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The hip is a ball and socket joint between the upper end of the femur (the ball part) and the hollow socket of the pelvis.
On the surfaces of the ball and the socket, where they touch and rub against each other, there is a special type of cartilage called articular cartilage. We have this cartilage in most of our joints in the body. It is similar to the white shiny surface you may have seen when you open up a chicken leg joint. The articular cartilage is very slippery and also acts like a cushion against shocks. This articular cartilage is only 2-3mm thick.
Arthritis can develop in almost any joint of the body, the hip being one of the most common. In hip arthritis (or in fact any other joint), the articular cartilage gets worn away as a result of various factors such as genetics, being overweight, aging, injury, inflammatory disease (e.g. rheumatoid arthritis), or the hip not being formed properly during infancy and childhood.
As the articular cartilage is worn away, the underlying bone is exposed in the joint causing symptoms of arthritis e.g. pain, limited movement and inability to do the physical activities that were possible previously.
In the early stages of hip arthritis, the symptoms may fluctuate i.e. patients may have days with little or no pain, and days with significant pain and disability. As the disease progresses, pain may be experienced on most days, on walking shorter distances, and with most activities of daily living such as bending, putting on shoes and socks, rising from a chair and stair climbing. In severe cases, pain can be present at rest and during the night causing disrupted sleep.
Although arthritis is a degenerative condition with deterioration of symptoms over time, the speed of progression of hip arthritis varies greatly between individuals. Many patients can cope with their arthritis for many years until something triggers an aggravation of their condition, after which they have difficulty coping with the pain and disability. However, there are some patients who have unrelenting pain from the beginning with rapid deterioration of the symptoms.
There is currently no treatment that can restore the worn out articular cartilage, therefore the exact cause of hip arthritis cannot be reversed.
There are non-surgical treatments which may relieve some of the symptoms of hip arthritis in the early stages. These may include analgesics (e.g. paracetamol), anti-inflammatory medications, relative rest, and use of walking stick.
Hip replacement surgery can be recommended, once symptoms significantly affect the patient’s quality of life.
Hip replacement surgery has been said to be one of the most successful operations of the past century. It is highly effective in relieving pain and restoring function.
In hip replacement surgery, the diseased bone with its worn cartilage is removed and replaced by an artificial prosthesis made of hard-wearing materials such as ceramics and metals.
There are generally four parts to an artificial hip prosthesis.
On the pelvis side, there is a hemispherical titanium socket which replaces the worn out socket. Inside this titanium socket is a liner made for rubbing against the new artificial ball or head. This liner is made of long wearing material such as a special ceramic or plastic, or metal. There are many pros and cons of each material which your surgeon would be happy to discuss with you.
On the femur (thigh bone) side of the joint, a metal stem made of a special alloy (usually titanium) is inserted into the canal or hollow channel in the center of the femur. On top of the stem is attached the new ball or head which is made of a hard wearing material such as ceramic or metal.
The surgeon uses special tools to shape the bone of the pelvis and the femur to accept the prosthesis. As people are of different shapes and sizes, the bones also vary in shape and size. The surgeon sizes the socket and femur during the operation and selects the appropriate size for that patient. There is a large range of sizes and shapes of prostheses available “on the shelf”, that the surgeon can use to custom fit the patient.
The chosen prosthesis can then be fixed to the bone by one of two methods. First option is to cement the prosthesis to the bone using a special acrylic bone cement. The other option is to use a prosthesis that has pores on it surface and/or a special calcium coating to which the bone will adhere to.
At the end of the operation the surgeon checks that the various components are positioned correctly, the hip is stable and the legs are the same length. The wound is then closed.
In order to implant a hip prosthesis, a surgeon needs access to the hip joint, which is a deep structure in the body. The pain and debility after a hip replacement arises from the act of obtaining access by the surgeon.
Obtaining access to the hip joint requires cutting of muscles and tendons.
If less muscles and tendons are cut, the recovery is faster and with less pain.
The direction from which the surgeon gains access to the hip joint is called the surgical approach. The hip can be approached from anterior (front), lateral (side) or posterior (back) directions. Traditionally, the lateral and posterior approaches have been the more popular approaches but they required more cutting of muscles and tendons.
Anterior hip replacement achieves access to the hip joint, via a smaller incision at the front, and by using natural planes or gaps between muscles, it avoids or minimises the cutting of important muscles and tendons. The technique requires the use of special tools and retractors, together with a special leg holder that helps the surgeon manipulate the leg during the operation.
