A garment-based system, construction and method controls knee brace displacement relative to a brace-outfitted lower extremity. The garment-based system includes or is cooperable with a knee brace, a waist-encircling anchor structure, an anchor-to-brace tether structure, and certain tether-to-brace attachment structures. The waist-encircling anchor structure is receivable about a users waist and fixable in a transverse anchor plane. The inelastic anchor-to-brace tether structure is fastened to the waist-encircling anchor structure and extends in a first direction orthogonal to the transverse anchor plane. The tether-to-brace attachment structure(s) fasten the knee brace to the anchor-to-brace tether structure, and are immovable in the first direction. The anchor structure, the tether structure, and the attachment structure together function to control knee brace displacement relative to the lower extremity for maintaining the a brace-based pivot axis in proper anatomical alignment with the variable knee axis.
