Evidence For Fusion In Spine With Orthoss®

Inclusion Criteria: * The patient (male or female) must be 18 years or older * The patient must be a candidate diagnosed with either degenerative disc disease including 1-2 level (L4-L5 and/or L5-S1) or dysplasic spondylolisthesis (degree 1 or 2) or lumbar stenosis * If the patient is of child-bearing potential, the patient confirms not to be pregnant * The patient is able to comply with the clinical investigation-related procedures such as attending all follow-up procedures * The patient is able to fully understand the nature of the proposed surgery and is able to provide a signed informed consent including the use of the anonymized data for scientific publication * The patient will not participate in another clinical investigation during this clinical investigation Exclusion Criteria: * General contraindications for surgical treatment are present * The patient has a history of malignancy, radiotherapy, or chemotherapy for malignancy within the past five years * The patient is currently being treated with radiation, chemotherapy, immunosuppression or steroid therapy dose equivalent of more than 5mg prednisolon * The patient is pregnant or nursing * Women of childbearing age who are not using a highly effective method of birth control * The patient has acute or chronic infection at the surgical site * The patient has a known allergy to bovine bone material * The patient has a medical history of alcohol or drug abuse within the last year prior to the screening examination * Vulnerable population * Patient is currently participating, or has participated in another clinical investigation within 6 months