Abstract
Study designRetrospective, comparative, multicenter.IntroductionGrowth modulating spinal implants are used in the management of scoliosis such as anterior vertebral body tethering. A motion-sparing posterior device (PDDC) was recently approved for the treatment of moderate AIS. The purpose of this study was to determine if the PDDC can modulate growth in skeletally immature patients with AIS.MethodsFrom a database of patients treated with the PDDC over 4 years, we identified those who had a minimum of 2 years follow-up. Pre-operative and post-operative Cobb angles and coronal plane wedging of the apical vertebra were evaluated on standing full length radiographs. Independent sample t test and one-way ANOVA with post-hoc Tukey HSD analysis was used to compare three groups in varying skeletal maturity: Risser 0–1, Risser 2–3, and Risser 4–5.Results45 patients (14.2-years old, 11–17) were evaluated with a mean pre-op curve of 46° (35°-66°). The average preoperative major curve magnitude, of either Lenke 1 or 5 curve type, was similar among the three groups 47.6°, 46° and 41.5°. Deformity correction was similar in the three groups, with reduction to 26.4°, 20.4° and 26.2°, respectively, at final follow-up [p < 0.05]. Pre-op wedging 7.4° (3.8°–15°) was reduced after surgery to 5.7° (1°–15°) (p < 0.05). Of those patients, Risser 0–1 (n = 16) had preoperative wedging of 9.5° (6°–14.5°) that was reduced to 5.4° (1°–8°) postoperatively (p < 0.05); Risser 2–3 (n = 15) had pre-op 7.7° (4°–15°) vs. post-op 7.0° (3°–15°); Risser 4–5 (n = 14) had pre-op 4.8° (3.8°–6.5°) vs. post-op 4.7° (3.7°–6.5°). Delta Wedging in Risser 0–1 stage was significantly different than for Risser 2–3 and for Risser 4–5.ConclusionThe posterior dynamic deformity correction device was able to modulate vertebral body wedging in skeletally immature patients with AIS. This was most evident in patients who were Risser 0–1. In contrast, curve correction was similar among the three groups. This finding lends support to the device’s ability to modulate growth.
Highlights
Motion sparing and growth modulating spinal implants were recently incorporated into the surgical armamentarium of adolescent idiopathic scoliosis and currently utilize anterior implants such as vertebral body tethering (VBT) [1, 2] or vertebral body stapling (VBS) [3, 4]
We retrospectively compared the outcomes of three groups of patients with moderate AIS that were instrumented with posterior dynamic deformity correction device (PDDC), each group had a different Risser sign grade and was in a different stage of skeletal maturity (Risser 0–1, 2–3 and 4–5) at the time of surgery
The three groups were compared in regards to the magnitude of main curve reduction and the extent of remodeling in the coronal plane wedging of the apical vertebra following surgery with PDDC
Summary
Motion sparing and growth modulating spinal implants were recently incorporated into the surgical armamentarium of adolescent idiopathic scoliosis and currently utilize anterior implants such as vertebral body tethering (VBT) [1, 2] or vertebral body stapling (VBS) [3, 4]. VBT and to a lesser extent VBS, has been reported to promote growth modulation, their implantation necessitates an anterior approach to the spine. A novel posterior dynamic deformity correction device (PDDC) (ApiFix Ltd., Misgav, Israel) was developed to provide a less invasive, motion sparing means to correct single Lenke 1 and 5 AIS curves and control the deformity. The device may be looked upon as an internal brace not dependent on brace wear compliance This motion-sparing posterior device has a CE mark and was recently approved in the US by the Federal Drug Administration (FDA) for the treatment of moderate AIS. The ability of PDDC to significantly correct moderate AIS curves in patients fitting the current US indications i.e. 40°–60° single major curves reduced to ≤ 30° on bending, was recently reported [8]. It was found that in 82% of the cohort, it was possible to reduce the main curve to ≤ 30°at 2 years follow-up
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