Frequently Asked Questions

When should I have a hip/knee replacement ?

When the pain in your hip/knee  has started to restrict your mobility (what is your walking distance ?) , when you start to get pain at night, when it interferes with your activities of daily living,  when you need to take analgesic anti-inflammatory on a regular basis (this can have side effects such as  stomach ulcers/ kidney problems) When cortisone injections into the knee & physiotherapy have not worked.

Your GP will consider wether your general medical condition is good enough for you to undergo surgery

Have you got all the information about hip/knee replacement surgery to make an informed decision & do you want to have this operation ?

Am I too young or too old ?

There is no age cut off for hip or knee replacements but hip & knee do not last forever. Your doctor will therefore advise you to delay joint replacements for as long as possible as  you will require a  re-do (revision) of your hip & knee replacements when they fail.

Based on the indication for joint replacements we have performed hip replacements for patients  as young as 18  and  as old as 102 !

A discussion regarding the risks of surgery is to be balanced with the benefits . This is best done during a discussion with the surgeon. A young patient may say that he is unable to walk or work & needs the hip replacement “now” rather than being in a wheelchair until he is 70 & then having a hip replacement etc etc

Revision Hip replacement/Revision knee replacement.

How often can hip or knee replacements be re-done or Revised ?

The results of revision hip or knee replacement surgery are not as good as the first time operations and complications from revision surgery are twice as much. There is no limit on how many times it can be    re-done but if there is significant bone loss revision surgery becomes more & more difficult and may eventually reach a stage where it cannot be re-done (revised)

Which is the best hip replacement ?

Joint replacements are selected by surgeons based on the  “track record” of the implants (ODEP rating) & the experience + training of the surgeon.

There are essentially two basic types of Hip replacements (or how the hips are fixed onto the bones)- Cemented & Uncemented. The cemented hips do well in older patients where the quality of bone may be poor. Uncemented hips are performed in younger patients where the quality of bone is good & therefore complications from trying to “jam” a hip replacement without cement will be less.

As for the actual bearing surfaces (where movement occurs between the component/where the hip moves) there are numerous combinations such as “metal on plastic”, “ceramic on plastic”, “ceramic on ceramic” & the one which is avoided now a days the “metal on metals”. The quality of plastics have improved significantly (highly cross linked polyethylene) over the years & therefore currently “metal on plastic” or “ceramic on plastics” work very well and seem to last longer before needing revision surgery.

“ceramic on ceramic” does well as  well but has  a  small incidence of “squeaking” or breakage of the ceramic components (just like a ceramic cup breaking )

Which is the best knee Replacement ?

Knee replacements are less confusing than hip replacements. Basically again they are of two types :         Cemented  & Uncemented.  The vast majority being used are of the cemented variety (Components fixed onto bone with bone cement)  and have been shown to do very well. Very rarely your surgeon may advise you to have an uncemented knee replacement if there are specific indications (a malunited fracture close to the joint which prevents the keel of a cemented implant from seating inside the bone for e.g.,)                Also, almost all knee replacements will have metal implants on the ends of the bones with a plastic insert in-between the two metal “bits” (much like a bit of a “washer/cushioning” between the metal components)

Who is the best hip surgeon or best knee surgeon ?

There are vast amounts of data on the internet which can unfortunately confuse you sometimes. All hip & knee replacements performed in the UK are monitored by the government and  data regarding numbers of operations performed & major surgical outcomes (such as re-do’s and mortality) are available on the government website My NHS      You can look up surgeon data on this government web site. If there is anything which you can choose,  choose a good surgeon & discuss the choice of implants, hospital etc with that surgeon.

In general 9 out of 10 hip replacement patients are very happy and 8 out of 10 patients are very happy after knee replacements.

Are metal on metal hip replacements still done ?

There are essentially two types of metal on metals . One is the resurfacing hip & the other is the “usual hip/ conventional ” hip.

There is currently no indication to do the conventional metal on metal hip replacement due to the risk of metal ion toxicity in the body and risk of “pseudo tumours”

There is  a small place for the “metal on metal” resurfacing & if indicated  the resurfacing to be used is the one with the best track record- “the Birmingham hip resurfacing”


I have a squeaking hip ?

Due to an acoustic phenomenon some hip replacements particularly ceramic on ceramic hips squeak. Cause for this is multi-factorial. This does not indicate impending failure. For more information click on the American academy of orthopaedic surgeons website on :                                                         

How long will it last ?

This depends on the age of the patient, mobility status / activity the patient is involved in, type of joint replacement, associated medical conditions &  a  few other factors.

A very basic analysis would be :

90%  will last 10 years

80% will last 15 years

70% will last 20  years &  so  on  i.e,  a small percentage of hips/knees  will fail at 10, 15 , 20 years etc but the remaining will continue to do well . There are some hip & knee replacements which have lasted 30 -35 years.

What is the recovery period following hip or knee replacements ?

You will be in hospital for roughly 3 days &  will be walking the day after the operation. After discharge physiotherapy will be organised for you. If there are no complications and everything goes to plan you will be advised to commence most routine activities (incuding driving) 6 weeks after the operation.Some bruising & swelling is to be expected after these operations. If you however notice excessive brusing or swelling you will have to get in touch with the hospital.Excessively swollen & tense calf may be an indication of deep vein thrombosis and urgent consultation with the hospital or the doctor is indicated. Minor symptoms such as an ache or stiffness after rest can be expected to take upto one year to settle. Following knee replacements sometimes there is a small area of numbness lateral to the surgical scar. This is due to injury to the small nerves which supply the skin in this region. The sensation sometimes recovers fully , sometimes partially & rarely never recovers. This is however just a nuisance & does not cause any serious functional limitations.

Kneeling can sometimes be a problem post knee replacement as the scar can be a bit tender & knee bend will be restricted to only 110 to 120 degrees following knee replacement. These factors need to be considered while deciding on your knee replacement as it may mean that you may not be able to do the work you are currently doing if you are unable to kneel or squat after the knee replacement. There will be some restriction in hip movements after your hip replacement as  well & this is discussed in the leaflet “A guide to your total hip replacement”

I have back pain. Will this affect the operation ?

Back pain may be the cause for hip pain or sometimes knee pain but occasionally back pain is caused by altered gait caused by hip or knee arthritis and sometimes by the shortening caused by arthritis. It is important to differentiate the pain caused by back problems and the pain from hip arthritis. It should also be remembered when there is both hip arthritis & back pain, hip replacement will not take away the pain coming from the back and therefore some pain in the hip may persist after the hip operation if it is coming from the back.

What is minimally invasive hip replacement or minimally invasive knee replacement ?      

Minimally invasive surgery

What matters most is the positioning of the components, fixing the components in the bone properly (cemented or uncemented) alignment of the components, respecting soft tissues/ gentle handling of the soft tissues during surgery. The size of the incision ( a centimetre or two more) does not make any difference to the end result of the operation. Trying to make a small incision & getting the implant positions wrong or retracting & pulling on the tissues can have an adverse effect on the outcome of the operation. So the adage is “ As big as necessary but as small as possible”.

What about computer assisted surgery  or CAS ?

In the vast majority of hip & knee replacements  CAS  does not influence the outcome. Very rarely computer assisted surgery becomes necessary to get the alignment right particularly with knee replacements (for e.g., with malaligned bones due to fractures) Your surgeon will discuss this with you if it is indicated.

For  Patient Specific instrumentation click on tis link .