Total hip arthroplasty
The aim of total hip replacement is to relieve pain, restore mobility, and improve quality of life in patients with osteoarthritis or other hip conditions. First introduced in the 1960s, this procedure has advanced significantly over the years.
Today, hip arthroplasty is a very common surgical procedure with excellent clinical outcomes. In an arthritic hip, the femoral head is replaced with a ceramic ball attached to a stem, which is inserted into the femur and may be either cemented or uncemented. This articulates with a cup containing a ceramic or polyethylene liner. On the acetabular side, the implant is fixed using a press-fit technique.
Ceramic on Ceramic arthroplasty
Ceramic was first introduced in hip surgery in 1970. It was initially used by Pierre Boutin in France, followed by Mittelmeyer in Germany. The aim was to reduce the production of wear particles and achieve better outcomes in younger patients. Since then, more than 300,000 ceramic-on-ceramic prostheses have been implanted worldwide. Early experience with this type of implant was marked by several problems, including ceramic fractures and osteolysis at the bone-prosthesis interface. At the same time, however, other large-scale scientific studies reported more encouraging results. The first implants failed not only because of the poor quality of the ceramic used at the time, namely oxidized aluminum, but also because of implant design and surgical techniques that were still relatively rudimentary. The most important feature of the ceramic-on-ceramic bearing is its biocompatibility, together with its inert nature. Under normal conditions, (ideal biomechanical conditions after implantation) wear of the prosthetic components is minimal. The biological reaction is also minimal and is characterized by the presence of fibrous tissue with only a very small number of macrophages and giant cells. However, when mechanical conditions are compromised, for example in cases of fracture or loosening of the prosthetic components, a more significant biological reaction may occur as a result of a greater number of wear particles. Thanks to improvements in the mechanical properties of ceramic, more suitable prosthetic designs, and more advanced surgical techniques, the problems previously associated with ceramic have now been overcome. As a result, ceramic-on-ceramic is now considered the most advantageous option and offers the longest survival rate in young patients.
Hip resurfacing
Hip resurfacing surgery is the option that comes closest to preserving the natural hip:
- greater bone preservation
- better biomechanical recovery
- a more natural feel
- a greater ability to return to impact sports
- normal gait recovery
The hip resurfacing system consists of two hemispherical metal shells that cover the joint surfaces. Unlike traditional hip replacement surgery, this procedure is less invasive to the bone, since in most cases the degenerative process mainly affects the cartilage.
For this reason, hip resurfacing replaces the joint surface on both the acetabular and femoral sides, creating a new load-bearing surface.
Advantages 1) A more natural walking pattern Studies have shown that gait is more natural after hip resurfacing than after traditional hip replacement. Gait analysis has also demonstrated increased hip loading and improved push-off. Patients often report that hip resurfacing feels very natural. 2) Greater stability and a higher level of activity Because the size of the ball and socket is similar to that of the natural hip, the risk of dislocation is much lower with hip resurfacing than with conventional total hip replacement, even during activities that require a wide range of motion, such as surfing, tennis, and football. Hip resurfacing uses bearing surfaces that are resistant to impact and wear, making them more suitable for patients with higher activity demands. This applies both to the traditional metal-on-metal resurfacing implant and to the newer ceramic-on-ceramic implant. Combined with better bone preservation, this gives patients a greater chance of returning to activities such as running and impact sports. 3) Bone preservation and revision surgery Hip resurfacing preserves more of the patient’s natural bone. Since the components used in both hip replacement and hip resurfacing are mechanical implants, they may wear out or loosen over time and require a second operation, known as revision surgery. If revision surgery becomes necessary in the future, preserving more bone can make the procedure simpler and more comparable to a standard total hip replacement.
Considerations When the procedure is performed by an experienced surgeon, the risks are limited. There is a possibility of hypersensitivity or allergic reactions to the metal alloy components, as well as potential damage to the enclosed femoral head. Overall, the risk rate is around 1%. Abnormal wear caused by incorrect positioning can lead to complications in all prosthetic systems. With polyethylene, which is currently the most widely used material worldwide, polyethylene disease may occur. With ceramic, the implant may fracture, while with metal, metallosis may develop. The key difference is that only with metal are there measurable markers, specifically blood chromium and cobalt levels, that can help detect abnormal wear at an early stage. With other bearing surfaces, the problem is usually identified clinically only after damage has already occurred. For this reason, it is essential to follow the recommended follow-up protocol for prosthetic implants, which varies according to the type of bearing surface.
The Right Candidate for Hip Resurfacing
Until recently, hip resurfacing was generally reserved for young, active men with a femoral head measuring more than 50 mm in diameter. This was because higher failure rates had been observed with metal-on-metal hip resurfacing in women and in patients with smaller femoral heads.
With the introduction of ReCerf, a ceramic-on-ceramic implant, these limitations may no longer apply, and hip resurfacing may become an option for all active patients.
The main remaining limitations are patients with severe hip dysplasia, meaning a markedly abnormal hip shape, or severe avascular necrosis, where the bone of the femoral head has died and can no longer support the resurfacing implant.
From 2025, ceramic hip resurfacing (CoC hip resurfacing) will also be available in Europe. MatOrtho has announced that ReCerf*, the world’s first commercially available ceramic hip resurfacing implant, has received CE marking and confirmation of compliance with European safety and performance standards.
The implant was first approved by the Australian Therapeutic Goods Administration in November 2024. Since it was first used in 2018, more than 1,600 patients have received the device.
Preliminary data from the study supporting approval, published in Bone & Joint, show excellent improvements in patient-reported outcomes and implant survival of up to five years, regardless of sex or implant size, with results that compare favorably with metal-on-metal (MoM) hip resurfacing.
This alternative system may therefore make hip resurfacing a suitable option for small-framed women and for patients with suspected hypersensitivity or allergy to nickel.
Until recently, hip resurfacing was reserved for young, active men with femoral heads greater than 50 mm in diameter. This was due to the high failure rates observed with metal-on-metal resurfacing in women and patients with small femoral heads.
With the introduction of ReCerf, a ceramic-on-ceramic implant, these limitations can be removed and the resurfacing can be offered to all active patients. The only remaining limitations are patients with very severe dysplastic hips (abnormal shape) or severe avascular necrosis, in which the femoral head bone is dead and cannot support the resurfacing implant.
Ceramic on ceramic Resurfacing
Hip revision surgery
Revision surgery is performed when one or both prosthetic components become worn or loose and need to be replaced.
There are several possible causes of prosthetic loosening:
- osteolysis (bone loss) caused by polyethylene wear particles
- infection
- fracture, for example after a fall
Revision surgery is a longer and more complex procedure than a primary hip replacement, and it is associated with higher complication rates.
Triplanar acetabular osteotomy
Hip dysplasia is a condition that develops at birth or during early childhood and is more common in women.
Hip dysplasia may be genetic in origin, but it can also develop as a result of other disorders affecting the hip joint, such as Legg-Calvé-Perthes syndrome.
The condition is bilateral in 50% of patients and is most commonly diagnosed between the ages of 15 and 30, although symptoms may appear earlier or later in life.
In patients with hip dysplasia, the acetabulum does not develop properly around the femoral head and, as a result, does not provide adequate coverage to distribute load correctly during walking.
When dysplasia causes pain and persistent discomfort in everyday life, in the absence of advanced coxarthrosis, and symptoms become more pronounced with increased activity, PAO (periacetabular osteotomy), also known as Ganz triplanar osteotomy, may be considered.
During the procedure, the acetabulum is partially detached from the pelvis so that it can be reoriented, improving coverage of the femoral head.