Knee osteoarthritis, also known as degenerative knee osteoarthritis and deformed knee osteoarthritis, is the most common knee pain condition in pain medicine. Depending on its etiology, knee osteoarthritis can be divided into primary and secondary. In primary cases, the cause is unknown, while in secondary cases, there is a clear etiology, and knee injury is only a secondary manifestation of the disease.
Causes and predisposing factors
Etiology
Knee joint structureKnee joint structure
The cause of primary knee osteoarthritis is unknown and may be the result of multiple factors.
The incidence of the disease is found to increase with age, especially in middle and old age. It may be related to the following factors.
(1) After middle age, neuromuscular function gradually decreases, resulting in joint damage due to uncoordinated movement.
(2) Progressive increase in inorganic salt content in bone with age, resulting in a decrease in bone elasticity and toughness. At the same time, the blood flow to the joints decreases, and the articular cartilage becomes thinner, less matrix, and fibrotic due to reduced nutrition, resulting in changes in the weight distribution in the joints and making the joint surfaces and articular cartilage vulnerable to injury.
(3) Pre- and postmenopausal women, due to estrogen imbalance and increased bone loss, osteoporosis occurs.
2, injury and overuse is one of the more recognized causes.
3, obesity foreign statistics found that at the age of 37 years more than standard weight 20% of men, the risk of primary knee osteoarthritis is 1.5 times higher than standard weight people, while women obese people have a higher risk of disease than standard weight people 2.1 times. It may also be related to the posture, gait, and exercise habits caused by increased joint weight bearing and obesity.
4, genetic many secondary knee osteoarthritis has a clear genetic tendency.
5, Other such as changes in the cartilage matrix of the joint, increased intraosseous pressure, etc.
Predisposing factors
The following factors may have a role in promoting degenerative changes in the knee joint.
1. Inflammatory processes such as rheumatoid disease, where inflammation of the periarticular and synovial tissues can erode and destroy articular cartilage.
2, metabolic disorders such as gouty uric acid deposits, pigmentation of black uric acid urinary browning disease, accumulation in the articular cartilage, so that the nature of the articular cartilage changes and destruction occurs. Hemochromatosis is similar to its role.
3, biomechanical factors such as joint deformity (for example, knee valgus or knee inversion), so that the joint increased load imbalance, a large distribution of one side, and finally cartilage destruction. Abnormal body forces can also cause internal disorders of the joint. The direction and velocity of the forces acting on the joint are determined, for example, by using a method that envisions the center of force transmission in the joint at one moment. The difference between normal and abnormal conditions of the joint can be found by connecting any point on the joint surface with the center of force transmission of the joint at one moment, perpendicular to the plane of action.
In normal cases, the velocity and direction of the force in contact with the joint surface is parallel to the joint surface. In patients with medial meniscal tears, which arise as a momentary center of force transmission, there is a tendency for the direction of the velocity of the joint force to be transmitted from the femur to the tibia as the joint twists and shifts so that the knee extends. This large contact force causes a meniscal tear and subsequent degenerative joint disease.
The relative compression of the articular surfaces can cause nutritional disorders of the articular cartilage, leading to chondrocyte necrosis. This is followed by depletion of matrix protein (PG) polysaccharides, whereupon the articular cartilage is unable to withstand the stresses and shear forces of the back and forth motion of the joint, resulting in degenerative changes. In some experimental animals with knees immobilized by long-term flexion forces, adhesions can occur between the articular cartilage and synovium in the parts of the joint surfaces that are not in contact with each other. It may be due to cartilage nutritional disorders, so the adhesions below the cartilage degenerative changes.
4, the role of hormones acromegaly patients with articular cartilage changes significantly. Growth hormone stimulates chondrocytes, accelerating and enhancing the metabolic activity of chondrocytes. When the animal ages, the lack of growth hormone is obvious, which can cause degenerative changes in chondrocytes and reduced chondrocyte metabolism. In diabetic patients, they are highly susceptible to osteoarthritis because of progressive chondrocyte abnormalities.
5, chemical injury systemic or local use of chemical drugs, harming the vitality and metabolic activity of chondrocytes. For example, intra-articular injections of glucocorticoids significantly reduce their synthetic activity for periods ranging from a few hours to 1 week or more. When systemic glucocorticoids and immunosuppressants are used, they can likewise cause a decrease in anabolism and loss of PG (glycoprotein). The histological changes are called focal cartilage chondrogenesis or early osteoarthritis. Intra-articular injection of alkaline drugs (such as nitrogen mustard or thiotepa) can also damage articular cartilage.
