Inclusion Criteria  Male or Female aged 18-75 years. Primary anterior cervical discectomy fusion (ACDF) and required two level spinal fusion or were active smokers and required either single or two level spinal fusion. Pain VAS score >5 and/or extreme weakness at target operative level(s). At least one post operative clinical outcome assessment (VAS pain/ NDI/OC score) at each follow up interval. Completed 6 month follow up visit or time to fusion assessment, whichever is sooner.  Exclusion Criteria  Treated with a bone growth stimulator device other than the SpinalogicTM CMF device. Previous cervical vertebrae fusion surgery at any level (posterior or anterior approach) Systemic administration of any type of corticosteroid, antineoplastic, immune- stimulating or immunosuppressive agents within 30 days of primary ACDF surgery and/or within 12 weeks post-operatively. Active history of systemic malignancy at pre-operative assessment or during 12- month follow up period. Untreated malignant neoplasm(s) or underwent radiotherapy or chemotherapy at pre- operative assessment or during 12-month follow up period. Implanted with cardiac pacemaker or implantable cardioverter defibrillator at pre- operative assessment or during 12-month follow up period. Pregnant at pre-operative assessment or during 12-month follow up period. Mental or physical condition that would interfere with post-treatment assessments and/or care (e.g., neuromuscular disease, psychiatric disease, Paraplegia, quadriplegia, etc.) at pre-operative assessment or during 12-month follow up period. Prescribed non-steroidal anti-inflammatory, calcium channel blockers and/or diphosphonate therapy within 12-weeks of surgery period. Prescribed bone morphogenic protein (BMP) during 12-month follow up period. Implanted with a Titanium cage during the primary ACDF that precludes an outcome determination via plain radiographs. Osseous or ligamentous spinal trauma at pre-operative assessment or during 12- month follow up period. Paget's disease at pre-operative assessment or during 12-month follow up period. Absence of X-ray fusion assessment documentation at 6 months follow-up visit.