The hip joint consists of a ball (femoral head) and socket (acetabulum which is part of the pelvis).
The joint itself is lined with cartilage that provides a smooth surface for the two bones to move in a pain free manner. As part of an arthritic process the cartilage layer gets worn away exposing the bone surface underneath resulting in pain and stiffness of the joint.
When this occurs and your symptoms are particularly intrusive you may be offered a hip replacement to replace the worn out joint surface. This is called a Total Hip Replacement (THR) and involves replacing the ball at the top of the thigh bone (femoral head) and the socket in the pelvis (acetabulum).
The hip joint is opened through a cut down the outside of the hip (lateral side). The approach most commonly used is called the posterior approach to the hip. This allows good clear access to joint and helps with a smooth recovery. Once inside the joint the ball is dislocated from within the socket and the worn out femoral head (ball) is cut of from the thigh bone. The socket is then prepared with special instrument called a reamer that removes the remaining cartilage within and helps shapes it to receive the new artificial socket. The new socket (acetabular component) is then inserted and secured, this can either be with acyllic bone cement (cemented) or the socket itself has a special coating on its surface to help your bone grow onto it and secure it (uncemented). If after discussion with your surgeon the cemented socket is the best option (normally for patients over 70 years of age) then this is made of polyethylene (plastic). However if an uncemented socket is used (normally under the age of 70 years of age) then the majority of the time the liner inserted into this metal shell is made of polyethylene (plastic) but sometimes it can be ceramic.
The top of the thigh bone (femur) is then prepared to receive the femoral implant (stem) of the top hip replacement, it is onto this that the ball sits which when put back into the socket forms your new ball and socket joint of your new hip joint. This stem can be either cemented in place using bone cement or uncemented where the component has a special coating to secure it in the bone and the encourage bone growth onto it to provide long tem stability. Your surgeon will discuss these options and the best option for you after taking a detailed history. Both methods are reliable in the long term however in those patients over 65 years of age a cemented stem is more often used.
What are the risks of surgery?
At the time of surgery or before your surgeon will explain in detail the nature of the surgery, expected rehabilitation for you personally as well as the risks of surgery.
Below are some of the main risks of hip replacement surgery
- Infection – this risk is less than 1% with the majority of the small number of infections being superficial wound infections that can be treated with a course of antibiotics. If a deeper joint infection occurs then this may require a further operation firstly to wash the joint out with saline and then treat with antibiotics via a drip. On the very rare occasions this is unsuccessful the hip replacement may need to be taken out in order to remove any bacteria and then a new hip replacement re-implanted a few weeks later when the hip is completely free of any infection.
- Blood clots in the leg (Deep Vein Thrombosis - DVT) and blood clots in the lung (Pulmonary embolus- PE) – the overall risk of a blood clot is less than 1%. You are at risk of a blood clot following surgery due to firstly the relative period of inactivity during the initial post-operative period and secondly the leg swelling following surgery. To try and reduce this risk considerably we begin to mobilise you as soon as possible after your surgery even with simple calf stretches whilst you are still in bed. We use special pumps on your calves during and after surgery and lastly you will be prescribed a tablet to thin the blood slightly which you will take for 2 weeks after your operation. All of these things reduce the risk but we cannot get rid of this risk completely.
- Nerve damage – running just behind the hip joint is the sciatic nerve that provides movement and sensation to the foot. It is very rare that this nerve is damaged during 1st time hip surgery however if it is it is usually bruised meaning the nerve recovers with time (months). In this situation you may have muscle weakness in the foot resulting in ‘foot drop’.
- Dislocation – this term means that the ball comes out of the socket and occurs in less than 1% of hip replacements. The risk of this happening is highest within the first 6-8 weeks when your tissues are healing. A stable hip joint requires the components to be positioned correctly at the time of surgery but more importantly you as the patient need to avoid bending and twisting movements and positions where the ball is at risk of ‘jumping’ out of the socket (dislocation). During your hospital stay you will be reviewed regularly by our physiotherapy team who will explain the ‘do’s and don’t following surgery to help minimise the risk of this happening.
- Leg length discrepancy – it is very common that as part of the arthritic process within the hip that you may experience a difference in leg lengths (the affected hip being shorter). As part of the surgery great care is taken to restore your leg lengths to being equal, however on occasions this is not always possible and after surgery a small difference in length can result, anything less than 1 cm you will not be aware of long term as your body will compensate.
- Revision surgery (repeat) – sometimes hip replacements can wear out after several years and become loose causing increasing pain. If this happens then it is possible to remove the worn out hip replacement and replace it.
- Persistant pain – following surgery over 95% of patients are satisfied with their hip replacement surgery however a small percentage of patients can still have a degree of discomfort for which a cause cannot be found.
Important: this information given above is only a guideline as is not complete. For more information or to book an appointment please contact us.
Your surgery is likely to be carried out under a spinal anesthetic with an injection in the lower back that results in you loosing the feeling in your legs for a few hours. You will then be offered sedation whilst the surgery is being carried out or you can listen to music or watch a film with some headphones.
The surgery takes between 60-90 mins to carry out.
Following your operation your hip will have a adhesive dressing which remains in place for the 7 days if possible to keep the wound clean and dry as it heals.
Once your spinal anaesthetic has worn off and the sensation has returned to your legs, under the supervision of either the physiotherapy team or nursing staff on the ward you may be able to start gentle mobilsing on the day of your surgery over a short distances using a zimmer frame.
- Pain control
- Swelling reduction with leg elevation if sitting out
- Mobilising with frame/sticks with assistance
- Sitting out in chair (2-4 hours during day)
- Eating and drinking normally
- Mobilising more independently short distances (to bathroom) but assistance for longer distances
- Aim to become more mobile throughout the day
- Sitting out in chair for longer periods
- Pain control still required regularly
- Sleeping becomes more settled
- Mobilising independently
- Managing stairs confidently unaided
- Pain management well controlled with more regular strength analgesia
- Wound clean and dry with no wound oozing
- Mentally feeling ready and confident to leave the hospital and return home
- Once over the initial post-operative period the focus over the next few weeks and months is to increase the range of movement of your hip to approximately 90 degrees bend and walking independently short distances outside and increase this accordingly.
- Continue to develop strength and confidence in the hip
- Consider returning to work between weeks 6-12 post-operatively
- Driving when confident beyond 6 weeks post-operatively not before
- The aim of hip replacement surgery is to achieve a hip that you forget has been replaced but this can take up to a year to achieve