In a normal joint the bone ends are covered in gristle (cartilage) which cushions the joint and spreads load. The cartilage is very smooth and slippery allowing the bone ends to move freely.
When osteoarthritis develops it is because the cartilage has gradually worn away and the fluid in the joint is less effective causing the hip to stiffen and become painful. The cartilage can wear away further and the bone becomes exposed often causing bone-to-bone contact, reducing the space within the joint. When this happens the choice of surgery will be dependent on a number of factors but essentially it will be necessary to have either a hip resurfacing or a total hip replacement.
Osteoarthritis only affects approximately 10% of the population, but is one of the most common causes of hip problems in people of varying ages, and is the reason why so many people need surgery.
Approximately 80% of cases of osteoarthritis of the hip are attributable to mechanical factors, usually subtle forms of childhood disorders, such as hip dysplasia, slipped upper femoral epiphyses (often referred to as SUFE) or Perthes’ disease. A small number are due to post-traumatic problems.
The remaining 20% are due to inflammatory disorders, avascular necrosis (a condition where, for various reasons, the blood supply to the thighbone, Femur, is affected and the bone dies), infection or metabolic bone disease and bone dysplasia.
In recent years it has become appreciated that the thighbone (femur) and/or hip socket can twist outwards (retroversion) causing subtle malformation to the upper end of the thighbone at the edge of the socket. These eventually cause osteoarthritis but they develop long before osteoarthritis is obvious. These are often referred to as flexion impingement, the cam effect where there is too much bone produced on the front (anterior aspect) of the thigh (femoral neck). Diagnosis requires experienced x-ray and CT evaluation.
Tears of the acetabular labrum (the gristly fibrocartilaginous edge to the socket) often develop in the very early stages of osteoarthritis.
Labral tears that develop as a result of exuberant activity can be treated arthroscopically (keyhole surgery), much like cartilage tears are treated in the knee. If the labral tear develops in the presence of hip dysplasia, the hip dysplasia needs to be treated. There is controversy as to the effectiveness or relevance of selective treatment of the labral tear: certainly in such circumstances the labral tear should not be treated on its own.
Reorientation of the socket or the femur to correct to the normal physiological position has been shown in several papers to improve function and reduce symptoms over the short to medium term, but we do not have enough longer-term experience (10 to 20 years) to be certain of the longer-term effectiveness of these procedures.
The cam effect and the anterior bony exuberance (over production of bone) can be treated by specific and detailed nibbling back at the exuberant bone, with a success rate approaching 80% in the hands of experienced people.
Osteoarthritis of the hip, once it has developed, cannot usually be treated by any form of joint preserving operation – it is necessary as the minimum to replace the bearing surfaces – a resurfacing or, in older patients and where the foundations of the bone will not sustain a resurfacing, a total hip replacement would be required.
Q: Is osteoarthritis irreversible?
A: Once changes of joint space narrowing or osteophyte formation have occurred, it is very rare indeed for osteoarthritis of the hip not to get worse.
Q: Are there treatments other than orthopaedic surgery that are helpful?
A: Weight reduction to an appropriate rate for your height will reduce the stresses on the joint and will tend to reduce symptoms, occasionally alleviating them completely.
A walking, stick carried in the hand opposite the affected hip, will share the weight as you take each step and help reduce symptoms.
There is a huge range of anti-inflammatory and painkilling drugs that can be prescribed for osteoarthritis of the hip, but they simply blunt the pain but do not alter the natural history of the disease, and indeed may worsen it because the alleviation of the pain will allow you to do more damage to your joint. Occasionally patients who have taken anti-inflammatories for an excessively long period have done such damage to the joints that resurfacing is impossible.
There are alternatives available including Glucosamine, Vitamin C, Cod Liver Oil and some other remedies in health food shops. It has not been my experience that any patient has obtained any benefit to their hips by the time they came to me, but some of these patients have found that, for instance, their neckache or backache improved with this treatment. The inference of this would be that this treatment is only effective in the earlier stages of degenerative joint disease.