Osteocel® Plus in Posterior Lumbar Interbody Fusion (PLIF)

Inclusion Criteria: 1. Persistent back and/or leg pain unresponsive to conservative treatment for at least six (6) months, unless clinically indicated earlier 2. Indicated for interbody fusion of one or two contiguous lumbar segments (L1 to S1) 3. Objective evidence of primary diagnosis must be confirmed by appropriate imaging studies 4. 18-70 years of age at the date of written informed consent 5. Able to undergo surgery based on physical exam, medical history and surgeon judgment 6. Expected to survive at least 2 years beyond surgery 7. Willing and able to return for post-treatment exams according to the follow-up called for in the protocol 8. Signed and dated Informed Consent Form Exclusion Criteria: 1. Patient has a mental or physical condition that would limit the ability to comply with study requirements 2. Lumbar spine abnormality requiring treatment at more than two levels 3. Systemic or local infection; active or latent 4. Previous failed fusion at the operative level 5. Diseases that significantly inhibit bone healing (osteoporosis, metabolic bone disease, uncontrolled diabetes, dialysis dependent renal failure, symptomatic liver disease) 6. Undergoing chemotherapy or radiation treatment, or chronic use of steroids (defined as more than 6 weeks of steroid use within 12 months of surgery, other than episodic use or inhaled corticosteroids) 7. Pregnant, or plans to become pregnant during the study 8. Subject is a prisoner 9. Involvement in active litigation relating to the spine (worker's compensation claim is allowed if it is not contended) 10. A significant general illness (e.g., HIV, active metastatic cancer of any type) is present; subject is immunocompromised or is being treated with immunosuppressive agents 11. Participating in another clinical study that would confound study data