Objective To compare the clinical efficacy, safety, mechanical stability and bone defect repair ability of one-stage posterior lesion removal, non-structural bone grafting and internal fixation in the treatment of single-gap thoracolumbar tuberculosis with different bone defect ranges. Methods A cohort of patients with single intervertebral space thoracolumbar tuberculosis was retrospectively selected, who were treated by one-stage posterior lesion removal, non-structural bone grafting and internal fixation at the Third People’s Hospital of Chengdu between January 2010 and December 2023. Patients with spinal tuberculosis bone defects covering less than 50% of the vertebral body were classified as Group A, while those with bone defects no less than 50% were categorized as Group B. Clinical indicators, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), Visual Analogue Scale (VAS) score for pain, Oswestry Disability Index (ODI), Cobb angle, American Spinal Injury Association (ASIA) classification, and bone graft fusion time were compared between the two groups. Results A total of 70 patients met the inclusion criteria, with 40 in Group A and 30 in Group B. The follow-up duration was (19.1±3.9) months in Group A and (27.5±9.2) months in Group B, with a statistically significant difference (t=?5.195, P<0.001). No statistically significant difference was observed in gender, age, or preoperative and final follow-up CRP, ESR, or VAS scores between the groups (P>0.05). Surgical complications, time to ambulation, and hospitalization duration also showed no significant differences (P>0.05). At the final follow-up, all parameters including CRP, ESR, VAS scores, ODI, ASIA classification, and local Cobb angle demonstrated marked improvement compared to preoperative levels (P<0.05). Notably, both groups exhibited statistically significant loss of local Cobb angle at 1 week postoperatively (P<0.05), though no significant difference was found in postoperative correction rates or loss rates (P>0.05). Group A showed statistically significant advantages over Group B in surgical duration, intraoperative bleeding, internal fixation segments, and bone healing time (P<0.05). Conclusions The clinical efficacy of one-stage posterior lesion removal combined with non-structural bone grafting and internal fixation for single-gap thoracolumbar tuberculosis with varying bone defect ranges is favorable. The reliable mechanical stability ensures early recovery of daily living abilities, with the procedure being simple to perform and having fewer complications. Compared with the group with smaller bone defects (<50% vertebral body), the group with larger bone defects (≥50%) requires more extensive surgical trauma, necessitates longer segmental internal fixation, and exhibits prolonged bone healing time. Clinical application demands comprehensive evaluation and cost-benefit analysis.