Hip Impingement

Who does this affect?

This is a relatively common condition in which there is a structural abnormality in either the femoral head or the pelvic cup. Normally, as the hip flexes up, the bony pelvis and flexible cartilaginous rim (Labrum) sit into the concave femoral neck.



Figure 1: Normal hip movements

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.



Figure 2: Cam Impingement



Figure 3: Pincer Impingment

Symptoms

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. 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.

Investigations

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.

Non-surgical Treatment

Professor Fehily has designed a specialised hip rehabilitation program. This was done in conjunction with his 2 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.

Surgical Treatment

If there is an underlying bony abnormality 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, all patients are different and advantages and disadvantages of the various treatment options can be discussed at the time of your consultation.


Cam Impingement: Courtesy of primal pictures


Pincer impingement: Courtesy of primal pictures