Which total hip replacement surgery should you choose ?
Two of the biggest factors in deciding on hip resurfacing or conventional hip replacement are age and activity levels. Hip resurfacing is often used in a younger, more active person as it is easier to do revision surgery in later years once the hip implant wears out.
Hip revision surgery means replacing the hip prothesis that is currently in place. Outcomes of revision surgeries are generally not as good as the first surgery, so the less procedures over your life, the better.
A Conventional Hip Replacement, although still the best option for most, is harder to revise when the hip replacement fails.
Assuming a long life, all hip replacements will eventually fail, most commonly due to loosening and wear, infection, fracture or dislocation. 2 So, the age of the patient and when or whether they are likely to need a revision procedure is an important consideration when deciding what surgery, and when the surgery should be done.
How long does a hip replacement last?
The information available from joint registries have shown:
85% of prostheses last 20-years
58% of prostheses last 25-years
Some have even lasted 40 years! 2
It’s important to note that the materials that were used when these surgeries were done, over 20 years ago, were much inferior to the materials used now. The newer materials are much more hard wearing, so surgeons are anticipating that the life of the prostheses they are using now could be much longer.
How long a hip prothesis is likely to last will be a factor in the surgical decision making, together with the age of the patient. Someone young who is likely to need their hip revised at some time in the future, may be considered a possible candidate for hip resurfacing. 3
Who is suitable for Hip Resurfacing
Up until recently, hip resurfacing was considered as an option for the larger framed male who is less than 65 years of age, so the younger patient. However, the research is constantly evolving in this newer area of hip arthroplasty surgery, and resurfacing may be an option in some over 65 year old, older patients as long as they meet certain criteria.
Those who want to be more physically active after their replacement may also want to consider hip resurfacing as a surgical option.
Who is unsuitable for hip resurfacing
Generally, people with hip dysplasia are not suitable for hip resurfacing. People with hip dysplasia are more likely to struggle with hip arthritis but the shallow hip socket that is found in people with hip dysplasia means they are at higher risk of failure with this type of surgery.
As size of the bone at the top of the femur, the “femoral head size”, is currently extremely important in deciding if hip resurfacing is an option, females with hip arthritis are often not suitable for this type of surgery unless they meet the skeletal size requirements.
What are the different Approaches for Total Hip Replacement Surgery
There are usually one of three ways that your hip orthopaedic surgeon (“orthopedic surgeon” in the United States) will actually do your surgery, although other variations do exist. The most common approach is from the back of the hip, known as the posterior approach. Until recently the “anterior approach” was less frequently used, that is, approaching from the front of the hip. However, this is fast becoming a frequently offered alternative by many surgeons. The lateral approach is the third approach that has been around for some time.
The posterior approach for total hip arthroplasty.
The surgeon will cut through the gluteus maximus muscle at the back of the hip and detach the deep hip external rotator muscles to view the back of the hip joint.
This is the most commonly used approach.
Offers the surgeon excellent access to the hip joint.
The abductor muscles, or the muscles at the side of the hip are spared. This means patients are less likely to limp in the recovery period than those who have a lateral approach (see below).
The sciatic nerve, a large and very important nerve in the back of the hip can be clearly seen, making it easier to protect this structure.
The disadvantage of approaching from the back is that there can be a higher rate of dislocation after surgery, compared to other approaches. However, dislocation rates have been improving over time and some recent studies show rates as low as other surgical approaches. It is always important that post-operative instructions are followed to keep the hip safe in the healing period.
The anterior approach for total hip arthroplasty
The anterior approach, or anterior hip replacement, is where the surgeon approaches from the front of the joint. They go through between two of the major muscles at the front of the hip, the rectus femoris and the TFL.
No muscles are cut and so no muscles need to be repaired afterwards.As the muscles at the side and back of the hip are not cut, there is less chance of dislocation afterwards so there are less restrictions with what you can and cannot do after your surgery compared with other approaches. Patients often require less time in hospital and can achieve a faster recovery in the early phases, although with improvement in surgical technique and physical therapy post operative routines all approaches generally do well in the long term.
As the surgery is performed with the patient lying on their back, the position of the new hip prosthesis can be checked with xray during the hip surgical procedure.
The surgeon has to work through a smaller “window” so this is not the typical choice for more complex cases or difficult revision surgery.
This approach requires specific training and instruments that may not be available at some hospitals.
Direct lateral approach for hip arthroplasty.
The Lateral Approach is where the hip replacement surgery is performed by the orthopedic surgeon from the outer side of the hip. The surgery involves temporarily detaching the muscles at the side of the hip from the top of the thigh bone (femur). These are the abductor muscles – the gluteus medius and gluteus minimus muscles. These two muscles help you to balance your pelvis on your thigh bone when you stand on one leg. They also help to lift the leg up to the side. The muscles are reattached to the bone once the prosthesis is in place.
The back of the hip is protected so there is less chance of dislocation of the replaced hip out the back of the hip joint. However, it takes time for the repaired abductor muscles to heal.
