Patient Education


Ankle Equinus

The forward motion during walking is a combination of flexion and extension of the major joints of the lower extremity including the ankle, knee and hip. Each of these joints has a normal range of motion during the walking cycle that allows a coordinated and fluid forward movement.

Flexibility of the muscles around these joints plays an important role of the joints to go through the minimum range of motion to provide this motion. Tightness in any of the muscle groups around these joints may have a significant influence in the development of injury. Tightness in the calf muscle termed ankle equinus can play a significant role in the development of lower leg, ankle and foot problems.

The calf muscle consisting of the soleus and gastrocnemius muscle group helps to lift the heel off of the ground during the propulsive phase of gait. When the foot is fully on the ground the long leg bones of the tibia and fibula are moving forward as momentum carries the body forward. The lower leg moves forward from the ankle joint approximately 15 degrees before the calf muscle begins to contract as it lifts the heel off of the ground. A calf muscle with normal flexibility will begin lifting the heel off of the ground during the late midstance portion of the gait cycle as it leads into propulsion. A calf muscle that is tight will begin to lift the heel off of the ground prematurely during the early midstance cycle of gait which can increase abnormal foot pronation. Increase foot pronation can create instability of the foot which may lead to the development of injury.

Children and adults can develop ankle equinus. In children, tightness in the calf muscle group may be related to an accelerated growth of the long bones of the tibia and fibula as compared to the calf muscles. Adults may develop ankle equinus related to the prolonged use of heeled shoes which over time can shorten the muscle group. Some people ultimately have poor flexibility around many joints including the ankle joint related to genetic factors.

Calf muscle flexibility can be measured with the knee in a straight as well as partially flexed position to determine which of the calf muscles is tight. Normal ankle flexibility with the knee in a straight position is 15 degrees of extension. Ankle joint motion less than this may contribute to the development of pathology.

Calf stretching exercises may be stressed by your physician or physical therapist to help treat your specific problem. Increased flexibility of the calf muscle may take many months to achieve and should be approached as a general long term goal with gentle daily stretching.

The amount flexibility of the calf muscle is so important that is not uncommon for the patient who is being evaluated for a surgical foot and ankle procedure to have in addition a calf muscle lengthening procedure termed gastrocnemius recession. The surgical release of the muscle fibers of the gastrocnemius will improve overall ankle flexibility which will help improve the outcome of the surgical care provided.

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Please call 805.543.7788 for San Luis Obispo, 805.434.2009 for Templeton, or email us to request an appointment.