(1) Types of artificial joints and materials.
Femoral head necrosis such as early diagnosis and treatment can make more than 70% of patients to avoid or delay artificial joint replacement. However, because in China, delayed diagnosis, non-standard treatment is more common, so that many patients with femoral head is already late (III, IV) other methods are difficult to work, had to perform artificial joint replacement. However, with the improvement of artificial joint materials, prosthesis design and the skill of physicians, the efficacy of artificial joint replacement is rapidly improving and excessive concerns are unnecessary.
The types of artificial hip joints include.
①Femoral head surface replacement;
②Artificial femoral head replacement;
③Total hip artificial joint replacement.
The commonly used artificial joint implant materials are.
①Metallic alloys;
②Polymer materials;
③Ceramic materials.
The commonly used metals can be divided into three categories: titanium-based (titanium and titanium alloys), cobalt-based (cobalt-chromium, cobalt-nickel alloy, cobalt-chromium-molybdenum, etc.) and iron-based (stainless steel). Polymer materials refer to ultra-high polymer polyethylene, which is mainly used to make acetabular cup prosthesis and acetabular cup prosthesis lining. Alumina and zirconia ceramics have good inert stability and can be used in artificial joints for the cephalic portion of the artificial total hip joint. In both in vivo and in vitro experiments, the abrasion and wear rates of the artificial joint surfaces of alumina and zirconia were significantly reduced.
Depending on the different materials of the artificial total hip joint cephalic socket, the components of the joint bearing surface are.
①Metal-polyethylene;
②Ceramic-polyethylene;
③Metal-metal;
④ceramic-ceramic. The first two of these combinations are commonly used today.
According to the different fixation methods of artificial total hip prosthesis, they are divided into.
① Non-cemented biological fixation ;
②Bone cement fixation.
(2) How long is the service life of the artificial joint?
For patients who are about to undergo total hip arthroplasty, the most important concern is the service life of the artificial joint. Although artificial total hip replacement has been widely carried out in China in the past decade, and orthopedic surgeons are becoming more and more mature, there is a lack of more frequent follow-up results. According to the results of foreign multicenter, large sample and long time studies, the survival rate of artificial joint reaches 80% in 20 years and 64% in 30 years, that is, about 80% of patients’ artificial joints can still be used 20 years after artificial joint replacement, and 64% of patients after 30 years, and the prosthesis they use is designed in 1970s or 1980s.
In the 21st century, the material selection and design of artificial total hip prosthesis are now more reasonable, and the surgical techniques are widely improved, so the service life of the prosthesis is expected to be longer and the efficacy is more optimistic. There are many factors affecting the service life of artificial joint prosthesis, the choice of prosthetic material and the location of the prosthesis (i.e. the surgical technique of the orthopedic surgeon) and the quality of the patient’s bone are the three main factors. 60% of the service life of the prosthesis depends on the surgical technique, 20% on the prosthetic material and 20% on the quality of the bone. Among these factors, such as osteonecrosis of the femoral head, the occurrence of disuse osteoporosis due to long-term non-weight bearing of the affected limb, and the replacement of the artificial joint will definitely affect the service life. The Osteonecrosis and Joint Preservation and Reconstruction Center of China-Japan Friendship Hospital has accumulated more than 700 cases of artificial joint surgery experience, and since March 2003 was the first in China to carry out minimally invasive artificial hip and knee joint replacement under navigation guidance again, achieving excellent results and accumulating rich experience.
(3) Bone cement artificial joint and its application.
In 1961, we first introduced the technology of bone cemented total hip joint, and this technology has been continuously improved and has developed to the fourth generation of bone cement technology, which has significantly extended the service life of the joint prosthesis. The cemented total hip joint is mainly suitable for patients with osteoporosis or patients with straight barrel-like proximal femur and elderly patients (>65 years old).
(4) Non-cemented artificial joints and their applications.
Its theoretical basis is that the porous metal surface of the prosthesis can occur bone growth into the prosthesis indicating that the bone is tightly pressed to match the posterior bone union, thus achieving the purpose of biological fixation of the prosthesis, mainly for young and middle-aged people with good bone quality.
(5) Minimally invasive surgery in artificial joint replacement.
With the continuous development of artificial total hip replacement surgery technology, minimally invasive total hip arthroplasty with small incisions has become possible. Its surgical incision length is within 10 cm, and the operation time is not prolonged or can even be shortened. This technique means more than simply a small incision; its technical focus is to reduce damage to ligaments, muscles and bone tissue, and to be safe, effective, repeatable and time-tested. The advantages are.
①Small incisions are aesthetically pleasing (intracutaneous sutures can be used);
②Less trauma to the soft tissues around the joint during surgery, less bleeding, less postoperative wound pain and fewer complications;
③ Early resumption of both daily life and function. Patients can walk on the ground with the help of crutches on the second to third day after surgery, which greatly reduces the complications in the perioperative period.
(6) Application of navigation technology in artificial joint replacement.
Image-guided surgical navigation system is a new technology developed in the past 10 years and has been widely used in clinical practice. Since the angle of acetabular cup prosthesis placement is crucial to prolong the life of the prosthesis, it is not very reliable when using mechanical guides for placement.
(7) Femoral head surface replacement.
Since there is no fundamental solution for osteolysis and prosthesis loosening due to polyethylene abrasive debris of the cup after total hip arthroplasty, a femoral head surface replacement has emerged that preserves the amount of bone in the hip joint as much as possible and replaces only the femoral head surface. This procedure is technically demanding and requires the training and clinical experience of an orthopaedic surgeon. It is considered as a transitional surgery and some people call it a “money for time surgery”, which can delay the time of total hip replacement.
Common surgical complications include.
① Fracture of the femoral neck;
②Poor placement of the prosthesis;
(3) Loosening and dislocation of the prosthesis.