This means that walking may remain a little more difficult for several months after surgery. This varies between individuals.
Crutches or a walking aid may be needed for longer to provide support when walking.
In rare cases, a permanent limp may result due to impact on the abductor muscles or from damage to the nerve that serves these muscles. The risks of this happening are very low, but this is a risk specific to this surgical approach.
What is the best type of hip replacement implant to use?
Choosing which type of conventional hip replacement to have is a bit like trying to buy a car. There are many options and many factors taken into account to decide which implant may be most suitable for you. . Below we will look at all the different types of hip implants.
The individual parts of a total hip replacement implant
Let us first understand what the parts of a standard total hip replacement implant are. Typically, the hip implant (hip prosthesis) is made up of approximately four individual components, 2 parts on the pelvis, or acetabular side and 2 parts on the upper thigh bone, or femoral side.
Cup—inserts into the pelvic bone Liner—inserts into the cup—essentially becomes your new cartilage
Stem—inserts into the femur or thigh bone Ball—fits onto the end of the stem
Two main categories of total hip replacement surgery
Now that you understand the parts of a hip replacement prosthesis, let’s talk briefly about the two main methods of fixing the implant into the body.
This means a form of grout is used to bond the implant to the bone.
This means that no grout is used. Instead, the bone will grow directly onto the implant. This bone growth is what makes the implant stick. Generally, the stem of an uncemented prosthesis that attaches to the top of the thigh is made of titanium
Titanium is well tolerated. It is not associated with allergy, and it bonds well to bone.
The downside of titanium is that it is relatively soft, therefore other materials are used for the weight bearing parts of the implants.
Type of material used on the weight bearing surfaces of a hip implant
As we mentioned above, the ball and stem replace the top of the thigh and femoral head. The ball can come in varying sizes that relate to the size of the cup implant chosen for use in the pelvis. The ball can be made of different materials.
Ceramic – this is a very hard surface, extremely resistant to scratching or damage. A ceramic head, or ball, can be paired with a ceramic or plastic liner in the pelvis.
Polyethylene – this is a plastic-type material that has evolved considerably over the years. It is now extremely wear-resistant. As a result, most prostheses have some polyethylene component.
Combination – the Dual Mobility Implant. This is made up of both a ceramic inner ball and a second polyethylene bearing surface over the top, which rotates freely over the inner ceramic ball.
Cobalt-chromium – also a hard-wearing surface. The metal ball was typically paired with a metal or plastic liner in the pelvis. However, concerns over potential reactions and problems with metal debris from the metal parts when paired with the metal liner, mean that this type of ball is now more commonly paired with a plastic liner in the pelvis.
The acetabulum or pelvic part of the implant
The pelvic part of the hip prosthesis implant is referred to as the “acetabular component”, meaning the “socket” of the hip joint. The socket implant is often made of two parts.
A titanium metal shell is used, which as we mentioned above is great for the bone to grow onto but not so good at weight bearing.
A weight bearing liner is then used that matches the size of the ball. This may be made of different materials.
Ceramic – this is a very hard-wearing materiel. A ceramic on ceramic is a term you may hear, meaning both the ball and the socket implants are made of ceramic material. Polyethylene – as we discussed above, this is a highly wear-resistant type of plastic.
Cobalt Alloy – this is a hard-wearing resistant metal, often used in the dual mobility implant.
Which type of Hip Replacement should I have?
In summary, there is no one glove fits all. Your Total Hip Replacement surgery should be customised to you and your individual requirements. Your orthopaedic surgeon will consider many things, including:
your frame size, the size of the bones of your hip,
your bone density (how strong or weak your bone is),
the stability of your joint,
the length of your soft tissue structures,
any complications that may exist,
what you want or need your hip to do, and
how active you are.
Make sure you discuss your options with your surgeon and understand what type of surgery and implant you are having, why and what it means in both the short and long term. Being able to continue to perform your normal daily activities is important to help you have a good quality of life after the surgery. Again, make sure you discuss these with your surgeon.
Physical Therapy and Total Hip Replacement
Pre-operative physical therapy can better prepare you for surgery, if you still have some time before your operation. This might be just a couple of appointments to learn about what to expect after surgery and familiarise you with the post operative exercises. You may want to see an occupational therapist to help you understand what changes you can make around your home to make your recovery time easier after the surgery.
If you have more time before surgery, engaging in 6-12 weeks of pre-operative conditioning with a physical therapist can help make sure you are best prepared for your surgery and post-operative rehabilitation.
After surgery, make sure that you complete all your physical therapy treatment for the best possible outcome. Rehabilitation may need to go on for longer if you have any complications or major problems, and also if you have more specific requirements from your hip, for example, to achieve a higher level of involvement in activity or sport. Your physical therapist will help you to achieve the long-term results you want out of your hip.
You can find a physical therapist or physio who knows hips, at our Hip Pain Help “ Find a Professional” Directory.