Anterior stand-alone fusion revisited: a prospective clinical, X-ray and CT investigation

The purpose of this study was to assess the mid-term clinical and radiological results as well as patient safety in terms of complication and reoperation rates in patients treated with a novel anterior stand-alone fusion (ASAF) device (Synfix-LR, DePuy Synthes, West Chester, PA, USA) in a cohort of patients with predominant and intractable low back pain originating from monosegmental degenerative disc disease at the lumbosacral junction. Clinical outcome scores visual analog scale (VAS), Oswestry disability index (ODI) and patient satisfaction rates were acquired within the framework of an ongoing single-center prospective clinical trial. Evaluation of radiological data included segmental and global lumbar lordosis, neuroforaminal height and width. Interbody fusion was assessed from post-operative CT scans. The minimum follow-up (FU) was 12 months. 71 out of an initial 77 patients were available for final FU (92.2 % FU rate) after a mean FU of 35.1 months (range 12.0-85.5 months). The overall results revealed a highly significant improvement from baseline VAS and ODI levels (p < 0.0001). 77.5 % (n = 55/71) of all patients reported a 'highly satisfactory' (n = 37/71; 52.1 %) or a 'satisfactory' (n = 18/71; 25.4 %) outcome; 22.5 % of patients were not satisfied. The overall complication rate was 12.7 % (n = 9/71). Two cases required post-operative revision surgery (2.8 %). Radiographical analysis demonstrated a highly significant increase of segmental lordosis from 16.1A degrees to 26.7A degrees (p < 0.0001). A high rate of solid interbody fusion was confirmed in 97.3 % of all cases (n = 36/37). The current study delineates satisfactory clinical results following ASAF at the lumbosacral junction. Patient safety was demonstrated with acceptable complication and low reoperation rates. Radiological data demonstrated a significant reconstruction of lordosis at the lumbosacral junction. Solid interbody fusion was achieved in 97.3 % of all cases in a highly selected cohort with optimal predisposition for fusion. ASAF may serve to avoid a variety of negative side effects for a considerable number of patients which, otherwise, would have been candidates for posterior instrumented fusion techniques.