Total Hip Replacement Surgery

Total Hip Replacement (THR), also known as hip arthroplasty, is a surgical procedure in which a damaged or diseased hip joint is replaced with an artificial joint or prosthesis. The ball (femoral head) and socket (acetabulum) is removed and a new ball and socket is implanted. This procedure is commonly performed to relieve pain, improve mobility, and enhance the overall function of the hip joint. The surgery is often considered when other non-surgical treatments, such as medications and physical therapy, have not provided sufficient relief.  Hip replacement surgery is extremely successful at getting patients back to their normal activity levels.

The Primary Goals of a Total Hip Replacement include:

  1. Pain relief – improving pain associated with the diseased joint.
  2. Improved function – optimising the range of motion and kinematics of the hip to optimise mobility.
  3. Joint stability – restoring stability of the hip joint, reducing instances of dislocation and instability.
  4. Correction of deformities – correction of any underlying joint deformity to improve biomechanics.
  5. Restoring anatomy – restoring normal anatomy whilst balancing the soft tissues and optimising leg length is important at improving pain, function and overall hip biomechanics.
  6. Joint Durability – implanting a joint replacement which is durable and provides good function over a long period of time.
  7. Quality of life – improving the overall quality of life of the patient by improving pain and function enabling patients to return to their chosen activities.

Types of Total Hip Replacements

A THR can be cemented, uncemented or a combination of both (a hybrid).

Cemented Total Hip Replacement

A cemented total hip replacement is a surgical procedure whereby the implants are stabilised to the bone via a bone cement or ‘grout’.  The cement helps distribute the load between the implants and bone and can facilitate implant stability in cases where bone stock and/or quality is compromised.

Uncemented Total Hip Replacement

An uncemented total hip replacement is a surgical procedure whereby the implants are ‘fixed’ or stabilised to the bone via a press fit technique. The implants have a specialised coating to stimulate bone growth (biological fixation) onto the implant which bonds the implant to the bone in the long term.

It is often chosen for younger, more active patients whereby the bone quality is often better and has the advantage of perhaps better durability in the long term.

Hybrid Total Hip Replacement

A hybrid total hip replacement is a surgical procedure whereby both uncemented and cemented surgical techniques are used. Typically, it involves cemented femoral stem and an uncemented acetabular ‘socket’ component.  Occasionally the femoral stem can be uncemented and the socket cemented. This is called a reverse hybrid.

By utilising a hybrid fixation, the surgeon is able to be adaptable to an individuals varying bone quality and allows the surgeon to tailor the hip replacement to the individuals needs. The uncemented component promotes biological fixation whereas the cemented component facilitates implant stability and load sharing where necessary, which in turn may optimise the durability of the total hip replacement in such circumstances.

Bearing Surfaces

The material of which the ball and liner of the socket is made of is called the bearing. The aim is to provide a low friction bearing surface that is durable and has a low amount of wear. Wear is the process whereby the bearing surface is worn down over time. It’s a process that cannot be abolished but it can be optimised.

There are several bearing options:

Ceramic on Highly Cross-Linked Polyethylene​

This is perhaps the most common bearing currently in use. It involves the use of a ceramic femoral head on a highly cross-linked polyethylene liner. Some of the potential advantages include:

Hard on soft bearing: Hard ceramic femoral head on a soft acetabular liner providing a durable bearing surface with low friction allowing the ‘wear’ to happen the ball and socket interface in a predictable manner.

Low Friction: Ceramic is very smooth and ‘wettable’ which reduces the friction against the polyethylene liner. This low friction surface helps to minimise / optimise the wear on the implants.

Wear resistance: Ceramic is highly wear-resistant which can contribute to a longer survivorship of the hip replacement

Stability: The conforming surface with low wear produces a stable articulation. The polyethylene can be implanted with a lip / elevated rim to enhance the stability of the total hip replacement and optimise the range of motion of the hip.

Biocompatible: Both ceramic and polyethylene are biocompatible meaning they are well tolerated by the human body.

Ceramic on Ceramic

This bearing surface involves the use of a ceramic femoral head on a ceramic liner. Some of the potential considerations include:

Hard on hard bearing with low friction: Hard ceramic femoral head on a hard ceramic acetabular liner providing a low friction interface which can contribute to reduced wear at the bearing surface.

Wear resistance: Ceramic is highly wear-resistant which can contribute to a longer survivorship of the hip replacement. Stability: The conforming surface with low wear produces a stable articulation.

Biocompatibility: The ceramic components are biocompatible meaning they are well tolerated by the human body.

Squeak or mobility associated noise: Ceramic on ceramic bearings have been associated with an audible squeak or noise upon moving. There can also be an associated grating sensation. Although the incidence of such a noise / grating sensation is low, certain factors can increase the risk of this happening and careful consideration needs to be undertaken when considering this bearing.

Ceramic fracture. This refers to the fracture of ceramic components in a total hip replacement. Ceramic components are known for their hardness and wear resistance, though they are very scratch sensitive. As such, either as a result of a scratch or manufacturing imperfection, a ceramic component can fracture leading to a revision procedure. The incidence of this is very rare.

