Joint mobility refers to the range and type of movement a joint permits. Joints are classified as either slightly movable cartilaginous joints or freely movable synovial joints. Based on movement axes, joints are further categorized as uniaxial, biaxial, polyaxial, or plane joints.
Restrictions in joint range of motion can result from skin tightness or scar tissue, muscle weakness or spasticity etc. Prevention and treatment involve identifying the underlying cause and applying appropriate interventions.
Hello friends, in this article, we will cover Joint Mobility. We will understand:
- The classification of joint movement.
- What are the causes and restrictions of joint movement?
- We will also cover the prevention of joint stiffness and the mobilisation of joints.
This chapter is a transcript of one of the video lessons on joint mobility classification taken from the course “Exercise Therapy and Massage”.
So first of all, what is joint mobility?
What is joint mobility?
Whatever movement happens in our body — the range of that movement and the type of that movement — depends on the anatomical structure of that joint. Broadly, we can understand joints in two types.
One is slightly movable, which we also call cartilaginous joints, and the second is freely movable, which we also call synovial joints.
So the cartilaginous joints are in our median plane. Examples of this are the pubic symphysis and the joints of the vertebral body — I will show you in a figure.
And the second type is synovial joints, which are in our limbs — in our upper limbs, in our lower limbs — where the range of movement is very high. That is why we call them freely movable joints, or synovial joints.
So if you look at this figure — the joints present on the median plane are slightly movable joints, or cartilaginous joints. The first example of this is the pubic symphysis. And the joints of the vertebral body here are also cartilaginous joints.
And the remaining joints that are in the upper limbs — such as the shoulder, elbow joint, joints of the fingers, wrist joint — the joints of the upper limb — these are freely movable joints; we also call them synovial joints. And in the lower limb, hip joint, knee joint, and ankle joint — all of these are synovial joints.
Now, let us understand the classification of joint movement.
Classification of joint movement
According to the movement they permit, a joint can be uniaxial, biaxial, polyaxial and plane joint.
1) Uniaxial joint
The first type is the uniaxial joint. In this, movement occurs only in one axis. A good example is the hinge joint.
The elbow is a hinge joint — you can see it in the figure. So it has only one axis, and movement happens along that axis. So in our elbow joint, flexion and extension — these two movements occur in only one axis.
2) Biaxial joint
The second type is the biaxial joint. In this, movement occurs in two axes. The examples of this are movement in the ellipsoid joint and movement in the saddle joint. Let me explain through a figure.
So the joint in our wrist is an ellipsoid joint. In this joint, movement occurs in two axes. That is why we can do both flexion-extension at our wrist joint — this is flexion-extension — and radial deviation and ulnar deviation as well.
And the combination of all of these allows us to do circumduction of the wrist. So here, movement is occurring in two axes.
From the same category, another example is the saddle joint. In our thumb, the carpometacarpal joint is a saddle joint. And in this joint too, flexion-extension of the thumb occurs, as well as abduction and adduction.
3) Polyaxial joint
The third type of joint is called the polyaxial joint because movement occurs in many axes here — multiple axes. The best example of this is the ball-and-socket joint. The shoulder has a ball and socket joint, and many movements are possible here.
We can do abduction-adduction, we can do flexion-extension, we can do rotation of the shoulder, we can do elevation. So many movements are possible here. That is why we call it a polyaxial joint.
There is another ball and socket joint in our body — that is the hip joint, where abduction, adduction, internal rotation, external rotation, flexion, extension — movement occurs in many axes there as well.
4) Plane joint
The next type of joint is called the plane joint. In this, a small gliding movement occurs. This gliding movement and rolling movement — here, small gliding movement happens.
An example of this is the acromioclavicular joint. The joint between the acromion process and the outer end of the clavicle bone. This joint forms the tip of our shoulder. In this joint too, slight movement occurs when we do shoulder abduction and elevation — so there, a slight sliding movement occurs.
What causes limitation of joint range of motion?
Now, let us try to understand the limitations of joint range of motion. What causes the joint’s motion to become limited or reduced?
Tightness of skin, superficial fascia and scar tissue
The first one is due to the tightness of skin, superficial fascia, and scar tissue. You can see in this figure — I have tried to explain it here.
This is a post-operative knee replacement case, in which there is a scar in the skin. So due to the scar in the skin, flexion limitation of the knee occurs. The same principle applies after hand trauma: scar adhesion is a major reason for stiffness after a hand blast injury, which is why early scar care and mobilisation are critical.
If you recall, when we were children, our knees would get hurt and the skin over our knees would get scraped. So when it was in the healing process, we would feel pain while trying to bend our knee.
