Again, given that this is such a complex biomechanical function, I can only present it in a somewhat "generic" fashion...that is, to present a broader perspective from which we can all then begin to plug in the holes and begin the process of further formulation and evaluation. In my opinion, anything worthy of presentation should manifest some fact, extrapolation of fact, or theory that can be relatively easy to explain. Let's see if it pans out!
A potentially strange title that can lead to some confusion...but my intent is to simply point of that development and evolution are essential frameworks that hold fundamentals truths and realities that often go overlooked.
Evolution itself is a construct that effectively states that we as humans evolved from the oceans, then to land, and essentially began our journey as quadrupedal beings...meaning we walked on all fours. In fact, the interesting part is that we still maintain some aspects of this "early evolution" today...as babies and toddlers, we move on all fours. This leads to the first fundamental reality:
Bipedal locomotion must first pass through the process of quadrupedal development.
When we understand the process of quadruped-to-biped with respect to human locomotion, it makes sense to identify the specific characteristics that define (or differentiate) the quadruped versus the biped. Although there are likely to be many, my theory revolves around 2 main considerations: the pelvis and the spine.
We therefore come to a fundamental question: What is the difference between a quadruped pelvis and a biped pelvis? The answer to this raises quite a few interesting points:
1. The quadrupedal pelvis is proportionally alot smaller than a bipedal pelvis
This means that, in relation to the rest of the body, the pelvis occupies a smaller percentage of the entire body mass and frame.
If we take 2 examples of our most popular domesticated animals (dogs and cats) we are immediately struck with the fact that, although they are amazingly agile creatures, their pelvis is realtively small in comparison to the rest of their body. In fact, it is almost comparable to the shoulder blade. This shouldn't be too much of a shocker...afterall, their weight is designed to be transmitted through 4 limbs, so the shoulder blade and pelvis would naturally be of comparable size. However, when we put it into the context of HUMAN development, this begs the question: Is it that the shoulder blade is that much bigger in proportion, or is it that the pelvis is that much smaller? I think the answer is clearly skewed towards a small pelvis.
We can even extrapolate this theory even further to include our most genetically similar cousin, the primate. The interesting thing about the primate (beyond the fact that it shares almost 90% of our genetic makeup) is that it is paradoxically considered as BOTH quadruped and biped.
We can therefore safely assume that the primate is a reflection of the transition from quadruped to biped. This is quite a luxury to be be able to examine this animal within this context. When we have a look at the above image, we can identify that there is indeed a larger pelvis (in comparison to the rest of the body), but it remains somewhat smaller in comparison to our own representation within the human frame. This is a strong indication that the transfer process from 4 limbs to 2, requires significantly more structural consideration with respect to the pelvis...in other words, its formal "architecture" needs to change.
To supplement all of the above images, the pelvis is also quite narrow...which completes a more 3-dimensional understanding of how the pelvis plays a role in the understanding of our evolution.
Using all of the images previously posted above, the spine becomes the second area of focus. What is it?
2. The quadruped spine manifests a single-curve.
If we look at the overall "layout" of the spine, it definitely represents what would be considered a primary curve within the human context...meaning that the lumbar and cervical spine do not manifest the secondary convex curve. Perhaps more interesting is the observation of the larger pelvis in conjunction with the disappearance (reduction) of the length of the tail. The tail is essentially an extension of the spine, therefore there is an inverse relationship...smaller tail, larger pelvis. This can be attributed to the changes in center of gravity and equilibrium.
...So what in the world does all of this mean?
Let's have a look at how we humans play into this theory. Take a look at the picture below...given the explicit observations mentioned in the previous sections, what do you notice?
|Human Baby Skeleton|
For the sake of formality, I will detail my specific observations:
In the earliest developmental stages, the human organism manifests a singular curve of the spine and a pelvis that is proportionally smaller to the rest of the body.
Therefore, as developmental evolution dictates, the human organism is formally prepared for quadruped locomotion BEFORE entering into bipedal locomotion. As the baby develops into a toddler, the pelvis will transform into a more substancial load-bearing structure (and therefore grow volumetrically and circumferentially) and the spine will begin its journey towards the characteristic secondary curves. All of this will converge at the 10-14 month period when the toddler eventually begins to walk.
Links to Cerebral Palsy
The fundamental objective of this post is to tie this theory into some practical understanding of how CP is manifest and to hopefully provide some clarity on an otherwise overwhelming confusion. The realities of CP play directly into this theory in some very straightforward ways:
Cerebral Palsy falls under the umbrella of "developmental delay", therefore the early developmental phases (quapruped phase) persist well beyond the first year of life and can still be manifest into puberty. We therefore are confronted with a confusing reality: chronological age is not congruous with developmental age. This "mismatch" potentiates a possible deviation from developmental priorities and some potential misinterpretation of "progress".
The expectation, if the individual is older than 2 years, is that they should be walking and therefore a large proportion of strategic planning (and expectation) is skewed towards verticalization, casting, and cosmetic "straightness". However, if the developmental manifestation remains that of a quadruped, then bipedal locomotion is not only unrealistic, but also counterproductive. In other words, if the pelvis in relation to the rest of the body remains small and the spine persists in a singular curve (or even straight), then developmental evolution dictates that ANY load-bearing strategy should be oriented towards quaprupedal equilibrium / stability / locomotion.
The truth about walking and CP is that it formally has nothing to do with the legs...which is paradoxical!
The pelvis is the essential architectural weight-bearing structure that needs to be in place if any realistic expectations are to be considered. Further, it has been long studied and determined (largey by the works of Gracovetsky) that movement is derived from the spinal "engine"... meaning that the spine is functionally the genesis for all motion and that the legs simply "magnify or amplify" that motion.
Links to Practical Rehabilitation Strategy
There are countless "ideal" strategies populating the landscape, however if you apply these fundamentals of evolution, you will be left with some tangible frameworks to derive an appropriate and effective strategy:
1. Promote systemic development and function
Any mechanical performance depends on effective absorption and utilization of all systemic assets (nutrition, oxygen, blood, etc...) therefore promotion of the respiratory, digestive, immune, and circulatory systems will contribute exponentially.
2. Implement strategies that help to potentiate pelvic health and integrity
3. Reduce / avoid any unnecessary load-bearing or verticalization
The notion that simple vertical positioning will resolve the issue is formally simplistic when placed against the evolutionary litmus test.
4. Always refer to developmental milestones as a blueprint for priorities.
Development in the human organism always follows the same sequence...meaning that development from basic postural performance to more complex movements has a very explicit order. This order is not revolutionary, nor is it some unknown "secret"...it is the gradual progression from simple horizontal exposure to gravity straight through to a completely vertical position. This sequence can readily be found and searched as "developmental milestones".
As always, these rants tends to evolve into "mini-novels", but the hope and expectation is to shed some light and to tie in some well understood realities...not to attempt to generate full understanding, but more importantly to provide some basic idea of "direction".