Hip

The hip joint, scientifically referred to as the acetabulofemoral joint is the joint between the femur and acetabulum of the pelvis.  It is a ball and socket joint whose primary function is to support the weight of the body in both static (e.g. standing) and dynamic (e.g. walking or running) postures. The hip joints play an important part in retaining balance, so any damage to the hip can cause a limp.

It is a synovial joint meaning it is filled with fluid (produced by the joint lining) that acts as a lubricant between the two bones which in turn are covered in smooth articular cartilage.  It has a strong thick capsule around it and has a good blood supply.   When all these parts are healthy then the hip functions well, but if any of them are damaged, by trauma or arthritis then problems can occur.

With inflammation of the joint lining (as with rheumatoid arthritis) the hip becomes painful and over time this inflammation can spread over the cartilage covering of the hip and cause further damage and pain.

When cartilage is damaged then the hip can become painful as bony surfaces rub against each other because the body cannot regenerate this type of cartilage.  This can occasionally be due to trauma, but more often by osteoarthritis and is irreversible.

If the blood supply is damaged then the bone can die and this causes severe pain.  This loss of blood supply could be due to trauma or sometimes as a side effect of some drugs such as alcohol and steroids.

All of the above can lead to arthritis of the hip which your doctor can diagnose by asking some careful questions and taking X-Rays.

X-ray of normal hip and one with osteoarthritis next to each other.

 

Pain around the hip.

Hip arthritis commonly causes pain in the groin.  It also causes pain down the front of the thigh and even referred pain in the knee.  Sometimes it can cause pain on the outside of the thigh and even in the buttock.  These last two symptoms can also be related to other causes such as arthritis of the spine, sciatica or nerve problems.  Hip problems as a rule don’t cause any pain past the knee into the foot this is more commonly linked to a back problem.  Sometimes, when things are not so clear, the surgeon they may offer an injection to see exactly where the pain is coming from.

Trochanteric Bursitis

This  is pain on the outer part of the hip that is thought to be due to inflammation of a bursa.

A bursa is a fluid filled sack that acts as cushioning between muscles, bones and tendons.  You may have heard of these before as they are present all around the body. 

Common ones you can feel are on the tips of the elbows and in front of the knee.  There are 4 of these bursae present on the outside of most people’s hips but are difficult to feel because they are deep within the tissues on the surface of the bone.

Studies have shown that these bursae are not always inflamed so the pain is more likely to be due to tears or inflammation of the tendons and muscles that are present in this area so this problem is better described as Greater Trochanteric Pain Syndrome or GTPS.  This includes any kind of pain over and around the outer part of the hip.

Other causes include arthritis of the back or other hip, tightness of the muscles, rheumatoid arthritis and trauma or overuse.

Patients present with any of the following symptoms:

• Pain when lying on the affected side in bed.
• Discomfort when sitting in the car.
• Pain when climbing stairs.
• Pain when sitting with legs crossed.

This pain is on and around the outer part of the hip with a pin point area and generalised surrounding tenderness spreading up and down the outer thigh but rarely below the knee or to the back.

For a long time patients with these symptoms have been ignored or not taken very seriously however with the advent of better understanding of the problem and MRI scans there is some hope!

Treatment

Because of the complex nature of this pain syndrome treatment is not straight forward.  It is based on what structure is causing the pain and ruling out other important causes such as back or hip arthritis.

Most treatments can be carried out by the GP and include:

• Rest and ice therapy.
• Anti-inflammatory medication.
• Steroid injections.

Sometimes, however, the pain does not settle or comes back quickly.  In these cases the patient can be seen by a specialist and once other causes have been ruled out or treated then further investigation can be carried out.  An MRI scan is useful to look at the bursae and the tendons and muscles around them and can guide further treatments which include:

• Image guided injections.
• Targeted physiotherapy.
• ESWL (shock wave therapy) to the tendons.
• Finally surgery to repair chronic tears of the affected tendons.