Interspinous devices: are they as attractive as they seem? An intermediate-term follow-up

A retrospective cohort of 68 patients who underwent insertion of the DIAM (Medtronic Sofamor Danek, Switzerland) interspinous device (ISD) during 2006-2008 at one medical center.

To assess the short- and intermediate-term outcomes and complications associated with ISD.

Evaluation of files and all patients who underwent insertion of a DIAM ISD was performed. Patients walking distances and pain (visual analog scale score) were compared with data gathered before surgery. Outcome and all complications related to ISD have been identified and analyzed.

All 68 patients were available for follow-up. Mean follow-up was 34 months (23-52 months). The average age was 57 (±13) years. Walking distance increased by 890% and patient's pain score improved by 3.27 points on visual analog scale. Twenty-one (32%) of the 68 patients had perioperative or late complications. Nine complications (75%) were unrelated to ISD and included 5 dura tears, 3 wound-related complications, and 1 transient ischemic attack. Spinous process fractures occurred in 5 cases, leading to revision in 2 cases. In total, 7 of the patients required revision surgery. These patients were older, with an average age of 69 years.

The outcome of patients who had an implantation of the DIAM ISD is good. In this cohort, 6% developed recurrent claudication symptoms in the second postoperative year. In an older population, the combination of softer bone and rigid stenosis increase the risk of spinous process fracture, resulting in failure and leading to revision surgery. Other solutions should be sought for these patients. [Table: see text] The definiton of the different classes of evidence is available on page 55.