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. 2025 Mar;15(2):1174-1185.
doi: 10.1177/21925682241229677. Epub 2024 Jan 24.

A Prospective Multicenter ≥2 Years Clinical Study of the Active Apex Correction (APC) Technique in Early Onset Scoliosis (EOS) Patients

Ahmad M Hammad  1 , Mohammad Emar  2 , Farah Shahin  2 , Ayat Aljuba  2 , Asala Hasani  2 , Mohammad Awad  2 , Siraj Abdelnabi  2 , Daksh Gayaswal  3 , Mohammad Armouti  4 , Shubhankar Shekhar  5 , Bhavuk Garg  5 , Alaaeldin A Ahmad  2   3   4
Affiliations

A Prospective Multicenter ≥2 Years Clinical Study of the Active Apex Correction (APC) Technique in Early Onset Scoliosis (EOS) Patients

Ahmad M Hammad et al. Global Spine J. 2025 Mar.

Abstract

Study design: prospective multicenter study.

Objectives: Active apex correction (APC) is posterior tethering technique for correction of early onset scoliosis (EOS) via reverse modulation at the apex. Active apex correction has been increasingly used worldwide. This study aimed to assess short-term outcomes of multicenter study with ≥2 years of APC on spine length, curve correction, complications, unplanned surgeries, and proposed low crankshaft phenomena incidence.

Methods: Prospective multicenter study including 24 EOS patients treated by APC; involves inserting and compressing pedicle screws on convex side of apex proximal and distal to most wedged vertebra allowing apex modulation according to Hueter-Volkmann law. Excluded patients with <2 years follow-up whom APC was not primary surgery.

Results: Mean age 85.97 ± 32.43 months, 71% congenital scoliosis, mean follow-up 35.54 ± 12.36 months. At final follow-up, statistically significant improvement in Cobbs angle (∆ = 23.96%, P < .0001), spinal length T1-T12 (∆ = 12.83%, P < .0001), T1-L5 (∆ = 13.41%, P < .0001) but not in apical vertebral translation (AVT) albeit clinical improvement (∆ = 7.9%, P = .36) compared to preoperative measurements. Comparing immediate postoperative measurements to >2 years follow-up, statistically significant improvement in spinal length T1-T12 (∆ = 6.03%, P = .0002) and T1-L5 (∆ = 6.26%, P < .0001) but not in Cobbs angle (∆ = 4.93%, P = .3) or AVT (∆ = 14.77%, P = .25). 9 complications requiring 3 unplanned surgeries recorded in all patients including 2 broken rods, 2 adding-on and 4 screw dislodgement.

Conclusion: Active apex correction is a novel technique that has been incorporated in several countries as treatment modality for EOS. Short-term outcomes are promising in terms of clinical improvement, complication rates and decreased need for multiple operations or unplanned surgeries.

Keywords: active apex correction; apical vertebral translation; crankshafting; early onset scoliosis; spine correction.

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Conflict of interest statement

Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: AA discloses consultancy from Tria Spine, consultancy from Proximie, Committee chair at SICOT, Committee member at SRS, NASS, AO spine. The rest of the authors have nothing to disclose.

Figures

Figure 1.
Figure 1.
Schematic showing key differences in the established SHILLA procedure and the modified APC approach used in this study, used with permission.
Figure 2.
Figure 2.
Intra-operative depiction of the implant construct used in the APC technique. The screws at the tethered levels on the convex side are shown in yellow.
Figure 3.
Figure 3.
Method of measurement of displacement of the tethering screws, quantifying compression done during the APC.
Figure 4.
Figure 4.
Surgical intervention involving distraction on the concave side (green arrows). One part of a cross link (yellow) was added proximal to the unlocked part of the domino (blue). Post distraction, the cross-link piece (which can be replaced with a screw head) is locked to prevent the rod sliding to go proximally.
Figure 5.
Figure 5.
Comparison of Radiographic images at pre-operative (L) and post-operative (R) time points in a patient undergoing APC. The most wedged vertebra (green) seen on pre-operative AP radiograph is used to identify apical region during surgical planning. Post-operative image indicates control of apex via compressive remodulation through screws above and below the most wedged vertebra on the convex side.
Figure 6.
Figure 6.
Comparison of Radiographic images at post-operative (L) and 1-year follow-up (R) time points in a patient undergoing APC. Position of proximal rods with respect to screw(red) and rib-hook (yellow) indicate sliding of rods due to guided-growth.
Figure 7.
Figure 7.
A preoperative radiograph (on right) and clinical appearance (on left) of a 4-year-old boy with severe right-sided syndromic scoliotic deformity.
Figure 8.
Figure 8.
Postoperative radiograph showing the treatment of the scoliotic deformity using APC. Yellow/red (concave/convex sides, respectively) circles identify the sliding units of this modified SHILLA construct.
Figure 9.
Figure 9.
Postoperative (day 2) portrait of the clinical improvement and correction of the appearance of the upper body of the same child following APC.
See this image and copyright information in PMC

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