Background: Previous studies have shown that the long-term clinical
outcome does not correlate with the radiographic outcome in patients treated
with Harrington instrumentation for adolescent idiopathic scoliosis.
Cotrel-Dubousset instrumentation has been reported to provide better
correction radiographically, but it is unclear whether it provides better
long-term clinical or functional outcomes. We are not aware of any long-term
studies comparing Harrington and Cotrel-Dubousset instrumentation.
Methods: Seventy-eight patients in whom adolescent
idiopathic scoliosis was treated with Harrington instrumentation and
fifty-seven in whom it was treated with Cotrel-Dubousset instrumentation
participated in this study. The mean duration of follow-up was 20.8 years for
the Harrington instrumentation group and 13.0 years for the Cotrel-Dubousset
instrumentation group. The mean age at the time of follow-up was thirty-six
years and twenty-eight years, respectively. Radiographs were made
preoperatively and at the two-year and final follow-up examinations. The
Scoliosis Research Society questionnaire was completed, a physical examination
was performed, and spinal mobility and non-dynamometric trunk strength were
measured at the final follow-up visit.
Results: The mean preoperative Cobb angle of the thoracic curves was
53° in the Harrington instrumentation group and 55° in the
Cotrel-Dubousset instrumentation group. The mean numbers of vertebrae included
in the instrumentation were 10.7 and 9.9, respectively. At the two-year
follow-up evaluation, the mean postoperative Cobb angles were 38° and
25°, respectively (p < 0.0001). At the final follow-up evaluation, the
mean angles were 45° and 32° (p < 0.0001). No significant
difference in thoracic kyphosis or lumbar lordosis was observed between the
study groups at the final follow-up evaluation. The average score on the
Scoliosis Research Society questionnaire was 97 points in both groups.
Measurements of non-dynamometric trunk strength corresponded with age and
sex-adjusted reference values, on the average, but patients with
Cotrel-Dubousset instrumentation performed significantly better in the
squatting test (p = 0.010). Abnormal lumbar extension and trunk side-bending
were significantly more common in the Harrington instrumentation group (p =
0.050 and p = 0.0061, respectively). Complications were recorded for nine
(12%) of the patients treated with Harrington instrumentation and fifteen
(26%) of those treated with Cotrel-Dubousset instrumentation (p = 0.027).
Conclusions: Cotrel-Dubousset instrumentation yielded better
long-term functional and radiographic outcomes in patients with adolescent
idiopathic scoliosis than did Harrington instrumentation. However,
complications were more common in the Cotrel-Dubousset instrumentation
Level of Evidence: Therapeutic study, Level III-2
(retrospective cohort study). See Instructions to Authors for a complete
description of levels of evidence.