Shear wave elastography of lumbar annulus fibrosus in adolescent idiopathic scoliosis before and after surgical intervention.

OBJECTIVES

To determine lumbar intervertebral disc properties with shear wave elastography in adolescent idiopathic scoliotic (AIS) patients before and after surgery, and compare them with asymptomatic controls.

METHODS

Twenty-five severe AIS patients with an indication for fusion surgery (15 ± 1.5 years old, the Cobb angle ranging between 40 and 93°) and fifty-nine asymptomatic adolescents (13 ± 2 years old) were included prospectively. Shear wave speed (SWS) was measured in the annulus fibrosus of L3-L4, L4-L5, and L5-S1 discs of each subject. In AIS patients, measurements took place before surgery, and 3 months (N = 13) or 1 year after (N = 12).

RESULTS

No difference was observed between disc levels in any group. When pooling disc levels, SWS was significantly higher in preop AIS patients (4.0 ± 0.5 m/s) than in asymptomatic subjects (3.1 ± 0.5 m/s, p < 0.0001). SWS decreased 3 months postop (3.5 ± 0.3 m/s), and it decreased further towards normal values 1 year after (3.3 ± 0.4 m/s). SWS in preop AIS patients tended to decrease with the Cobb angle (Spearman's rho = - 0.4, p = 0.05).

CONCLUSION

Shear wave elastography measurements showed that discs in AIS patients were altered relative to asymptomatic ones, and this alteration tended to normalize 1 year post fusion surgery. Further studies should aim at determining if bracing of mild scoliosis has an effect on disc properties.

KEY POINTS

• Shear wave elastography shows alteration of annulus fibrosus in adolescent idiopathic scoliosis. • Disc elastography tends to normalize 1 year after surgery.