80. Cellular bone matrix in multilevel ACDF: A prospective evaluation of 1-year fusion rates and patient reported outcomes

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<h3>BACKGROUND CONTEXT</h3> Multilevel ACDF has an increased risk of pseudarthrosis compared to single-level fusion. Most current graft options carry some degree of morbidity or downside. Cellular bone matrix (CBM) is an off the shelf product containing allograft bone, mesenchymal stem cells and demineralized bone matrix. It possesses osteoinductive, osteoconductive and osteogenic properties. Early studies have shown high fusion rates, good patient reported outcomes (PROs), and low morbidity. <h3>PURPOSE</h3> To assess 12-month PROs and fusion rates in patients undergoing multilevel ACDF using CBM. <h3>STUDY DESIGN/SETTING</h3> Prospective, single center case series performed in a large private hospital system. <h3>PATIENT SAMPLE</h3> Patients >18 indicated for a 2-4 level ACDF between C2 and T1. Exclusion criteria included 1) BMI over 40 2) diagnosis of metabolic bone disease, 3) active infection, open wounds or lack of appropriate skin coverage, 4) history of previous cervical surgery, 5) known metal sensitivity or allergy to any components of CBM, 6) immunocompromised state, 7) history of substance abuse, 8) workman's comp for neck pain, 9) Prisoners, pregnant mothers or those planning to become pregnant. <h3>OUTCOME MEASURES</h3> Primary outcome measure was the NDI, using an MCID of 17.3%. Secondary measures were Bridwell grade I or II fusion at 12 months and statistically significant improvement on VAS and SF-36. <h3>METHODS</h3> ACDF was performed at each pathologic level. The graft was prepared by removing the cancellous center of an allograft spacer and filling the void with CBM. Operative levels were fixed with a standard titanium plate.NDI, VAS and SF-36 as well as AP and lateral X-rays were completed preoperatively and at 3, 6 and 12 months. CT was obtained at 12 months. Fusion was determined by the presence of bridging bone on 12-month CT. X-rays were graded by the senior author using the Bridwell anterior fusion grading system. Changes in NDI, VAS and SF-36 were calculated using a 1 sample t-test with Bonferroni correction. p<0.05 was used for significance. <h3>RESULTS</h3> NDI improved from 51.7% ± 8.8 to 31.2% ± 13.4 by 3 months and 29.1 ± 13.8 at final follow-up (p <0.001). SF-36 PCS improved from 40.7 ± 6.2 to 51 ± 9.1 at final follow-up (p<0.005). SF-36 MCS improved from 48.4 ± 8.3 to 52.8 ± 7.5 at final follow-up, which fell short of statistical significance (p=0.200). VAS improved from 78.9mm ± 15.3 to 14.8mm ± 19.4 by 3 months and 12.3mm ± 18 at final follow-up (p<0.001). Grade I or II fusion was present in 31/33 levels (93.9%) and 11/13 patients (84.6%) at 6 months. One level demonstrated grade IV resorption and collapse at 6 months. By 12 months there was grade I or II fusion at 33/33 levels. CT scan demonstrated bridging bone within or behind the allograft spacer in 33/33 levels. There were no major adverse events. <h3>CONCLUSIONS</h3> CBM used in multilevel ACDF resulted in high patient satisfaction, high fusion rate, and low morbidity. NDI at final follow-up showed a mean improvement of 23%, surpassing the MCID of 17.3%. We also saw significant improvements in the VAS and SF-36 PCS at 3,6 and 12 months, as well the SF-36 MCS at 6 months. At 6 months there was 93.9% fusion by level, and 84.6% by patient. By 12 months 100% of patients were fused. To our knowledge this represents the first prospectively collected, nonindustry funded study of its kind which adds to a small yet growing body of research in support of CBM in the cervical spine. <h3>FDA DEVICE/DRUG STATUS</h3> ViVigen Cellular Bone Matrix (Approved for this indication)