Lumbar Fusion With Nanotube Versus Titanium Cage

This study is comparing two FDA-approved cages used during lower back surgery. The study will look at whether one cage helps the bones in the back fuse together better than the other. Adults who are having a 1 or 2 level lumbar fusion surgery will be randomly assigned to receive either the Adaptix nanoPEEK cage or the Capstone PTC cage. Participants will have follow-up visits with imaging and questionnaires to evaluate bone fusion, back and leg pain, physical function, and overall health.

Inclusion Criteria: * Subject is scheduled to undergo 1- or 2-level TLIF with the principal investigator. * Subject has failed nonoperative management for a minimum of 3 months prior to enrollment. * Diagnosis is degenerative disc disease (DDD), defined as discogenic back pain with disc degeneration confirmed by history and radiographic studies, at 1 or 2 contiguous spinal levels from L2 to S1. Subjects may have up to grade 1-2 spondylolisthesis or retrolisthesis at the index level(s). * Subject is able to provide written informed consent. * Subject is, in the investigator's opinion, psychosocially, mentally, and physically able to comply with the protocol, required follow-up visits, and completion of required study forms. Exclusion Criteria: * Prior lumbar arthrodesis surgery at any level. * Diagnosis of osteoporosis (T-score = -2.5) or severe osteopenia (T-score = -2.0 with fragility fracture history). * Body mass index (BMI) greater than 40 kg/m². * Requirement for additional bone grafting materials beyond milled local autograft bone (e.g., rhBMP-2, iliac crest autograft, allograft structural spacers). * Active local or systemic infection. * Known metal sensitivity or foreign body reaction to titanium or PEEK. * Active malignancy or history of spinal malignancy. * Known diabetes mellitus with preoperative HbA1c =8%, confirmed within 90 days of the planned surgery date. Diabetic patients with HbA1c \