A series of Blogs and Vlogs from the Gray Institute has described how a specific joint motion is created by the motion of the bones that make up that joint. RELATIVE refers to the joint motion, while REAL refers to the actual motion of the bones in three-dimensional space. Any relative difference between the motions of the bones will result in the joint moving.
Practically, whenever we observe a bone moving there will almost always be joint motion occurring. The one rare exception is when the adjacent bones that make up the joint move the exact same amount. Not only would they have to move the same amount, they would have to move at exactly the same speed. If the right femur and the pelvis both rotated 15 degrees to the right, then that would satisfy the first condition. However, if the femur moved quickly and then slowed down while the pelvis moved at a slower but more consistent speed, RELATIVE joint motion would still be occurring.
So assuming that when bones move that there will be RELATIVE joint motion, let’s consider the possibilities. At the Gray Institute, we state that a single joint motion can be created by five different combinations of REAL bone motions. Some of these are more likely to occur than others. Some combinations would be considered dysfunctional depending on the specific activity. Recognizing and promoting the proper combination and sequence is critical to proper training and rehabilitation.
Using hip flexion in the sagittal plane as our example, what are the five possible bone motion combinations of the femur and the pelvis?
- Femur flexes while the pelvis is stationary
- Pelvis rotates anteriorly while the femur remains stationary
- Femur flexes and the pelvis rotates posteriorly – femur moving faster
- Femur extends and the pelvis rotates anteriorly – pelvis moving faster
- Femur flexes and the pelvis rotates anteriorly
The first two possibilities (only one bone moving) are easy for us to see but are much less common during function. Most of the times both bones are moving. The third and fourth possibilities represent situations where both bones are moving in the same direction in the sagittal plane, but one bone is moving faster. The fifth possibility has the two bones rotating in opposite directions. The last three are very common during function. The combinations can switch during functional human movements.
The Analysis Movements of the 3DMAPS takes advantage of the last three possibilities in order to assess the functional capabilities of 66 essential joint motions occurring simultaneously. The Analysis Movements cover both directions in each of the three planes of movement. By utilizing the combination of lunges with bilateral hand swings, the Analysis Movements drive the pelvis and femur in directions that maximize the RELATIVE joint motion. This makes it difficult for the body to hide the dysfunctional areas. The movement practitioner can quickly identify the dysfunctions. Then, utilizing the Performance System Movements can easily create a structured program to rectify the movement faults.