BIOMECHANICAL DETERMINANTS OF HUMAN WRIST BIOMECHANICS.

Marked differences exist in biomechanial properties between intrinsic and extrinsic human wrist ligaments in their ultimate stress and strain, stiffness, and elastic limit. To determine possible biochemical reasons for these observed differences the authors quantified the amount of the structural proteins, collagen and elastin, in two intrinsic, scapholunate and lunotriquetral, and two extrinsic, radiocapitate and radiolunate, human wrist ligaments. Six specimens of each ligament were hydrolyzed and subjected to animo acid analysis to quantify hydroxyproline and demosine content as quantitative markers of collagen and elastin, respectively. All ligaments were found to have essentially the same biomechanical content, 95% collagen and 0. 2% elastin. No ligament had a unique biochemical content which predicted its biomechanical performance. Alternate explanations are discussed.