The aim of this study was to report the restauration of the normal vertebral morphology and the absence of curve progression after removal the instrumentation in AIS patients that underwent posterior correction of the deformity by common all screws construct whitout fusion. A series of 36 AIS immature patients (Risser 3 or less) were include in the study. Instrumentation was removed once the maturity stage was complete (Risser 5). Curve correction was assessed at pre and postoperative, before instrumentation removal, just post removal, and more than two years after instrumentation removal. Epiphyseal vertebral growth modulation was assessed by a coronal wedging ratio (WR) at the apical level of the main curve (MC). The mean preoperative coronal Cobb was corrected from 53.7°±7.5 to 5.5º±7.5º (89.7%) at the immediate postop. After implants removal (31.0±5.8 months) the MC was 13.1º. T5–T12 kyphosis showed a significant improvement from 19.0º before curve correction to 27.1º after implants removal (p<0.05). Before surgery, WR was 0.71±0.06, and after removal WR was 0.98±0.08 (p<0.001). At the end of follow-up, the mean sagittal range of motion (ROM) of the T12-S1 segment was 51.2±21.0º. SRS-22 scores improved from 3.31±0.25 preoperatively to 3.68±0.25 at final assessment (p<0.001). In conclusion, fusionless posterior approach using a common all pedicle screws construct correct satisfactory scoliotic main curves and permits removal of the instrumentation once the bone maturity is reached. The final correction was highly satisfactory and an acceptable ROM of the previously lower instrumented segments was observed.

Rebound growth after hemiepiphysiodesis may be a normal event, but little is known about its causes, incidence or factors related to its intensity. The aim of this study was to evaluate rebound growth under controlled experimental conditions.

A total of 22 six-week-old rabbits underwent a medial proximal tibial hemiepiphysiodesis using a two-hole plate and screws. Temporal growth plate arrest was maintained for three weeks, and animals were killed at intervals ranging between three days and three weeks after removal of the device. The radiological angulation of the proximal tibia was studied at weekly intervals during and after hemiepiphysiodesis. A histological study of the retrieved proximal physis of the tibia was performed.

The mean angulation achieved at three weeks was 34.7° (standard deviation (sd) 3.4), and this remained unchanged for the study period of up to two weeks. By three weeks after removal of the implant the mean angulation had dropped to 28.2° (sd 1.8) (p < 0.001). Histologically, widening of the medial side was noted during the first two weeks. By three weeks this widening had substantially disappeared and the normal columnar structure was virtually re-established.

In our rabbit model, rebound was an event of variable incidence and intensity and, when present, did not appear immediately after restoration of growth, but took some time to appear.

Cite this article: Bone Joint J 2015;97-B:862–8.