Spinal Fusion Concurrent With Construct Removal Is the Preferred End Point of the Shilla Growth Guidance Procedure.

BACKGROUND: Treatment of early-onset scoliosis (EOS) with the Shilla growth guidance ("Shilla") procedure typically concludes by "graduating" to: (1) posterior spinal fusion (PSF) immediately or later, (2) Shilla construct removal, or (3) Shilla construct retention after skeletal maturity. The optimal final outcome of the Shilla procedure has not been determined.

METHODS: An international, multicenter database of EOS patients was queried for Shilla patients with a minimum 2-year follow-up after the initial Shilla procedure who reached skeletal maturity or had implant removal with PSF with segmental spine instrumentation (SSI) concurrent with Shilla construct removal; implant removal with PSF+SSI during a later, unplanned surgery; or implant removal only. Radiographs were evaluated for major coronal deformity and skeletal maturity (Risser score ≥4). Conclusion of Shilla treatment was confirmed from clinical summaries provided by patients' board-certified orthopaedic surgeons. Subsequent surgeries and complications were tracked.

RESULTS: We retrospectively reviewed 74 patients [mean age at implantation was 6.8±2.1 y (range 2 to 10 y), 48 (65%) female]. At the most recent follow-up [mean 8.9±3.2 y (range: 0.3 to 15 y)], 10 patients retained their Shilla construct, of whom 2 (20%) experienced instrumentation-related complications. The remaining 64 underwent construct removal: 49 (77%) underwent immediate PSF + SSI, 3 (6%) of whom experienced deep wound infection (DWI); of 15 (23%) who had construct removal, late PSF+SSI was required in 9 (60%), 2 (22%) of whom experienced DWIs, and the Shilla construct remained removed at latest available follow-up in 6 (40%). Mean progression of major curve angles of those who underwent PSF+SSI with late construct removal was 27±31 degrees/year.

CONCLUSION: Many patients who have their Shilla construct removed eventually undergo PSF+SSI because of substantial deformity progression. Patients who underwent late PSF+SSI after construct removal had larger curves and a 22% infection rate, compared with 6% in those who underwent immediate PSF. Retaining a construct still risks instrumentation-related complications, even after reaching skeletal maturity; to minimize later complications, immediate PSF+SSI concurrent with construct removal may be the preferred endpoint of Shilla treatment.

LEVEL OF EVIDENCE: Level III.