Re: Clinical outcomes with selectively constrained SECURE-C cervical disc arthroplasty: two year results from a prospective, randomized, controlled, multicenter investigational device exemption study. Vaccaro A, Beutler W, Peppelman W, et al. Re: Very late complications of cervical arthroplasty: results of 2 controlled randomized prospective studies from a single investigator site. Hacker F, Babcock R, Hacker R. Spine 2013;38:2223-39.