Hip Replacement
Hip Anatomy
The hip is a strong, stable ball and socket joint. The ball is the head of the femur (the thigh bone), which sits in the cup of the acetabulum (part of the pelvis). The ball and the socket are both covered in very smooth, slippery cartilage which is important for keeping your joint pain-free.
Hip Arthritis
Hip arthritis describes symptomatic deterioration of the cartilage so that the joint is no longer normal. The most common form of arthritis is osteoarthritis which implies age related degeneration of the joint. Osteoarthritis is common. Risk factors include a genetic predisposition (many patients will have parents who have had hip arthritis), abnormal morphology of the joint (a socket that is too shallow or a ball that is non-spherical) or a history of previous trauma. Other causes of arthritis to the hip include inflammatory conditions such as rheumatoid arthritis or avascular necrosis.
Symptoms of hip arthritis normally develop gradually over time and include pain around the hip, especially the groin, and stiffness. Activities such as putting on shoes/socks, getting into the car or getting out of low seats may provoke symptoms in early arthritis. Advanced hip arthritis often causes pain at nighttime, pain when walking short distances, and often causes a noticeable limp.
Once established, arthritis cannot be reversed. Many patients can manage their symptoms by modifying their activities, taking simple pain relief such as anti-inflammatory medications, and using a walking stick in the opposite hand.
Hip Replacement / Arthroplasty
Many patients require surgery for their arthritic hip. This is generally in the form of a total hip replacement. This involves removing the abnormal cartilage of the hip as well as the femoral head and replacing it with prosthetic components. When first introduced, this revolutionised the treatment of patients with arthritis and remains one of the most successful operations in all of medicine. The vast majority of patients have an excellent outcome after surgery.
Any surgery does entail risk. Any decision to proceed with a hip replacement involves weighing the likely benefit of the operation against the potential risks. Rare but significant risks include infection, dislocation, leg length discrepancy, fracture, nerve injury, revision surgery or medical complications such as chest infection, heart attack, stroke, or blood clot.
Hip Replacement FAQ
Do I require surgery for my hip arthritis?
A diagnoses of hip arthritis only needs treatment if it is troubling you. The decision to proceed with hip replacement surgery is determined by how sore the hip is and how much it is slowing you down. The goal of surgery for hip arthritis is to relieve pain and improve function.
What is a hip replacement?
Joint replacement is a surgical intervention that involves removing the arthritic cartilage of the joint and replacing it with prosthetic or artificial implants. In the hip this involves removing the femoral head or ball and replacing it with an artificial head. The socket is replaced with an artificial shell.
What implants are used?
Care is taken to use implants that have a proven track record and have robust data supporting the long-term function of the hip replacement. The most common implants on the socket side include a titanium shell with a highly cross-linked polyethylene liner or ceramic liner. This forms one side of the bearing surface. The most common implants on the femoral side or thigh bone side include titanium uncemented stems or stainless-steel cemented stems. This forms a solid interface with the bone. An artificial head, either made of metal or ceramic, is then applied to the stem and this forms the other side of the bearing surface.
How is the surgery performed?
The surgery is performed under either a general anaesthetic or under a spinal anaesthetic with sedation. The operation is performed either utilising a direct anterior approach or posterior approach to the hip. Not all patients are candidates for a direct anterior approach and a discussion about what the safest and most appropriate surgical approach for each patient will be made on a case-by-case basis.
What is the recovery after surgery?
Patients are encouraged to weight bear and walk immediately after their surgery. Most patients use crutches for several weeks but will remain quite mobile. An adhesive dressing will be applied to the surgical wound and remains on until the wound is checked two weeks after the surgery. Before returning to driving, patients need to be able to safely navigate the pedals and be able to react in the case of an emergency. Generally, this involves no driving for four weeks after a left total hip replacement and no driving for six weeks after a right total hip replacement.
How long will the implant last?
Implant longevity is determined by a number of factors. Younger, more active patients are more likely to require revision surgery compared to older, less active patients. However, hip replacements using contemporary implants are robust and have good overall implant survival. Data from the New Zealand Joint Registry show 90% of hip replacements remain revision free after fifteen years.