Muscle weakness and inefficiency
The second reason is muscle weakness and inefficiency. If there is some kind of weakness in the muscle, or paralysis, then also we cannot produce movement in the joint.
And the other situation is when the muscle’s strength is fine, but there is tightness in the muscle or spasticity — because of that, the joint movement gets restricted.
Adhesion formation
The third is adhesion formation. Say there is a joint effusion in our joint. Due to that effusion in the joint, when fibres gradually start forming there, and if the effusion stays there for a long time, those fibres adhere to each other.
They go and adhere to the joint’s ligaments and tendons, and restriction develops in the joint. Both passive and active restrictions occur.
The best example of this is frozen shoulder. In frozen shoulder, the capsule of the joint becomes dry, and the fibres adhere to each other, because of which the movement there is quite painful and restricted.
Injury to joint capsule
The fourth cause of joint range limitation is tearing of the joint capsule. If there is any kind of injury to the joint capsule, if it tears, then movement gets restricted.
Or, if there is a foreign body inside the joint — if a piece of bone breaks and goes inside the joint, that also causes movement of the joint to be restricted.
Cartilaginous and bony destruction
The fifth cause is cartilaginous and bony destruction. The best example of this is knee osteoarthritis, in which the cartilage of our joint gets eroded, and it becomes rough, because of which movement in the knee becomes quite painful.
Then there is bony destruction, which is seen in ankylosing spondylitis. In this, our spine’s vertebral bodies — the joints between them, the intervertebral joints — extra bony growth forms in the bones, and the bone fuses. We call this bamboo spine.
Or Myositis ossificans, which is usually seen in the hip joint or the elbow joint. What happens there is that extra bone formation occurs and it fuses our joints. We could say it is a kind of cementing of the joint, and because of that, the movement in the joint gets restricted.
Organic cause
The sixth cause is no organic cause. There is no organic cause — it is just that movement of some kind is not happening there. Or the patient themselves does not want to do that movement.
How to prevent joint stiffness
Now we will try to understand how to prevent joint stiffness.
So, to prevent joint stiffness, we first need to identify its cause. Before this, we have already understood what the different causes of stiffness are. Accordingly, we will take prevention measures.
So the first point — when joint stiffness is due to the tightness of skin, tissue, and scar — for that, we will give a hot pack and do a massage.
As I just showed you in the example — in post-operative knee replacement, the scar mark that remains over the knee — for that, we do slight kneading with the thumb there, and we give ultrasound there, so that the skin relaxes, loosens, and detaches from the subcutaneous tissue, and allows the knee to move freely.
The second — if muscle weakness is the cause, then we will give strengthening exercises, resisted exercises, and prescribe static strengthening exercises to the patient. If there is flaccid paralysis, we will do passive movement there.
After that, if the restriction in the joint is due to adhesion formation, then we need to prevent swelling or oedema there. How can we do that? By crepe bandage. Say there is swelling in my wrist joint or ankle joint — so we will give a crepe bandage there and try to disperse the swelling. We can also give a cold pack there.
Elevation of limbs — when there is swelling in our legs, we tell the patient to lie down in supine lying and keep their legs elevated. Give two layers of pillows under the legs and keep the legs on top. So elevation of the legs also reduces swelling. Similarly for swelling in the hand, we can keep our hand elevated.
Another method is contrast bath. In contrast bath, we take cold water and hot water, and alternately dip our limbs in them. What happens is that due to the temperature contrast, there is a massage effect, and the swelling there gets reduced.
Friends, that was prevention — but if restriction has already occurred in the joint, what do we do for that? For that, we will mobilise the joint.
Joint mobilising — the first thing is relaxation. Then relaxed passive movement. Then passive manual mobilisation — this includes mobilisation, manipulation, and controlled sustained stretching.
Controlled and sustained stretching is very useful in spasticity — that is, to stretch in a controlled and sustained manner in spasticity. This is a specialised technique that is very important for us physiotherapists.
Active exercises: After that comes active exercises — in exercises, we need to do active-assisted exercises, free exercises, and resisted exercises. I have already covered all of these in great depth. You can go to our previous episode and read about these active exercises there.
So I hope you found this lecture useful. Thank you all very much for reading this article.
FAQ
The author is a physiotherapist who has been practising for the last 17 years. He holds a Bachelor's in Physiotherapy (BPT) from SVNIRTAR (Swami Vivekananda National Institute of Rehabilitation and Research), one of the prestigious physiotherapy schools in India.
Whatever he learns dealing with his patient, he shares it with the world through blogs and e-books. He also owns a YouTube channel, "Sunit Physiotherapist" with over 8 lakh active subscribers. Here, he shares everything he gets to learn serving the patient.
