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NATIONAL INSTITUTE FOR HEALTH AND CLINICAL EXCELLENCE

Interventional procedure consultation document

Interventional procedure overview of insertion of individually MRI-designed unicompartmental interpositional implantin osteoarthritis of the knee

Osteoarthritis of the knee can cause pain, stiffness, swelling and difficulty in walking. In this procedure, an individually designed implant is inserted at the knee between the thigh and shin bones with the object of realigning the knee and preventing bone-on-bone rubbing. This aims to reduce pain and delay the progression of osteoarthritis and the need for further, more invasive surgery, such as knee replacement.

 

The National Institute for Health and Clinical Excellence (NICE) is examining interventional procedure overview of insertion of individually MRI-designed unicompartmental interpositional implantin osteoarthritis of the knee 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 insertion of individually MRI-designed unicompartmental interpositional implantin osteoarthritis of the knee.

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  • The Advisory Committee will then prepare draft guidance which will be the basis for NICE's guidance on the use of the procedure in the NHS in England, Wales, Scotland and Northern Ireland.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 opiPercutaneous endoscopic laser cervical discectomy nion of NICE, the comments are voluminous, publication would be unlawful or publication would otherwise be inappropriate.

Closing date for comments: 24 March 2009

Target date for publication of guidance: June 2009

 

1 Provisional recommendations
1.1 Current evidence on the safety and efficacy of insertion of individually magnetic resonance imaging (MRI)-designed unicompartmental interpositional implant in osteoarthritis of the knee is inadequate in quantity and quality. Therefore, this procedure should only be used in the context of research studies. These should include clear descriptions of patient selection; and report clinical and patient-reported outcomes and the length of time before joint replacement is required.
1.2 NICE may review the procedure on publication of further evidence.

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2 The procedure
2.1 Indications and current treatments
2.1.1 Osteoarthritis of the knee is the result of progressive degeneration of the menisci and articular cartilage of the joint, leading to exposure of the bone surface. It causes pain, stiffness, swelling, and difficulty in walking.
2.1.2 Treatment options depend on the severity of the osteoarthritis. Conservative treatments include medication to relieve pain and inflammation, physiotherapy and/or prescribed exercise, and corticosteroid injection. Surgical options include upper tibial osteotomy to realign the leg, and unicompartmental knee replacement. Patients with severe osteoarthritis may need total knee replacement.

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2.2 Outline of the procedure
2.2.1 The aim of this procedure is to correct the leg axis so that the line that passes through the centre of the hip to the centre of the ankle joint also passes through the centre of the knee joint (as in patients without this condition). By insertion of an individually MRI-designed metallic implant into either the medial or lateral compartment of the knee joint (whichever is required), this correction is intended to prevent the damaging eccentric loading of the knee, thereby delaying the progression of osteoarthritis and the need for a total knee replacement.
2.2.2 An MRI scan of the knee is performed to enable bespoke design of a metallic implant. The operation is usually performed with the patient under general anaesthesia, and may be done as a day case. Before implantation, the patient may have an arthroscopic procedure to remove osteophytes. The individually designed metallic implant is inserted into either the medial or lateral compartment of the knee joint depending on the change in leg axis required. Fluoroscopy may be used to confirm the position of the implant.

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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/IP705overview.

 

2.3 Efficacy
2.3.1 In a case series of 27 patients with early- to moderate-stage unicompartmental knee osteoarthritis treated by arthroscopic removal of osteophytes followed by insertion of an MRI-designed implant, the average correction in leg axis improved from −4.4° preoperatively to −0.9° postoperatively. Successful leg axis correction to 0° and/or slight undercorrection of up to 2° was reported in 85% (23/27) of patients (preoperative leg axis measurements not given). The remaining four patients were reported to have had an overcorrection of leg axis of 0.2°, 0.5°, and two patients with 0.9°. The follow-up MRI showed a low average loss of correction of 0.5° (range 0–1°) at 12–22 months. For all 27 patients, the correlation coefficient between implant offset (minimal thickness of the implant) and extent of axis correction was reported to be r = 0.84 (a coefficient of 0.8 has been proposed as ‘good').
2.3.2 The Specialist Advisers considered key efficacy outcomes to include reduced pain, ability to return to work, and ability to perform activities of daily living and sports. The Specialist Advisers considered uncertainties around the efficacy of the procedure to be similar to the uncertainties relating to the non-customised implants that preceded the MRI-designed implant. These included failure to provide good pain relief, dislocation or subluxation of the devices, and a high revision rate compared with standard types of knee replacement. One Specialist Adviser expressed concern that loosening of the implant may cause further wear to the joint which may make knee replacement more difficult.

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2.4 Safety
2.4.1 The case series reported that there were no dislocations during or after the procedure but did not report any other safety data.
2.4.2 The Specialist Advisers listed theoretical adverse events including implant dislocation, infection, persistence of pain and general medical complications such as venous thromboembolism, cerebrovascular accident and myocardial infarction.

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3 Further information
3.1 This guidance requires that clinicians undertaking the procedure make special arrangements for audit. NICE has identified relevant audit criteria and is developing audit support (which is for use at local discretion), which will be available when the guidance is published.
3.2 NICE has published interventional procedures guidance on arthroscopic knee washout, with or without debridement, for the treatment of osteoarthritis (www.nice.org.uk/IPG230) and artificial trapeziometacarpal joint replacement for end-stage osteoarthritis (www.nice.org.uk/IPG111). NICE has also published guidance on the use of cyclo-oxygenase (Cox) II selective inhibitors, celecoxib, rofecoxib, meloxicam and etodolac for osteoarthritis and rheumatoid arthritis (www.nice.org.uk/TA27) and a clinical guideline on osteoarthritis: the care and management of osteoarthritis in adults (www.nice.org.uk/CG59).

 

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee

December, 2008

 

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