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Chapter 5
Results
Between October 2008 and September 2011, 203 patients with intermittent neurogenic claudication due to spinal stenosis were referred to the Leiden-The Hague Spine Prognostic Study Group. For all patients, the including neurosurgeon confirmed a single or two level, magnetic resonance imaging confirmed, degenerative stenosis and intermittent neurogenic claudication according to the referring neurologists. One hundred and sixty two patients gave informed consent and were enrolled in the FELIX trial (fig 1[f1]). One patient died while waiting for the operation. Two patients were found to have a severe spondylolysis of the L5-S1 segment at the final preoperative check-up and were excluded from the study, because this could cause a detrimental effect in the implant group. The remaining patients were randomly assigned to interspinous process device or decompression, and 159 patients received the allocated treatment. All patients had had intermittent neurogenic claudication for an average period of 23 (intermittent neurogenic claudication group) and 22 (decompression group) months. No significant differences were noted in baseline characteristics between patients in the two treatment arms (table 1[t1]). Seven patients were lost to follow-up in the interspinous process device group and one patient in the bony decompression group.
Successful recovery according to the Zurich Claudication Questionnaire at short term follow-up (eight weeks) was achieved by 63% of the patients in the interspinous process device group compared with 72% in the bony decompression group (odds ratio 0.73; P=0.44). Long term (one year) successful recovery according to the Zurich Claudication Questionnaire was similar in the two groups, resulting in 66% good results in the interspinous process device group and 69% in the bony decompression group (odds ratio 0.90; P= 0.77). Overall, the Zurich Claudication Questionnaire analysis showed no differences between the two treatment arms (table 2[t2]; fig 2[f2]).
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