Open femoro-acetabular surgery for hip impingement syndrome: consultation document

Interventional procedure consultation document

Open femoro-acetabular surgery for hip impingement syndrome

Treating hip impingement syndrome with open femoro-acetabular surgery

Hip impingement syndrome is caused by unwanted contact between abnormally shaped parts of the head of the thigh bone and the hip socket. This results in limited hip movement and pain.

The aim of femoro-acetabular surgery is to improve range of movement and reduce pain. It is believed that it may also help prevent hip arthritis in later life. With the patient under general anaesthesia, the joint is opened and dislocated so that the surgeon can see both of the bones in the hip joint. The surgeon removes some of the cartilage or bone, with the aim of reshaping the joint surface.

The National Institute for Health and Clinical Excellence (NICE) is examining open femoro-acetabular surgery for hip impingement syndrome and will publish guidance on its safety and efficacy to the NHS in England, Wales, Scotland and Northern Ireland. NICE’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisers, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about open femoro-acetabular surgery for hip impingement syndrome.

This document summarises the procedure and sets out the provisional recommendations made by the Advisory Committee. It has been prepared for public consultation. The Advisory Committee particularly welcomes:

  • comments on the provisional recommendations
  • the identification of factual inaccuracies
  • additional relevant evidence, with bibliographic references where possible.

Note that this document is not NICE’s formal guidance on this procedure. The recommendations are provisional and may change after consultation.

The process that NICE will follow after the consultation period ends is as follows.

  • The Advisory Committee will meet again to consider the original evidence and its provisional recommendations in the light of the comments received during consultation.
  • The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.

For further details, see the Interventional Procedures Programme manual, which is available from the NICE website (

Through its guidance NICE is committed to promoting race and disability equality, equality between men and women, and to eliminating all forms of discrimination. One of the ways we do this is by trying to involve as wide a range of people and interest groups as possible in the development of our interventional procedures guidance. In particular, we aim to encourage people and organisations from groups who might not normally comment on our guidance to do so.

In order to help us promote equality through our guidance, we should be grateful if you would consider the following question:

Are there any issues that require special attention in light of NICE’s duties to have due regard to the need to eliminate unlawful discrimination and promote equality and foster good relations between people with a characteristic protected by the equalities legislation and others?

Please note that NICE reserves the right to summarise and edit comments received during consultations or not to publish them at all where in the reasonable opinion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 21 April 2011

Target date for publication of guidance: July 2011

1   Provisional recommendations

1.1  Current evidence on the efficacy of open femoro-acetabular surgery for hip impingement syndrome is adequate in terms of symptom relief in the short and medium-term and there are well understood safety concerns. Therefore this procedure may be used provided that normal arrangements are in place for clinical governance, consent and audit.

1.2  Open femoro-acetabular surgery for hip impingement syndrome involves major surgery with the potential for serious complications and should only be undertaken by surgeons who are well-trained and highly experienced in this type of procedure.

1.3  NICE encourages further research and data collection on open femoro-acetabular surgery for hip impingement syndrome. Research studies should in particular address patient selection, and long-term outcomes (specifically relating to the development of osteoarthritis).

2   The procedure

2.1   Indications and current treatments

2.1.1  Hip or femoro–acetabular impingement results from abnormalities of the femoral head or the acetabulum. It can be caused by jamming of an abnormally shaped femoral head into the acetabulum (especially during flexion), or as a result of contact between the acetabular rim and the femoral head–neck junction. It is believed that it may lead to the development of osteoarthritis.

2.1.2  Symptoms may include restriction of hip-joint movement, pain and ‘clicking’ of the hip joint. Symptoms are typically exacerbated by hip flexion or prolonged sitting.

2.1.3  The management of hip impingement syndrome includes conservative measures, including modification of activity and non-steroidal anti-inflammatory medication. Patients with advanced osteoarthritic degeneration may require a total hip replacement.

