Arthrokinematic Movement and Joint Mobilization

Kinesiology is the study of human movement. One of the basic principals of kinesiology are joint movements. You have probably learned that an elbow is a hinge joint and a shoulder is a ball-and-socket joint etc. Their subsequent movements are technically called osteokinematic movements. You will better know them as flexion, extension, supination, abduction etc. 

Basic joint models and osteokinematic motions are great for basic understanding, but the human body is not very basic. There is a second category of movements referred to as accessory motions or arthrokinematic motions. Arthrokinematic motions define the subtle motions that occur at a joint to allow for proper or full movement. Arthrokinematic movements are comprised of roll, spin, and glide.

 

To understand the importance of arthrokinematic, I think it is best to picture what would happen without them. Consider any of the joints of your fingers. Using the osteokinematic model, the joints flex and extend like a door hinge. However, the joint in the finger is not able to hinge or pivot the way that a door hinge does. If the finger joints did pivot that way, they would pinch the regressive (closing) angle and over stretch the progressive (opening) angle. The arthrokinematic gliding of the joint allows for the movement while keeping the surfaces of the joints articulating. If you can't quite grasp this concept, don't worry, the important thing is understanding when a joint's arthrokinematic motion may be limited and how to fix it.

Examples of arthrokinematic motions

In the above example, I mentioned that without arthrokinematic motion you would have pinching and stretching in the joint. It is not uncommon for joints to be limited in arthrokinematic motions leading to limited movement. When this happens, you make feel a pinch in the regressive movement which is termed impingement. 

Let's look at another example. If you were to sprain your ankle, the ankle swells to effectively splint and immobilize the joint. As the damaged joint tissue heals, the swelling goes down and the motion increases. Ideally, this includes the arthrokinematic motion. However, sometimes there are issues and the arthrokinematic motions do not fully return. If this is the case there will be limited range of motion thus limiting the function of that joint. Typically in the ankle, this is an anterior impingement in the ankle that limits dorsiflexion and leads to a pinch in the front of the ankle. 

Clinicians are able to use manual therapy techniques called joint mobilizations or joint "mobs". Joint mobilizations are arthrokinematic motions applied by the clinician to try to encourage the natural motion of the joint to return it's function. The most commonly known joint mob is probably the chiropractic adjustment or manipulation. An adjustment is a high velocity joint mobilization but joint mobilizations can be done at lower velocities and don't necessarily need an audible "pop" to be effective. Furthermore, joint mobilizations can be done on your own.

I am absolutely not advocating for "cracking" or "popping" your own back or neck. These should be done by a trained professional. However, there are safe and effective ways to mobilize joints without high velocity movements on yourself. Let's return to our ankle example. If there is a pinching in the anterior aspect of the ankle that is limiting dorsiflexion, a band can be used to posteriorly glide the shin on the foot to allow for fuller range of motion. As a clinician, I will typically do this with my hands while also prescribing bands for my athletes in conjunction to my treatment. 

The same principles carry over into most of the joints of the body. Consider all of the articulating surfaces in the body. In addition to the knees, hips, shoulders, etc. every vertebrae and every rib head must utilize arthrokinematic motion. I can't stress enough the importance of arthrokinematic movement for functional movement. 

These may be difficult to self identify for someone without clinical training and you may need to rely on a clinician to help identify and treat limitations in arthrokinematic motion. One sign of an arthrokinematic limitation is the feeling of a pinch when the joint angle is regressing. Another test I like to use is to ask the athlete where the end range of motion on a particular stretch is felt. If we consider the ankle again, I will have the person do a standing calf stretch. I then ask where the limitation is felt. If the limitation is felt in the calf (the soft tissue) then I think that the calf should be stretched. If the limitation is felt in the back of the ankle, I might think more about joint mobilization. These are two rough examples. Clinicians use palpation to test arthrokinematic movements for purposes of evaluation and treatment. 

The bottom line is that arthrokinematic motion allows for the osteokinematic movement and sometimes arthrokinematic motion may be limited. To fix joint limitations, clinicians use joint mobilizations, including chiropractic adjustment, to restore arthrokinematic movement and restoring functional movement. Clinicians will probably need to identify arthrokinematic limitations but they can usually give you self mobilization exercises to supplement manual therapy. That's all for now...from the training room.