Interventional procedure consultation document

Insertion of an annular disc implant at lumbar discectomy

 

The tough covering of a spinal disc (annulus) can sometimes break, allowing the soft centre to bulge through.  This is called herniation, also known as a ‘slipped disc’. This may cause pain in the back and leg, and numbness and weakness in the leg (‘sciatica’). Inserting an annular disc implant involves removing the bulging part of the disc (lumbar discectomy) and inserting an implant to close the hole that is left in the disc. The aim is to reduce the risk of further herniation.

 

The National Institute for Health and Care Excellence (NICE) is examining insertion of an annular disc implant at lumbar discectomy and will publish guidance on its safety and efficacy to the NHS. 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 an annular disc implant at lumbar discectomy.

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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of the procedure in the NHS.

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, advance equality of opportunity, 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: 2 September 2014

Target date for publication of guidance: November 2014

 

 

 

 

1                      Provisional recommendations

1.1                  Current evidence on the safety and efficacy of insertion of an annular disc implant at lumbar discectomy is limited in quantity and quality. Therefore this procedure should only be used with special arrangements for clinical governance, consent and audit or research.

1.2                  Clinicians wishing to undertake insertion of an annular disc implant at lumbar discectomy should take the following actions.

·      Inform the clinical governance leads in their NHS trusts.

·      Ensure that patients and their carers understand the uncertainty about the procedure’s safety and efficacy and provide them with clear written information. In addition, the use of NICE’s information for the public [URL to be added at publication] is recommended.

·      Audit [URL to audit tool to be added at publication] and review clinical outcomes of all patients having insertion of an annular disc implant at lumbar discectomy (see section 6.1).

1.3                  NICE encourages further research on insertion of an annular disc implant at lumbar discectomy, particularly comparative trials. In addition, data should be collected on all patients for local audit and review, with a view to collaborative publications. All studies should report details of patient selection and recurrence rates.

 

 

 

 

 

2                      Indications and current treatments

2.1                  Lumbar disc herniation occurs when the nucleus pulposus of an intervertebral disc protrudes through a tear in the surrounding annulus fibrosus. Symptoms include pain in the back or leg, and numbness or weakness in the leg. Serious neurological sequelae may sometimes occur.

2.2                  Conservative treatments include analgesics, non-steroidal anti-inflammatory medication and physical therapy. Epidural corticosteroid injections can also be used to reduce nerve pain in the short term. Lumbar discectomy is considered if there is evidence of severe nerve compression or persistent symptoms that are unresponsive to conservative treatment. Surgical techniques include open discectomy or minimally invasive alternatives using percutaneous approaches.

2.3                  Lumbar discectomy usually leaves a hole in the annulus fibrosus through which the nucleus herniated, which may lead to reherniation and progressive loss in disc height.

 

 

 

 

 

3                      The procedure

3.1                  Insertion of an annular disc implant at lumbar discectomy aims to reduce the incidence of recurrent herniation and the degree of intervertebral disc collapse.

3.2                  With the patient under general anaesthesia, the herniated disc material is removed and the annular disc device is implanted. The device typically contains a metallic bone-anchoring component and a woven polymer mesh. The bone-anchoring component is inserted using a mallet and tamp into one of the vertebral bodies adjacent to the discectomy site, and the woven mesh component is inserted into the annular disc defect, so covering the residual nucleus pulposus. Fluoroscopy may be used to guide the procedure.

 

 

 

 

 

4                      Efficacy

This section describes efficacy 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 interventional procedure overview

4.1                  A non-randomised comparative study of 102 patients (30 treated with discectomy plus annular disc implant and 72 patients treated with discectomy only) reported improvement in Oswestry Disability Index (ODI) scores in both groups from 62.7 and 49.4 respectively (p=0.0004, between group comparison) before surgery to 31.4 and 30.7 respectively (p=0.75, between group comparison) at 6 weeks, with further improvement to 11.6 and 19.8 respectively (p=0.076, between group comparison) at 24 months.

4.2                  The non-randomised comparative study of 102 patients reported that back pain scores (measured on a 100‑point visual analogue scale, with higher scores indicating more severe pain) improved from 66.3 before surgery to 10.5 at 24 months after surgery in the implant group and from 43.1 to 19.1 in the control group (no p values reported). Leg pain scores improved from 79.8 before surgery to 8.9 at 24 months after surgery in the implant group and from 58.8 to 21.2 in the control group (no p values reported). Although the scores for back and leg pain were significantly different between the 2 groups before surgery (p=0.0000 for back pain and p=0.0001 for leg pain), at 12 months and 24 months after surgery, they remained significant for leg pain (p=0.0160 and 0.0046 respectively) but not for back pain.

4.3                  The non-randomised comparative study of 102 patients reported no reherniations in the implant group within 2 years after surgery, whereas 3% (2/72) of patients in the control group had a reherniation within 3 months after surgery and 4% (3/72) had a reherniation between 4 months and 2 years after surgery (p value not reported). A non-randomised comparative cohort study of 76 patients (30 patients from the same implant cohort as in the previous study versus 46 patients treated with discectomy only) reported no reherniations 24 months after surgery in the implant group but 7% (3/46) in the control group (no significant difference).

4.4                  The non-randomised comparative cohort study of 76 patients reported a lower mean loss of disc height from 8.60 mm to 7.63 mm (0.97 mm loss) in the implant group compared with 8.30 mm to 6.90 mm (1.40 mm loss) in the control group 12 months after surgery (p=0.054). A case series of 45 patients reported a decrease of the mean disc height to 92.8% of baseline at 12 months (p<0.01).

4.5                  The specialist advisers identified a key efficacy outcome as recurrence of herniation over a 10‑year period.

 

 

 

 

5                      Safety

This section describes 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 interventional procedure overview.

5.1                  Incidental durotomy (potentially causing cerebrospinal fluid leakage and complications such as headache) occurring during disc fragment removal was reported in 3% (1/30) of patients treated with discectomy plus annular disc implantation and 1% (1/72) of patients treated with discectomy only in a non-randomised comparative study of 102 patients (level of significance not stated). Incidental durotomy was reported in 3% (1/30) of patients treated with discectomy plus annular disc implantation and 2% (1/46) of patients treated with discectomy only in a non-randomised comparative cohort study of 76 patients that used the same implant cohort as in the previous study (p value not reported).

5.2                  Suspected discitis 56 days after surgery was reported in 3% (1/30) of patients treated with discectomy plus annular disc implantation and none of the patients treated with discectomy only in the non-randomised comparative cohort study of 76 patients (level of significance not stated). The infection was successfully treated with intravenous antibiotics.

5.3                  Reoperations were reported in 7% (3/45) of patients treated with the annular disc implant after discectomy in a case series of 45 patients: 1 was a symptomatic reherniation 4 months after surgery because the device was implanted too deep into the disc space, 1 was a contralateral herniation 3 weeks after surgery possibly caused by the implant, and 1 reoperation was performed for excessive scar tissue 5 months after surgery.

5.4                  The specialist advisers listed additional theoretical adverse events as haematoma, cauda equina damage, implant displacement causing nerve root damage, pain, numbness, weakness and neurological compression.

 

 

 

 

 

6                      Further information

6.1                  This guidance requires that clinicians undertaking the procedure make special arrangements for audit. NICE has identified relevant audit criteria and is developing an audit tool (for use at local discretion), which will be available when the guidance is published.

 

 

 

 

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee
June, 2014

 

^{Personal data will not be posted on the NICE website. In accordance with the Data Protection Act names will be anonymised, other than in circumstances where explicit permission has been given.}

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