt to assess the feet and ankles, it is important for you to have a fundamental understanding of the structures you will be evaluating. A brief description of the basic anatomy of the feet and ankles is provided below to help you better comprehend the general elements of the body parts you will be assessing. Descriptions of the deviations and imbalances you will be assessing are also discussed.
Basic Structural Anatomy
The foot and ankle complex is very complex indeed. In one foot alone, there are 26 bones, 33 joints, and over 100 ligaments, muscles and tendons (Gray, 1995). The primary function of the feet and ankles is to ensure stress is displaced correctly throughout the body when a person is in a weight-bearing situation. If the foot and ankle complex is not functioning optimally, then any malalignment in other areas of the body will be compounded when the foot interacts with the ground or any other contact surface. In addition to displacing forces, the foot and ankle must also be able to adapt to changes in surfaces and terrains. As such, the feet and ankles are continually subjected to stress since they bear the physical load from above and below (Schamberger, 2002).
The foot and ankle complex can be broken into five distinct parts - two joints of the ankle and three areas of the foot (see Figure 1).
The joint below the tibia and fibula in the ankle is known as the true ankle joint. This structure helps the lower leg interact with the foot and ankle and displaces stress downward through to the heel (via the talus bone). The other main joint in the ankle is called the subtalar joint (below the talus bone). It helps transfer forces forward through the foot and has lateral movement capabilities from side to side to help distribute pressure and adapt the body to the terrain or contact surface (Gray, 1995).
The three areas of the foot are known as the hindfoot, midfoot, and forefoot (see Figure 2). The hindfoot, which includes the calcaneus (heel bone) is below the ankle and acts as a shock absorber to help displace forces from above. It also aids in the transfer of kinetic energy through the midfoot to the forefoot. The midfoot, which includes the medial longitudinal arch (the long arch from the heel to the toes) and other structures between the hindfoot and forefoot, also absorbs shock (Martini et al., 2014). The midfoot also helps dissipate forces through side-to-side movement. The forefoot, which includes the toes, is very flexible and ensures that the terrain and the body’s forces interact appropriately.
The areas of the foot can also work together in an interlocking fashion to slow forces down as the foot comes in contact with the ground. This allows the ankle to rotate to a lesser extent and keeps the foot and its system of arches from completely collapsing. This stabilization function is very important to help reduce any risk of injury and is dependent on all the areas of the foot being able to function correctly. The foot is also responsible for sending signals to the brain about the terrain to help the body continually adjust so that future interactions with the ground can be predicted.
As you can see, the feet and ankles are very sophisticated elements of the body with the capacity to bear a lot of stress. Any injury or malalignment in these structures will be amplified because they never really get to rest, especially during weight bearing activities. Therefore, it is crucial that the foot and ankle complex are healthy and aligned, and functioning as optimally as possible.
Common Musculoskeletal Imbalances of the Feet and Ankles
There are two main deviations that cause pain and injury in the foot and ankle area. They are:
- Lack of dorsiflexion
Pronation is a normal function in the body that occurs when the foot collapses inward toward the midline of the body. This movement causes the heel to roll inward and the medial longitudinal arch of the foot to elongate and flatten. Overpronation, however, occurs when the foot collapses too far inward for normal function and disrupts proper functioning of foot and ankle (and the rest of the body) (Schamberger, 2002).
Dorsiflexion involves bringing the foot toward the shin or vice versa. This can happen when the foot is in contact with the ground, such as when squatting and the shin moves forward over the foot, or when swinging the leg forward and lifting the foot up to clear the ground as when walking. Dorsiflexion is a natural and important function of the foot and ankle. However, when people lack the ability to dorsiflex through a full range of motion it not only impairs function of the foot and ankle, but other movements of the body as well (Cook, 2010).
These common imbalances typically occur together, meaning that a person who overpronates usually also lacks dorsiflexion. It is also important to note that most people typically overpronate rather than oversupinate. Since the aim of this course is to cover the most common deviations of the foot and ankle complex, assessments and other information related to oversupination will not be discussed.