1062 Effect of Interbody Implant Design on Early Clinical and Radiographic Outcomes in LLIF Surgery: Interim Analysis of a Prospective Comparative Trial

INTRODUCTION: LLIF patients have shown a high success rate of fusion, but limited data exist on the influence of implant design on clinical and radiographic outcomes from prospective, comparative clinical studies. METHODS: Prospective, comparative multi-center study, randomized to receive allograft cancellous chips with autologous bone marrow aspirate or allograft cellular bone matrix. All subjects had 6-month CT imaging reviewed for fusion by three spine surgeons, and for implant condition and subsidence by an independent core lab. RESULTS: 117 subjects were included (SP, n=53; PTI, n=35; PP, n=29), 60% female, mean age was 64.7 years, and mean BMI was 31.5 kg/m2. Demographics were similar when compared between groups; all p>0.05. The most treated level was L4-L5 (74%), for degenerative spondylolisthesis (80%). Operative times (anterior: 62.4 min and posterior: 75.8 min), estimated blood loss (anterior: 60.4 ml and posterior: 73.5 ml), and length of stay (2.1 days) were similar between groups. At 6 months post-op, mean VAS back and leg pain improved by 4.0 and 5.7 (SP), 4.9 and 4.6 (PTi), and 3.5 and 3.9 (PP), respectively. Mean ODI score improved by 20.5 (SP), 25.4 (PTi), and 20.6 (PP). No significant difference between groups; all p>0.05. Fusion rates by level were significantly higher in the PTi (n=41) group with 82.9% fused (p<0.05), after controlling for biologic type, compared with SP (n=62) and PP (n=32) groups with 32.3% and 40.6%, respectively. No incidence of implant migration or subsidence was reported. CONCLUSIONS: LLIF surgery using either SP, PTi, or PP interbody implants led to improvement in clinical outcomes. Fusion rate at 6 months was significantly higher in the PTi group compared with SP and PP.