Surface topography demonstrates gradual improvement in spinal range of motion in all three planes following posterior spinal fusion in adolescent idiopathic scoliosis.

introductionAfter posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS), there is alteration in trunk range of motion (ROM) in the coronal, sagittal and axial planes. Previous studies have shown that ROM decreases with increased number of levels fused, which may affect the ROM between patients who undergo non-selective thoracic fusion (NSF) and selective thoracic fusion (STF) patient groups. This study sought to longitudinally evaluate the ROM of the trunk in patients with AIS who underwent posterior spinal fusion, using surface topography, comparing STF and NSF patient motion at multiple time points postoperatively.

methodsA retrospective review of data from a single-center prospective registry was conducted. Inclusion criteria required subjects to span 11-21 years of age at surgery, a diagnosis of AIS, and valid ROM measurements obtained via ST scanning. Axial, sagittal and coronal ROM was performed at six timepoints: preoperative, 6 weeks, 3, 6, 12, and 24 months postoperative. All patients had an upper instrumented vertebra (UIV) of T2, T3 or T4, and a lower instrumented vertebra (LIV) of T12, L1, L2 or L3. STF was defined as an LIV of T12 or L1, and NSF as LIV as L2 or L3. SRS22r was collected at all time points. Generalized estimation equation modeling across timepoints were conducted.

results54 patients were evaluated: 40 patients in the NSF group (average preoperative Cobb angle of 56.4 ± 12.3°) and 14 in the STF group (average preoperative Cobb angle of 57.4° ± 6.7°). In the NSF group, ROM in the coronal and axial planes decreased significantly postoperatively and remained significantly decreased at 24 months postoperatively (25% decrease in the axial plane, 20% in the coronal plane). Sagittal ROM had significant decrease in ROM at all time points, but at 2 years postoperatively was no longer significant, although still 17% decreased. In the STF group, all three planes had significantly decreased initially but axial and coronal planes returned to baseline (no significant difference from preoperative values) at 24 months, while sagittal plane motion remained significantly diminished, although only by 4%. STF demonstrated no difference in SRS22r total, pain or self-image scores between preoperative and 2 years, while NSF had worse SRS22r total, pain, and self image scores at 2 years vs. preoperative values. When comparing NSF to STF, there was diminished axial, sagittal and coronal plane range of motion at 24 months postoperatively, but no differences in SRS22r total.

conclusionThe coronal, sagittal, and axial ROM as measured by ST demonstrated significant decreases from preoperative to postoperative following PSF; however, this deficit trends towards improvement over time. Our data demonstrates that at two years, NSF has poorer motion than STF patients in all three planes.