6. Repeated intra-articular bleeding in patients with defective coagulation factors, repeated intra-articular bleeding can lead to severe damage to articular cartilage as well as subchondral bone structures. Ionic pigments within the cartilage matrix can alter the physicochemical properties of the cartilage, or chondrocytes engulfing large amounts of ionic pigments in the cytoplasm can cause lysosomes to release degradative enzymes. There is a decrease in glycoprotein (PG) concentration and a decrease in the synthetic activity of chondrocytes. 1 or occasional intra-articular bleeding may not present a serious problem.
Clinical presentation
Osteoarthritis of the knee is a common condition in pain clinics, with patients presenting with joint pain, locking, and functional impairment. In the early stages of the disease, the joint pain may only be vague when moving, but as the patient progresses, the pain gradually worsens and changes to a distending pain, which is apparent when walking up and down stairs, squatting, or standing up, or in severe cases, even at rest. In some cases, the pain is manifested by gravelly sounds, joint hollowing and strangulation in the joint cavity during walking. Some manifest as joint stiffness. Severe osteoarthritis of the knee may also be accompanied by joint swelling, peripheral edema, and muscle atrophy.
On examination, there may be pressure points and edema around the knee joint, and the floating patella sign may be positive when there is joint effusion. X-ray examination of the knee joint may show bone formation, narrowing of the joint space, osteoporosis, and loss of the subpatellar fat pad.
Diagnosis
Osteoarthritis of the knee Osteoarthritis of the knee
It is generally not difficult to make a correct diagnosis of knee osteoarthritis based on the patient’s clinical symptoms, signs and knee joint changes. The international diagnostic criteria for osteoarthritis of the knee and the diagnostic criteria for osteoarthritis of the knee established by the American College of Rheumatology in 2001 are described below.
(A) International diagnostic criteria for knee osteoarthritis
1. Clinical diagnostic criteria ① Knee pain for most of the time in the first month. (ii) There is bone friction sound. ③ Morning stiffness <30min. ④ Age ≥38 years. ⑤ Knee examination shows bony hypertrophy. The diagnosis of osteoarthritis of the knee can be made if ①②③④ or ①②⑤ or ①④⑤ are met.
2. Clinical, laboratory and radiological diagnostic criteria: ①Knee pain for most of the first month. ②X-ray film shows bone flab on the edge of the joint. ③The joint fluid examination is consistent with osteoarthritis. ④Age ≥40 years. ⑤Morning stiffness <30min. ⑥Bone rattling sound when the joint moves. The diagnosis of osteoarthritis of the knee can be made if ①② or ①③⑤⑥ or ①④⑤⑥ are met.
(2) The American College of Rheumatology established the diagnostic criteria for knee osteoarthritis in 2001
1. Patients with knee pain have 3 of the following 7 items ① Age ≥ 50 years. ②Morning stiffness <30min. ③Bone rattling sound during joint activity. ④The examination of the knee shows bony hypertrophy. ⑤ There is bone pressure pain. ⑥No obvious synovial warming. ⑦There is bone redundancy formation on radiological examination.
2. The patient with knee pain has 5 of the following 9 items ① Age ≥ 50 years. ②Morning stiffness <30min. ③Bone rattling sound during joint activity. ④Knee examination shows bony hypertrophy. ⑤ There is bone pressure pain. ⑥No significant synovial warming. ⑦ESR <40mm/h. ⑧Rheumatoid factor (RF) <1:40. ⑨Signs of osteoarthritis in the synovial fluid.
Treatment
Treatment of osteoarthritis of the knee is aimed at disease education, pain relief, prevention and delay of structural changes in joint tissues, and restoration of its normal function.
(i) General treatment
1, disease education knee osteoarthritis is mostly caused by degenerative changes, the general prognosis of patients is good. While relieving the patient’s ideological concerns, the patient should be given the necessary life guidance. Make them realize that it is very important to control diet, reduce weight, pay attention to vitamin and mineral supplements (including calcium), and adhere to moderate functional exercise. In addition, attention should be paid to the use of appropriate shoes and insoles, as well as crutches and knee pads. Also, pay attention to self-protection in daily life to avoid overworking and catching cold.
