The Foot and Industrial Consequences of Injury - Part 1

Wednesday, January 5, 2005 | 0

This article by foot and ankle specialist, Dr. Jodi Schoenhaus, and all the articles in this four part series, are printed here with her permission.

Part One: Facts about the Human Foot

The human foot contains 26 bones comprising a total of 33 joints. There are 107 ligaments and 19 muscles and tendons to aid in foot structure during stance and gait. During locomotion there are two distinct phases: the stance phase and the swing phase. During the swing phase, no pressure is placed on the foot and internal rotation of the contralateral limb as well as momentum propels the body forward.

The stance phase of gait is broken down into three parts: heel strike, midstance, and propulsion. With every step there is an average force that is 2-3 times an individual's body weight that occurs during heel strike and propulsion. As the average person takes approximately 8000- 10,000 steps a day, there is an exuberant amount of force that goes through the foot and lower extremity. Certainly, the demands that a person places on their feet during a rigorous work day can lead to many foot and ankle ailments. An average of 19% of the US population has roughly 1.4 foot problems a year!

A traumatic incident does not need to occur for one to feel symptoms in their lower extremity. For example, a postal worker who walks with the added weight of mail freight can develop heel pain or shin splints. The basic foot structure, which is hereditary, will predispose an individual to certain conditions. Appropriate education, shoe gear and management of the condition are crucial in order to have the mail carrier operate their route quickly and efficiently. For an injured worker, speed in recovery is very important. However, making sure that appropriate care is rendered so that the worker is efficient on the job is just as important. Returning a person to work too early can result in a worsening of the condition and less effective outcomes.

A normal foot is considered to be a rectus foot type with a visible arch in the correct angle and base of gait with the joints of the foot appropriately aligned. A flattened arch is considered a pronated foot type and is called pes planus. On the opposite spectrum, an arch that is higher than normal is a supinated foot type termed pes cavus.

Pronated and supinated foot types may predispose individuals to various conditions and injuries. In a flatfoot condition, the most common etiology is a tight Achilles tendon. A tight Achilles tendon will limit the amount of ankle dorsiflexion needed in the gait cycle and the foot will attempt to provide the necessary movement through pronation. The foot becomes hypermobile and the arch collapses over time. A condition commonly seen in adults is called posterior tibial tendon dysfunction and is associated with a flat foot condition. The posterior tibial muscle is the strongest supinator of the foot and attempts to maintain an arch. As the foot flattens, this muscle works overtime to hold up the arch and eventually tenosynovitis and tendinosis occurs. This can lead to arch pain, lower leg pain, shin splints, complete tear of the tendon and, if not treated, severe degenerative joint disease.

Other conditions associated with a pes planus foot type include hammertoes, bunions, arch pain, heel pain, shin splints, medial knee pain, hip pain and even lower back pain. These conditions can be aggravated with ambulation or rigorous activity. Heel pain is extremely common and 90% of people with heel pain will respond to conservative care.

Treatment consists of a combination of anti inflammatory medication, orthotic management and control (shoe insoles), steroid injections, stretching and physical therapy, night splints, and extra corporeal shockwave therapy. Arthritis is commonly seen in adults who have flat feet and attempt to increase activity or change their activity. Conservative therapy for arthritis is more difficult and may require a series of steroid injections and physical therapy as well as orthotic management. Surgery to include arthroscopy of the ankle, fusions or implants may need to be employed to provide relief of pain and symptoms.

In a supinated or cavus foot type the heel will make ground contact with the calcaneus (heel bone) in a position that is greater than five degrees (normal). This can lead to ankle instability, chronic sprains, laxity, and ankle injuries. As the foot tries to adapt, it will quickly try to drop the arch. This can lead to abnormal forces running through the midfoot and rearfoot as well as muscular and ligamentous strain. Hammertoes, heel pain, excess pressure under the metatarsal bones, and arthritis are commonly associated conditions.

Remember, a minor traumatic event or overuse can instill pain and discomfort in patients with the foot types discussed above. Orthotic management and control is a commonly used treatment modality that aligns the foot during the gait cycle. Worn in an individuals' shoes, the orthotics provide biomechanical control of the pronated or supinated foot type.

The next article in this series will contain facts about the human ankle and possible ailments due to work-related injuries.

Contributed by foot and ankle specialist, Dr. Jodi Schoenhaus of Total Orthopaedic Care, Ft. Lauderdale, FL. Dr. Schoenhaus can be reached at 954-735-3535.

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