This study is a post-market clinical follow-up study to fulfill the post-market surveillance obligations according to Medical Device Directive and MEDDEV 2.12-2_Rev2_January 2012. The data collected from this study will serve the purpose of confirming safety and performance of the TM Ardis implant. The goal of this study is to demonstrate that implant is effective in reducing patient disability.

This study is a post-market clinical follow-up (PMCF) study to fulfill the post-market surveillance obligations according to Medical Device Directive and MEDDEV 2.12-2_Rev2_January 2012. The data collected from this study will serve the purpose of confirming safety and performance of the TM Ardis implant. The goal of this study is to demonstrate that implant is effective in reducing patient disability, which will be assessed with the ODI questionnaire.

Inclusion Criteria:

• Age > or = 18 years
• Degenerative disc disease DDD with up to Grade 1 spondylolisthesis or retrolis-thesis at the involved level. DDD is defined as discogenic back pain with degener-ation of the disc confirmed by history and radiographic studies.
• ODI 40 out of 100
• Back pain 4 out of 10
• Mono segmental or two level lumbosacral disease
• Skeletally mature patients
• Six months failed conservative treatment.
• Gave written consent to take part in the study by signing the Ethics Committee's approved Patient Informed Consent Form.
• Physically and mentally able to comply with the protocol, including ability to read and complete required forms and adhere to the follow-up requirements of the pro-tocol.

Exclusion Criteria:

• Prior surgical procedure at the index level(s) using the desired operative approach.
• Severe degenerative lesions at more than two level of the lumbosacral spine.
• Morbid obesity (BMI greater than or equal to 40).
• Active local infection in or near the operative region.
• Active systemic infection and/or disease.
• Severe osteoporosis or insufficient bone density, which in the medical opinion of the physician precludes surgery or contraindicates instrumentation.
• Known or suspected sensitivity to the implant materials.
• Endocrine or metabolic disorders known to affect osteogenesis (e.g.Paget's disease, renal osteodystrophy, hypothyroidism)
• Systemic disease that requires the chronic administration of nonsteroidal anti-inflammatory or steroidal drugs.
• Significant mental disorder or condition that could compromise the patient's ability to remember and comply with preoperative and postoperative instructions (e.g. current treatment for a psychiatric/psychosocial disorder, senile dementia, Alzheimer's disease, traumatic head injury)
• Neuromuscular disorder that would engender unacceptable risk of instability, implant fixation failure, or complications in postoperative care.
• Pregnant.
• Unwilling to follow postoperative instructions, in particular with respect to athletic or occupational activities.
• Current vertebral metastatic tumors.
• Symptomatic cardiac disease.
• Severe congenital or acquired vertebral deformities.