Hip impingement, also called femoro-acetabular impingement (FAI) by doctors, is an abnormal contact between the hip socket (acetabulum) and the upper leg (femur) and a common cause of pain and discomfort in young and middle-aged adults. The abnormal contact also causes the joint to no longer enjoy its normal range of motion. In addition, it often results in cartilage damage or a labral tear and can be a precursor to hip osteoarthritis.
- Types of hip impingement
- Implications
- Symptoms
- Causes
- Diagnosis
- Treatments
- Prognosis
Types of hip impingement
There are two different forms of hip impingement, which can occur separately or together. In a normal joint, the head of the thigh bone and the socket of the hip bone form a ball-and-socket joint, similar to the shoulder. The labrum (also called the meniscus of the hip) improves the stability of the joint. With hip impingement this normal functioning is disturbed.
CAM
There may be bone growth on the upper leg that forms a mound. When the hip joint moves, this bone growth can bump against the cartilage and labrum on the hip bone and cause damage. This is more common in men between the ages of 25 and 35.
Pincer
Here the problem is at the hip bone. The edge of the hip bone leans too far, leaving less room for the thigh during hip movements, which means that frequent contact can irritate or damage the thigh and intermediate structures. We see this more in women and in middle age.
Combination of both
In 85% of cases we see a combination of both cases (to a greater or lesser extent).
Implications
Repeated contact and friction can cause damage to the labrum, articular cartilage and/or ligaments surrounding the hip joint, resulting in pain and stiffness. The cartilage can come loose and cause blockages in the joint, while the ligaments can cause instability complaints that may or may not be accompanied by a clicking sound.
Symptoms
Pain
Pain is the most common complaint, especially in the hip or deep in the groin. Furthermore, it can also cause lower back pain, pain in the buttock or thigh. In an advanced phase, typical pain symptoms that match the picture of coxarthrosis may also occur, such as radiation to the knee and morning pain.
Movement restriction
Patients mainly report complaints with deep bending or rotating movements of the hip. Sports such as hockey, football, horse riding, hurdles, fitness and water polo are often featured.
Problems with certain activities
In the first phase, the complaints mainly occur during exercise. Later the pain can also occur with:
- Sitting still for long periods of time (e.g. in the car or on a plane)
- Walking/running
- Ascend the stairs
- Putting on or taking off shoes/stockings
Typical activities that require deep and/or repetitive hip flexion.
Noises & blockages
Frequent contact can release pieces of cartilage (also called joint wear) that can block normal movement in the joint. Injured ligaments can rub against bone structures, causing rubber band-like sounds such as clicking and snapping.
Causes
Not much is known yet about the possible cause of hip impingement. However, it is assumed that one often cannot point the finger at one factor, but that there are various causes that interact.
Intrinsic factors
There is scientific evidence that hip impingement is more common in siblings of those who suffer from this condition. There is also a different occurrence of the condition in women versus men.
Certain sports during adolescence
Frequent and extensive bending and rotation of the hip during exercise is an important risk factor. Football, basketball, ballet or martial arts are often found in history.
History of hip disorders
People who have suffered from a specific hip condition such as epiphysiolysis or Legg-Calvé-Perthes in childhood often have a different morphology in the hip that can more easily develop into hip impingement.
Complication after a hip fracture and/or surgery
After a fracture, poor natural healing may occur, causing the bone pieces to no longer fit together properly. Surgical overcorrection can also occur, causing pincers to develop.
Diagnosis
There is no single clinical or radiographic sign that can provide a conclusive diagnosis of hip impingement. People can show signs of CAM and/or pincers on medical images, without ever experiencing any complaints. The typical painful movements can occur with many other conditions. As a result, a combination of various clinical signs, the correct history and medical imaging is required to arrive at the correct diagnosis.
Anamnesis
Here the GP or specialist asks about the typical symptoms that occur with hip impingement. The complaints and associated activities are queried here. The doctor may also ask about a history of hip disorders and hereditary factors. If this interview reveals signs of hip impingement, clinical tests may follow.
C sign
When asked where the patient feels the most pain, they often grab the outside/front of the hip with their thumb and index finger in the shape of a “C”. This may indicate a condition inside the joint (as opposed to outside), which is a possible sign of hip impingement.
FADIR test
During this test, pain is elicited by the examiner performing a vigorous flexion and rotation movement (Flexion-ADduction-Internal Rotation = FADIR) of the hip, while the patient lies supine on the table. The structures at the front of the hip come under pressure and impingement can be provoked, which causes the typical complaints. This test is often positive, even in people who do not suffer from hip impingement.
Strength tests
There is moderate evidence that patients with this condition have reduced strength in their hip flexors and adductors (the muscles on the outside of the hip/thigh). Single-leg squats, stair climbing, or strength tests against examiner resistance can detect this reduction in strength.
Medical imaging
When various clinical and anamnestic signs of hip impingement are present, radiographic examination can provide further information. Initially this can be done via X-rays. If a more comprehensive picture of the morphology of the joint is required, a CT scan or MRA/MRI is used.
Treatments
There is no one-size-fits-all solution for this condition. Depending on the clinical picture, activity level and patient preferences, various options are possible.
Conservative
This can be done independently with the advice of the GP, or with the help of a physiotherapist. This allows the patient’s daily activities to be examined in order to determine triggering factors and to temporarily avoid them and then gradually build up again. Specific exercise therapy can resolve loss of strength, stiffness, instability and coordination problems, so that compression occurs less often. In the short term, anti-inflammatories (NSAIDs) can provide relief. A final option before surgery is an infiltration of the hip joint with cortisone or hyaluronic acid.
Operative
If conservative management fails, keyhole surgery (arthroscopy) can be used to try to improve the fit of the femoral head and socket. This is done by removing any excess bone and joints and/or repairing labral injuries. Complications are exceptional, but are more common in the elderly, women and patients who have had complaints for a long time. In an advanced phase of the condition, where extensive cartilage damage has occurred and one therefore speaks of coxarthrosis, a (total) hip prosthesis may also be necessary.
Prognosis
Although there are indications that there is a good chance that the complaints will worsen if no action is taken, many patients with the right help return to their old activity level without (or with hardly any) complaints.