Minimally invasive two-incision surgery for total hip replacement The National Institute for Clinical Excellence is examining minimally invasive two-incision surgery for total hip replacement and will publish guidance on its safety and efficacy to the NHS in England, Wales and Scotland. The Institute’s Interventional Procedures Advisory Committee has considered the available evidence and the views of Specialist Advisors, who are consultants with knowledge of the procedure. The Advisory Committee has made provisional recommendations about minimally invasive two-incision surgery for hip replacement.

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 preliminary recommendation
• the identification of factual inaccuracies
• additional relevant evidence.

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

The process that the Institute 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• The Advisory Committee will then prepare draft guidance which will be the basis for the Institute’s guidance on the use of the procedure in the NHS in England, Wales and Scotland.

For further details, see the Interim Guide to the Interventional Procedures Programme, which is available from the Institute’s website (www.nice.org.uk/ip).

Closing date for comments: 26 October 2004

Target date for publication of guidance: January 2005

Note that this document is not the Institute's guidance on this procedure. The recommendations are provisional and may change after consultation.

Minimally invasive two-incision surgery for hip replacement aims to reduce trauma and hasten recovery. However, evidence on the procedure’s safety and efficacy is currently inadequate for it to be undertaken without special arrangements for consent and for audit or research.

Clinicians wishing to undertake minimally invasive two-incision surgery for hip replacement should take the following actions.

• Inform the clinical governance leads in their Trusts.
• Ensure that patients understand the uncertainty about the procedure’s safety and efficacy and provide them with clear written information. Use of the Institute’s Information for the Public is recommended.
• Audit and review clinical outcomes of all patients having minimally invasive two-incision surgery for hip replacement. Clinicians are encouraged to submit data to the National Joint Registry (www.njrcentre.org.uk) for all patients having this procedure.

Training is particularly important and the British Orthopaedic Association has been asked to produce standards for training.

Further research will be useful in reducing the current uncertainty. Clinicians are encouraged to enter patients in well-defined randomised controlled trials and to collect longer-term follow-up data. The Institute may review the procedure upon publication of further evidence.

The most common indication for a total hip replacement is degenerative arthritis (osteoarthritis) of the hip joint. Other indications include rheumatoid arthritis, injury, bone tumours and necrosis of the hip bone.

Conservative treatments for arthritis symptoms include medications for pain and inflammation, and physiotherapy. If conservative treatments fail, a standard hip replacement may be necessary.

Two small incisions are made, one at the front of the hip directly over the femoral neck and one at the back in line with the femoral canal. Fluoroscopy may be used to define the femoral neck before the incisions are made and to confirm the position of instruments and prostheses during the procedure. The muscles are retracted to expose the joint capsule. The capsule is divided and retracted, using specially designed illuminated retractors, and a saw is used to remove the femoral head and neck. Specially designed instruments are also used to prepare the socket; position the acetabular prosthesis through the front incision, and to ream the femoral canal before inserting the prosthetic stem through the posterior incision. The prosthetic head is placed on the stem, gently impacted in place and the incisions are closed.

This procedure uses the same prostheses that would be used in a conventional hip replacement, but the minimally invasive two-incision approach entails less trauma to the soft tissue than conventional surgery.

Results on this procedure have been published from five centres, describing a total of 517 patients. Efficacy outcomes were poorly reported and mainly focused on the operating time and length of hospital stay, rather than the function of the prosthesis. In four studies, the proportion of patients discharged from hospital within 24 hours of the surgery ranged from 77% (58/75) to 90% (90/100). These data were from the USA, where the median hospital stay following standard total hip replacement was 5 days in one large series dating from 1995–1996. For more details, refer the Overview (see Appendix).

In one study of 142 patients followed up for between 6 weeks and 2 years, the acetabular component angles were satisfactory in 99% (141/142) of patients. For more details, refer the Overview (see Appendix).

The Specialist Advisors stated that there was some uncertainty about the long-term outcome of this procedure, compared with a conventional total hip replacement.

Femoral fracture was reported as a complication in all five studies, affecting between 1% (1/100) and 3.5% (5/142) of patients. This fracture rate is similar to that of the conventional total hip replacement, reported as 2% (20/1130) in one UK study. Other early complications such as dislocation, infection and deep vein thrombosis have also been reported with similar frequency for the two approaches. However, the numbers of patients who had undergone minimally invasive two-incision hip replacement were relatively small. For more details, refer the Overview (see Appendix).

The Specialist Advisors were concerned about the potential for malposition of the components through the minimally invasive two-incision approach and stressed the importance of training for this technique.

The following document, which summarises the evidence, was considered by the Interventional Procedures Advisory Committee when making its provisional recommendations.

• Interventional procedures overview of minimally invasive two-incision surgery for total hip replacement, May 2004

Available from: www.nice.org.uk/ip240overview