Restoring freedom of movement: How to choose the right hip replacement for you

Author: Li Tao, deputy chief physician, Nanfang Hospital, Southern Medical University

Reviewer: Wang Jian, Chief Physician, Nanfang Hospital, Southern Medical University

Artificial hip joints, as an important medical technology, have brought new hope to many patients with hip joint diseases. When choosing an artificial hip joint, you need to consider a variety of factors. Different types differ in material, performance, and applicable population. So how should patients choose an artificial hip joint?

1. What is an artificial hip joint?

Artificial joints are joint prostheses made of artificial materials based on the shape, structure and function of human joints. Artificial hip joints are mainly composed of three parts.

1. Artificial femoral head: It is round and very smooth. It covers the upper end of the femoral stem and is inserted into the acetabulum. It can move in the acetabulum. The materials include ceramics, cobalt-chromium-molybdenum alloy, etc.

2. Artificial femoral stem: One end of the artificial femoral stem is used to place the femoral head, and the other end can be inserted into the upper medullary cavity of the human femur. The material is mainly titanium alloy. There are two main methods to tightly combine the femoral stem with the femur: ① bone cement; ② biological fixation.

3. Acetabular part: including the acetabular cup and its lining. The acetabular cup is usually made of titanium alloy and is embedded in the human pelvis. Its lining surface is smooth and buckled on the artificial femoral head to form a smooth, wear-resistant and mobile artificial hip joint. The lining materials include ultra-high molecular polyethylene (plastic), ceramics, etc.

Figure 1 Copyright image, no permission to reprint

2. How to choose the material of artificial hip joint?

When you decide to undergo hip replacement surgery, the next important step is to discuss with your doctor and choose the right hip replacement for you. Which type of hip replacement is the best? The answer is like choosing a pair of shoes, "there is no best, only the most suitable one". Different parts of the hip replacement are made of different materials, and the doctor fixes the hip replacement prosthesis on the bone using appropriate methods. There are three factors that affect the effect of the surgery: ① The doctor's skills; ② The material of the hip replacement prosthesis; ③ The rehabilitation exercise after the operation.

The choice of artificial hip joint should be based on the patient's age, activity level, economic situation, etc. There are three common combinations of artificial femoral head and acetabular liner in clinical practice: ceramic femoral head-plastic liner, metal femoral head-plastic liner and ceramic femoral head-ceramic liner.

Figure 2 Copyright image, no permission to reprint

1. Wear resistance of joint surface: ceramic femoral head-ceramic lining> ceramic femoral head plastic lining> metal femoral head-plastic lining. The friction surface of metal femoral head-plastic lining wears 150-200 μm per year; ceramic femoral head-plastic lining wears relatively slowly, wearing 10-90 μm per year (materials from different manufacturers vary); and ceramic femoral head-ceramic lining wears 5-10 μm per year.

2. Extensive clinical use: ceramic femoral head-plastic lining > ceramic femoral head-ceramic lining > metal femoral head-plastic lining.

Metal femoral head-plastic liner: This is the most classic combination of artificial hip joints and is still in use. Its advantages are that it rarely breaks and is relatively cheap; its disadvantages are that plastic is not as wear-resistant as ceramics, and the plastic particles produced by the friction between metal and plastic can cause osteolysis in patients. Therefore, it is suitable for elderly patients with less active activities. In recent years, the progress of medical plastic manufacturing technology has significantly improved the wear resistance of plastics.

Ceramic femoral head-ceramic lining: Its advantages are wear resistance and good mobility, but its disadvantages are that it is relatively fragile, has a high risk of joint dislocation, and may also cause abnormal "crunching" noises. It is suitable for young patients with high activity levels.

Ceramic femoral head-plastic liner: The wear is between the above two combinations and it is not easy to dislocate, so it is more widely used clinically.

3. Applicable age: The general principle is that the younger the age, the more likely it is to choose ceramic femoral head ceramic lining. ① For patients under 60 years old, since they need to use it for a long time, they can choose artificial joints that wear slowly. ② For patients aged 60 to 70, ceramic femoral head-plastic lining is more suitable. ③ For patients over 70 years old, metal femoral head-plastic lining can usually meet their needs.

Regardless of the material chosen for the artificial hip joint, patients must be aware of "maintenance" after being discharged from the hospital, such as appropriately controlling or avoiding strenuous exercise and difficult movements.

3. Is there any difference in the “lifespan” between domestically produced artificial joints and imported artificial joints?

If someone asked 20 years ago whether there is a difference in the "lifespan" of domestic artificial joints and imported artificial joints, the answer is that there will be a big difference in the "lifespan" of domestic artificial joints and imported artificial joints. But now, with the advancement of my country's industrial technology, the difference between domestic and imported artificial joints has become smaller and smaller. my country has started to develop domestic artificial joint prostheses since the beginning of artificial joint replacement surgery, and it has been nearly 30 years now. Looking at the development of domestic artificial joints in the past 30 years, there have been great progress in material quality, design concepts, and process precision. Even many parts of imported products are produced domestically. There are also some core components of domestic products, such as ceramic heads and ceramic liners, which are actually produced abroad. In other words, if ceramics are used for the core components that affect the service life of artificial joints, there is not much difference between domestic and imported ones. If your financial conditions are limited, domestic artificial joints are relatively cheap and are a good choice.