Hip resurfacing is a technique of hip surgery developed in Birmingham and referred to as the Birmingham Hip Resurfacing System or BHR. It has been developed to preserve the bone around the hip, reduce the frequency of dislocation and allow patients to keep their hip replacement for a long period without problems. The commonest reason for this is hip pain secondary to osteoarthritis. Hip replacement, along with knee replacement, gives some of the highest quality of life increases of all medical interventions.
Survival rates, the length of time which the patients have their hip implant without problems, are high with rates of 98% or more being reported. The level of revision operations (where the hip surgery has to be redone) has been reported as the lowest of all the different types of hip replacement operations. The BHR components appear to be naturally stable and possess good long term performance.
Standard designs of femoral components in hip arthroplasty used in cement-less systems tend to lead to loss of bone in the upper thigh due to the area being shielded from normal stresses. Resurfacing systems have been shown by orthopaedic surgeons to preserve bone density in the femoral neck areas. Keeping bone density allows future hip surgery options to be maintained so that a replacement hip can easily be performed later.
The BHR is cast in a specialised process which allows it to have superior wear properties compared to other forms of cobalt chrome alloy. It has a hemispherical cup design and is coated with a material which promotes the ingrowth of bone so that a firm bone to metal bond can be created. It is a metal on metal hip resurfacing with two hemispherical surfaces and seems to have a large surface area of pressure but in reality a small area is typically under pressure at any one time. There is a fluid film present between the joint surfaces. The hemispherical shapes are cast very close to the perfect hemisphere so that the fit is perfect. This is a metal on metal hip resurfacing as compared with the metal on plastic system with hip replacement.
Hip Resurfacing Surgeons
In contrast to different types of hip replacement, hip resurfacing surgeons remove very much less bone overall. A hip replacement removes a lot of bone from the socket, the entire head and neck of the femur and drills down into the shaft of the femur. Preparing the socket is similar for both procedures with the cartilage and a layer of bone removed ready to accept the socket with its metal interior in the resurfacing hip and plastic in the total hip.
Preparation of the head of the thigh bone is, however, quite different. In the total hip replacement the whole head and neck are removed as mentioned above but in the hip resurfacing the cartilage and a layer of bone is all that is removed. A head is then pressed onto the bone to fit, while in the hip replacement the artificial head is much smaller than the original.
In hip replacement the possibility of loosening if the patient is too active is present although loosening has decreased as techniques have improved. In the hip resurfacing this limitation on activity is not present so patients can be more active and this makes this type of hip more suitable for younger, more active patients. Dislocation is also a risk with hip replacement due to the head of the replacement being much smaller than the normal hip.There are hip resurfacing complications but they may be less onerous than hip replacement.
Hip Resurfacing Recovery
Due to the natural loading of the bone it is likely your surgeon will allow you to be normally active once the rehabilitation period has passed, with early performance of hip replacement exercises. Restrictions may last for part or the whole of the first year as the bone around the joint replacement remodels and grows in to make an intimate seal with the metal. After this you may be able to do pretty much what you want, while hip replacement patients must remain careful about certain positions and impact activities however long they have the new hip.
Hip Replacement/Hip Resurfacing
If you have a hip replacement under the age of 60 it is very likely that it will need to be re-done at some point, known as a revision operation. Revision operations are much more difficult and risky than the originals and results are not as good, so the hip resurfacing avoids these problems by allowing activity, maintaining bone, having good survival performance and retaining the possibility of having a hip replacement if required in the future. Results show that 98.4% of patients still had their hip resurfacing working well at five years after operation, a similar success rate to hip replacement.
Although follow up rates are not available for more than 10 years, the ongoing data collection looks encouraging that hip resurfacing will turn out to have very good long term results at least comparable to hip replacement. And there are the other advantages of allowing the patients to be normally active and in conserving the bone of the upper thigh.
Disadvantages of hip resurfacing surgery are the possibility of a broken hip or femoral neck fracture (0-4% and relatively common in older people with normal hips), loosening of the implant and wear of the metal. Small levels of the metal due to wear have been found in the urine and blood of patients, but along with research on other metal on metal hips there have been no adverse reactions reported.
Women do not do so well as men with the hip resurfacing techniques as do those who require smaller rather than larger component sizes. So people with smaller bone sizes may be less appropriate for this approach and it is not recommended in rheumatoid arthritis. Hip replacement costs are roughly similar to hip resurfacing costs.
Hip resurfacing recovery may be a bit faster than that for hip replacement due to a lack of hip resurfacing problems such as dislocation of standard hip replacement which means people can do hip resurfacing exercises with the physiotherapist more freely without fear of problems.
In those patients who have more limited damage to the joint surface of the cartilage there are partial hip resurfacing operations available. A smaller stud like joint cap may be placed over the patch of damage or dead bone and this technique is only useful for very limited and specific areas of joint damage.
While private operations make up many instances of hip resurfacing, NHS specialised units do offer hip resurfacing.
As with all these complex operations such as hip resurfacing and hip replacement, seeing and understanding the operation visually is very useful in being able to fully participate in the rehabilitation so watching a hip replacement video can be very helpful.