Interventional procedure consultation document

Minimally invasive total hip replacement

Hip replacement surgery using a minimally invasive approach may be an option for people with worn or damaged hip joints. This condition is usually due to degeneration of the joint (osteoarthritis), which can make walking painful.

The procedure replaces the damaged hip joint (the top part of the upper leg bone and the socket in the hip bone that it fits into) with an artificial one. In order to undertake the surgery through small incisions without muscle damage, specially designed equipment is used to support the leg and pull back the surrounding tissues so the surgeon can see the joint. X-rays are sometimes used to check the position of the bones and the artificial joint.

The National Institute for Health and Clinical Excellence (NICE) is examining minimally invasive total hip replacement 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 minimally invasive total 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 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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE's guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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 (www.nice.org.uk/ipprogrammemanual).

NICE is committed to promoting through its guidance race and disability equality and 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 guidance on interventional procedures. In particular, we aim to encourage people and organisations from groups in the population who might not normally comment on our guidance to do so. We also ask consultees to highlight any ways in which draft guidance fails to promote equality or tackle discrimination and give suggestions for how it might be improved. 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: 23 June 2010

Target date for publication of guidance: September 2010

1 Provisional recommendations

1.1 Current evidence on the safety and efficacy of minimally invasive total hip replacement appears adequate to support the use of this procedure provided that normal arrangements are in place for clinical governance, consent and audit.

1.2 Surgeons undertaking this procedure should have specific training in the minimally invasive technique they are using, and in use of the instrumentation it requires.

1.3 Patient selection should be done by surgeons and their teams who can offer both conventional and minimally invasive total hip replacement.

1.4 Clinicians should submit data on all patients treated using this procedure to the National Joint Registry (www.njrcentre.org.uk).

2 The procedure

2.1 Indications and current treatments

2.1.1 Disability due to hip pain is common and is usually caused by osteoarthritis. Conservative treatments include medication (anti-inflammatories and analgesics) and physiotherapy. If conservative treatments fail, a hip replacement may be necessary.

2.1.2 A traditional hip replacement involves accessing the joint through a large incision (approximately 20 - 30 cm) with division of muscles, ligaments and tendons. A number of different approaches may be used.

2.2 Outline of the procedure

2.2.1 Minimally invasive total hip replacement is carried out with the patient under general or epidural anaesthesia, using an approach that aims to avoid damage to the muscles and tendons around the hip joint. A short incision is made (either a single incision of 10 cm or less in length, or incisions at the front and back of the hip). Division of muscles may be necessary but is less extensive than in standard approaches. Specially designed retractors and customised instruments are typically used to expose the hip joint, prepare the acetabular socket and the femur, and insert the prosthesis. A specialised operating table may also be used. Fluoroscopic guidance and computer-assisted navigation tools may be used to aid positioning of the implant.

2.2.2 A range of different prostheses are available for this procedure, which may be cemented or uncemented.

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 www.nice.org.uk/guidance/IP240aoverview

2.3 Efficacy

2.3.1 A systematic review of 1205 patients reported that there was no significant difference in the mean change of Harris hip score (which assesses functional ability and hip dynamics, scored from 0 to 100, higher scores better) from baseline in patients treated by mini-incision total hip replacement (n = 597) compared to those treated by the standard-incision approach (weighted mean difference [WMD] 3.99) (95% confidence interval [CI] -0.18 to 8.16) (p = 0.06) (follow-up not stated). A case series of 759 patients (1000 hips) reported that the mean Harris hip score improved from 34 points at baseline to 92 points at a mean 37-month follow-up (significance not stated).

2.3.2 A randomised controlled trial of 219 patients treated by mini-incision or standard-incision hip replacement reported that 85% (88/103) and 91% (96/105) of patients respectively were able to 'mobilise' the day after the operation (p = 0.54).

2.3.3 The systematic review of 1205 patients reported that mean length of hospital stay was significantly shorter after minimally invasive procedures than after standard-incision procedures: WMD -3.59 (95% CI -5.69 to -1.50) (p = 0.0008).

2.3.4 The Specialist Advisers listed key efficacy outcomes as length of hospital stay, requirement for analgesics and long-term functional result.

2.4 Safety

2.4.1 Revision surgery was required in 1 patient in a case series of 400 hips at 18-month follow-up; in 2% (21/1000) of hips in the case series of 759 patients at a mean 37-month follow-up; and in 9% (8/90) of hips in the case series of 70 patients at a mean 11-year follow-up.

2.4.2 The systematic review of 1205 patients reported that the overall rate of complications was not significantly different between patients treated by minimally invasive surgery and those who had standard-incision procedures: odds ratio 1.08 (95% CI -0.59 to 1.97) (p = 0.81) (follow-up not stated).

2.4.3 Deep vein thrombosis or pulmonary embolism was reported in 1% (12/1000) of hips in the case series of 759 patients at a mean follow-up of 37-months.

2.4.4 The UK National Joint Registry reported rates of calcar crack (femoral crack around the insertion of the prosthesis) of less than 1% (95/19,041) in patients treated by the procedure and less than 1% (1185/306,625) in patients treated by surgery using a standard approach. The rates of femoral shaft fracture were less than 1% (10/19,041 and 192/306,625 respectively) at follow-up of 0.1 to 6.5 years.

2.4.5 The case series of 759 patients (1000 hips) reported heterotopic ossification in 20% (198/1000) of hips at a mean follow-up of 37-months, but none of these were high grade (grade IV) or required further treatment. The case series of 70 patients (90 hips) reported osteolysis in 11% (8/70) of hips that underwent radiographic assessment at a mean follow-up of 11 years.

2.4.6 The Specialist Advisers commented that malposition of components leading to dislocation, and femoral fracture are reported adverse events. They considered theoretical adverse events to include neurovascular damage due to poor operative view and blood loss.

2.5 Other comments

2.5.1 Most of the evidence presented to the Committee was on single incision minimally invasive hip replacement. The Committee saw some evidence on minimally invasive 2-incision total hip replacement (much of it mixed with evidence on single-incision surgery). They noted that the 2-incision technique is seldom used in UK practice at present. NICE has asked the National Joint Registry to collect data on 1-incision and 2-incision minimally invasive hip replacement separately, to inform any future review of these different approaches.

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

May 2010

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_{It is the responsibility of consultees to accurately cite academic work in order that they can be validated.}