Object: The need for interbody fusion or stabilization after anterior cervical microdiscectomy is still debated. The objectives of this prospective randomized study were 1) to examine whether combined interbody fusion and stabilization is more beneficial than microdiscectomy only (MDO) and 2) if fusion is found to be more beneficial than MDO, to determine which is the best method of fusion by comparing the results achieved using autologous bone graft (ABG), polymethylmethacrylate (PMMA) interposition, and threaded titanium cage (TTC).
Methods: A total of 125 patients with a single-level cervical disc disease were included in this prospective study. All patients were randomized and assigned to one of the four following groups: Group 1 (33 patients), MDO; Group 2 (30 patients), microdiscectomy followed by ABG; Group 3 (26 patients), microdiscectomy followed by injection of PMMA; and Group 4 (36 patients), microdiscectomy followed by placement of a TTC. Clinical outcome according to Odom criteria was summarized as 1) excellent and good or 2) satisfactory and poor. One-year follow-up examination was performed in 123 patients. Patients in the TTC group experienced a significantly better outcome 6 months after surgery (92% excellent and good results) compared with those in the MDO and ABG groups (72.7 and 66.6% excellent and good results, respectively). Twelve months after surgery there was still a significant difference in outcomes between the TTC group (94.4% excellent and good results) and the MDO group (75.5% excellent and good results). Outcome in patients treated with PMMA was comparable with that in those treated with TCC after 6 (91.6%) and 12 months (87.5%), but no segmental fusion was achieved. Differences compared with MDO and ABG were, however, not significant, which may be related to the smaller number of patients in the PMMA group.
Conclusions: Interbody cage-assisted fusion yields a significantly better short- and intermediate-term outcome than MDO in terms of return to work, radicular pain, Odom criteria, and earlier fusion. In addition, the advantages of interbody cages over ABG fusion included better results in terms of return to work, Odom criteria, and earlier fusion after 6 months. These results suggest that interbody cage-assisted fusion is a promising therapeutic option in patients with single-level disc disease. Polymethylmethacrylate seems to be a good alternative to interbody cage fusion but is hindered by the absence of immediate fusion.