Providence nighttime brace is as effective as fulltime Boston brace for female patients with adolescent idiopathic scoliosis: A retrospective analysis of a randomized cohort

Abstract

Background: Progressive moderate scoliotic curves in patients with adolescent idiopathic scoliosis (AIS) are usually treated with a fulltime brace, e.g., the Boston brace (BB). The Providence nighttime brace (PNB), is an alternative which is designed to reach the same treatment effectiveness by nighttime wear only. Few studies compared treatment effectiveness between full and nighttime bracing with contradictory results.

Methods: Immature female patients older than 10 years with progressive moderate AIS curves with an apex below T6 were randomized into PNB (n=62) or BB (n=49) treatment. Inclusion criteria were AIS, age ≥ 10 years, no previous treatment, main curve Cobb angle 20°-40° and skeletal immaturity. The increase of the main curve by > 5° of Cobb angle at the final follow-up was established as the primary outcome measure. Secondary outcome measures included (1) the Scoliosis Research Society assessment criteria of effectiveness for brace studies, (2) progression of secondary curves, (3) in-brace correction and (4) compliance to the treatment. The patients were followed until 1 year after reaching maturity.

Results: A total of 105 patients (n=62 and n=43 in PNB and BB group, respectively) completed the follow-up (95%). In the PNB group, 71% patients were treated successfully compared to 65% patients in the BB group (p=.67). No significant difference of the curve progression was found between the groups (3.1°±6.3° and 2.6°±8.3° in PNB and BB group, respectively; p=.73). No significant differences were found for the thoracic or thoracolumbar/lumbar subgroups. PNB showed a superior in-brace correction for all curve types. One of four secondary curves progressed > 5°. The compliance to the treatment was significantly higher in the PNB than BB group.

Conclusions: Both brace regimes are equally effective in treating moderate AIS curves with apex of the main curve below T6 in immature female patients older than 10 years.

Fig. 1

Comparison of the AIS curves. Left: Boston brace treatment of the thoracic AIS curve, pre-brace (28°) and in-brace standing (12°). Right: Providence brace treatment of the double AIS curve, pre-brace (36° thoracic and 32° lumbar curve) and in-brace supine (3° thoracic and 13° lumbar curve).

Fig. 2

Study enrollment and treatment. All included patients were also available for in-brace measurements. Six patients were lost to follow-up and 60 and 45 patients in the Providence and Boston groups, respectively, finished the study. The patients were allowed to change the treatment group. Thus, 62 and 43 patients in the Providence and Boston groups, respectively, were included in the as-treated analysis.

Fig. 3

Clustered box plot of Cobb angle medians of main curves for the Boston and Providence braces at different time points. Upper and lower margins of the box delineate IQR (0.25–0.75). Whiskers show maximal and minimal values (1.5 IQR). The correction in Providence brace was significantly better than in the Boston brace (p<.0001). There was no statistically significant difference in effectiveness of the braces at final follow-up.