Hip Impingement
Who does this affect?
Hip impingement 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.
Symptoms
Patients with hip impingement present with deep seated groin pain, usually worse on bending and may be present on both sides. There 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 inflammation 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.
Causes
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 real 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 above. 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 seen on both the plain x-rays and the CT reconstructions. Depending on the severity, the bony rim can be trimmed back 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 labrum using special 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 may need to be addressed if the patient is to get the best 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 mobilisation.
Investigations
All patients undergo specialized 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.
Non-surgical Treatment
Professor Fehily has designed a specialized 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, for example, liquid thc, as a more natural approach, and modification of activity can also be tried.
Surgical Treatment
If the hip impingement is due to 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 overhanging front rim, instead, the entire cup is rotated backward (acetabular retroversion). If this is the case, then a simple rim trimming will not solve 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 position 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 preserve the joint using a combination of techniques such as micro-fracture and stem cell treatment (see Stem Cell Therapy). All patients are different and the advantages and disadvantages of the various treatment options can be discussed at the time of your consultation.
