means such as rivets 66 the alignment bars 64 and slotted receptacles 60 in combination connect the first and second sides 12 14 to form a dynamic orthotic device 10 which encompasses the trunk and provides for as little unwanted front and rear and up and down relative motion between the first and second shells 12 14 as possible fig1 and 6 show straps 68 69 which secure the first and second shells 12 14 together the straps 68 69 pass over each of the alignment bars 64 and slotted receptacles 60 straps 68 69 are secured to either first or second shells 12 14 by any suitable means such as rivets 72 straps 68 69 then pass through loop pieces 76 which are secured to the opposing first or second shell 12 14 by any suitable means such as rivets 78 straps 68 69 are fastened to the first or second shells 12 14 to which straps 68 69 are secured by any suitable means such as a velcro fastener 80 in addition there can be provided an elastic member in strap 69 which passes over the alignment bar above the open chest cutout 30 the elastic member in strap 69 in conjunction with the open chest cutout 30 facilitates the chest expansion associated with breathing elastic strappings 82 83 provide the dynamic force and are utilized in pull straps 84 85 respectively which are positioned so as to cross.