A Clinical Study to Evaluate Safety and Performance of PEEK-OPTIMA™ HA Enhanced Interbody Cages in the Lumbar Spine

Inclusion Criteria: * Is the subject aged 18 years of age or older and skeletally mature? * Does the subject have a primary diagnosis of symptomatic degenerative disc disease (DDD) or symptomatic degenerative disc disease (DDD) with spondylolisthesis (Grade 1) at one or two contiguous levels from L2 to S1? * Does the subject have discogenic back pain with degeneration of the disc confirmed by medical history, radiographic examination and MRI (MRI must be obtained within the 6 months prior to subject surgery and radiographs obtained within 3 months prior to subject surgery)? * Is the subject judged by the Investigator to be suitable for transforaminal lumbar interbody fusion (TLIF) surgery based on their medical history? * Is the subject indicated for surgical treatment with the EVOS Lumbar Interbody System with autologous bone graft? * Has the subject completed at least 6 months of conservative non-operative treatment without obtaining adequate symptomatic relief? * If the subject is female and of childbearing age, do they have a negative pregnancy test (by Beta HCG qualitative analysis), or do they have a history of a surgical sterilisation, or a history of no menses in the past twelve months? * Is the subject, in the opinion of the Investigator, able to understand this clinical study, co-operate with the procedures and are they willing to return to the hospital for all the required post-operative follow-ups? * Is the subject able to give voluntary, written informed consent to participate in this clinical study and from whom consent has been obtained? Exclusion Criteria: * Has the subject undergone previous spinal surgery at the affected disc level(s), excluding discectomy and laminectomy procedures? * Does the subject have evidence of tumour and/or malignant disease with resultant life expectancy of less than two years? * Does the subject have known osteoporosis or severe osteopenia as determined by the Investigator? * Does the subject have rheumatoid arthritis, ankylosing spondylitis or are they immunocompromised? * Does the subject have a known allergy to the material used in the instrumentation? * Does the subject have evidence of an active infection and/or do they have any condition that would compromise their participation and follow-up in this clinical study? * Is the subject receiving any drug treatment that may affect bone metabolism? * If the subject is female, are they pregnant or lactating? * Is the subject a current smoker, or have they stopped smoking less than 6 months ago? * Is the subject a known drug or alcohol abuser or do they have a baseline opioid use greater than 30 mg of morphine equivalent/day or do they have psychological disorders that could affect follow-up care or treatment outcomes? * Is the subject currently enrolled in a clinical study?