Category Archives: Biomechanics

Biomechanics, Foot Problems

What is a Plantar Plate Tear

A plantar plate tear is a relatively common problem under the ball of the foot. The plantar plate is a strong thicker ligament below the metatarsaophalangeal joints in the ball of the foot. There can be a tear, strain or what often is described as a ‘dysfunction‘ of that ligament that causes pain under the joint and just distal t the joint. One weird sensation that often get describes is that of the feel of a sock bunched up under the toes, when its not.

A plantar plate problem is more common in those who are over weight, who are more active and have foot problems such as bunions.

The treatment of a plantar plate tear is to rest the area by holding the toe plantar flexed with strapping. A rocker sole shoe also stops the toe from bending so much and is often helpful. This “rest” of the strain on the ligament usually helps most cases. In the few that this does not help, then a surgical repair of the small tear is often indicated.

Biomechanics, Foot Problems

Dealing with Severs Disease

Sever’s disease, or more appropriately called calcaneal apophysitis is an overuse problem with the growth plate at the back of the heel bone in children. It is more common around the ages of 10-12 years and always goes away by the mid-teenage years when growth of the heel bone stops and the cartilage growth plate merges with the rest of the heel bone.

The pain is typically at the back of the heel bone and at the sides, especially on squeezing the heel bone and especially after sports activity. It is more common in those who are more active. On occasion the pain from Severs disease can be so bad as to make the child cry, but there is very little or no swelling visible.

Severs disease is best managed with reducing activity and managing expectations. The child will grow out of it, but as it painful it still needs o be treated. The reduction in activity needs o be negotiated with the child as they will be reluctant. ICE can be used after activity to help with the pain. A cushioned heel raise is often used to protect the area.

Biomechanics

The Term ‘Overpronation’

Overpronation is one of the most overused and misunderstood terms in running and health professional communities, especially when it comes to the use of running shoes. The whole traditional model of the design of different running shoes are based on the concept of the normal or neutral alignment of the foot. Pronation is when the foot rolls inwards at the ankle joint and the arch collapses. Supination is when the foot rolls outwards at the ankle and the arch height increases. These are normal healthy movements that are needed for normal function of the foot. It is how the foot adapts to uneven surfaces and absorbs shock. There is nothing wrong with the motions of pronation or supination.

The term overpronation is used to describe when there is too much pronation. The reason is that this is an issue is that overpronation assumed to be a risk factor for many different running injuries. For this reason, running shoes have design features in them that are supposed to help control this overpronation. These design features include medial heel posts, dual density midsoles and rigid heel counters. These shoes are supposed to be used by those who overpronate. Those who do not overpronate should use cushioned neutral shoes.

The problem with this concept is that the term is overused a lot. There is no consensus as to the cut-off point between normal pronation and overpronation. There is also very little evidence linking overpronation to running injury and if there is any, it is showing that it is only a very small risk factor. Plenty of runners overpronate severely and never have problems. Similarly, there are plenty of runners who do not overpronate that have a lot of problems. Due to this confusion, there has been a recent change in the use of the term and the understanding of overpronation in relationship to running injury and the use of running shoes.

Biomechanics, Foot Problems, Sports Medicine

Cuboid Syndrome

The cuboid is a smaller cube shaped bone on the lateral side of the foot around about the center of the foot. The bone is a little bigger than a common gaming dice. The bone participates in three joints and operates as a lever for the tendon of the peroneus longus muscle to pass under. Since this is a strong muscle it can move the cuboid bone too much if it is not secure and strain those joints that the bone is a part of resulting in a ailment known as cuboid syndrome. This is probably one of the more common causes of pain on the outside of the foot, generally in athletes. The pain commonly begins quite mild and is located around where the cuboid bone is on the outside of the foot. The pain is only at first present during activity. If the exercise levels are not lessened the problem will most likely progress and then show up after exercise in addition to during. From time to time the pain can radiate down into the foot. Although this is the commonest reason for pain in this area, there are others like tendinopathy and nerve impingements.

The main management of cuboid syndrome is relief of pain. This is normally done with a reduction in exercise levels and the using of low dye strapping to immobilise and support the cuboid. Mobilisation and manipulation is frequently used to fix this condition. Over the longer term foot orthoses may be required to control the movement and support the lateral arch of the foot. This helps make the cuboid more stable so it is an efficient lever or pulley for the tendon to function around. Generally this approach works in most cases. If it doesn’t there are no surgical or more advanced treatments and a further reduction in activity amounts is usually the only option.