Safety and Effectiveness Study of the TOPS System, a Total Posterior Arthroplasty Implant Designed to Alleviate Pain Resulting From Moderate to Severe Lumbar Stenosis

This study is being conducted to evaluate a new surgical implant (TOPSâ„¢ System, Impliant).
The TOPSâ„¢ System is an alternative to spinal fusion that is designed to stabilize but not
fuse the affected vertebral level following decompression surgery to alleviate pain stemming
from moderate/severe lumbar spinal stenosis while maintaining range of motion.

When non-surgical treatment is ineffective, decompression (including laminectomy and medial
facetectomy) and fusion of the spinal segments with moderate/severe lumbar spinal stenosis
has been used to stabilize the motion segment and to alleviate the patient's clinical
symptoms. Spinal fusion surgery using metal instrumentation is designed to stop motion at
a painful, unstable spinal segment by permanently fusing the segment. While fusion may
decrease pain generated at the treated segment, the procedure also eliminate motion at the
implanted level and transfers and thus increases loads on the adjacent segments.

The TOPS System is intended to provide stabilization following decompression in patients
with disease at one level from L3 to L5. The ideal goal of stabilization is to preserve
mobility but eliminate abnormal motion and prevent deformity. By using the TOPS System, it
may be possible to preserve load-bearing dynamics and spinal biomechanics, and thereby
maintaining motion at the treated segment.

The TOPS surgical technique, utilizing a standard top loading pedicle screw-based system, is
the same as a standard posterior spinal fusion with the exception of the placement of the
TOPS motion segment. Therefore, the surgeon will be executing the steps of surgical
exposure, decompression, insertion of pedicle screws (with attention to proper
placement/alignment) and closure in the same manner as he/she would in a standard posterior
spinal fusion.

The objective of the clinical investigation is to compare the safety and effectiveness of
the TOPS System to a control group of patients undergoing posterior spinal fusion with
pedicle screws and local autograft bone in the treatment of back and leg pain that results
from moderate/severe lumbar spinal stenosis at a single vertebral level between L3 to L5.

Prior to entering the study, patients will be evaluated by the investigator according to the
inclusion/exclusion criteria. Patients recruited to the study will be randomized in a 1:1
ratio to undergo implantation of the TOPS System or the control spinal fusion procedure.
Patient follow-up will be evaluated immediately post-operatively and at discharge, 6 weeks,
3 months, 6 months, 12 months, and 24 months.