Min Implants Max Outcomes Clinical Trial

The MIMO Study Group proposes to conduct a prospective randomized controlled trial in order
to determine whether a low implant density cohort has equivalent clinical and radiographic
results to a high implant density cohort. This study is proposed as a trial of equivalence.
The null hypothesis is that significant differences exist in percent major Cobb angle
correction between high- and low-implant density cohorts for Lenke 1A curve types, the most
common scoliotic curve pattern (73). Consecutive qualifying patients will be screened and
enrolled by high-volume spine surgeons at 14 sites and randomized to spinal instrumentation
with a low- or high-density screw pattern. Patients will return at 3-months, 1-year, and
2-years for exam, radiographs, and collection of patient-reported outcome scores. The Harms
Study Group Foundation will serve as a collaborating organization and will provide database
development and management, secure online data collection, centralized radiographic
measurements, and data quality control. The University of Minnesota team will lead study
design, protocol development, IRB/data use agreement contracts, patient randomization, and
statistical analysis, including quarterly data review. Imaging will be obtained either with
an EOS system or using a calibration belt during the radiographs, which allows for subsequent
with the 3D modeling of the deformity. Six enrolling sites currently have this capability
(EOS - Montreal, St. Louis, Iowa, Mayo, DuPont, and San Diego). An additional five sites
already have calibration belts - Dallas, New York, Baltimore, Boston, U. of Rochester), and
new calibration belts will be fabricated for the additional sites. The Montreal site will
supervise collection of radiographic data with 3D capability and assist with troubleshooting
and radiographic quality control. Although the study is primarily powered to detect change in
percent correction of the major coronal curve, preliminary data will be gathered on axial and
sagittal plane correction as well as complications, surgical factors, and patient-reported
outcomes.

Inclusion Criteria:

- Patients aged ≥10 and ≤ 18 years

- Male or Female

- Diagnosis of idiopathic scoliosis for which surgery is recommended to prevent the
curvature or to correct trunk disfigurement Lenke 1A curve pattern

- Curve cobb of 45° to 65°

- T5-T12 kyphosis measuring 0° to 40°

- Spina bifida Oculta is permitted

- Spondylolisthesis and Spondylolysis are permitted, as long as non- operative

Exclusion Criteria:

- Prior spinal surgery

- MRI abnormalities (including >4mm of Syrinx and/or Chiari malformation)

- Neuromuscular or other serious co-morbidities

- Thoracogenic or cardiogenic scoliosis

- Associated syndrome or developmental delay

- Unable or unwilling to firmly commit to returning for required follow-up