15
Consistent users (n=64) of the device in this phase had an initial success
rate of 92.2% with a success rate of 70% after four years (a 24% reduction).
Inconsistent users (n=34) and the entire placebo group (n=97) had an
initial success rate of 65% with a success rate of 50% after four years (again,
a 24% reduction). Long-term follow-up data indicates the success rate
differentials between active and placebo units are maintained over time.
Long-term, consistent SpinalStim users benefit with a 40% increase in fusion
success, when compared to inconsistent and placebo device users. Based
on this analysis, the reduction in long-term success rates appears unrelated
to treatment with the SpinalStim. During this four year period, 10% of the
original patients in the randomized double-masked phase were lost to
follow-up and are not reflected in these success rates.
Failed Fusion Clinical Trial
SpinalStim was also tested for nonoperative salvage in patients presenting
with established pseudarthrosis of lumbar fusion in an open trial. Without
concomitant regrafting, 67% of these cases reached a successful fusion with
consistent (an average of at least 2 hours per day)
PEMF treatment.
2
The four year success rates for these patients in the open trial, non-operative
salvage phase for all subjects (consistent and inconsistent users combined)
was 39% (n=119) as compared with 57% in this phase of the original clinical
trial (i.e., one year postoperative). Consistent users (n=93) of the device in this
phase had a success rate of 44% after four years. Inconsistent users (n=26) of
the device in this phase had a success rate of 19% after four years.
The reduction in success rates from the time of commercial marketing
compared with those at four years showed a similar percentage decrease
(31%) to those in the randomized double-masked trial. During this four year
period, 6% of the original patients in the open phase were lost to follow-up
and are not reflected in these success rates.
1
Mooney, V., “A Randomized Double-Blind Prospective Study of the Efficacy of Pulsed Electromagnetic
Field for Interbody Lumbar Fusions”, SPINE, Vol. 15, No. 7, P708, 1990.
2
Simmons, JW, Hayes, MA, Christensen, KD, Dwyer, AP, Koulisis, CW, Kimmich, SJ: “The Effect of
Postoperative Pulsed Electromagnetic Fields on Lumbar Fusion: Open Trial Study”. Presented at the
Annual Meeting of the North American Spine Society, Quebec City, Canada, 2 July 1989.
