Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P63. Pain-related safety outcomes seven years following lumbar total disc replacement in mobile core devices versus constrained core devices

Abstract

BACKGROUND CONTEXT Total disc replacement (TDR) is an alterative to fusion for treating patients with disabling discogenic back pain. While several studies report significant improvements in overall back pain following TDR, some patients may experience recurring episodes of pain in the lumbar and/or lower extremities. Competing lumbar disc arthroplasty devices include a mobile core device versus a constrained core device. Long-term follow up (>7 years) from investigational device trials is now available to better assess long-term outcomes with arthroplasty with the two device types. PURPOSE To evaluate pain-related adverse events in patients 7years following single-level total disc replacement at L4–L5 or L5–S1 with either a mobile core disc (MCD) or a constrained core device (CCD) to determine if implant design is associated with increased pain serious adverse effects at 7-year follow-up. STUDY DESIGN/SETTING This post-hoc analysis of a multicenter, prospective, randomized, controlled, investigational device exemption trial included patients with symptomatic lumbar degenerative disc disease at L4–L5 or L5–S1. PATIENT SAMPLE The patients had lumbar arthroplasty surgery with either an MCD (n=218) or CCD (n=65) implant and were randomized prior to surgery in the IDE study. OUTCOME MEASURES The study reviewed events deemed to be serious adverse events in a FDA IDE study. METHODS This post-hoc analysis of a multicenter, prospective, randomized, controlled, investigational device exemption trial included patients with symptomatic lumbar degenerative disc disease at L4–L5 or L5–S1. Pain related adverse events (AE) at 7years post implantation for TDRs as a class and by device type (MCD vs. CCD) are reported. RESULTS Of the reported AEs, 23% (N=327) were categorized as pain of the lumbar and/or lower extremities: lumbar only (7%), lumbar and bilateral lower leg (5%), and lumbar and unilateral lower leg (3%). Patients presenting with AEs reported an average of two pain related AEs at 7years post-op. Of the pain related AEs, 11% were device related, 8% were procedure related and 9% were serious AEs (SAEs). Onset of the first pain related SAE occurred on average at 49days (range: 0–118 days) and 395days (range: 0–2,728 days) following CCD and MCD implantation, respectively (p=.21). Overall, the majority of pain related SAEs were classified as severe (69%). A greater proportion of patients implanted with the CCD device presented with severe SAEs (88%) compared to patients with MCD (61%; p=.17). At the 7-year follow-up, over half of the SAEs occurring in MCD patients were resolved (56%) while the SAEs in CCD patients remained mostly unresolved (75%; p=.14). CONCLUSIONS While the rate of pain related AEs were the same between patients implanted with an MCD or CCD implant, there were observed differences in the quality of SAEs between the two TDR devices. On average, the first pain related SAE in MCD patients occurred approximately 1 year after CCD patients. Furthermore, a smaller proportion of SAEs were severe and a greater proportion was resolved by the 7-year follow-up appointment with MCD versus CCD implanted patients.