Selecting the SSV-1 as LIV in Scheuermann's Kyphosis
Condition: Scheuermann's Kyphosis
MeSH terms: Kyphosis; Scheuermann Disease; Spinal Osteochondrosis
Study type: Observational

Summary: 
      The proper selection of the lowest instrumented vertebra (LIV) remains controversial in the
      surgical treatment of Scheuermann's disease and there is a paucity of studies investigating
      the clinical outcomes of fusion surgery when selecting the vertebra one level proximal to the
      sagittal stable vertebra (SSV-1) as LIV. The purpose of this study is to investigate whether
      SSV-1 could be a valid LIV for Scheuermann kyphosis (SK) patients with different curve
      patterns.
    

Detailed description: 
      The proper selection of the lowest instrumented vertebra (LIV) remains controversial in the
      surgical treatment of Scheuermann's disease and there is a paucity of studies investigating
      the clinical outcomes of fusion surgery when selecting the vertebra one level proximal to the
      sagittal stable vertebra (SSV-1) as LIV. The purpose of this study is to investigate whether
      SSV-1 could be a valid LIV for Scheuermann kyphosis (SK) patients with different curve
      patterns.

      This was a prospective study on consecutive SK patients treated with posterior surgery
      between January 2018 and September 2020, in which the distal fusion level ended at SSV-1. The
      LIV was selected at SSV-1 only in patients with Risser > 2 and with LIV translation less than
      40mm. All of the patients had a minimum of 2-year follow-up. Patients were further grouped
      based on the sagittal curve pattern as thoracic kyphosis (TK) and thoracolumbar kyphosis
      (TLK). Radiographic parameters including global kyphosis (GK), lumbar lordosis (LL), sagittal
      vertical axis (SVA), LIV translation, pelvic incidence (PI), pelvic tilt (PT), sacral slope
      (SS) were measured preoperatively, postoperatively and at the latest follow-up. The
      intraoperative and postoperative complications were recorded. The Scoliosis Research Society
      (SRS)-22 scores were performed to evaluate clinical outcomes.
    

Intervention name(s): Select the vertebra above sagittal stable vertebra as the distal fusion level
Intervention type(s): Procedure
Intervention description(s): The surgeries were performed by the same surgical team. Multi-level Ponte osteotomies were performed across the apex of the kyphosis after complete exposure of the spine, with resection of supra- and inter-spinous ligaments, ligamentum flavum, and the whole facet joints. After placement of the pedicle screws at the expected fusion levels, pre-contoured rods were attached to the screws followed by segmental compression. During rod placement, two to three rounds of compression in the area with Ponte osteotomies were employed to enhance kyphosis correction. Satellite rods were routinely added to long rods and implanted with duet screws. The final tightening was performed, and the posterior fusion was completed with a mixture of local and allogeneic bone. Due attention was given to preserving the posterior ligamentous structures at the upper and lower junctional areas.
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        A total of 36 SK patients (including 23 with TK and 13 patients with TLK) were included in
        this study, among which 29 were male, and 7 were female.