Dynamic splinting: a systematic approach to the selection of elastic traction.

Elastic traction is an important but occasionally misapplied component of upper-extremity dynamic splints. Information regarding a systematic approach for selection of elastic traction has been limited. A biomechanical analysis of dynamic splinting methods was done to identify factors that might help educate therapists in the proper application of elastic traction. Material properties of elastic traction were measured with a mechanical testing system capable of accurately identifying physical properties of various substances. Results of this analysis indicated that specific spring constant values for clinically used bands ranged from 134 to 531 g, original length values ranged from 0.7 to 3.2 in., the consistency of bands labeled as identical by the manufacturer was generally very good, and each band's ability to maintain its material properties with repeated elongation was similar from band to band and showed gradual diminution after several hundred repetitions. These data were combined with theoretical constructs of splint fabrication to devise a simple and logical method for analysis and determination of elastic traction requirements for various diagnostic applications. A goniometer, ruler, and spring scale are the only tools necessary to perform the analysis. Simple charts depicting forces and moments provide identification of the appropriate rubber band for application.