There is a total of 26 bones in the foot, creating a total of 30-40 joint articulations. Each of these have several supporting ligaments and tendons.
The two main joints in the foot are the sub talar and the mid-tarsal joints.
The mid-tarsal joint is primarily involved with inversion/eversion movements of the foot, with some motion in other planes.
The sub-talar joint is able to move in triplanar motion, and hence compensate for leg, hip and back anomalies through its ability to move in any direction and translate movement into the lower limb. Pronation and supination are such movements. The sub talar joint is the joint next distal to the ankle (talo-crural) joint. Its neutral or most stable and effective position can be palpated when the bony prominences of the talus are equally palpable on the lateral and medial aspects of the dorsal foot. It is the most important joint in the foot.
The following information categorises our feet into two types and discusses factors that affect the way we walk and run.
- Flat feet
- High arch feet
- Biomechanics and Sport
‘Flat feet’ or hyper pronation can be attributed to abnormal foot position, poor footwear, insufficient arch support, loose ligament and tendon structures, and genetic factors.
Signs that a person may have flat feet include:
- Drop in medial (inside) arch height
- Subtalar joint pronation
- Rear foot eversion (calcaneal valgum)
- ‘Bulging’ of navicular bone medially
- Associated joint abnormalities, such as bunions, hallux limitus/rigidus, hammer/claw toes, and other foot pathologies
- History of lower limb injuries
- Claw toes
High Arched Feet
A high arched foot can also cause problems in the foot, ankle and lower limb. A high arched foot has less pronation and so less shock absorption during gait. Angles in the foot also show an increase in the force through joints due to the high arch. Signs someone has high arched feet: They have a significantly higher medial (inside) arch Higher calcaneal inclination angle Greater metatarsal declination angle Possibly high pressure areas or hard skin on the balls of the person’s foot Claw toes Bunions, Bony growths In both low and high arched feet changes occur to compensate for the abnormal foot positioning. Treatment for both these conditions depends on the severity, symptoms/pain and family history. Treatment can range from a change in footwear to custom orthoses to accommodate foot position.
Biomechanics and Sport
The way we walk and run varies greatly between individuals. This is obvious just by observing people's walking/running styles (their gait cycle) in the street, or on the sporting field. The reasons for these often distinct differences, are related to variation in body size, posture, and more importantly lower limb biomechanics.
Often we pass off variations in style as "Oh, that's just Johnny, he's always been a little awkward", or, "they walk like their father/mother". However, such variations in style may be affecting their level of sporting achievement, and can be corrected.
A few classical signs that indicate significant problems in people's gait include:
Awkwardness, clumsiness or duck\pigeon toed walking result in less efficient walking/running mechanics, thus creating conditions such as premature tiredness, aching/tired legs and often injury
Normal (or so called normal) shoe wear should display even distribution along the sole of the shoe. There is commonly slight outside heel wear also. Differences to this ie excessive outside or inside heel wear, forefoot wear in a particular spot (eg under big toe), or tearing of the upper material of the shoe are all indicators of poor mechanics and inefficiency
Repetitive overuse injuries can indicate that perhaps the individual's gait is resulting in additional stresses placed on lower limb muscles, causing them to prematurely tire and injure. Variable growth rates between limbs and feet, and also between bones and muscles, can often exaggerate the co-ordination, shoe wear and injury, especially in sporting individuals. The intensity of training and games and poorly functioning/fitting shoes can also contribute to this.