Gluteal tendonopathy and the frontal plane pelvis posturing.

See that foot turned out into the frontal plane ? Ya, all the time. Finding the cause is where the meat is though.

"Individuals with gluteal tendinopathy use different frontal plane kinematics of the hip and pelvis during single leg stance than pain-free controls. This finding is not influenced by pelvic dimension or the potentially modifiable factor of body mass index, but is by hip abductor muscle weakness."

https://www.ncbi.nlm.nih.gov/pubmed/27395451

The Pelvis and COM in locomotion.

"Biomechanics of unobstructed locomotion consists of synchronized complex movements of the pelvis, torso, and lower limbs. These movement patterns become more complex as individuals encounter obstacles or negotiate uneven terrain."

This data was taken on 10 healthy young adult individuals investigation specifically the mechanics of the pelvis, torso, and lower limb segments and how they relate to obstacle negotiation of varying sized objects combined with temporal constraints to perform the task.

The data "revealed a significant increase in sagittal (posterior tilt) and frontal (ipsilateral hike) plane pelvic angular displacement and higher sagittal plane posterior torso lean angular displacement with increased obstacle height. Furthermore, both sagittal plane hip and knee maximum joint flexion were significantly higher with increasing heights of the obstacles during negotiation."

https://www.ncbi.nlm.nih.gov/pubmed/28297177

Do I Really Need My Pinky Toe?

Just the other day we saw this article in Popular Science written by Sally Zhang.  Sally obviously does not read our blog, but she got a lot of stuff right.

“If you’re born without a pinky toe or have an accident and it’s removed, you can completely do everything you wanted to do,” Dr. Anne Holly Johnson, instructor in orthopaedic surgery at Harvard Medical School, says.

Above you will see a photo of one of the gait guy’s feet.  It is quite clear from the photo that competent use of the pinky toe is not necessary for adequate, and possibly exceptionally skilled, foot function.  Here, check out this video of our foot in these 2 videos (here and here) for some advanced foot function (sans pinky toe). As you can see in the photo above, this 5th toe has likely never felt the ground, this is a fixed deformity.  Flexor and extensor function of the toe are intact, but it does not reach the ground and so assistance in gaining adequate purchase of the 5th metatarsal on the ground is absent. 

This brings us to a deeper question, what about the 5th metatarsal then? Is it necessary ?  Our answer even without deeper research is a solid “yes”. The foot tripod is severely compromised without the 5th metatarsal. The lateral stability of the foot is impaired without the 5th MET.  The natural locking of the calcaneocuboid joint mechanism will be impaired, the peroneal muscles that provide such critical lateral ankle and foot stability will have fascial planes and tendon attachments disengaged, the natural walking gait lateral to medial foot progression would be impaired, propulsion would be impaired and the list goes on and on. And, not even on the local foot/ankle level. Because, if you take out the function and stability of the lateral foot the hip is very likely to suffer lateral (frontal plane) stability deficits. Meaning, the gluteus medius and abdominal obliques will have more difficulty guarding frontal plane drift when in stance phase rendering all of the “cross over gait” risks (link) highly probable.  

So, not much exciting stuff here today. The presence of a functioning pinky toe does not appear to be critical but don’t take away its big brother neighbor, the 5th Metatarsal or trouble is just around the corner. Don’t believe us? Just ask anyone with a non-union fracture (Jones fracture) of the 5th metatarsal.

The answer goes back to the evolutionary history of humans, explains Dr. Anish Kadakia, assistant professor in orthopaedic surgery at Northwestern University. "Primates use their feet to grab, claw, to climb trees, but humans, we don’t need that function anymore,“ Kadakia says. "Clearly we’re not jumping up and down trees and using our feet to grab. We have toes embryologically, evolutionary for that particular reason because we descended from apes, but we don’t need them as people.”

The gait guys, working with 4 toes on each foot, one step ahead of evolution it seems.

Shawn and Ivo,

The gait guys

reference:

http://www.popsci.com/science/article/2013-05/fyi-do-i-really-need-my-pinky-toe?dom=tw&src=SOC

Fundamental Hip Biomechanics: Part 1

Hip Biomechanics

The following excerpted text is copywrited from the textbook; “Form and Function: The Scientific Basis of Movement and Movement Impairment” (Dr. S. Allen, Dr. E. Osar)


Frontal Plane Functional Biomechanics

The hip is a very complex joint.  It is a ball and socket joint with great stability and potentially great mobility.  One of the most critical and essential planes of motion and stability is the frontal plane of hip joint motion.  This plane (coronal/frontal) of motion and stability is largely determined by the hip abductor muscle (HAM) group through an axis of oriented in the anterior-posterior direction through the head of the femur.  The most obvious and simple function of the hip abductor muscles is to produce a movement or moment of abduction of the femur in the acetabulum in the frontal/coronal plane (as in a side lying leg lift).  As mentioned, this is a simple way to determine open kinetic chain range and open chain strength in this range but it is neither true nor transferable in theory or practicality when the foot is on the group.  When the foot engages the ground the typically usable functional range is much less and the muscular function is now to move the pelvis on the stable and somewhat static femoral head in the frontal plane.  Explained in another way, in this closed chain, the insertion of many muscles remains static and the force generated through the muscle will pull at the origin and generate movement at the joint in this manner.  In a nutshell, the hip abductor muscles (HAM) will produce either leg motion to the side (abduction) or it will produce a lateral bending or lateral flexing of the pelvis-torso into the same range of motion (abduction). 

The most critical and commonly considered hip abductor muscles (HAM) are the gluteus medius, gluteus minimus and tensor fascia lata-iliotibial band complex.  These muscles have the most favorable line of pull and all have a femur and pelvis attachment.  We will call these muscles collectively the HAM group.  In the stance phase of gait the body’s center of gravity (COG) is medial to the hip joint axis of motion.  Thus, in this single leg support phase of gait the tendency will be for the body mass above the hip to rotate or drop towards the swing leg side.  This gravitational movement should be offset by the concentric, isometric and eccentric muscular activation of the HAM group through the anterior-posterior oriented axis through the head of the femur.  Any functional strength deficits (concentric, isometric or eccentric) of the HAM group and/or neighboring synergistic stabilizers will result in an altered joint stability challenge because not only do the HAM and surrounding muscles product movement but they also generated joint compression and thus stability.  The possible undesirable outcome may be an altered movement patterning characterized by inappropriate muscle or muscle group activation in either timing, force, speed or coordination with typically coupled muscles.  These challenges to the joint and its normally expected movement patterns will result in the body’s search for more stable positions in the frontal, sagittal or oblique planes.  These newly established, yet less efficient, positions and patterns of movement are initially welcomed compensations but in time as the new accommodations become rooted in pattern the synergists and other recruitments become overburdened and further demand compensations from other neighboring muscles eventually resulting in pain, joint derangement and dysfunction.  These compensations in recruitment and movement eventually will lead to non-contractile soft tissue changes such as hip capsule pattern changes in tension and length. These non-contractile soft tissue changes can not only dictate or perpetuate the newly established aberrant joint movements but help engrain the abnormal movement patterns and their new neurologic patterns.