Elastic Strain Energy in Hip

Kevin A. Kirby, DPM, demonstrates how the hip joint can store and release elastic strain energy. In a subject that is lying completely relaxed in a supine position, manually rotating the hip into an internally rotated position and then releasing the lower extremity shows how the hip joint may store and release transverse plane elastic strain energy. When the capsular ligaments and muscles that cross the hip joint are stretched by internal hip rotation, these soft tissue structures will store elastic strain energy or potential energy. When the limb is suddenly released, the stored elastic strain energy is converted into kinetic energy that causes a rapid external rotation acceleration of the thigh, leg and foot due to rapid shortening of these ligaments and muscles. This storage and release of transverse plane elastic stain at the hip is an important contributor to the gait phenomenon known as abductory twist, where rapid external rotation of the foot occurs at the time of heel off in individuals where the hip has been excessively internally rotated during the late midstance phase of gait by excessive pronation of the subtalar joint. Elastic strain energy is also an important energy-conservation mechanism in many forms of animal locomotion.

Category:

Sports

Tags:

• Hip biomechanics
• abductory twist

[jerryheschsr]

PIRIFORMIS: BeyondPiriformisSyndrome1

[jerryheschsr]

Dr Kirby,

This is fabulous! this is an evaluation technique I utilize throughout the body. The test you show is great for finding residual tightness in hip after piriformis syndrome treatment has restored hip rotation in prone, knee bent 90 degrees. Please look at my brief video and it will make sense. I am interested in looking at more of your posting, great work-this is such a fundamental connective tissue property. Best Regards, Jerry Hesch, Hesch Institute