This condition occurs when there is degeneration in the hip causing damage to the joint surface (figures 1 and 2). There are numerous different causes but the most common is osteoarthritis. However, it can occur earlier due to abnormalities within the hip. This may be due to a previous injury, childhood hip disease, femero-acetabular impingement (A misshapen hip that catches and causes damage to the hip joint) or problems with the blood supply to the hip.
Commonly, this causes groin pain often going down the thigh to the knee. The hip is stiff, and the patient walks with a limp. As arthritis becomes more widespread and severe, the pain becomes more constant, it may occur at night and be associated with increased stiffness, decreased mobility and ability to exercise.
What investigations do you need?
X-rays of the hip to confirm the diagnosis are taken as standard. More complex scans such as CT or Magnetic Resonance may be needed to pin down the diagnosis and help surgical planning.
To begin with, simple measures are tried such as painkillers, weight loss and activity modification. Oral supplements such as glucosamine and chondroitin may benefit some patients, especially with early arthritis. Injections such as steroid, hyaluronic acid or PRP may be used to either confirm the source of the pain (e.g. if the patient also has back pain) or in those patients who are not ready for a joint replacement.
When a patient has severe arthritis and painkillers no longer control the pain, hip joint replacement is advised. This has the benefit of relieving the pain and allowing the patient to return to a near normal level of activity.
In simple terms, the ball of the hip is removed and the thigh bone is prepared before the metal stem is inserted. The pelvic cup is then prepared and the artificial cup is inserted and held using either bone cement or an artificial coating that bonds directly to the surrounding bone surface (figures 3,4 and 5).
There are different forms of hip replacement and each one has a role to play depending on the patient’s age and activity level. Younger (<70) and more active patients, will have implants where the cup liner is made of a wear resistant plastic and the ball of the hip will be made of ceramic, which is very smooth, hard wearing and produces less wear debris than traditional implants.
In general, a hip replacement is a safe and reliable operation. The vast majority of patients are either pain-free following the surgery or have a significant improvement in their symptoms, returning to a level of activity that has not been possible for some time.
Approximately, 5% of patients will develop a post-operative complication. The most important of these are a deep infection, hip dislocation, leg lengthening, nerve and blood vessel injury, blood clots, fracture, future need for revision and medical complications such as stroke or heart attack. Great care is taken to minimize these risks including the use of antibiotics and blood thinning drugs around the time of the operation. Using information from The National Joint Register, we know that in general (if a proven combination of implants is used), approx. 95% of hip replacements will still be functioning well at 14 years although this drops in patients less than 55 years old to 93% at 10 years, due to their higher activity level. Patients tend to remain in a hospital for between 2 and 4 days.
It is important to undergo a focused rehab program both before and after surgery, focusing on hip strength and core stability as this will help patients to return to activity sooner. Patients should be able to return to a wide range of sports after surgery including cycling, swimming, tennis and skiing.