Choosing the right prosthetic hip: Materials, durability and risks

Choosing the right prosthetic hip is a decision that you and your surgeon will make together. Your new hip will become part of you for the next 15 years or more, so knowing all the characteristics of it - including the materials used, durability and any associated risks - is important.

Leading consultant orthopaedic surgeon, Mr Pramod Achan, has put together this quick guide to inform you of the types of hip implants he routinely uses at his practice and the risks you should be aware of following this life-changing procedure.

What are the different types of hip implants?

Artificial hips are generally divided up into categories based on their features. The most common being their method of fixation to the patient’s bone. There are generally two approaches:

• Cemented implants: These rely on a grout to fix and hold the implant in place.
• Uncemented implants: These have a coating that allows the patient’s bone to grow into them.

Hip implants can also be classified by their lengths: short stems, long stems and “normal” stems. The stem is the part of the hip prosthesis that is cemented into the femur (thigh bone) and the ball that is fitted into the hip socket. Cemented stems are usually made of stainless steel and the uncemented stems more commonly of titanium.

Patients are often concerned about metal allergies (e.g. nickel), but the high-grade alloys used in the manufacture of these implants mean proven cases of metal allergy after hip replacement is extremely rare.

Which one is most commonly used?

Both cemented and uncemented hips are commonly used in the UK. At my practice, I tend to use cemented implants in older patients, as we don’t want to rely on the host bone doing any crucial load-bearing work. However, in younger patients where the host bone is healthy and can be relied upon, I tend to use an uncemented implant.

How durable are hip implants?

Most of the implants I use at my practice have good survivorship data at 15 years with over 85% surviving beyond 20 years. Once they are implanted, they can tolerate all loads of normal day-to-day activity and most general sporting activities. 

What are the risks related to hip implants?

The risks of this procedure are low. Most commonly, we divide the risks up into those associated with anaesthesia and those related to the hip replacement itself.

With regards to the risks related to the hip replacement procedure, the greatest risks are:

• Infection
• Dislocation
• Leg length discrepancy
• Deep vein thrombosis (a clot in your leg)
• Pulmonary embolism
• Fracture
• Wear and tear of the implant

Some risks or complications can be made worse by hip or knee symptoms in the other leg during the recovery phase. Low back pain can also cause problems because the pelvis is reoriented and needs to get used to walking without pain.

Are there any new developments in prosthetic hips?

There are constant developments in prosthetic hips with people trying to address the perceived shortcomings. The problems with these innovations are that they don’t have the same tried and tested track record as more established, older implants. These older implants are not only predictable in their behaviour and longevity, but surgeons like myself have vast experience in dealing with their complications or problems. Newer implants, however, have been shown to sometimes bring about new, unforeseen problems, especially in metal-on-metal hips. Therefore, these should be implanted as part of a closely monitored study group to get better and more frequent surveillance.

If you need a hip replacement or any other orthopaedic treatment, do not hesitate to visit Mr Pramod Achan’s Top Doctors profile today to check his availability.