Author: Geng Shuo The First Affiliated Hospital of Harbin Medical University
In many film and television works, you can always see the plot of someone breaking their joints to "click". Attentive friends can find that this wonderful sound from the joints is also very common in our own bodies, and the knee joint bounce is one of them. So, does the knee joint need treatment when it makes a noise? What are the differences? This article answers them all for you.
What is a knee bounce?
Knee ringing in the general sense refers to the popping sound produced by all knee joints. These include the sound of the surrounding tendon sliding when the knee is moving, such as the sound of the lateral popliteal muscle sliding of the joint when the knee is flexed and extended, which is medically called "bouncing the knee"; it also includes the crisp sound of the bubbles in the synovial fluid in the joint capsule vibrating due to pressure change and rupture. 【1】
Knee bouncing is just a symptom, not a disease. According to the cause of the pop, we can roughly divide it into two categories: physiological pop and pathological pop.
1. Physiological pops
The joint cavity is related to the joint fluid, which plays a role in lubricating the joint. There is negative pressure in the joint cavity, which maximizes the stability of the joint structure. When the joint is pulled or flexed (both the finger pull and the finger can make a bouncing sound), the tension exceeds the negative pressure of the joint cavity, and a distinct cavity will appear, and the surrounding gas will spread rapidly into the cavity, vibrating with the liquid, and a crisp sound will be emitted. [2] That is to say, the vast majority of physiological bouncing is caused by gas vibrations in the joint cavity.
Characteristics of physiological pops:[3]
1) The sound is crisp, single and non-repetitive;
2) Occurs only when the joint is suddenly pulled or bent;
3) The joint must have a certain period of rest between the two bounces;
4) Accompanied by a slight pain or discomfort, there is often a feeling of relaxation after the sound.
2. Pathological pop
When you feel that your knee ringing does not belong to the above situation, then your knee joint may also be due to some pathological changes, such as meniscus injury, disc meniscus, osteoarthritis, synovial fold syndrome, knee internal ligament injury, etc.
1) Meniscal injury: Meniscal injury is one of the most common causes of pathological pop [3], its pop occurs in the medial or lateral space of the tibia-femoral joint, the sound is crisp, the frequency of occurrence is high, often accompanied by joint interlocking - that is, in walking, squatting and other activities, knee joint flexion and extension is suddenly limited, like being stuck, unable to move, and there is obvious pain. Mild meniscal injuries are painless, and walking or even jogging are not affected, so they are easily overlooked. In the long run, it is easy to cause joint cartilage damage, which may eventually progress to osteoarthritis, and in severe cases, knee replacement may be required.
2) Discoid meniscus [4]: Discoid meniscus due to the thick texture, easy to cause joint bounce, located in the lateral space of the tibial joint, the sound can be large or small, the frequency of occurrence is very high, occasionally accompanied by joint interlocking. If there is no pain in locking, it can be temporarily observed. However, due to the poor strength of the discoid meniscus, it is prone to damage. If interlocking or pain occurs, discoid meniscal injury requires surgery.
3) Knee synovial fold syndrome [4]: Generally on the medial side of the patellofemoral joint, located around the patella, the voice is crisp, often accompanied by local pain. If there are no obvious symptoms, it may not be treated. Severe pain can be obvious, especially when going up and down stairs or squatting, such patients, magnetic resonance imaging can have no obvious abnormal performance, such as severe symptoms, affecting life, must be treated by surgery.
4) Knee osteoarthritis [4]: Due to the wear and tear of joint cartilage, the friction between joints increases, and when the knee joint is moved, a loud sound will occur. This type of pop sounds is dull, occurs frequently, and is often accompanied by local swelling and pain. In this case, if the symptoms are relatively mild, it can be alleviated by conservative treatment methods such as hot compresses, baking electricity, and physiotherapy. If the condition continues to progress, surgery is indicated.
In addition to the above common causes, there are many other causes of knee ringing: such as iliotibial tract contracture, joint capsule ligament hyperplasia, joint free body, synovial chondromatosis, meniscal calcification, congenital knee dislocation, old knee ligament injury, joint fluid insufficiency, etc. 【3】
Therefore, when there is an unexplained knee ring, you should seek medical attention in time; for the symptoms of the pop due to the disease, the treatment of the primary disease should be the mainstay.
bibliography:
【1】Sandoz R.The significance of the manipulative crack and other articular noises[J]. Ann Swiss Chiropract Assoc,1969,(4):47-49.
【2】Brodeur R. The audible release associated with joint manipulation [J]. J Manipulative Physiol Ther,1995,18(3):155-164.
[3] Zhao Zhenzhang. The essence and clinical significance of physiological joint bouncing[J].Massage and Guidance,1997(06):4-5.
[4] Feng Yingqi,Xu Bin,Xu Honggang,Zhang Fuwen. The occurrence of knee ringing and arthroscopic diagnosis and treatment[J].Journal of Anhui Medical University,2006(01):94-96.