FORWARD TRUNK LEAN IN STANCE

during LOADING RESPONSE	during MIDSTANCE

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This common gait deficit occurs when the quadriceps fail to perform their customary role during LOADING RESPONSE and the first part of midstance. This might occur in the event of:

• QUADRICEPS WEAKNESS
• PAIN WITH QUADRICEPS ACTIVATION
• PROPRIOCEPTIVE DEFICIT

During loading response, a forward leaning of the trunk produces an anterior inclination in the ground reaction force vector. Because this relocated vector passes closer to the knee joint, it produces a smaller flexor moment at the knee. If the GRF vector passes in front of the knee joint, it can hyperextend the knee during loading response.

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When the person leans forward with the trunk DURING MIDSTANCE, but not during loading response, quadriceps weakness or knee pain are less likely causes. Instead, it may be a compensation that helps move the body's center of gravity forward over the stance foot. This compensation is necessary when:

• the ankle has limited range of motion in dorsiflexion
• plantar flexor strength is inadequate to control midstance dorsiflexion.

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Last updated 5-15-98 Dave Thompson PT