A hip replacement, total hip replacement, or artifical hip: all the same thing. If your old hip is no good, and not going to work any more, it may be time to cut it out and replace it with metal (or a mixture of metal, ceramic and polythene). In many cases, this performs a small piece of surgical magic: you can walk, and the pain has stopped. It has become an incredibly common surgical procedure since it was first performed, in England in 1962 by Sir John Charnley and introduced to the US in 1969. There are now around 125,000 hip replacements a year in the US, with about a 96 per cent success rate. But, here's a little more information:
First, the basics: why would you need a hip replacement?
Hip replacements are most common in old women: bones become more brittle with age, especially in women, and women have an average longer lifespan than men. But it's not just little old ladies falling down stairs that need new hips (although about 70 percent of hip replacements are done on people over 65). There are several common reasons for needing a total hip replacement:
The most obvious symptom is pain. Lots of pain. Stiffness and major problems walking are also there in the mixture, depending on the cause of the problem. In most cases, surgeons will do their best to leave a total hip replacement as the final step. If anti-inflammatory drugs, physical therapy and walking assistance don't help, surgical options like fusing the joint, removing the joint, grafting additional bone onto the socket, pinning, cutting or otherwise trying to take the stress off the hip joint will almost always be preferred. A replacement will only be attempted once the other options have been exhausted. The younger you are, the more likely you will have to go through the mill of trying everything else first. In recent years, particular outside the US, resurfacing has become a popular and successful treatment pre-THR for those with suitable bones and conditions. (Fusing and joint removal have become less and less common. This is a good thing.)
If you are a "young" patient (i.e. under 50) this can be frustrating, even when you know the main reason: artificial hips do not last forever. The expected lifespan of a modern artificial hip (of metal on metal, or metal on ceramic) is around twelve to fifteen years. It is no guarantee. Each new replacement hip
- is likely to last a shorter time that the one before;
- takes away more of your femur and your pelvis;
- increases the risk of infection;
- and is less likely to be a 'perfect fit'.
So, what do they do?
n.b. This is not delicate surgery--it is closer to carpentry than needlepoint--but it is very skilled, and some orthopods are more equal than others.
There are two parts to an artificial hip: the acetabular section that sits in the hip socket, and the femoral component, or stem section, that replaces the femoral head and a portion of the thigh bone.
The hip is dislocated, to get some space between the femoral head and the hip socket, then the top of the femur, is cut off.
The socket is prepared, with a drill and a special reamer, to remove the cartilage and prepare the surface and shape to receive the hemispherical socket component. The acetabular section is then inserted (held in place with epoxy cement, with screws, or with the tightness of the fit).
The femoral canal then has to be prepared: the metal shaft of the artificial hip sits down inside the thigh bone, with the head section protruding from the cut-off top. The hollow femur is shaped to hold the rasped edges of the stem section, and the stem is inserted into the bone. Uncemented, this is held in place by a tightness of fit; cemented, it's held with epoxy. In the first case, the canal is made a little too small, in the second, a little too big to allow space for the glue.
The metal ball that makes up the head of the femoral component is added to the top of the stem section, and the whole thing is put back together. There's some mopping up, some stitching, some repacking of soft-tissue and a quick count of the scissors and forceps, and off you go to the recovery room.
Cemented or uncemented?
A cemented prosthesis is held in place by a type of epoxy cement that attaches the metal to the bone. An uncemented prosthesis has a fine mesh of holes on the surface that allows bone to grow into the mesh and attach the prosthesis to the bone.
Both types of hip are used, though uncemented hips are more common in younger patients: if the surgeon is almost certain of having to revise a hip, leaving the first one uncemented can make this simpler. Cemented hips are more brittle, but they heal faster. With a cemented hip, you will be up on your feet, putting weight through your hip within two to three days of surgery. An uncemented hip may mean a few weeks in bed, then two to three months non-weightbearing (i.e. hopping on crutches) followed by another two months of partial weightbearing on crutches. Again, there are different opinions from different doctors. In the US, but rarely in the UK, some surgeons will get uncemented hippies up and weight-bearing from the start. (This hasn't been going on long enough to have any long term test stats on relative success.)
