715558 - Improved Bone-removal Using a New Device in Open and Minimal Invasive Approaches: Cadaver Study and a 2-center Experience with 143 Patients

Background: Spinal procedures often require the removal of bony tissues to prevent nerve compression and reduce pain. Sufficient bone removal is complicated by the need to minimize supporting bony structure destruction. Traditional bone removal tools and methods limit the surgeon ability to reach difficult-access regions and therefore increase healthy bone removal and procedure time.

Purpose: Here we describe the experience accumulated using a recently developed, FDA-approved, shielded curved drill, designed to provide efficient disc and bone removal from difficult-access areas such as the foramen, while improving procedure safety and speed.

Study design: Case series and a cadaver study.

Case series eligible population: The device was used in three centers to perform foraminotomy, osteophyte removal and disc-space preparation since February 2013. All the procedures for which a record of device-use was available, were included in the analysis.

Case series patient accountability: 551 patients were treated using the device in three independent centers. The procedures included lumbar, thoracic and cervical spinal fusions and decompressions, of which 108 were minimally-invasive.

Outcome measures: In the cadaver study, the device was compared to traditional tools on the lumbar vertebras of three cadavers. CT scans performed before and after the procedures were used to quantify the relative changes of the lateral recess diameter, foraminal area, minimal-foraminal-volume (foraminal area multiplied by lateral recess diameter), and the pars-interarticularis (pars) diameter (indicating potential spinal instability).
In the clinical series, procedure length was recorded, as well as the duration of device use. Surgeon assessment was obtained using questionnaires at the end of each procedure.

Methods: The pre-operative and post-operative CT scans of the cadavers were used to quantify the parameters of interest described above. Changes due to the procedure were calculated and used to assess the extent of bone removal.
The clinical series questionnaires and operative data was analyzed to evaluate surgeon assessment and device-use patterns.

Results: In the cadaver study, the foraminal area, lateral recess diameter and minimal-foraminal-volume increases were higher by 129%, 92% and 115%, respectively, for the cadaver foramina treated by the new device compared with traditional methods (p=0.11, 0.11 and 0.03, respectively). Average pars decrease was reduced by 24% suggesting this device enables a more effective procedure while sparing healthy tissue and reducing the risk of spinal instability.
All clinical procedures were successful, with one device-related dural tear (<0.2%). Surgeon satisfaction rate was 97%. Surgery time reduction was the most common comment in surgeon questionnaires. In some cases, of multi-level complicated fusions, the time reduction was estimated at several hours. Lumbar foraminotomy using the device required, on average, 2 minutes/foramen. Osteophyte removal required, on average, 3 minutes. The device was successfully used in both open and minimal invasive settings.

Conclusions: The device is safe and effective for performing spinal surgery in both open and minimal invasive settings. Procedure time reduction was noted as the most significant advantage by the surgeons. The cadaver study demonstrated the ability to achieve improved bone-removal with reduced damage to healthy spinal structures.