2. Coordinated muscle movement and muscle strength enhancement can effectively reduce joint pain symptoms. In order to enhance the muscle strength and endurance around the joint, maintain and enhance the range of motion of the joint, and improve the patient’s ability to perform daily life, it is very beneficial to perform appropriate physical exercise. Aerobic exercises and quadriceps strengthening exercises have significant effects in relieving pain and improving function.
(1) Quadriceps strengthening training: the method is: the patient takes a sitting position, drops the lower leg, hangs a 2-3kg weight at the ankle joint, consciously makes the quadriceps contract and makes knee extension and flexion movement. Quadriceps contraction exercise can increase the contraction force of quadriceps, promote blood circulation around the knee joint, prevent local muscle atrophy and reduce the loss of bone calcium.
(2) Muscle isometric exercise can enhance muscle strength, about 4 times a day.
For patients undergoing physical therapy, if limb pain occurs during exercise or pain persists for more than 15min after exercise, the intensity and number of exercises should be reduced appropriately, and then increased after the patient gradually adapts.
3, food therapy more calcium-rich food, such as milk, soy products, seafood and green vegetables, etc., to supplement the calcium required by the normal body, reduce the loss of body calcium, especially to prevent women before and after menopause bone calcium loss has a positive effect.
(B) drug therapy
1, non-steroidal anti-inflammatory drugs (NSAIDs) NSAIDs are still the basic drugs for the treatment of pain in patients with osteoarthritis of the knee. In recent years, newly developed cyclooxygenase-2 (COX-2) specific inhibitors such as: celecoxib, rofecoxib, its therapeutic effect is comparable to traditional NSAIDs, while the side effects are significantly reduced. The safety of long-term acetaminophen (paracetamol) is significantly higher than that of other traditional NSAIDs, and has been recommended by European expert groups as the first choice of oral analgesics, especially for the elderly, but care should be taken to prevent its damaging effects on the liver.
2.Analgesics, opioids ①Ampedrine (diacetin): The advantage is that it can be used in combination with NSAIDs. It is reported that the drug can promote cartilage repair. ② Tramadol: It is a weak opioid analgesic, and can be chosen for patients who are not suitable for NSAIDs. ③Oxycodone hydrochloride controlled-release tablets (Oxycontin): it is a strong opioid, a pure opioid receptor agonist, with no capping effect on analgesia.
3.Glucosamine sulfate (GS): It is a physiological substance necessary for the biological metabolism of chondrocytes, and chondrocytes use GS to synthesize large molecules of mucopolysaccharide, which constitute an important part of cartilage matrix and maintain the morphology and function of cartilage together with type II collagen fibers.
4.Calcium preparations and vitamin D can prevent bone loss and osteoporosis, delay the development of osteoarthritis and improve the quality of life of patients. The more commonly used are calcium D, alpha-D3, calcium gluconate, calcium bone health, etc.
5, psychotropic drugs can improve the patient’s depression and anxiety and other mental changes, long-term application of antidepressant drugs can not only relieve the depression caused by chronic pain, but also increase the function of the central nervous system of downstream pain inhibition. Commonly used are amitriptyline, doxepin, diazepam, etc.
(iii) Nerve block therapy
Nerve block therapy is currently a better method for the treatment of knee osteoarthritis, and its therapeutic effect is exact. It also has the significance of differential diagnosis for hip and ankle joint-derived knee pain.
1. Intra-articular injection of local anesthetic drugs into the joint cavity can be used to determine whether the cause of pain is intra-articular or extra-articular by the degree of pain relief.
Previously, some people injected a mixture of local anesthetics and glucocorticoids into the joint cavity. The drug formula is 5-10 ml of a mixture of 0.5% lidocaine or 0.25% bupivacaine and 5 mg of dexamethasone, which is injected once a week, 3-5 times for a course of treatment, usually one course of treatment can be effective. However, because glucocorticoids can increase the chance of local infection, they are no longer commonly used.
At present, the more recognized and effective method at home and abroad is to inject sodium hyaluronate directly into the joint cavity, and the commonly used dose is 20mg of sodium hyaluronate, once a week, 5 times for a course of treatment. The mechanism of action may be related to the following factors: (i) inhibition of inflammatory mediators (e.g. cytokines, prostaglandins). (ii) Stimulation of cartilage matrix and endogenous hyaluronic acid production. (iii) Inhibition of cartilage degradation. ④Direct protection of nerve endings that sense injury. ⑤Lubricating and elastic effects, which can relieve stress between tissues, protect articular cartilage, and promote healing and regeneration of articular cartilage.