Once an uncemented hip has healed, it's (generally) less likely to loosen. Beyond that, there are about a dozen different designs of artificial hip, all of slightly different shape, construction, and composition. The choice of which implant is best left to your surgeon (though be aware that your surgeon may hve particular ties with particular manufacturers, or the hospital may have an odd policy on what can and can't be used). (That thing about choice sounds obvious, but I've lost count of the number of times I've seen people ask 'should I have a ceramic or metal hip?' or 'Stryker or Zimmer?' on THR mailing lists. Weird.)
How do you look after a new hip?
You try very very hard not to dislocate it in the first few months after surgery. For the first two to three months, you should not:
Opinions do vary on the restrictions imposed post-op. Much depends on the nature of your surgery, the structure of your hip, and the experience of your doctor. Some people may have fewer restrictions, some may be told to avoid certain behaviours for life. Listen to your surgeon. S/he knows what is going on inside your redesigned hip. These are, obviously, only an indication of the normal limits.
- bend more than 90 degrees at the hip (e.g. if you are sitting down, you must not lean forwards, you can forget putting on your socks without help, or picking up a dropped book without a grabby hand on a stick)
- cross your legs (when you are sitting or lying down)
- twist at the hips or waist at all
- turn the foot on your operated inwards
- sleep on your side
- lift heavy weights
After three months, it's alright to go ahead with all of these once you have your surgeon's nod of approval (except kneeling, which should be avoided for at least six months). You can probably sleep on your side with a pillow or a wedge between your knees after about six to eight weeks, if you are not a tosser and turner in bed. Sex is possible, but not straightforward or of a gymnastic variety after three months.
Otherwise, it's a case of doing your exercises, taking your daily walk, avoiding all impact (no running, no jumping down stairs, no skiing) and not being silly. Oh, your leg will almost certainly have changed length. Don't trip over!
What are the risks?
The worst thing that can happen with a new hip is an infection. This can happen during surgery, or at any time afterwards. It sort of hangs over you. There is about a one per cent chance of infection with a major joint replacement. If this happens, it's very likely that you are whisked back into hospital (if you had left), the new hip is taken out, and you are put on a massive drip feed of antibiotics. Only after two to three months, once it is certain the infection has gone, will you get your hip back.
If you have any dental surgery, or any bladder or colon surgery it is essential that you inform your doctor, and your hip surgeon, in case of infection risk. Even if you're having dental work done years later - tell your dentist you've got a joint replacement, so that s/he can give you prophylactic antibiotics. These days it's advised that a dental cleaning, or any dental work should be covered with antibiotics, if not for life then at least for three years post surgery. (Opinions on this swing back and forth, but caution is a good thing when it comes to joint infections.) Be warned, though, if they go into the bone, you'll be on a massive dose of antibiotics for a few days, and it may well make you throw up a few times.
Thrombophlebitis (or Deep Vein Thrombosis) is always a risk after major surgery. Your blood will be tested daily, and you may be given a course of wharfarine (or other blood thinning drugs like aspirin) to help prevent clotting. many hospitals will make you wear pressure stockings, which are hugely uncomfortable but are thought to reduce the chance of clots developing. Getting moving again is the best way to reduce the risks.
Dislocation is something to avoid. Following the guidelines on movement is crucial. If you dislocate, especially more than once, you will probably need further surgery to stabilise your joint.
The main reason for a joint failing is loosening: the metal and/or the cement comes away from the bone, there is movement and a steady increase of pain. Ninety per cent are doing fine after ten years, seventy percent may still be going strong at twenty years. But if your joint comes loose, once the pain becomes unbearable, you will need a revision. Artificial hips do not last forever.
Corrections, additions, information welcome.
Source: experience. I'm not a doctor, and this stuff should not be read as medical advice, only an overview from the perspective of someone on their
second third replacement hip (and I'm not a little old lady who fell down stairs.)
For those who have been following along, that's my third in just eleven years. Through a combination of crap bones and crap luck I'm getting through hips at an almost unprecented rate. The implants have not worn out, but the joins between implants and bones have done. Yes, I am ridiculously young for this whole process--I had the first THR at 25--and that has contributed. Yes, I am absolutely convinced it's all worth while.