Anterior hip replacement is not a new surgical technique, but has not been popular in the past because it gave relatively poor access to the hip joint (i.e. it made the surgeon’s job more difficult).
In France, since 2004, there has been a revival of the anterior approach with the invention of new surgical tools, which allowed the surgery to be performed more efficiently. Currently, approximately 80% of hip replacements performed in Paris are via the anterior approach.
Anterior hip replacement was first performed in Australia in 2006 and is gradually gaining popularity among surgeons.
As the incision is smaller than that of the traditional methods, the visibility of the hip joint is less and hence making it more difficult for the surgeon (discussed later). However, with adequate training and experience these problems can be minimised. It also takes a little longer to perform the surgery.
After the operation, some patients may be left with a small patch of numb skin on the side of the thigh adjacent to the surgical incision. This is a result of the unavoidable cutting of a small nerve that gives feeling to the skin of this region. Patients are not usually troubled by this.
Not all patients may be suitable for anterior hip replacement (discussed later).
The surgeon requires additional training to perform anterior hip replacement and x-rays may be required during surgery to ensure that the hip is implanted in the correct position.
Anterior hip replacement is not a type of hip prosthesis, it is a surgical approach to obtain access to the hip joint.
The types of complications after anterior hip replacement are similar to those encountered with the traditional posterior approach. These complications may include infection, deep venous thrombosis, dislocation of the prosthetic joint, fracture of bone, leg length inequality, and loosening of the prosthesis.
There can also be complications not specific to hip surgery, which can occur with any other type of operation. These may include anaesthetic complications, allergies, reactions to medications and treatments, etc.
Serious complications are uncommon but may occur in approximately 2-3% of cases. The risks are higher in patients with diabetes, severe osteoporosis, severe obesity, age >85yo and those with other serious illnesses.
Please consult the information pamphlet given to you by the surgeon during your consultation for the full list of potential complications. If you have any concerns, please discuss with the surgeon.
|Activity||Typical Recovery Time|
|Walking frame / two crutches||1-2 days|
|One crutch or walking stick||2-4 days|
|Rise from chair or toilet without assistance||2-3 days|
|Driving – left hip(automatic car)||1-2 weeks|
|Driving – right hip||2-3 weeks|
|Return to sedentary work||2-4 weeks|
Note: The above recovery times are from typical cases. Time and speed of recovery will vary between individual cases. Before resuming driving, please check with your surgeon.
Anterior hip replacement is suitable for most patients requiring hip replacement surgery. The patients who benefit the most are younger active patients who have a desire or need to return to their occupation, live independently, or care for their families as soon as possible. However, there are some patients for whom the traditional posterior approach may be more suitable. These include:
The surgeon will need to decide suitability on an individual basis for anterior hip replacement.
Several large clinical studies show that Anterior Hip Replacement has a lower dislocation rate compared to the traditional posterior approach.
Dislocation rates of less than 1% are reported in the following studies:
As stated above, anterior hip replacement is a relatively new technique in Australia, but as more surgeons learn the technique, its popularity should increase.
The traditional method by the posterior approach has been a reliable technique of performing hip replacement, though the recovery may be slower compared with the anterior approach.
Some surgeons remain sceptical about anterior hip replacement until further research data become available. At the moment it is fairly evident that recovery after an anterior hip replacement is faster than after the traditional approach in the first 2-3 months after the operation. However, it is not clear at this stage whether there are long term benefits of the anterior hip replacement. Also, it should be remembered that the most critical factors in the long term success of a hip replacement are related to the choice of the type of prosthesis and the surgical technique (i.e. the components are placed in the correct position and secured well) rather than the surgical approach.
One obstacle for surgeons to undertake this new technique is the learning curve. Most surgeons are taught in the traditional posterior approach and require additional training to perform the anterior approach. One study has shown that in the early stages of the surgeon’s learning curve for anterior hip replacement, the complications were higher until the surgeon has performed approximately 40 operations. (Seng et al, ”Anterior-supine minimally invasive hip arthroplasty: defining the learning curve”. Orthop. Clin. N. A 2009; 40:343-350)
The National Joint Replacement Registry (NJRR) is an Australian government funded register that records every hip replacement performed in Australia. The register has showed that in the early years (from 2006) after the introduction of the new Anterior Hip Replacement method, the complication rates were higher than compared to the traditional approach. As surgeons gained more experience, this complication rate has decreased and eventually it is expected to be similar to that of the traditional approach.
