Long-term curve progression of idiopathic scoliosis: 40-year follow-up

Lærke Ragborg

In idiopathic scoliosis (IS) patients, long-term curve progression for curves between 30 and 50° at skeletal maturity is both substantial and comparable to curves that are greater than 50°, new research shows. The findings of the study—which was presented at the Scoliosis Research Society’s (SRS) 57th annual meeting (14–17 September 2022; Stockholm, Sweden) by Lærke Ragborg (Rigshospitalet, Copenhagen, Denmark) where it won the Russell A. Hibbs Best Clinical Research Paper award—also indicated that curve progression tends to be larger for thoracic than for thoracolumbar/lumbar (TL/L) main curves, however with no difference in terms of health-related quality of life (HRQoL).

The purpose of the single-centre study was to assess long-term curve progression and HRQoL in patients with IS and compare thoracic and TL/L curves. It is generally accepted that curves >50° will progress throughout adulthood, but less well described what happens with mild to moderate curves and whether curve size and location affects long-term HRQoL, note the researchers.

A total of 177 patients diagnosed with a paediatric spinal deformity who were treated at the Copenhagen hospital from 1972 through 1983 were included in the study. From this pool, 104 (69%) completed follow-up, of which 91 were diagnosed with juvenile (n=5) or adolescent IS (n=86). Patients with infantile, neuromuscular, syndromic, and congenital scoliosis were excluded.

Patient files from treatment/observation in childhood were reviewed including detailed descriptions of main curve, type and magnitude. At follow-up, the researchers assessed long-standing full-spine radiographs and HRQoL using the SRS-22R questionnaire.

Mean follow-up was 40.8 ± 2.6 years and 95% of the patients were female. Overall, the SRS-22R subscore was 3.8 (95% confidence interval [CI], 3.7–3.9) which, state the researchers, is lower than an age-matched normal population.

A total of 18 patients underwent Harrington rod instrumentation in adolescence and an additional three patients underwent surgery later in adulthood, leaving 70 patients for analysis of curve progression, of which 43 (61%) had been treated with a Boston brace.

The study found that, for curves <30° at skeletal maturity (n=32), mean curve progression was 10 ± 12° (range –5 to 44); for curves 30–50° (n=28) mean progression was 19 ± 12° (range –3 to 49); and for curves >50° (n=7) mean progression was 17 ± 6° (range 10–25). This corresponds to a curve progression of 0.3° per year, 0.5° per year and 0.4°per year, respectively.

Main curve size at follow-up was larger for thoracic curves 53 ± 18° than for TL/L curves 35 ± 21° (p<0.001). However, there was no difference in SRS-22R subscore between the two groups (3.8 ± 0.7 and 4.0 ± 0.7, respectively).

For curves 30–50°, there was shown to be a greater curve progression for thoracic curves (mean 22°) than for TL/L curves (mean 17°), but this was not statistically significant [95% CI for mean difference, –17 to 2].

Speaking to Spinal News International, Ragborg said: “A few milestone studies have described the natural history in patients with idiopathic scoliosis with varying results on curve progression and disability over time. Our study provides new insight to what happens with patients with idiopathic scoliosis later in adulthood and how their scoliosis significantly affects some of these patients’ quality of life.

“It also challenges the generally accepted statement that only curves above 50 degrees at skeletal maturity will continue to progress throughout adulthood. Therefore, some patients with curves less than 50 degrees may have benefited from surgery in adolescence.”


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