This is why i like to read articles, and then sit back and say, "but what else?".
Here is a study (link below) that said,
"It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. "
Ok, maybe. . . . in stroke patients. We will give them that, but not the extrapolation to everyone else who is "non-stroke". They should have put that in their title, a little misleading in our opinion.
Clearly, hip abduction is a possible strategy for reduced knee clearance. Just because it is not a energy efficient strategy deemed by their study, it DOES NOT mean it is is not a possible pattern that is feasible for a client. People do not pick compensations by their calculated energy efficiency. The brain picks it because it is what makes sense at the time. Variables including pain avoidance, leg length discrepancy, weakness or strength or other variables are what the brain takes into account. One could argue that ANY compensation is less energy efficient than the optimal biomechanical pattern, but still we ALL compensate in some way every day around our weaknesses, limitations, pain, habitual patterns everyday. Energy efficiency is only one small variable, and i would argue that pain limitation or avoidance is a much stronger "choice" determinant that energy efficiency.
*But, here was my thought of the day, one that will percolate all day i suspect.
If a person has significant limitation of hip internal rotation on one side , completing swing phase on the opposite side is a challenge mechanically. Pelvis hike or obliquity is an option to help get that swing leg through. But is swing leg hip circumduction a possible strategy to help get past the internal hip rotation loss on the stance leg? Could it help hike the pelvis a little and assist the process as part of the package? We have to get that swing leg through. We can, and often do, work harder through the swing leg hip flexors, but that is not their job, they are perpetuators of swing, not drivers of the motion. This increased use and tone can be a contributing source of anterior hip pain. But, a more common strategy is to adductory twist the stance leg foot (spin it into external rotation) to help oblique the pelvis and thus get that swing leg through more effortlessly. But what about a little swing leg circumduction to add to that? MAybe a little of both is less drastic by just using one strategy ? Hmmmmmmm, something i need to be on the look out for. More on this another time.
We alter our kinematics to suit us, whether it is from pain, avoiding or minimizing pain, but i would fathom to guess that energy efficiency is not the top shelf choice. That is when we are healthy, strong, full ROM, pain free.
Shawn Allen, the other gait guy
J Biomech. 2019 Apr 18;87:150-156. doi: 10.1016/j.jbiomech.2019.02.026. Epub 2019 Mar 8.
Hip circumduction is not a compensation for reduced knee flexion angle during gait.
Akbas T1, Prajapati S2, Ziemnicki D2, Tamma P2, Gross S2, Sulzer J2.
Photo courtesy of Pixabay.com