Metal on Highly Cross-Linked Polyethylene

This involves the use of a metal femoral head on a highly cross-linked polyethylene liner. Some of the potential advantages include:

Hard on soft bearing: Hard metal femoral head on a soft acetabular liner providing a durable bearing surface with low friction allowing the ‘wear’ to happen the ball and socket interface in a predictable manner. Low Friction: Metal is smooth which reduces the friction against the polyethylene liner.

Wear resistance: Metal is wear-resistant which can contribute to a longer survivorship of the hip replacement. Stability: The conforming surface with low wear produces a stable articulation. The polyethylene can be implanted with a lip / elevated rim to enhance the stability of the total hip replacement and optimise the range of motion of the hip.

Biocompatible: Both metal and polyethylene are biocompatible meaning they are well tolerated by the human body.

Dual Mobility

This bearing surface involves an extra articulation to enhance the stability of the hip replacement. It often involves a large polyethylene insert (inlay) articulating with the femoral head and acetabulum. The dual mobility design aims to increase joint stability, especially in cases where a patient may be of a higher risk of dislocating.

The bearing surfaces are either ceramic on polyethylene or metal on polyethylene and are biocompatible to the human body.

The Process of a Hip Replacement and What to Expect

Pre operatively

Prior to your surgery Mr Griffiths will meet with you at a consent appointment to discuss with you the risks of the surgery and the rehabilitation back to your normal activities. You will also have a separate pre assessment appointment whereby you are reviewed by the pre assessment teams to ensure you are fit for surgery. They will go through your medications with you and tell you what to stop and when to stop them.

It is very important to stay as fit and healthy as possible to speed up your recovery post operatively. Regular exercise preoperatively is important to strengthen your muscles and improve your overall cardiovascular health. Painkillers can be helpful to allow you to mobilise if pain is an issue.

It is important to prevent any cuts or grazes before your surgery as they could pose an increased risk of infection and could lead to a delay in your surgery.

On the day of surgery

Typically, you will be asked not to have any food for a minimum of 6 hours before your surgery.

Typically, you can continue to drink water up until your surgery.  

You will be reviewed by Mr Griffiths and the anaesthetist before your surgery.  

The surgery is usually undertaken either under spinal or general anaesthetic and this can be discussed with the anaesthetist prior to the surgery.

The surgery typically takes about an hour, but you’ll spend some time in recovery before going back to the ward. During the procedure, Mr Griffiths will ‘block’ the hip with a local anaesthetic block and this, along with the regional anaesthetic (if used) will act to make you feel more comfortable in the immediate few hours following your surgery. The local anaesthetic will, however, wear off several hours following the surgery. It is therefore important to keep on top of your pain killers following the surgery so that you have a good baseline level of pain relief for when the local anaesthetic wares off.  

Mr Griffiths has a specialist interest in enhanced recovery with the aim of early mobilisation, typically within hours following your surgery, in order to optimise your pain and overall function while reducing your overall risks of complications. As such, unless otherwise stated, you will be mobilised, fully weight bearing with crutches for confidence, either the same day or the next morning following your surgery.

Following Discharge

Upon discharge you will be mobilising with crutches and, unless stated, you can come off the crutches when confident. The physiotherapist teams will also guide you on this. You can drive when you can perform an emergency stop and most people return to driving within 4-6 weeks following their surgery. Although the pain relating to the diseased joint disappears very quickly it can often take a period of time to get over the hip replacement surgery. The first 6 weeks involves intensive physiotherapy to strengthen the muscles around the joint, though it can take 3-6 months to get over the surgery fully. If your aim is to get back to social sports, typically patients return to sports around the 3 months mark with a phased approach, though this can be discussed at the time of your follow up appointment.  

You will be followed up closely by Mr Griffiths and a member of the rehab team to ensure your expectations are met and your outcomes are fully optimised.

Risks

Hip replacement surgery is highly successful at improving pain and function whilst restoring quality of life. Although rare, there are risks of the surgery. These include:

  1. Bleeding – you may require a blood transfusion, although this is very rare.
  2. Infection – the risk of infection is extremely low. (<0.5%) You will have antibiotics at the time of surgery to help prevent against this. Early mobilisation is important to help reduce infection risk.
  3. Wound problems.
  4. Nerve injury. The risk of nerve injury is very low. It can cause weakness and numbness in the leg which would usually resolve but in rare circumstances can be long lasting.
  5. Pain and stiffness – early mobilisation is important to improve pain and stiffness.
  6. Dislocation –The incidence is around 1-2%.  The physiotherapy teams will guide your rehab and show you how to protect the hip.
  7. Leg length changes.
  8. Fracture.
  9. Loosening of the implant.
  10. Failure of the implant.
  11. Revision surgery.
  12. Heterotopic ossification – new bone formation in the tissues around the hip. This is rare but can lead to stiffness.
  13. Deep vein thrombosis / Pulmonary embolism – you will receive blood thinners (anticoagulation) after your hip replacement. This will be discussed at the time of your consent appointment.
  14. Anaesthetic complications – The anaesthetist will review you on the day of your surgery and discuss the anaesthetic options and risks of the anaesthetic with you at that stage.

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