Modified bone-disc-bone osteotomy (MBDBO) for the treatment of spinal kyphotic deformity secondary to old thoracolumbar vertebral fracture: a retrospective study with 2-year follow-up

OBJECTIVE: To investigate the clinical efficacy and safety of modified bone-disc-bone osteotomy (BDBO) in the treatment of kyphosis caused by old thoracolumbar vertebral fractures. METHODS: A retrospective analysis was performed on 22 consecutive patients (mean age 65.1 ± 5.9 years) who underwent posterior-only modified BDBO combined with internal fixation and fusion between September 2020 and December 2023. Radiological parameters, including global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS), were measured on standing full-spine lateral X-rays. Clinical outcomes were evaluated using the Scoliosis Research Society-22 (SRS-22) questionnaire. All indicators were assessed preoperatively, on the 5th postoperative day, and at the final follow-up (minimum 24 months, mean 25.45 ± 2.24 months). Surgical data and complications were also recorded. RESULTS: Modified BDBO significantly corrected global kyphosis. For GK, the preoperative mean value was 45.32 ± 10.76°, which decreased to 10.51 ± 4.08° on the 5th postoperative day (significant difference, t = 15.82, p < 0.001) and 11.15 ± 4.25° at the final follow-up (compared with preoperative: t = 15.4, p < 0.001; compared with 5th postoperative day: t = - 10.88, p = 0.031). For TK, the preoperative mean value of 40.21 ± 11.24° significantly decreased to 24.5 ± 2.17° on the 5th postoperative day (t = 8.1, p < 0.001) and 24.82 ± 2.31° at the final follow-up (t = 8.01, p < 0.001), with a slight difference between the 5th postoperative day and final follow-up (t = - 6.25, p = 0.049). For LL, it decreased from 47.62 ± 14.74° preoperatively to 42.73 ± 6.58° on the 5th postoperative day (t = 2.79, p = 0.011) and 39.59 ± 7.18° at the final follow-up (t = 4.92, p = 0.006), with continuous adjustment between the 5th postoperative day and final follow-up (t = 23.1, p = 0.010). For SVA (a marker of spinal balance), the preoperative mean value of 37.95 ± 8.02 mm drastically decreased to 12.11 ± 3.92 mm on the 5th postoperative day (t = 29.06, p < 0.001) and 13.39 ± 4.07 mm at the final follow-up (t = 28.36, p < 0.001), with no significant drift. PI, PT, and SS also showed significant improvements and remained stable. No major neurological injury occurred. One patient had a superficial wound infection cured before discharge, and one had a pulmonary infection resolved with anti-infection treatment. All patients achieved solid fusion without internal fixation failure or pseudarthrosis. SRS-22 scores in Function (3.0 ± 0.3 vs. 3.8 ± 0.2, p < 0.001), Appearance (2.8 ± 0.2 vs. 4.0 ± 0.2, p< 0.001), and Pain (2.8 ± 0.2 vs. 3.6 ± 0.1, p < 0.001) domains improved significantly, with a mean satisfaction score of 4.1 ± 0.23. CONCLUSION: Modified BDBO is an effective and relatively safe surgical technique for kyphosis secondary to old thoracolumbar vertebral fractures. It provides powerful sagittal correction, sustains improved spinal alignment, and enhances patient-reported pain relief and function.