Prospective Study of ProteiOS in Lumbar Interbody Fusion (TLIF)

This is a prospective, multicenter, randomized, controlled study evaluating Influx™ ProteiOS®, an allograft-derived growth factor product, in transforaminal lumbar interbody fusion (TLIF). Participants undergoing 1- to 2-level TLIF (L2-S1) are randomized 2:1 to receive ProteiOS or a control graft (local bone with optional cancellous chip augmentation, no ProteiOS). The primary objective is to determine whether the 12-month interbody fusion rate (assessed by CT using the Brantigan-Steffee-Fraser classification) with ProteiOS is non-inferior to control, using a 5-percentage-point non-inferiority margin. Patient-reported outcomes (ODI, VAS, EQ-5D-5L), safety, and healthcare utilization are also assessed. A separate exploratory cohort at one study site will evaluate the same outcomes in participants undergoing anterior lumbar interbody fusion (ALIF) with or without ProteiOS, without formal hypothesis testing.

Inclusion Criteria * Age 18-75 years, skeletally mature at time of surgery * Degenerative disease of the lumbar spine (L2-S1) requiring 1-2 level instrumented TLIF, with or without posterolateral fusion, as determined by the treating surgeon * For the ALIF study site only: degenerative disease of the lumbar spine (L2-S1) requiring 1-2 level instrumented ALIF * Radiographic evidence of degenerative lumbar disease on CT, MRI, or plain radiograph (decreased disc height, herniated nucleus pulposus, ligamentum flavum/annulus hypertrophy, facet arthrosis/osteophyte, spinal canal or foraminal stenosis, or vertebral translation \>3 mm) * Symptoms of low back pain, radiculopathy, or neurogenic claudication consistent with radiographic findings * Preoperative back pain ≥4 on a 0-10 VAS * Preoperative leg pain ≥3 on a 0-10 VAS, consistent with radiculopathy or neurogenic claudication * Preoperative ODI score ≥30 * Failure of ≥6 months non-operative treatment (may be waived for progressive neurological deficit, new/worsening motor weakness, bowel/bladder dysfunction, or cauda equina syndrome) * Willing and able to comply with follow-up schedule and provide written informed consent Exclusion Criteria: * Scheduled for surgery with synthetic bone grafts containing hydroxyapatite, tricalcium phosphate, or other radio-opaque material * BMI \>40 * Prior lumbar spine fusion surgery at a level currently scheduled for surgery * Malignancy or treatment for malignancy within the last 5 years (benign skin cancer permitted) * Osteoporosis/osteopenia (≤2.5 SD below age-matched mean) * Use of rhBMP-2 (Infuse) or other active biologics * Active or systemic infection, malignancy, or severe metabolic bone disease * Chronic steroid use (\>10 days) * Revision fusion at index levels * Participation in another interventional clinical study within 30 days of consent * Known pregnancy or intent to become pregnant during the study