Hip Impingement

What is hip impingement?
The hip joint (hip anatomy) is a ball and socket joint and consists of a round, smooth ball (the head of the femur, top end of the thigh bone) which rotates in a socket (the acetabulum) near perfectly matched in size and shape.

Hip impingement, FemoroAcetabular Impingement, (FAI) is caused by atypical contact between developmentally abnormal shaped parts of the ball and socket of the hip. As a result, particular movements cause undue pressure on certain parts of the joint cartilage and Labrum causing damage to these structures. This can be painful and restrict specific movements. If the articular cartilage injury continues it leads to early onset osteoarthritis. Interestingly, long-term research studies show that probably two thirds of patients with this condition develop problems while others do not but the reasons for these differences are not known. There are two types of hip impingement.

surgery for hip impingement tunbridge wells

Pincer – a change in the edge of the socket with an increase in bony growth at the front and outer edge of the socket covering more of the head of the femur than necessary.

Cam– bony growth at the junction of the head and neck of the femur. The ball acts like a cam moving/pushing into the socket which then causes the Labrum to be pinched and creates a shearing force on the joint cartilage next to the Labrum. Both Cam and Pincer can occur together. This is known as mixed or combined impingement.

What are the symptoms and Signs?

Pain or discomfort is the commonest symptom. Stiffness or restriction of movement and ‘clicking’ of the hip joint can be present as well.  Pain is typically deep-seated and felt in the groin or anterolateral (outer and front) aspect of hip. This is commonly precipitated by the hip flexion (bringing knee towards the chest) movement and hence sitting for long periods will make the pain worse. Any activity that involves repeated hip flexion such as driving, sitting in a low chair, sitting in the bath, using a rowing machine, deep squats, high kicks and sporting activities could all cause such impingement pain.

The impingement test is positive when there is pain in the hip on flexion, adduction and internal rotation of the hip as shown in the Fig 2. A positive test result is suggestive of hip impingement.


History, including details of pain characterisation, limitation of activities, other relevant symptoms as mentioned before, and expectations are crucial in planning treatment. Most of the time x-rays (Fig 3) will confirm the presence of impingement lesions. Other problems such as soft tissue pathology or early hip arthritis also can present with similar problems. An MRI is useful to assess the soft tissue around the hip and labrum cartilage and also confirms the presence of a FAI lesion. Also, it can rule out other conditions around the hip that could elicit pain in the hip and groin. A CT scan with 3D reconstruction (Fig 4) is very useful to understand the extent of impingement pathology and to plan surgery.

Conservative Treatment

Surgery is not always necessary for FAI.  The condition can often be improved with rest, avoiding or modifying activities and movement patterns to cope with the change in structure.  If possible, it is better to avoid activities that aggravate the pain, for example, running or squats. This must be accompanied by strengthening the muscles around the hip and ‘core’ (muscles controlling spine, abdomen, pelvis and hip). This helps to improve the spine – pelvic position which can reduce irritation to the hip and hence reduce pain and swelling. If the pain is due to soft tissue problems around the hip, like ligament or tendon problems, the sprain will get better with these measures.

This strategy only works if patients are committed to a rehabilitation programme and exercises are performed regularly over a period of at least three to six months. Since the change in activity and exercises can vary considerably from person to person, it is strongly recommended that patients have the areas that need addressing assessed by a professional and establish that the exercises are being done correctly. Some direct mobilisation of pelvis and hip can help but these will have to carried out by experienced practitioners.

The decision on whether to operate will be between you and your surgeon.  Whatever the ultimate decision a good trial of physiotherapy is necessary first and commitment to regular exercises at all stages cannot be overemphasised.

There is no harm in leaving surgery for few months so that everyone involved can decide if surgery is the correct course of action.   It is important to realise that there is a small but finite risk of complications with surgery and that surgery does not always improve symptoms.   This is especially the case if your muscles are weak or if you have arthritis in your hip.

Surgery (Hip Arthroscopy)

The aim of hip impingement surgery is to reshape the ball and/or the socket by removing prominent bone and stabilising the Labrum. When this condition was identified and treatment evolved, surgery was done through an open technique called surgical dislocation. It has evolved considerably and is now done with an arthroscope (telescope) using small cameras and instruments through incisions around 1.5 – 2cm long. The number of incisions needed depends on the extent of surgery; usually, two to three incisions are required. Nowadays open surgery is rare and recovery after open surgery is slower.

In cam lesion the prominence (bump) at the head neck junction is removed as shown in the picture below.  This is called osteoplasty or bumpectomy. Screening is done at the end of the procedure to ensure the hip impingement is cleared.

hip pain treatment tunbridge wells
hip pain treatment tunbridge wells

Labral tear repair/debridement – this will depend on the quality of Labrum cartilage, together with the type and extent of any tear (if present). After trimming the pincer impingement lesion along the rim of the socket the Labrum is stabilised with suture anchors (Fig 6) wih the aim of providing a stable Labrum cartilage without further impingement.

fai hip pain tunbridge wells

Microfracture – this can occur when there are full thickness faults in the lining of the joint and drilling a few tiny holes into the bone underneath produces a marrow clot and stimulates cartilage cells which can then form new cartilage. However, this is not the same (hyaline) cartilage and results are not as good as those achieved in knees. Considerable research into the matter is still ongoing.

Patients usually get discharged on the same day as surgery or the morning of the following day. They will be walking with crutches at the time discharge.

FAQs After Surgery

Patients will be partial weight bearing for five to seven days. After that they can return to driving as and when they feel safe to drive. They should be able to make an emergency stop. It is usually possible to start driving between one and three weeks post surgery but sitting in a car with hips flexed to 90 degrees can be uncomfortable in the first few weeks.

Most Deep Vein Thrombosis (DVT) occurs in the first six weeks after surgery. So it is better to avoid flying for six weeks but better still to take additional precautions up to12 weeks to prevent DVT.

This will be dependent on exactly what was done during surgery. Patients are advised to partial weight bear for three to seven days after surgery and to use crutches  for one to two weeks. If microfracture surgery has been done patients will be on crutches for six weeks post-surgery with some weight bearing restrictions.

This depends on what kind of work the patient does and should be decided following discussion with the consultant and physiotherapist.  Sitting for long periods of time may be uncomfortable and will not help to stretch the hip. It is best to inform your place of work that you may be off for up to a month from office or sedentary work.  If you have a heavy manual job, you may be off for two to four months.

Specific exercises will be provided by your physiotherapist. Some patients (Labral repair and microfracture) will be advised to restrict certain hip movements in the first few weeks after surgery. Exercises will be aimed at strengthening both core and hip muscles, mobilising the hip joint and balancing exercises during the first six weeks. After that stretches, strengthening any weak muscles around the hip and core and correcting movement patterns can be undertaken. Patients can use an exercise bike without any load from two weeks after surgery. Water-based exercise can also be started around this time. High impact exercise, such as jogging, will normally be avoided for 12 weeks, and can then be gradually increased.

Studies have shown it can take two to six months after surgery to have a reduction in pain and improvement in daily activities and between six to twelve months to have an improvement in functional ability at a sporting level.  In some studies pain levels continue to reduce even after the first year.

What are the reported complications of this surgery?

  1. Deep vein thrombosis
  2. Pulmonary embolism
  3. Infection
  4. Joint adhesion – fibrous scar tissue forming within the joint
  5. Damage to nerves and blood vessels
  6. Persistent pain or recurrence of symptoms
  7. Need for further surgery
  8. General complications related to heart, lungs and other vital organs
  9. Compartment syndrome
  10. Joint instability