In today’s post, I want to talk about 2 terms that are not so common in the world of physical preparation coaches or recreational fitness professionals. Usually, arthro and osteokinematics are more present in the vocabulary of physiotherapist and medical personal. Maybe we as physical coaching staff don’t need to have so deep understanding of these terms but some basic knowledge is so important and in this blog post I will try to explain why!
Let’s start with the meanings of these words:
Osteo = from the Greek osteon = bone
Arthro = from the Greek word arthron = joint
Kinematic/Kinetic = from the Greek word kinesis = movement
So in general Osteokinematics means bone movement and Arthrokinematics joint movement.
Osteokinematics is the gross movement that happens between two bones. This happens because our bone surfaces articulate at the joint where movements are: flexion/extension, abduction/adduction, and internal rotation/external rotation in different planes of motions.
From my perspective is critical to understand these movements for every joint in the human body. Next step is to know appropriate ranges in different planes of motion. In the picture above you can see hip joint, we need to be aware of optimal flexion/extension ranges in sagittal plane for example, how to assess this ranges, what can create limitations and interventions on how to solve problems. The same rules exist for other planes of motion where similar movements between bones exist. Is that mean that every hip of every person should move the same? Of course not, the general rule of thumbs for every joint exists but every human body is structurally slightly different.
If we are talking about hip joint here is a list of possible anatomical hip differences:
1) different variations of pelvis structures – round, wide, narrow..
2) variations in the angle of femoral neck
3) acetabulum position
4) acetabulum shape
Why we need to be aware of osteokinematics on daily basis?
Simply because our daily job is to evaluate our athletes or clients, how they move, how they create movement patterns. If one day we spot some changes in movement comparing one hip to another (what yesterday maybe was not the case) we need to react immediately. If one hip for some reason is lost movement of extension, and if this limitation persists for some time, the body will try to find other areas for that missing movement. That is called compensation.
Arthrokinematics represents the small movements happening at the joint surface itself. Movements are rolls, glides/slides, and spins.
A) Roll is a rotary movement, one bone rolling on another.
B) Spin is a rotary movement, one body spinning on another.
C) Slide is a translatory movement, sliding of one joint surface over another.
Muscles are producing force, by doing so bones are moving creating movement at the joints as well. During movement, we need to respect proper alignment of the joints, if not passive stabilizers (ligaments, meniscus) are under more pressure. Let’s take an example of push up, in the bottom position head of the humerus tends to glide forward in the glenoid fossa (translatory movement), this can lead to either increased tensile stress on the tendons or compression of the tendons with excessive stress on anterior capsule!
To explain as simple as possible, in my daily practice I see Osteokinematics as something we need to be aware of even before the main part of the training start, before we start to load the body with high intensity. Does everything move correctly today? Is this person ready to “go hard” from the structural and positional standpoint?
In the picture above we can see excessive pronation of the left foot together with flat midfoot comparing to the right. Also, there is noticeable left hip internal rotation, is this person clear to squat, deadlift or any kind of bilateral stance work? I guess not…
Arthokinematics, on the other hand, are especially important during training, meaning: I need to be aware when they start to lose efficiency with this small unnecessary extra movements at the joint area.
Notice here during the end of row how humeral head is gliding forward putting excessive stress on anterior capsule. We want to avoid this with everyone, especially with overhead athletes. We must be aware during exercise execution what are joints positions!
Respecting osteokinematics as well as arthrokinematics is meaning that we understand the principle of joint centration, which is vital to joint health & overall performance!