The vast majority of patients can expect pain-free walking, hiking, bending, stair & ladder climbing, kneeling, crawling and return to low-impact sports such as golf, swimming, cycling, social tennis, and most gym exercises. Some activities that require extreme flexibility (such as some yoga positions) may not be possible.
Many younger patients are able to jog (at least a short distance) following anterior hip replacement, although this is generally not advised, as it is an activity that involves impact loads to the joint. Sexual activity can be resumed when comfortable, although not recommended in the first six weeks post-operatively. It is best to avoid extreme positions, to prevent dislocation of the hip.
An average person takes more than a million steps per year, and the hip prosthesis being a mechanical device can wear out over time. It is difficult to provide an exact number on an individual basis as there are many complex factors that determine the life span of a hip replacement, but we do have some data on how long an average hip will last.
According to the National Joint Replacement Registry, when looking at thousands of hip replacements of all types performed in Australia, 6.5% had to be re-operated/revised (medical term for having to redo a hip for whatever reason) by the 10 year mark. In simple terms, if one hundred patients had hip replacements, 6.5 patients had to have a redo operation by the time the 10 year mark is reached. To put it another way, if 100 patients had total hip replacements, 93.5 patients have not required a redo operation after a period of 10 years.
We do not have results from the Registry to tell us what happens to hips after 10 years as the Registry has only been running for approximately 10 years. However, from looking at other studies, there is reason to expect that with modern hard wearing ceramic bearing surfaces, hips may last 20-30 years.
Please let your surgeon know all your regular medications (especially blood thinning tablets such as aspirin, clopidogrel, Plavix and warfarin), and your current medical conditions.
One or two weeks before the surgery you will be contacted for a pre-admission clinic appointment at the hospital where you will be having the surgery. At the pre-admission clinic appointment (which takes a couple of hours) you will meet a nurse who will do routine blood tests and an ECG. A physiotherapist will explain to you the exercises you will be doing after the operation and teach you how to use crutches.
On the day before surgery, the hospital will contact you by phone to advise you of the time you need to fast from, and the time to present to the hospital. Most patients will come into the hospital on the day of the surgery.
Please bring with you all your medications, the relevant x-rays as well as other personal belongings that you may need during your hospital stay. The hospital admission forms will give you more information with regard to the kind of items you may want to bring with you.
Your anaesthetist will meet you just before your operation to ask a few questions about your general health and previous anaesthetics. General anaesthesia or spinal anaesthesia or both can be used. The anaesthetist will discuss with you as to which is most appropriate in your case.
Day of operation: When you wake up in recovery you may notice a drip in your arm, a thin plastic tube draining excess blood from the surgical site and possibly a urinary catheter. You may feel drowsy after the anaesthetic. Most patients feel little or no pain, and are resting in bed on the day of the operation.
Day 1: With the help of a physiotherapist, you will be sitting out of bed and taking a few steps with the aid of a walking frame.
Day 2: Some patients after the anterior hip replacement may already walk with a walking stick, or no walking aids at all. If your progress is good, the physiotherapist will teach how to negotiate stairs on this day. Around this time, you may be able to take yourself to the bathroom without assistance.
Day 3-5: If recovery is good, patients often go home after day 3. Pain can be controlled with oral analgesia. Before discharge patients will be shown how to self administer Clexane injections (blood thinning medications to prevent blood clots).
What is Different about Anterior Hip Replacement?
Anterior Hip Replacement in performed through a small incision at the front of the hip, rather than through the traditional larger incision on the side and back of the hip.
What are the advantages of Anterior Hip Replacement?
Much of the early debilitation after traditional hip replacement stems from damage to the muscles and tendons of the hip, incurred during surgery. Anterior hip replacement eliminates or reduces the need to cut these muscles and tendons.
In particular, anterior hip replacement spares the gluteus maximus (buttock) muscle, the an important muscle for many activities of daily living e.g. rising from a chair or toilet seat, walking, getting in & out of cars, and climbing stairs.
What are the advantages over traditional hip replacement?
Disclaimer: These videos represent the type of recovery that is possible in favourable circumstances in younger patients after anterior hip replacement and therefore not every patient will achieve the same rate of recovery as in the videos. Not every patient should perform the same activities or movements as in the videos in the early post-op period without first checking with the surgeon.