Making a diagnosis of hip impingement

Patients presenting with femoracetabular impingement (FAI) usually present with symptoms that are rather typical; activity related groin pain being the most common. Pain, however, can be felt in other areas such as the buttock region, adductor region and the thigh. Sometimes the radiation of pain from the hip can be quite wide and the hip may not always  be thought of as the source of the pain.

There are a number of features on examination that point to the hip as the source in particular the impingement sign where the pain is made worse with the hip bent up and pushed inwards. If there is any doubt as to the source of the pain, we plan diagnostic hip injections with local anaesthetic which should improve the pain temporarily if it is coming from the hip.

A plain x-ray will usually give clues as to why the hip has become painful, but further imaging will be required to demonstrate more specifically the abnormality of the hip and the damage being caused to the joint.

An MRI scan shows up the damage to the articular cartilage and labrum but often this needs to be done with contrast material in the hip which can be rather uncomfortable. Some of the newer scanners show details of the hip that are amazing and in my view contrast tends to be less important.

We have done a lot of work using CT scans over the years and in my view this gives a much more objective view of the hip and the abnormality that may need to be addressed at the time of surgery. Technology has moved on such that now we can animate 3-D images of a patient’s hip so that we can work out how and where the impingement is occurring. This gives us the best chance of correcting the abnormality particularly when performing arthroscopic surgery where the overall view of the hip is more limited.

Future developments in imaging will be very exciting and will add to our understanding of how the hip gets into trouble, in particular I anticipate that we will have 3-D animations from MRI scans which will give both bone and soft tissue information – can’t wait!