Foot & Ankle

Equinus

Anatomy

The ankle joint connects the leg and the foot. It is formed by three separate bones, the tibia, fibula and talus. The shinbone (tibia) supports most of a person's weight when standing. The outer bone (fibula) is the smaller bone of the lower leg. A small, irregular-shaped foot bone (talus) connects the tibia and fibula. Acting as a hinge, these bones form the ankle. The ankle joint allows movement such as walking, running and jumping, and also contributes to lower limb stability.

The ankle is reinforced by fibrous tissue (ligaments) that connects bone to bone. Ligaments have an elastic structure that allows them to stretch, within their limits, and then return to their normal positions. Ligaments protect the ankle from abnormal movements—especially twisting, turning and rolling of the foot.

Description

When the ankle joint lacks flexibility and upward, toes-to-shin movement of the foot (dorsiflexion) is limited, the condition is called equinus. Equinus is a result of tightness in the Achilles tendon or calf muscles (the soleus muscle and/or gastrocnemius muscle) and it may be either congenital or acquired. This condition is found equally in men and women, and it can occur in one foot, or both. If both feet are involved, range of motion may be more limited in one foot than in the other. This limited muscle flexibility and range of motion can lead to injury.

People with equinus develop ways to compensate for their limited ankle motion, which often leads to other problems of the foot, leg or back. Common methods of compensation include: flattening the arch, picking up the heel early when walking, and putting increased pressure on the ball of the foot. In addition to contributing to a number of foot and ankle problems, equinus can hinder the healing of a foot or ankle injury.

Depending on how a patient compensates for the inability to bend properly at the ankle, a variety of other foot conditions can develop, such as:

• Plantar Fasciitis (arch/heel pain)
• Calf cramping
• Achilles Tendinitis (inflammation of the Achilles tendon)
• Metatarsalgia (pain and/or callusing on the ball of the foot)
• Flatfoot
• Arthritis of the midfoot (middle area of the foot)
• Pressure sores on the ball of the foot or the arch
• Bunions and hammertoes
• Ankle pain
• Shin splints

Symptoms

A person with equinus has a limited range of ankle motion and lacks the flexibility needed to bring the top of the foot upward, toward the shin (tibia).

Causes

Equinus is often it is due to tightness in the Achilles tendon or calf muscles. For some, this may be congenital (present at birth) or an inherited trait. For others, this tightness is acquired and the result of being in a cast or on crutches, or frequently wearing high-heeled shoes. Other causes include diabetes or having one leg shorter than the other. If a bone or bone fragment (following an ankle injury, for example) blocks movement of the ankle, the patient may experience equinus. Infrequently, equinus can be caused by spasms in the calf muscle, which may be a sign of an underlying neurologic disorder.

Diagnosis

Most patients with equinus are diagnosed when seeking treatment for other foot problems associated with equinus. During the examination, your orthopaedic surgeon will evaluate the ankle's range of motion when the knee is flexed (bent), and when it is extended (straightened). This enables the surgeon to identify whether the tendon or muscle is tight, and to assess whether bone is interfering with ankle motion. X-rays may also be ordered. In some cases, the foot and ankle surgeon may refer the patient for neurologic evaluation.

Nonsurgical Treatment

Some nonsurgical treatment strategies are aimed at relieving the symptoms and conditions associated with equinus. Treatment for the equinus itself may include one or more of the following options.

• Night splint—The foot is placed in a splint at night to hold it in the proper position to reduce tightness of the calf muscle.
• Heel lifts—Placing heel lifts inside the shoes or wearing shoes with a moderate heel may reduce symptoms by taking stress off the Achilles tendon.
• Arch supports or orthotic devices—Custom orthotic devices that fit into the shoe are often prescribed to ensure that weight is distributed properly, and to help control muscle/tendon imbalance.
• Physical therapy—To help remedy muscle tightness, exercises that stretch the calf muscle(s) are recommended. If appropriate, a foot and ankle conditioning program may be prescribed.

Surgery

In some cases, surgery may be needed to correct the cause of equinus if it is related to a tight tendon or a bone blocking the ankle motion. Your orthopaedic surgeon will determine the type of procedure that is best suited for you.

With any surgery there are some risks, and these vary from person to person. Complications are typically minor, treatable and unlikely to affect your final outcome. Your orthopaedic surgeon will speak to you prior to surgery to explain any potential risks and complications that may be associated with your procedure.