Effectiveness of three types of lumbar orthosis for restricting extension motion.

Spinal orthoses are implemented to restrict lumbar motion. Several studies have compared the effectiveness of various types of lumbar orthoses on restricting motion, but none have compared the effect of different back supports on restricting extension. This study sought to evaluate the effectiveness of three types of lumbar orthosis in regard to their ability to restrict motion during extension. Range of motion was quantified using the Spinal Mouse system to measure flexion and extension, and the load distribution of the back support was measured using a pressure sensor. Ten subjects (8 men, 2 women) were assessed under the following five experimental conditions: custom-made stay (CMS), aluminum stay (AS), plastic stay (PS), corset only, and no brace. None of the stays changed the flexion angle, and none of the supports prevented flexion bending. The mean extension angle after immobilization with the CMS, AS, PS, corset only, and no brace was 27.5° ± 8.5°, 33.4° ± 11.0°, 34.3° ± 9.4°, 37.8° ± 10.7°, and 42.6° ± 10.5°, respectively. The load in the CMS was concentrated at the vertical ends of the stay, with a mean load of 11.5 ± 2.4 N at the top and 8.9 ± 2.4 N at the bottom. The loads at the top and bottom of the support were 7.2 ± 4.3 and 5.3 ± 3.1 N with the AS and 5.8 ± 2.3 and 4.4 ± 1.7 N with the PS, respectively. All supports allowed similar flexion motion. Although the CMS, AS, and PS all restricted extension compared with no brace, the CMS was the most effective for restricting trunk extension motion.