US Patent 7077386 Adjustable staircase rail system

A hinge assembly which can be inserted into the bore of an end-bored bluster, fastened to the inside of the bore, and pivotally attached to a flange suitable for attachment to a rail. The hinge assembly requires no external modification to the normally exposed surfaces of the baluster. The flange includes an H-shaped foot which may be concealed in a groove defined by a hand rail or a shoe rail. The pivot point is raised slightly above the inner surface of the groove to prevent any unsightly gap, termed “bird's' mouth” in the industry, adjacent the baluster.