2.2   Outline of the procedure

2.2.1  The aim of open femoro–acetabular surgery for hip impingement syndrome is to reduce pain and improve the hip-joint range of movement.

2.2.2  The procedure is carried out with the patient under general or regional anaesthesia using an incision on the outer side of the thigh. The hip is dislocated to expose the femoral head and acetabulum, using a method that preserves the blood supply to the femoral head. Non-spherical sections of the femoral head, prominent sections of the anterior femoral neck and excessive acetabular rim are removed. After femoral and acetabular osteoplasty are completed, the hip is re-located, residual impingement is evaluated and further surgery performed as necessary. If impingement is due to a retroverted acetabulum, this may be separately treated by periacetabular osteotomy.  

Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview, available at


2.3   Efficacy

2.3.1  In a non-randomised controlled study of 52 patients comparing open femoro-acetabular impingement surgery with labral re-fixation (35 hips) versus open femoro-acetabular impingement surgery with labral resection (25 hips), mean Merle d’Aubigné pain scores improved compared with baseline in both groups, but significantly more so in the re-fixation group (73%) compared with the resection group (59%) at a median 2-year follow-up (absolute figures not stated, p = 0.0009). ‘Clinical status’ based on mean Merle d’Aubigné score (a scale of 4 to 18 points; higher score indicates better hip function) was 17 and 15 for the re-fixation versus removal, respectively at 2-year follow-up.

2.3.2  A case series of 46 patients (48 hips) reported that group mean function score (Merle d’Aubigné scale) improved from 13.0 points at baseline (indicating fair clinical status) to 16.8 points (indicating good clinical status) at 38-month follow-up (p < 0.001).

2.3.3  A case series of 94 patients (96 hips) reported that group mean Harris hip score (on a scale from 0 – 100; higher scores better) improved from 67 points at baseline to 91 points at a mean 26-month follow-up (p < 0.0001).

2.3.4  A case series of 34 patients (37 hips) reported that group mean University of California, Los Angeles activity score (on a scale of 1 – 10; higher scores better) improved from 4.8 points at baseline to 7.5 points at a mean 3.1-year follow-up (p < 0.001).  

2.3.5  The case series of 46 patients reported that restoration of normal hip offset was noted on X-ray in 100% (46/46) of patients postoperatively.

2.3.6  The Specialist Advisers listed key efficacy outcomes as pain relief and delayed progression to osteoarthritis.

2.4   Safety

2.4.1  The case series of 213 hips reported that there was no clinical or radiographic evidence of avascular necrosis of the femoral head at a minimum 2-year follow-up. A case series of 94 patients (96 hips) reported no osteonecrosis of the femoral head at a mean 26-month follow-up.

2.4.2  Heterotopic ossification was reported in 37% (79/213) of hips in the case series of 213 at a minimum follow-up of 2 years (clinical sequelae not described).

2.4.3  Postoperative partial neurapraxia of the sciatic nerve was found in less than 1% (2/213) of hips in a case series of 213 hips (both resolved by 6-month follow-up).

2.4.4  Painful internal fixation requiring screw removal occurred in 26% (9/34) of patients in the case series of 34 patients at a mean follow-up of 8 months.

2.4.5  In the case series of 22 patients (29 hips) subsequent surgery was required in 12% (3/26) of hips, 1 procedure each for postoperative loss of reduction, correction of posteroinferior impingement, and recurrent anterior impingement (timing of events not stated).

2.4.6  The Specialist Advisers listed adverse events known from reports or experience to include vascular insult to the femoral head causing  necrosis (rare but serious), non-union of trochanteric fragment, trochanteric bursitis, nerve injury, infection, deep vein thrombosis and accelerated osteoarthritis. They considered theoretical adverse events to include fracture, postoperative dislocation, haemorrhage and haematoma.

3   Further information

3.1  This guidance is a review of IPG 203 ‘open femoro-acetabular surgery for hip impingement syndrome’ published in 2007.

3.2  For related NICE guidance see

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

March 2011

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This page was last updated: 19 August 2015