Interventional procedure consultation document

Interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication

Lumbar spinal stenosis is a narrowing of the spinal canal in the lower part of the back. This causes discomfort in the legs when standing or walking because of pressure on the spinal nerves. This procedure involves implanting a device into the space between two back bones to relieve pressure on the nerves and, therefore, pain in the legs.

The National Institute for Health and Clinical Excellence (NICE) is examining interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication and will publish guidance on their 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 procedures. The Advisory Committee has made provisional recommendations about interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication.

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 these procedures. 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• The Advisory Committee will then prepare draft guidance which will be the basis for NICE’s guidance on the use of these procedures in the NHS in England, Wales, Scotland and Northern Ireland.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: 27 July

Target date for publication of guidance: November 2010

1   Provisional recommendations

1.1  Current evidence on interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication shows that these procedures are efficacious for carefully selected patients in the short and medium term, although further surgery may be needed. There are no major safety concerns. Therefore these procedures may be used provided that normal arrangements are in place for clinical governance, consent and audit.

1.2  Patient selection should be carried out by specialist spinal surgeons who are able to offer patients a range of surgical treatment options.

2   The procedure

2.1  Indications and current treatments

2.1.1  Lumbar spinal stenosis is most often caused by degenerative disease of the lumbar vertebrae and their associated joints. Neurogenic claudication can then result from compression of spinal nerves by inward buckling of the ligamentum flavum. The principal symptom is leg pain when standing or walking, relieved by sitting or by flexing the spine.

2.1.2  Conservative treatments include non-steroidal anti-inflammatory medication and rest. For patients with refractory symptoms, surgery may be performed to decompress the spinal nerve roots (laminectomy or ligamentectomy). Spinal fusion may also be performed.

2.2   Outline of the procedure

2.2.1  Interspinous distraction procedures involve placing an implant between the spinous processes of the affected vertebrae (usually L4/5) with the aim of limiting extension and so preventing or reducing leg pain when standing or walking.

2.2.2  These procedures are normally carried out with the patient under conscious sedation or general anaesthesia. The patient is appropriately positioned with their spine flexed: operative level(s) are usually confirmed by fluoroscopy. The vertebral spinous processes and their interspinous ligament are exposed through a midline incision. An implant of appropriate size is positioned through the supraspinous ligament, which helps to hold the implant in place, between the flexed spinous processes of adjacent vertebrae.

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 these procedures. For more detailed information on the evidence, see the overview, available at www.nice.org.uk/IP191aoverview

2.3   Efficacy

2.3.1  An RCT of 191 patients treated by interspinous distraction (n = 100) or conservatively (n = 91) reported improvements in symptom severity (measured using the Zurich Claudication Questionnaire) of 45% and 7% respectively at 2-year follow-up (p < 0.001). Clinically significant improvement in symptom severity (not defined) was reported in 60% (56/93) and 19% (15/81) of patients respectively at 2-year follow-up (p < 0.001).

2.3.2  A non-randomised controlled study of 61 patients treated by interspinous distraction (n = 30, mean follow-up 40.4 months) or by posterior lateral interbody fusion (n = 31, mean follow-up 38.4 months) reported a significant improvement (decrease) in visual analogue scores (on scale from 0–10) for low back pain  (from 4.7 to 2.4 and from 5.5 to 3.3 respectively) and for leg pain (from 6.9 to 2.4 and from 6.5 to 2.6 respectively; p < 0.001 from baseline to follow-up for all scores but no significant difference between groups).

2.3.3  The non-randomised study of 61 patients reported a significant decrease in Oswestry Disability Index (on a scale from 0–100 with 100 being greatest disability) for patients treated by interspinous distraction and those treated by interbody fusion, from 23% to 11% and from 21% to 11% respectively; p < 0.001; no significant difference between groups (mean follow-up 40.4 months and 38.4 months respectively).

2.3.4  The RCT of 191 patients showed significantly better Short Form-36 scores for physical function, health-related physical limitations, bodily pain, energy levels, social functioning and mental health in patients treated by interspinous distraction compared to those who had conservative treatment at 2-year follow-up.

2.3.5  An unpublished abstract of 69 patients treated by interspinous distraction reported that 27% (18/66) of patients required removal of the spacer and revision surgery (timing of events not stated). A case series of 175 patients reported that 5% (8/175) of patients required removal of the device because the procedure was unsatisfactory.

2.3.6  In a case series of 241 patients, 107 completed questionnaires at the final follow-up (mean 13.5 years). Among these, 59% (51) of the 87 patients who still had implants in place were very satisfied compared with 25% (5) of the 20 patients who had undergone implant removal and spinal fusion (p < 0.001).

2.3.7  The RCT of 191 patients reported that subsequent laminectomy because of unresolved stenosis was required in 6% (6/100) of patients who had interspinous distraction and 26% (24/91) of patients in the control group (time of conversion not stated).

2.3.8  The Specialist Advisers listed key efficacy outcomes as relief of claudication pain in the leg and functional improvement.

2.4   Safety

2.4.1  The RCT of 191 patients reported 1 case of implant malpositioning (not otherwise described) and 1 of implant migration after a fall, requiring removal without sequelae. An RCT of 75 patients reported that 1 of the 42 patients treated by interspinous distraction had implant malpositioning, detected on 6-month radiographic examination (not otherwise described).

2.4.2  The non-randomised study of 61 patients reported device fracture in 1 of the 30 patients treated by interspinous distraction (time of occurrence and further details not stated).

2.4.3  A case series of 69 patients (92 implantations) reported device dislocation in 4 devices (3 patients) at 4-day, 6-day and 2-week follow-up. The same study reported device malpositioning in 1 patient at 6-week follow-up. All 4 patients had revision surgery.

2.4.4  A case series of 69 patients reported spinous process fracture in 1 patient intraoperatively and 3 patients postoperatively (at 1 week, 4 months and 6 months).  The postoperative fractures were treated by revision surgery. One was caused by trauma.

2.4.5  The Specialist Advisers considered anecdotal adverse events to include infection and movement of the implant after placement. They stated that malpositioning of the implant was also a possibility.

2.5  Other comments

2.5.1  The Committee noted that interspinous distraction procedures may not provide a long-term cure, and patients should be warned that further surgery may be necessary.

3   Further information

3.1  This guidance is a review of ‘Interspinous distraction procedures for lumbar spinal stenosis causing neurogenic claudication’. NICE interventional procedures guidance 165 (2006).

3.2  For related NICE guidance see www.nice.org.uk

Bruce Campbell

Chairman, Interventional Procedures Advisory Committee
July 2010

_{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.}