Introduction to Artificial Joints
Artificial joints are artificial organs designed based on the development of metallurgy, biomaterials, biomechanics and orthopedic surgery to replace damaged and non-functional human joints for the purpose of relieving symptoms and improving function. Various artificial joints have been designed according to the characteristics of each joint in the body. Currently, artificial joints are the most effective artificial organs, and the artificial hip and knee joints are the most effective artificial joints. Other joints, such as artificial shoulder joints, elbow joints and ankle replacements, are also being developed.
People have been trying to use artificial joints to treat advanced joint diseases since the 19th century. After a long exploration, Sir John Charnley, a British physician, designed a hip prosthesis in 1962 that combined a metal femoral head with a polymer polyethylene acetabulum. Due to its advantages of low friction, stability and low loosening rate, the artificial hip joint replacement has been developed tremendously. To this day, the Charnley artificial hip is still used as the “gold standard” against which other artificial hips are measured, and he is therefore recognized as the father of modern artificial joints.
Based on the success of the artificial hip, other joints were studied in depth, and the artificial knee was first used in clinical practice. After more than 30 years of clinical practice, with the advancement of processing and material science, many types of artificial knee joints were introduced one after another. The efficacy of the artificial knee joint has been further improved, making it one of the most effective artificial organs available, and American physician John N. Insall has made a significant contribution in this regard.
Why Artificial Joint Replacement
Arthroplasty is a procedure in which a joint that has lost function is repaired and a specific artificial joint is inserted to restore function, relieving pain, stabilizing the joint, correcting deformity, and improving joint motion. Artificial joints are important for patients who have advanced joint destruction and for whom other treatments have failed. The advent of artificial joints has made it possible to cure many joint diseases that could not be treated in the past. It has enabled many patients with advanced joint damage who could only walk with crutches to walk like normal people, and has enabled some patients who were bedridden for a long time to regain their walking function and start a new life.
Results of Artificial Joint Arthroplasty
The outcome of artificial joint replacement depends on the patient’s confidence, the surgeon’s skill, bioengineering, and the design of the prosthesis and instruments. Over the past half century, artificial joint technology has evolved and been refined to become a major tool in the field of orthopedics for the treatment of advanced joint pathologies, and is considered a milestone in the development of orthopedics in the twentieth century. At present, artificial joint surgery has become a very successful procedure that can relieve and eliminate joint pain and restore joint movement. It allows people who have suffered from joint pain for a long time to walk, travel, work, shop, and exercise as normal after surgery. Because of the certainty and predictability of the efficacy of artificial joint surgery, more patients are willing to undergo this surgery. Currently, about 550,000 people in the United States alone undergo artificial joint replacement surgery each year, and the number is increasing every year.
What is an artificial hip joint and hip replacement
The artificial hip joint consists of a femoral prosthesis and an acetabular prosthesis. The prosthesis consists of a metal alloy with good compatibility with human tissue and a wear-resistant polymer polyethylene liner. The femoral prosthesis consists of a ball part and a dry body part. The ball part is made of a smooth and strong alloy, and the body part is mostly tapered and can be inserted into the bone marrow cavity of the upper part of the human femur, which is tightly integrated with the femur, and the head and the body part can be assembled together. The other part is the socket part which is integrated with the pelvis. It is lined with a polymer polyethylene liner and forms a smooth and wear-resistant joint with the metal ball head.
Artificial hip replacement is the replacement of a diseased hip joint with an artificial prosthesis. Artificial hip replacement can be divided into total hip replacement, which is a simple replacement of the femoral head, and total hip replacement, which is a simultaneous replacement of the acetabulum and the femoral head. Depending on the fixation method, there are cemented and non-cemented (biologically fixed) types. The cemented total hip joint consists of three parts: a polyethylene acetabular prosthesis, a metal ball head, and a metal femoral stem prosthesis. The non-cemented total hip joint consists of four parts: a metal outer cup, a polyethylene liner, a metal or ceramic ball head, and a metal femoral stem prosthesis. The type of artificial joint and the fixation method should be chosen by the surgeon according to the patient’s age, hip pathology and bone condition.
What diseases require artificial hip replacement?
Total hip replacement surgery is suitable for those who suffer from hip joint destruction, joint pain and movement disorders caused by diseases or injuries, which seriously affect daily life and quality of life and cannot be relieved and improved by conservative treatment. The common ones are hip joint destruction, pain and functional limitation caused by femoral head necrosis, osteoarthritis, ankylosing spondylitis hip arthritis, rheumatoid arthritis hip arthritis and traumatic arthritis. There are also secondary osteoarthritis caused by congenital hip dislocation, acetabular dysplasia, old dislocation or subluxation of the hip joint. For elderly patients with displaced or subtrochanteric femoral neck fractures, due to the high incidence of non-healing fractures and femoral head necrosis, it is also advocated to enable patients to recover early through artificial joint replacement, live on their own and improve their quality of life, so as to avoid many complications brought about by long-term bed rest.
