Hip replacement due to osteoarthritis
OSTEOARTHRITIS OF THE HIP
When the actual stress on the joint cartilage is higher than its genetical capability can withstand, the joint cartilage is worn down. A lasting imbalance leads to osteoarthritis of the hip, also called coxarthrosis.
The actual stress on the joint is increased by obesity, accidents, congenital malformations (hip dysplasia), natural ageing (loss of the cartilage’s elasticity and ability to store water) and jobs or sports, that strain the joints. All those things lead to a loss of cartilage, which promotes arthrosis.
We differentiate four stages of osteoarthritis. In the first phase there are only a few small tears on the surface of the cartilage. In the last stage most of the cartilage is worn off completely, so the rough, painful surface of the bone is exposed.
The four stages of cartilage damage:
Stage/Grade I: Soft cartilage
Stage/Grade II: Rough surface with tears
Stage/Grade III: Deep tears in the cartilage down to the bone
Stage/Grade IV: Complete depletion of the cartilage with exposed bone: this is known as bone on bone
In comparison to bones, cartilages contain no pain fibres (nerves). Therefore, the damage of the cartilage is only notices when the deterioration reaches the bone.
If you suffer from ongoing pain due to osteoarthritis of your hips, and all conservative treatments have failed, you might want to consider a hip replacement.
The aim of an artificial hip is the absence of pain and the improvement of mobility. Artificial hips come in various sizes and different materials. However, an artificial joint can never fully match the perfection of a natural joint.
With the well-developed, tissue-preserving keyhole surgery method, the artificial hip is implanted with a minimally invasive procedure. Unlike previous methods, the stabilising muscles of the hips are simply pushed to the side and not cut through. A skin incision of around eight centimetres is enough to insert the artificial hip. The patients suffer from significantly less pain after the surgery, as the muscles have not been injured. Thanks to this tissue-sparing procedure, the loss of blood can be limited so an autologous blood donation is no longer required.
Fixation of the prothesis
The artificial socket and the shaft can either be anchored in the bone with cement or without. Mixed forms are also possible, so called hybrids – where the socket is cemented but the shaft is not, or vice versa. The chosen fixation depends on the bone quality of the femur and pelvis. As this can only be determined during the surgery, unplanned changes to the surgical procedure are possible at short notice.
After the hip socket or shaft is carefully prepared, it gets firmly pressed into the corresponding bone, without using a fixation through cement. The artificial socket and shaft are specially coated so the bone can quickly grow into the new body parts. Nevertheless, it still takes up to six weeks for the bone to fully merge with the new artificial joint.
A fixation with cement is required, when the quality of the bone is not optimal due to brittle-bone disease or osteoporosis. The cement hardens rapidly, creating a solid bond between the artificial material and the natural bone. In addition, the cement can be premixed with antibiotics which are slowly released around the implanted prosthesis, reducing the risk of infection. This method allows full weight-bearing very soon after the surgery.
We always strive to use contemporary and innovative materials which are not only well tolerated but also highly resistant to corrosion and/or show little mechanical wear.
The metal components attached to the pelvis or femur are made of titanium or steel. Steel is a mixture of various metals such as cobalt, chrome, molybdenum, iron, manganese and nickel.
Wherever possible, cement-free fixations are used as well as sockets and shafts made of titanium, as it’s the best tolerated metal in humans. So far, no allergies have been reported. If the shaft or socket needs to be cemented due to an unstable bone quality, usually a shaft made of steel and a plastic socket are used. With this method allergic reactions to the cement itself or to components released from the steel shaft can occur.
The artificial cartilage of the new hip joint is situated on the femoral head as well as on the socket inlay. Wherever possible, ceramic products are used for this, as it causes no abrasion. Other glide pairings such as metal-metal or metal-plastic cause abrasion and can lead to inflammatory reactions, pain or early loosening of the artificial joint. If a metallic abrasion occurs components can enter the blood, causing poisoning of the organs such as the kidneys, liver or intestines. We therefore usually use ceramic and in rare cases, ceramic-plastic (ultra-high molecular polyethylene).
An artificial hip is a temporary solution, due to the wearing of the gliding pairing, especially if metal or plastic were used, or by the natural ageing process (osteoporosis), which influences the artificial joint’s stability.
The average lifespan of an artificial hip is currently at least 10 to 15 years due to the tissue-sparing surgical method and the materials available today (e.g. a ceramic-ceramic glide pairing). Infections, bone breakages (e.g. through a fall) or rapid progression of the osteoporosis lead to a decreased lifespan of the artificial hip.
Our experienced specialists will give you a personal consultation. Please contact us for more information or schedule an appointment directly: