Advancements in hip replacement surgery

Hip arthroplasty, commonly known as hip replacement surgery, may be necessary if you have osteoarthritis. A successful procedure can relieve your pain and improve mobility.

What is hip replacement surgery?

Hip replacement surgery is when a damaged hip joint is replaced with artificial parts. It’s usually done to ease pain and help you move better, especially if the joint has been badly affected by arthritis or other conditions. During the operation, the surgeon removes the worn-out ball and socket of the hip and replaces them with new parts made from metal, ceramic, or plastic.

Surgical innovations in hip replacement

Back in the 1960s, British orthopaedic surgeon Sir John Charnley popularised hip replacement surgery. Since then, advancements in the field have been gradual, which is a positive thing, according to Dr Gregory van Osch, an orthopaedic surgeon at Mediclinic Pietermaritzburg.

Dr Van Osch explains that there are different methods for hip arthroplasty. These include the traditional method from the back (posterior approach), a method from the side (antero-lateral approach), and a newer method from the front (direct anterior approach).

“During Charnley’s era, surgeons performed an osteotomy (bone cutting) of the femur (thigh bone) and used wires to secure it. We no longer perform femoral osteotomy because of the risk of non-union of the greater trochanter, a bony bump on the femur near the hip joint. Today, the focus is on the direct anterior approach, which is minimally invasive."

The main benefit of this method of hip replacement surgery is that no tendons are cut, as is necessary with the other approaches. Another major improvement is in anaesthesia, which has greatly enhanced pain control after surgery. “During hip replacements, we use a high volume of local anaesthetic to provide effective pain relief after the operation,” says Dr Van Osch. “This plays a key role in helping patients recover more comfortably and quickly.”

The downside is that it’s harder to extend the cut if there are problems during the surgery, which can make things more complicated. There’s also a learning curve for surgeons, which may lead to initial challenges with implant positioning.

New developments in hip implants

Despite advances in hip implants, not all have been viable in the long term.

“Over a decade ago, hip resurfacing was seen as a great new option, but it didn’t work for everyone or for all conditions and has since been largely discontinued in some parts of the world. Hip resurfacing is still done to a lesser extent in South Africa and England,” says Dr Van Osch.

Unlike a traditional hip replacement, which involves removing the femoral head (the rounded top of the thigh bone) and the acetabulum (socket in the hip bone), hip resurfacing is less invasive. In hip resurfacing, the surgeon only reshapes the femoral head and replaces the acetabulum with a new component. “For the right condition and the right patient, a hip resurfacing can be excellent,” explains Dr Van Osch.

Previously, implants were made using moulds, but now 3D printing allows for custom implants for each patient. This ensures a secure fit, correct cup positioning, and accurate hip rotation in revision cases. “3D-printed hip implants are made from titanium and can be designed with a porous surface that allows bone to grow onto and into the implant,” he explains. “This creates a natural bond with the bone, so there’s no need for cement to hold it in place.”

Traditionally, stainless steel and cobalt chrome alloys were used as bearing surfaces, but ceramics are now preferred for their superior wear resistance. This leads to longer implant life and reduced risk of the artificial joint loosening from the bone.

Improvements in polyethylene liners have made them more wear-resistant, decreasing loosening in femoral and acetabular components. Additionally, robot-assisted surgery options enhance the positioning of the acetabulum during implantation.

“Robotic hip surgery is still in its early stages and has some way to go before it becomes more user friendly and less time-consuming,” says Dr Van Osch.

“With all new developments, we must monitor the worldwide orthopaedic registries to ensure they’re not just fads or purely driven by market trends. As far as the longevity of the implants goes, we expect 90% of them to last 15-20 years. Some implants have lasted beyond 30 years – even with older technology. With the new technology, we need to see how these replacements perform, and hopefully they will last even longer.”

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