Rehabilitation after total hip arthroplasty
Total hip arthroplasty is an operation with very precise efficacy. Early postoperative rehabilitation plays an important role in promoting physical recovery, maintaining joint stability, enhancing muscle tone, improving joint mobility and restoring movement coordination.
Within one day after surgery, you should generally lie down according to the anesthesia and should not use pillows within 6 hours.
On the day after surgery, active flexion and extension of the ankle joint can be performed to promote blood return to the lower limbs and reduce the chance of deep vein thrombosis. On the second postoperative day, the bed can be shaken up to 60°, and active ankle flexion and extension exercises and quadriceps isometric contraction can be performed to maintain muscle tone. Day 3 to 4 after surgery The bed can be rocked up to 80° to 90°, and hip and knee flexion and extension exercises and straight leg raising exercises can be performed actively to increase venous return and prevent quadriceps atrophy. Note that hip flexion should be less than 70 degrees and the lower limbs should not be internalized.
About one week after surgery, perform sitting to standing exercises, shift the weight to the healthy side, support the bed with both hands, keep the affected leg abducted, slowly move the affected limb to the ground, then move the healthy limb to the ground and sit on the bedside. Then stand up with the support of double crutches and perform walking exercises.
The second week after surgery, the walking exercises were started: the walker was used for the initial walking training and to prepare for the use of crutches or canes. The affected limb is basically unweighted, the affected limb is stepped first, the weight is shifted forward, the weight is distributed on the walker and the healthy limb, and the healthy limb follows. Three-point axillary cane walking gait is suitable for people who have normal function of one lower limb and cannot bear weight on the other. The double crutch advances with the affected limb and then moves the healthy limb.
The method and timing of postoperative weight-bearing exercises differ according to the prosthetic material.
For cemented prosthesis, you can move to the ground 3-5 days after surgery, and practice walking with the help of a walker at first, and then you can practice normal walking with double crutches after a week.
For non-cemented prosthesis, early and firm mechanical fixation is necessary. In general, partial weight-bearing of the affected limb can be started 1 to 2 weeks after surgery, and full weight-bearing can be achieved after 1.5 to 3 months with the removal of the crutches, so that the bone tissue can fully grow into the micro-perforations of the prosthesis and reduce the loosening rate of the prosthesis in the long term after surgery.
In the early stage after total hip arthroplasty, avoid internal and external rotation of the hip joint and excessive flexion of the hip joint, and in the 3 months after the operation, you should pay attention to not sitting on a short stool or soft sofa, not crossing your legs and not bending over to pick up things to avoid complications such as joint dislocation.
Please note that each patient has his or her own special circumstances and conditions, and the specific methods of functional exercise should be carried out under the guidance of your surgeon.
What are artificial knee joints and knee replacements
The artificial knee joint is an artificial organ designed to replace the original knee joint in the human body based on developments in metallurgy, biomaterials, biomechanics and orthopaedic surgery. The artificial total knee joint consists of a femoral prosthesis, a tibial prosthesis and a patellar prosthesis, consisting of a metal femoral condyle, a tibial buttress, a tibial pad made of ultra-high molecular weight polyethylene-and a patellar prosthesis. Cobalt/or titanium alloy, which has good histocompatibility with the human body, and ultra-high molecular weight polyethylenes, which are resistant to wear and tear, are the two biomaterials commonly used in artificial knee joints today.
Total knee arthroplasty replaces the severely damaged surface of the knee joint with an artificial prosthesis that is unable to perform normal functions, thereby eliminating pain, correcting deformity, restoring stability and mobility, and improving quality of life. The surgeon uses special precision instruments to cut away the worn joint surface and then selects the appropriate metal or polyethylene prosthesis to be placed in the joint depending on the size and extent of the damage. The need for patellofemoral joint surface replacement is determined by the surgeon on the operating table based on the severity of your patellofemoral joint surface damage. Not every patient’s patella requires a patellar prosthesis.
There are two main types of fixation for the artificial knee: cemented and uncemented. Cemented fixation is currently the most widely used, and patients can be on the ground the day after surgery and can begin walking after 3 to 4 days.
What diseases require artificial knee replacement?
