Points of Consensus: Nocturnal Orthosis Design

Nocturnal orthosis biomechanics allow the orthotist the ability to take advantage of the recumbent position for increased reduction of the Cobb angle. There is a perceived value of the resultant stretch of the connective tissue on the concave side of the curve in the process.

The corrective forces for all curve types being addressed within the orthosis are applied at the level that is geometrically perpendicular to the apex of the curve. This approach enables the orthotist to increase the distance between the corrective forces applied to the spine. It is also theorized that this separation of forces may decrease the amount of force necessary to achieve an acceptable in-orthosis correction. With the elimination of the need to position the patient in an upright position with the head over the pelvis, a nocturnal orthosis can create a fulcrum from one or more vectors around which the spine may be rotated. This rotation around a fulcrum occurs primarily in the coronal plane, but rotatory correction also may be applied in the transverse plane. The combined effect of three factors [1) gravity eliminated application of forces that are 2) separated from each other because of their being placed perpendicular to the spine, and 3) where a fulcrum for shifting or bending is created] enables the orthosis designed for recumbent wear to achieve improved in-orthosis correction of the Cobb angle for a scoliotic curve compared with to orthoses designed to be worn in an upright position.

RESEARCH PRIORITIES

There is a need to better understand the relationship of wear schedule with treatment outcome.
In those requiring at least 16 hours/day orthosis wear, the possibility of improving outcomes by the combined use of a nocturnal orthosis and an orthosis designed for upright wear during the day needs to be investigated.