This is a prospective, multi-center, non-randomized post-market evaluation designed to collect and evaluate data on the safety and performance of the Fortilink IBF System with TETRAfuse 3D Technology.

This is a prospective, multi-center, non-randomized post-market evaluation designed to collect and evaluate data on the safety and performance of the Fortilink IBF System with TETRAfuse 3D Technology.

There will be 3 arms in the study, one for each configuration of the Fortilink IBF system (Fortilink-C, Fortilink-TS and Fortilink-L). Up to 50 subjects will be enrolled in each study arm for a total of up to 150 subjects at up to 20 sites in the United States (US) and European Union (EU).

Inclusion Criteria:

• The subject is skeletally mature and at least 18 years of age.
• The subject has degenerative disc disease (DDD) of the cervical spine with accompanying radicular symptom at one or two contiguous levels (Fortilink-C), or the subject has DDD and ≤ Grade 1 spondylolisthesis of the lumbar spine at one or two contiguous levels (Fortilink-TS and Fortilink-L).
• Subject plans to undergo one of the following procedures:

An anterior cervical interbody fusion at one to two continuous levels from C2-C3 to C7-T1 using autogenous or allogenic bone graft and supplemental fixation cleared and indicated for use at the proposed treatment level(s) (Fortilink-C), or

An interbody fusion in the lumbar spine at one to two continuous levels from L1-L2 to L5-S1 using autogenous or allogenic bone graft and supplemental fixation cleared and indicated for use at the proposed treatment level(s) (Fortilink-TS and Fortilink-L).

• The subject has undergone non-operative treatment of at least six weeks (Fortilink-C) or at least six months (Fortilink-TS and Fortilink-L) prior to treatment with the IBF system.
• The subject is willing and able to provide informed consent.
• The subject is willing and able to attend the protocol required follow-up visits and examinations.

Exclusion Criteria:

• The subject has an active infection
• The subject has had prior fusion attempt(s) or is undergoing revision of a previously implanted system at the involved level(s).
• The subject is a worker's compensation case, in active litigation related to the procedure or is a prisoner or ward of the state.
• The subject meets one or more of the contraindications outlined in the IFU.
• The subject is pregnant, nursing, or is planning to become pregnant in the next year.
• The subject has documented evidence of current substance abuse.
• The subject has other concurrent medical condition that, in the opinion of the investigator, does not make the subject a good candidate for the study.

Subjects in this study will be candidates who undergo interbody fusion of hte spine due to degenerative disc disease using the Fortilink IBF device.