5 year Outcomes and Survivorship Analysis of Posterior Pedicle Screw Non-Fusion Stabilization

Presented at SMISS Annual Forum 2014
By Neel Anand MD
With Eli M. Baron MD, Babak Khandehroo MD, Sheila Kahwaty PA-C,

Disclosures: Neel Anand MD None Eli Baron MD , Babak Khandehroo MD None, Sheila Kahwaty PA-C None,

Introduction:
For years pedicle-screw-based nonfusion system has been used for treatment of Spinal disorders such as stenosis and spondylolisthesis. This technique tries to stabilize the spine while preserving spinal motion without fusion. However, lack of long-term outcomes of implanting this device and possible failure of the device has been a big concern in adapting this new technique.

Aims/Objectives:
This study was conducted to assess the long term outcomes of Posterior Non-Fusion Stabilization for the treatment of spinal radiculopathy.

Methods:
This is a retrospective study of 75 consecutive patients (mean age 57.7) who underwent non-fusion stabilization with the Dynesys system for the treatment of spinal radiculopathy. Patients were divided in 2 groups. Group1: Patients with prior decompression surgery (n=31) and group2: Patients without prior decompression surgery(n=44) . A 5-year survival plot was constructed and the average survival of the device was determined among all patients who had the device removed because of treatment failure. Clinical and functional outcomes including Visual Analogue Scale (VAS) for back and leg, Treatment Intensity Score(TIS), Oswestry Disability Index (ODI) and quality-of-life (SF-36) were compared preoperatively and postoperatively

Results:
The minimum follow-up was 5yrs. At last follow up 16 patients in group 1 and 11patients in group 2 underwent revision surgery (p< 0.05). Starting with 75 implanted devices; 71pts (94.7%) had the system intact after 1 year, 70 (93.3%) after 2 years, 65 (86.7%) after 3years, 63 (84%) after 4 years and 62pts (82.7%) after more than 5yrs: Of these patients who had the device intact (n=62), 22pts (29.3%) reported pain: 12 (16%) at index level, 10(13.3%) at adjacent level and 40pts (53.3%) reported excellent outcomes with minimal to no pain and no complications. The mean VAS score changed from 6.63 to 3.35(p< .05), leg VAS from 8.0 to 2.82(p< .05), TIS from 52.7 to 40.8, ODI from 38.7 to 32.5, SF-36 mental from 48 to 66.6 and SF-36 physical from 28.1 to 64.1.

Conclusions:
At 5 years and beyond, our study demonstrates that clinical and functional outcomes of Non-Fusion stabilization are comparable with that reported with spinal fusion. 82.7% of the patients had their device intact and functioning beyond 5yrs. This approach may offer a viable long-term treatment for spinal stabilization. Our study suggests that the Dynesys system is a stable device with minimal failure and malfunction. Finally, we report that surgical outcomes may be considerably poorer in patients with prior history of lumbar decompression surgery.