Early clinical and biomechanical results following cervical arthroplasty

Abstract

Object Spinal arthroplasty may become the next gold standard for the treatment of degenerative cervical spine disease. This new modality must be studied rigorously to ensure in vivo efficacy and safety. The authors review the preliminary clinical experience and radiographic outcomes following insertion of the Bryan Cervical Disc Prosthesis (Medtronic Sofamor Danek, Memphis, TN). Methods This prospective cohort study included 26 patients undergoing single- or two-level implantation of the Bryan artificial cervical disc for treatment of cervical degenerative disc disease resulting in radiculopathy and/or myelopathy. Radiographic and clinical assessments were made preoperatively 1.5, 3 months, and at 6, 12, and up to 24 months postoperatively. The Neck Disability Index (NDI) and Short Form–36 (SF-36) questionnaires were used to assess pain and functional outcomes. Segmental sagittal rotation from C2–3 to C6–7 was measured using quantitative motion analysis software. A total of 30 Bryan discs were placed in 26 patients. A single-level procedure was performed in 22 patients and a two-level procedure in the other four. Follow-up duration ranged from 1.5 to 27 months, with a mean duration of 12.3 months. A statistically significant improvement in the mean NDI scores was seen between pre- and late postoperative follow-up evaluations. A trend toward improvement in the SF-36 physical component was also found. Motion was preserved in the treated spinal segments (mean range of motion 7.8°) for up to 24 months postsurgery. The relative contribution of each segment to overall spinal sagittal rotation differed depending on whether the disc was placed at C5–6 or C6–7. Overall cervical motion (C2–7) was moderately increased on late follow-up evaluations. Conclusions The Bryan artificial cervical disc provided in vivo functional spinal motion at the treated level. Overall cervical spinal motion was not significantly altered. Sagittal rotation did not change significantly at any level after surgery.