The effect of pedicle subtraction osteotomy for the correction of severe Scheuermann thoracolumbar kyphosis on sagittal spinopelvic alignment

PURPOSE: To analyze how pedicle subtraction osteotomy (PSO) treatment of severe Scheuermann thoracolumbar kyphosis (STLK) using pedicle screw instrumentation affects sagittal spinopelvic parameters. BACKGROUND: The medical literature on the post-surgical effects of treatments such as Ponte osteotomy is limited, but suggests few effects on spinopelvic profiles. Currently, there is no research regarding changes in sagittal spinopelvic alignment upon PSO treatment in STLK patients. METHODS: We performed a retrospective study on 11 patients with severe STLK. These patients underwent posterior-only correction surgeries with PSO and pedicle screw instrumentation between 2012 to 2017 in a single institute. Patients were measured for the following spinopelvic parameters: global kyphosis (GK), thoracic kyphosis (TK), thoracolumbar kyphosis (TL), lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic incidence (PI), pelvic tile (PT), sacral slope (SS), and administered a Scoliosis Research Society-22 questionnaire (SRS-22) pre-operation, post-operation and at final follow-up. RESULTS: GK improved from a median of 74.1° to 40.0° after surgery, achieving a correction rate of 48.8% with a median correction loss of 0.8°. TK, TL and LL all showed significant difference (P < 0.05) and SVA improved 22.7 (11.6, 30.9) mm post operation. No significant difference was found in pelvic parameters (PI, PT, SS, all P < 0.05). The absolute value of LL- PI significantly improved from a median of 26.5° pre-operation to 6.1° at the final follow-up. 72.7% in this series showed an evident trend of thoracic and lumbar apices migrating closer to ideal physiological segments after surgery. Self-reported scores of pain, self-image, and mental health from SRS-22 revealed significant improvement at final follow-up (all P < 0.05). CONCLUSIONS: PSO treatment of severe STLK with pedicle screw instrumentation can improve spine alignment and help obtain a proper alignment of the spine and the pelvis.