Who does this affect?
This is a relatively common condition in which there is a structural abnormality in either the femoral head (ball of the hip) or the pelvic cup. Normally, as the hip bends up, the bony cup and flexible cartilaginous rim (Labrum) sit into the concave femoral neck.
However, some patients have either a bump on their femoral head (cam impingement) or an over-hanging cup (pincer impingement) and this causes damage to the labrum and eventually the joint surface.
Patients present with deep seated groin pain, usually worse on bending and may be present on both sides. They may be an associated deep click, which can be either due to a torn rim cartilage, or more commonly, an inflamed tendon running over the front of the hip (Psoas Tendon). If the condition has been present for some time, there may also be inflammation of the tissues surrounding the hip such as the outer hip (trochanteric bursitis), the groin muscles (adductor tendonitis) or infammation of tendons in front of the hip (sartorius tendonitis). Eventually, as the damage continues, the patient may begin to develop more arthritic symptoms such as a dull ache in the groin and increasing stiffness. Hip-related pain is not always felt directly over the groin, it may also be felt on the outer aspect of the thigh, the buttock or traveling down the leg. Occasionally, the pain you do feel in the hip may actually be the result a problem in your back, a hernia or other diagnoses.
Hip impingement is caused by bony abnormalities on the acetabular or pelvic rim, the femoral head (ball of the hip) or a combination of the two. Using a combination of plain x-rays and CT scans with 3-D reconstructions, it is possible to very accurately identify where the abnormality is and what needs to be removed at the time of surgery. The routine use of 3D CT has made a significant difference to the success of the surgery and the eventual outcome for the patient.
Pure CAM deformity
In a CAM deformity, there is an abnormal bump at the junction between the head/ball of the femur and the neck. This is evident on the image below. This area can be accessed from within the joint and shaving carried out using a small burr until the appropriate shape has been created.
Pure PINCER deformity
In a PINCER deformity, there is an overhanging cup. This can be visualized on both the plain x-rays and the CT reconstructions. Depending on the severity, the bony rim can either be resected leaving the soft cartilaginous rim in place (peri-labral rim recession), if it is a mild deformity or in more severe cases, by removing it, shaving back the bony rim and then reattaching the cartilagenous labrum using highly specialized bony anchors.
Mixed CAM/PINCER deformity
In the majority of patients, there is a combination of CAM and PINCER impingement. In these cases both sides must be addressed if the patient is to get an optimal result. This can often be achieved by doing a peri-labral rim recession and a femoral head reshaping, thereby leaving the labrum in place and allowing for early mobilization.
All patients undergo specialised x-rays of the hip as well as more complex scans such as CT and Magnetic Resonance Arthrography (MRA). These scans are used to confirm the soft-tissue damage and to accurately map out the bony deformity. This is very important when planning the surgery.
Professor Fehily has designed a specialised hip rehabilitation program. This was done in conjunction with his specialist hip physiotherapists. This was initially developed for patients following key-hole hip surgery but it is now being used for general hip rehabilitation. Other therapies such as painkillers, anti-inflammatory drugs and modification of activity can also be tried.
If there is an underlying bony abnormality and physiotherapy has not cured the pain then surgery is recommended. The aim is to correct the bony deformity before there is irreversible joint damage. This is usually done by hip arthroscopy (keyhole surgery) where the deformity is shaved back via 2 or 3 small incisions. Occasionally some patients with pincer impingement do not simply have an over hanging front rim, instead the entire cup is rotated backwards (acetabular retroversion). If this is the case, then a simple rim trimming will not resolve the problem and by decreasing the amount of head coverage, may actually speed up the onset of arthritis. These cases may need more significant pelvic surgery to alter the postion of the cup (peri-acetabular osteotomy).
Hip arthroscopy is highly specialised and technically difficult surgery but can achieve excellent results if carried out correctly and on the right patient. Based on Professor Fehilys own experience and that of the wider orthopaedic community, certain patients do not do well from hip arthroscopy e.g. patients with significant hip arthritis, patients with severe childhood hip disease (hip dysplasia) or patients with inflammatory hip disease (e.g. rheumatoid arthritis). Occasionally, the bony deformity may be so large that an adequate bony reshaping is not possible using key-hole surgical techniques. In those cases the operation is done using an open technique. In some cases, the damage caused to the joint by the impingement may be so severe that the only reliable option is a joint replacement. However, if at all possible we will try to presume the joint using a combination of techniques such as microfracture and stem cell treatment. All patients are different and the advantages and disadvantages of the various treatment options can be discussed at the time of your consultation.