Thursday, September 27, 2018 3:35 PM–5:05 PM Section on Motion Technology Abstract Presentations: 140. Impact of range of motion on progression of adjacent segment disease: disc versus disc

Abstract

BACKGROUND CONTEXT Previously, long term outcomes investigating range of motion (ROM) preservation over time between an investigational arm mobile core device (MCD) and control arm controlled core device (CCD) have been reported. No studies have looked at the relationship of ROM to the progression of adjacent segment disease (ASD) between disc prostheses. PURPOSE The primary purpose of this study was to compare changes in ROM between two lumbar TDRs. Secondarily the relationship between incremental degrees of motion maintained to progression of ASD was investigated. STUDY DESIGN/SETTING This is a post hoc analysis of data collected from a large, prospective, multicenter clinical trial. PATIENT SAMPLE As part of the clinical trial, 175 patients received either the investigational MCD or the CCD control device. All patients were treated for symptomatic disc degeneration unresponsive to minimum 6 months nonoperative care. OUTCOME MEASURES The primary outcome measure was ROM and the progression of ASD. METHODS ROM was evaluated through radiographs at the index level at baseline (preoperative) and at 5-years postoperative. At 5-years, a change in adjacent ASD was defined as >1 grade increase. RESULTS Results: At baseline both MCD and CCD patients had similar index level ROM of 6.6° and 6.2°, respectively (p=.6). At 5-years postoperative patients with a CCD had an average ROM of 4.2° which represented a statistically significant reduction from baseline (p=.02). Patients with a MCD had an average ROM of 6.1° at 5-years which was similar to the baseline ROM (p=.4). In a comparison between groups, patients with a CCD had 31% less ROM at 5-years postoperative than patients with a MCD (p=.02). In this same patient group the protective effect of ROM on progression of ASD was measured. For every degree of ROM preserved, the likelihood of the progression of ASD at the superior level declined consistently. Patients receiving an MCD were less likely to have progression of ASD at 5-years than patients who received a CCD (8.8% vs. 19%, p=.05). CONCLUSIONS These data show that there may be a relationship between the maintenance of motion over time and the progression of ASD. While additional analysis is warranted, a novel new MCD may be better at maintaining ROM and thus better at delaying ASD than the earlier generation CCD. FDA DEVICE/DRUG STATUS aclivL, ProDisc-L and Charite are approved for this indication.