Abstract
Introduction
The objective of this study is to show that a minimally invasive percutaneous IPD is safe and non-inferior to SDS with regards to clinical outcomes in patients suffering from Degenerative Lumbar Spinal Stenosis with NIC (Neurogenic Intermittent Claudication), relieved by flexion.
Methods
One hundred and sixty three patients enrolled by 19 sites across 10 countries (mean age 65 ± 11 years, 51% female, mean duration of leg symptoms 2.5 years) were randomly assigned to IPD or SDS group and are followed until 24 months. Physical function, symptom severity and patient satisfaction were assessed by Zurich Claudication Questionnaire (ZCQ) at baseline, 14days, 6 weeks, 6 months and 12 months follow-ups. Leg, buttock/groin and back pain were assessed by VAS scores. SF-36v2 questionnaire was used to assess quality of life. In addition, physical examination data was collected at all-time points. Percentage of re-operations at index level at follow-up was determined. (Trial registration NTC00905359)
Results
ZCQ physical function mean percentage change from baseline to 12 months (primary outcome variable) decreased equally and without statistically significant difference over all points in time for IPD and SDS group (respectively, −32 ± 32%, −37 ± 23%, p = 0.158, CI −5, +15). As for secondary outcomes the IPD group showed lower mean surgical time and mean blood loss (respectively, 24 ± 11 minutes and 6 ± 10 ml, p < 0.001) compared with the SDS group (70 ± 39 minutes and 157 ± 145 ml, p < 0.001). Symptom severity improved in both groups equally (−31 ± 27%, −36 ± 25%, p = 0.140, CI −4, +14). No differences in patient satisfaction were observed. VAS leg pain score improved with 59% for the IPD and 66% for the SDS group from baseline to 12 months follow-up. SF-36 v2 physical and mental aggregated score improved equally over time for both treatment groups. At 12 months, 47 SAEs were reported, in 36 patients. Re-operations at index level occurred in 9% of the patients in the IPD group and in 7% in the SDS group. In 6 patients the IPD was explanted.
Conclusions
This study confirms two prior recent RCTs. Implantation of an IPD as well as open decompression achieve both equally satisfying results in patients with NIC. Both seem to be appropriate procedures with an advantage in some secondary outcomes for IPDs. So far the significantly higher reoperation rate for IPDs could not be confirmed in this study, which opens a window of indication in a subset of patients with NIC, i.e., those with cardiac or other comorbidities.