A total hip joint replacement is an operation to remove a severely impaired hip joint and replace it with an artificial joint. The aim of the surgery is to relieve pain and restore function to the joint.
This is a common operation undertaken in New Zealand as elective (non-urgent) surgery in both public and private hospitals, typically involving a 4-7 day hospital stay. If the operation is undertaken privately (i.e in a private hospital and paid for by the patient or through health insurance), the cost is likely to be between $15,000 and $24,900 (Health Funds Association 2013).
In 2012, a particular type of artificial hip joint was recalled by its manufacturer due to a higher than expected failure rate. People who have had a hip replacement and have concerns, or are experiencing pain or discomfort, should see their doctor. Despite these recent concerns arising from this joint recall, hip replacement is a safe and successful procedure that reduces pain and improves mobility.
In a healthy hip, smooth cartilage covers the ends of the femur (thighbone), as well as the socket (known as the acetabulum) in the pelvis into which the ball end of the femur fits. The cartilage acts as a cushion and allows the ball to glide easily inside the socket. The surrounding muscles support the joint, allowing it to move freely.
The most common cause of deterioration of the hip joint is osteoarthritis
. This condition causes the cartilage to become damaged and worn, allowing the bones within the joint to rub together. Movement of the joint causes the ball to grind into the socket, causing the bone ends to become roughened and irregular. This, together with the development of small breaks in the bone, causes pain and stiffness.
Other conditions that can damage the hip joint to the extent that it requires replacement include rheumatoid arthritis
(inflammatory arthritis) and hip fractures (particularly in the elderly).
An orthopaedic surgeon will assess the need for a hip replacement, taking into account medical history, lifestyle, physical examination and x-rays of the damaged hip(s). A hip replacement is a major operation and there are many things to consider before deciding upon surgery. As part of making a decision as to whether to opt for hip replacement surgery or not, the risks and benefits of the surgery should be discussed. The most common risks associated with hip joint replacement include:
- Anaesthetic risks (common to all surgery)
- Infection – both of the wound and of the artificial hip joint itself
- The development of blood clots
- Damage to the nerves and blood vessels surrounding the hip joint
- Dislocation of the artificial hip joint
- A change in the length of the leg that has been operated on.
A hip replacement operation can be performed using either local or general anaesthetic. This will be discussed with the anaesthetist prior to surgery and a decision made as to which anaesthetic is appropriate.
The artificial hip joint (prosthesis) consists of a ball and stem (the femoral component) and a socket (the acetabular component). There are many different types of prosthesis made of various metals (eg: stainless steel, chrome, titanium), ceramics, plastic, or a combination of these. The two components of the prosthesis fit together to form a smooth joint. Some prostheses are “cemented” into place using special acrylic bone cement. Others do not require cement and rely on bone growing around the prosthesis to anchor them into place.
Surgery begins with an incision being made along the side of the hip joint that is to be replaced. The muscles that support the hip joint are detached and the damaged ball of the hip joint is cut from the top of the femur. The femoral component of the prosthesis is inserted into the femur and the acetabular component of the prosthesis is inserted into the prepared socket area in the pelvic bone. The artificial ball and socket are then fitted together and the surgeon reattaches the muscles to the top of the femur. Drainage tubes may be inserted to drain any fluid and/or blood from the new joint and the incision is then closed.
Antibiotics are usually given during and after the operation to prevent the development of infection in the new joint. A blood transfusion may also be required. This will be discussed by the surgeon prior to surgery.
A Hip Prosthesis
After surgery, nursing staff will closely monitor blood pressure, heart rate, breathing rate and oxygen levels. Additionally they will monitor the circulation in the leg involved.
A catheter will be in place to drain urine from the bladder. This usually stays in place for 24 – 48 hrs. Pain will be managed by administering pain relieving medications by tablet and via a drip in the hand or arm. Some people may have an infusion of pain relieving medication administered through a small tube into the back (an epidural). This is usually given for up to 48 hrs after surgery.
Fluid will be administered through a drip (intravenously) until the patient is eating and drinking well. Antibiotics will also be given via the drip for the first 24 – 48 hrs after surgery.
A hip prosthesis has a limited range of motion compared to a natural hip and special care will need to be taken until the soft tissue around the new hip joint has healed. Certain movements and positions must be avoided to reduce the chance of dislocation. The first six weeks after surgery is the highest risk time for dislocation of the new hip.
After surgery the healthcare team will work together to set movement guidelines and exercises that will assist with recovery. The success of the surgery depends on following these instructions while in hospital and carrying out the prescribed exercises when at home. In general, the following guidelines may be given for recovery when at home:
- Don’t cross the legs (including the ankles)
- Don’t bend down low
- Avoid lifting heavy objects
- Avoid forceful or jarring movement of the hip
- Avoid twisting movements of the hip
- Don’t lie on the operated side
- Always have a pillow between the legs when lying on the unoperated side
- Don’t stand for long periods
- Sit in a firm chair with arms (to assist getting in and out of the chair)
- Treat scratches and cuts promptly to decrease the chance of infection affecting the new joint
The time spent in hospital can vary but is usually four to seven days. The health care team will make an ongoing assessment of recovery and will recommend when discharge home is appropriate. It is important to have support at home upon discharge. A part of the healthcare team’s assessment will be to discuss if special equipment needs to be installed to assist at home or if home help needs to be arranged.
Crutches will need to be used for up to six weeks after the operation. By six weeks, the majority of people should be able to return to most normal activities, including driving. Full recovery can take three to six months.
It is usual to see the surgeon two to six weeks after surgery to assess recovery. Long-term follow up may also be recommended in order to monitor the wear of the artificial joint. It may be that replacement of the artificial hip joint will be recommended if it wears significantly.
American Academy of Orthopaedic Surgeons (2011) Orthoinfo: Total Hip Replacement. Illinois: American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=A00377
Arthritis New Zealand (2012) concerned? Talk with your GP about your hip replacement. Wellington www.arthritis.org.nz/?s=replacement&x=0&y=0
Canterbury District Health Board (2004) Information about Hip and Knee surgery. National Joint Registry. Canterbury District Health Board. www.cdhb.govt.nz/NJR/Hipknee.htm
Davidson, T (2006) Joint replacement. The Gale Encyclopaedia of Medicine. Third Edition. Longe J. L. (editor). Farmington Hills. MI. Thompson Gale.
Last Reviewed – 26 April 2013