Artificial knee joint replacement is suitable for patients who have severe pain, deformity, instability, and mobility disorders in the knee joint caused by disease or injury, which seriously affects daily life and quality of life, and for whom conservative treatment has failed or is not effective. There are various diseases treated by artificial knee replacement, such as osteoarthritis, ankylosing spondylitis, rheumatoid arthritis, knee joint destruction due to trauma, knee inversion, valgus or flexion contracture deformity, etc.
How to protect the artificial joint after surgery
After total knee replacement surgery, the majority of patients will experience a significant reduction in pain and improved function and can return to normal life, but the surgery will not make the hip or knee function better than before the onset of the disease.
After arthroplasty, you need to develop good habits of life and activities to maintain the stability of the joint. Biking, walking, dancing, swimming, golfing, etc. are allowed after surgery, but strenuous sports such as running and jumping as well as long distance walking and climbing are not encouraged and high impact contact sports should be prohibited. Under normal activity, the artificial joint will produce a little wear and tear. However, excessive activity and weight bearing will accelerate the wear and tear of the prosthesis and may lead to loosening of the prosthesis.
Special care should be taken not to fall over and get injured, and if there is a fracture around the artificial joint it usually requires surgery.
Rehabilitation after total knee arthroplasty
Total knee arthroplasty is a very definitive procedure, and the success of the surgery is not achieved without effective rehabilitation. For knee arthroplasty, functional exercise is as important as surgery, as it is related to the future function and mobility of the knee. Under the guidance of a physician, the sooner functional exercises are started, the better. Functional exercises should be based on active activities, supplemented by passive activities. It is as important, if not more important, to practice knee extension as well as flexion. It is normal to feel pain during the early activities, and it is important not to lose the best practice period (within one week after surgery) for fear of pain, which can affect the function of the knee.
The purpose of postoperative rehabilitation is to restore the patient’s limb function and ability to take care of himself through early functional training.
Ankle pump movements: foot and ankle extension and flexion activities can be started after awakening from anesthesia, 2 to 3 minutes each time, 2 to 3 times per hour.
Quadriceps exercises: On the second day after surgery, quadriceps exercises were started to maintain muscle tone. Extend the ankle joint as far as possible dorsally, straighten the knee joint and do leg lifts for 5 seconds, relax for 5 seconds and then repeat until the thigh muscles feel fatigued.
Knee lift exercises: lower limbs straight, as for quadriceps exercises, lift the leg a dozen centimeters from the bed, maintain 5 to 10 seconds, slowly lower, repeat this action until the thighs feel fatigue. You can also do straight leg raising exercises in the sitting position by contracting the thigh muscles to straighten the knee joint and hold it for 5 to 10 seconds.
Knee extension exercises: supine position, put a small pillow above the heel so that the heel is suspended, contract the thigh muscles, so that the knee is completely straight, and try to make the back of the knee contact the mattress, maintain 10 to 15 seconds, repeat this action until the thigh muscles feel fatigue.
Heel slide knee flexion exercise: start after the drainage tube is removed. Lie on your back and make the sole of the foot slide on the bed toward the buttocks while flexing the knee to its maximum and hold it in this position for 5 to 10 seconds, repeating it several times until the leg feels fatigued.
Sitting-assisted knee flexion exercises: Begin after getting off the floor, sitting next to the bed or in a chair, and slowly flex the knee joint to its maximum natural descent. Then move one foot to the back of the other foot and use gravitational pressure to flex the knee again as far as possible and maintain it for 5 to 10 seconds, repeating several times until the leg feels fatigued.
Early movement to the ground
On the second day after surgery, you can go down to the ground and practice standing under the guidance of the doctor. On the third to fourth postoperative day, after the postoperative inflammatory response has subsided, you can begin short-distance walking exercises. These early exercises help to regain muscle strength around the knee joint, improve joint mobility and restore balance and coordination.
Walking exercises
Correct walking is the best way to help the knee recover, starting with a walker or crutches. The first step is to feel comfortable and balanced while standing upright, then move the walker or crutches forward a small distance, straightening the knee on the operated side and moving forward, first following the foot to the ground, moving the body forward, then flattening the foot and finally releasing the toes from the ground. The walking frequency, pace distance and speed should be even. When muscle strength and endurance are increased, the walking time can be gradually extended.
Going up and down stairs
Going up and down stairs requires strength and coordination, and is the best exercise to enhance the strength and endurance of the limbs, which requires help at the beginning until sufficient strength and balance coordination is regained.
Rehabilitation after total knee arthroplasty should vary from person to person due to the patient’s physical condition, medical condition, psychological quality, subjective requirements, and surgical procedure. In addition, since patients who receive total knee replacements have a history of long-term knee pain, deformity and dysfunction, functional exercise should be gradual and should not be rushed to avoid undue injury.