Clinical and Radiographic Outcomes after ALIF, TLIF, LLIF, or PLIF with Spinous Process Fusion in an Elderly Cohort

Presented at SMISS Annual Forum 2014
By Amir Vokshoor MD
With Arian Esmaili BS, Sanjay Khurana MD, Dean Wilson PA, Peter Filsinger MD,

Disclosures: Amir Vokshoor MD None Arian Esmaili BS A; Lanx, Inc., B; Lanx, Inc., C; Lanx, Inc., Sanjay Khurana MD None, Dean Wilson PA None, Peter Filsinger MD None,

Introduction:
Spinous process fusion (SPF) combined with interbody fusion (IBF) is becoming a common technique to treat lumbar back pain, however little data on clinical outcomes has been reported to date.
Aims/Objectives: In this study we describe VAS and fusion outcomes in a cohort of elderly patients with lumbar back pain due to degenerative changes in the spine.

Methods:
This was a retrospective cohort study. Charts from 39 consecutive patients from 3/2009-10/2011 who had ALIF, LLIF, TLIF, or PLIF plus interspinous fusion (ISF) facilitated by a SPF device (Biomet Spine, LLC (by its subsidiary Lanx, Inc)) were reviewed. Six early patients also had unilateral pedicle screws. Demographic, diagnostic, complications, and operative data were recorded, as well as radiographic and clinical (VAS) outcomes. VAS improvement over time was assessed with a linear mixed model which included a random intercept to account for repeated measures. Posterior ISF and IBF were assessed as follows: For ISF: Grade 1 = small islands of bone. Grade 2 = larger islands of coalescence with bridging to the surrounding anatomy. Grade 3 = technically fused: some solid incorporation and bridging bone. Grade 4 = solid fusion with incorporation and obvious stability and maturity. For IBF the Brantigan, Steffee, Fraser (BSF) criteria were utilized.

Results:
Mean age was 63 years (SD=11). There were 17 women in the cohort. 10 patients had prior lumbar surgery. Diagnosis was spondylolisthesis/stenosis. The mean preoperative VAS score was 6.7 (SD= 2.3). VAS score was reduced by a mean of 3.3 points (95% CI= -4.2 - -2.2, p=<0.001)) at three months and this improvement was maintained out to 12 months (figure 1). Mean Estimated blood loss was 213.4 ml, (SD=210.2). Mean length of stay was 3.3 days (SD=1.7). 28 patients had high quality CT images available to assess fusion status. Fusion rate was 96% for ISF, and 85.2% for IBF. There was no difference in fusion rates for the six patients with unilateral pedicle screws. Bone graft material was either autologous, Mastergraft, Vitoss, demineralized bone matrix or a combination. There were no spinous process fractures, or instances of device dislodgement or breakage. Three patients had an intraoperative complication; all were durotomies. There were six revisions due to pseudoarthrosis (2), adjacent segment disease, infection, and post-operative trauma (patient fell down the stairs).

Conclusions:
Lumbar IBF with interspinous fusion and fixation results in clinically and statistically significant improvement in pain scores with reasonable fusion rates.