Intra-articular injections should be performed with strict aseptic protocols, as the consequences of intra-articular infection in the knee can be quite serious. At the same time, the operation should be gentle in order to avoid damaging the articular cartilage.
2.Local pain point block is performed one by one at the tendon and ligament attachments around the knee joint where there is spontaneous pain or pressure pain, 2 to 3 ml per point. B120.5mg mixture, 2～3ml of each point injection.
3.Joint cavity irrigation is suitable for patients with fluid accumulation in the joint cavity. The method is: after the joint fluid is extracted through the joint cavity puncture, 50ml of saline equivalent to body temperature is repeatedly and rapidly injected and suctioned. Once a week, for 2-5 times in a row, the pain symptoms can be significantly reduced.
4.The operation method of branch river injection therapy for knee branch river therapy is the same as local pain point block.
(iv) Physiotherapy
The more commonly used physical therapy methods are TEHNS, acupuncture, massage, etc.
(E) Surgery
It is suitable for patients with long-term conservative treatment, intractable pain with incapacitation and severe destruction of the knee joint as shown by X-ray. Common surgical procedures include arthroplasty, osteotomy, arthroscopic removal of free bodies, and autologous chondrocyte implantation (ACI).
Treatment Myths
Myth #1: Equating knee osteoarthritis with osteoporosis
Knee osteoarthritis is mainly cartilage degeneration and wear; osteoporosis is a reduction in bone mass due to a decrease in organic components and minerals of bone, often caused by calcium deficiency or vitamin D deficiency.
Misconception 2: Not receiving or carrying out standard treatment
Many middle-aged and elderly people, osteoarthritis of the knee is treated year after year, year after year, like a “tight band” that can not be removed. In fact, one of the most important reasons why the disease is not cured is that it is not treated or standardized.
Misconception 3: Failure to detect and consult early
Many people do not think that they may have osteoarthritis of the knee and do not seek medical attention when they feel stiffness in their arms and legs, or when they suddenly feel that some joints are “locked” after sitting for a long time, or when bones click when they touch each other during joint activities.
Myth 4: Young people don’t get osteoarthritis of the knee
Secondary knee osteoarthritis caused by joint trauma and overuse of the joints is often not related to age. In recent years, there has been a significant increase in osteoarthritis of the knee among young and middle-aged people such as car owners and sports enthusiasts.
Myth 5: Osteoarthritis of the knee is a minor disease
Many patients believe that osteoarthritis of the knee is a minor disease and do not receive effective treatment, the joint damage is bound to become more and more severe and can eventually lead to disability.
Myth 6: Rely on oral w ignore side effects
Due to the age of most patients, the side effects of such w substances are large, such as gastrointestinal reactions, nephrotoxicity, blood changes, etc. Currently, no w substance can reverse the pathological changes in patients with osteoarthritis of the knee.
Myth 7: No pain is a “cure”
Many patients with osteoarthritis of the knee think that they have achieved the goal of treatment when they are “pain-free” after treatment, especially after joint injections. However, this does not mean that they are cured. As long as the joint cartilage has not returned to normal, pain can reappear at any time. If the pain does not return to normal, the pain will reappear at any time and the condition will worsen with repeated attacks.
Myth 8: Minimally invasive and adjuvant treatment is not taken seriously
For patients with earlier osteoarthritis of the knee, conservative treatment can be implemented, such as traction, acupuncture, w-objects, massage, etc.; for patients in the middle and late stages and those for whom conservative treatment is ineffective, minimally invasive treatment or application of chondroprotective agents can be considered to improve the condition; those who really need open surgery for joint replacement are very few.
Myth 9: Ignore the impact of weight on knee osteoarthritis
Overweight people are more susceptible to knee osteoarthritis because being overweight increases the load on weight-bearing joints and promotes cartilage destruction, and obesity can induce knee osteoarthritis through intermediate products of the metabolic process.
Myth 10: Lack of joint protection
Lack of self-protection, such as frequently squatting or kneeling to retrieve objects, sitting on a low stool, sleeping on a low bed, etc., can increase the friction and weight on the joints. Wrong exercise can also aggravate arthritis, such as knee osteoarthritis patients like to use Tai Chi, climbing and other sports to exercise the joints, these will make the joints more wear and tear.