Types and selection of prosthetic knee kit
Artificial joint replacement is the ultimate operation for the treatment of the late diseases of the knee joint, which is a mature and effective treatment. At present, more and more patients with osteoarthritis will choose the knee replacement surgery, but the majority of patients know little about the prosthetic knee kit, how to choose a suitable prosthetic knee kit, is the concern of the majority of patients.
Let's take a look at the prosthetic knee kit. At present, the prosthetic knee kit is made of cobalt chromium molybdenum alloy and high cross-linked super high molecular polyethylene, which is durable. According to the location of the prosthesis, it can be divided into single condylar prosthesis, double condylar prosthesis and three compartment (whole knee) prosthesis. According to the fixation method, it can be divided into cemented prosthesis and non cemented (biological) prosthesis. According to the limited degree of prosthesis design, it can be divided into non limited prosthesis, partial limited prosthesis, high limited prosthesis and total limited prosthesis.
The prosthetic knee kit usually consists of three parts: 1. Femoral prosthesis: femoral condyle prosthesis placed at the distal femur, which is composed of metal alloy; 2. Tibial prosthesis: it can be a single prosthesis design of high cross-linked polyethylene, or a combination design of two parts, which is composed of metal bracket and high cross-linked polyethylene gasket, which is fixed or sliding on the metal bracket; 3. Patella Prosthesis: it is placed on the residual bone bed of the patella and forms the patellofemoral joint surface with the intercondylar of the femoral prosthesis, generally composed of high cross-linked polyethylene.
Generally speaking, total prosthetic knee kit arthroplasty is to replace the damaged articular surface with these three components. In some patients, the patella does not need to be replaced, only the femoral and tibial prostheses are used.
What we are most exposed to is the total prosthetic knee kit. In the choice of the type of total knee prosthesis, the stability and joint mobility of the knee prosthesis is a pair of contradictions. Generally speaking, the lower the mechanical limit of the artificial knee joint kit, the better the joint movement function. More limited prosthesis can obtain better stability, but also sacrifice part of the movement function. There are many kinds of prostheses and manufacturers in clinic, but the design concept is similar, so the selection of artificial knee joint kit is also regular.
Most of the knee joints in the first replacement were non limited and partial limited prosthesis. The representative of unrestricted total knee arthroplasty is posterior cruciate ligament sparing prosthesis (CR). With the posterior cruciate ligament preserved, the proprioception of the human body is preserved, and the posterior stability of the prosthetic knee kit after implantation is obtained, thus allowing greater joint mobility of the tibiofemoral joint surface. But because the contact surface between the femoral condyle and the tibial joint surface becomes smaller, it is easy to wear.
The posterior cruciate ligament replacement prosthesis (PS), also known as the posterior stability prosthesis, has a wide range of indications because it does not need to retain the structure of the posterior cruciate ligament. For patients with posterior cruciate ligament dysfunction or knee flexion contracture who can't retain the posterior cruciate ligament, such as rheumatoid arthritis, it is more suitable to choose the post stable prosthesis.
In the revision of the prosthetic knee kit, the high limited prosthesis is is mainly used for the patients with side collateral ligament dysfunction, large bone defect or severe varus deformity, as well as the patients with knee joint revision. The total limited prosthesis, such as the hinged knee joint (Figure 06), can be used in the joint replacement of patients with near knee joint tumor or the revision of the total knee joint with stable loss of the knee joint.
In addition, for patients with osteoporosis or severe obesity, or patients with knee repair, when choosing the prosthetic knee kit, it is necessary to appropriately increase the extension rod to increase the stability and load-bearing capacity of the joint, so as to prevent premature mechanical loosening of the prosthesis.
At present, there are dozens of brands of knee prostheses, including imported and domestic ones. The efficacy of knee replacement depends not only on the prosthesis, but also on the operation technology and correct rehabilitation of the operator, as well as the cognition and familiarity of the operator to the prosthetic knee kit. Therefore, in the clinical selection of the prosthetic knee kit, we should take the operator as the leader, follow the basic principle of prosthesis selection, and select the familiar prosthetic knee kit according to the type of knee joint deformity and the integrity of soft tissue. In a word, the best is the right one.