Prediction of Stress Distribution Applied to the Triangular Fibrocartilage Complex: A Finite Element Analysis.

Purpose: The triangular fibrocartilage complex (TFCC) is an important tissue stabilizer for the distal radioulnar joint, but stress distribution on the TFCC is not clear. The purpose of this study was to report the stress distribution of the TFCC using finite element analysis (FEA). Methods: Pathological specimens of the wrist joint from an 80-year-old man were imported into a finite element analysis software package, and regions of interest including bone, soft tissue, and TFCC were extracted to create a 3-dimensional model. The material properties were obtained from previous research using cadaver specimens. To allow large deformations, we used hyperelastic elements to model the TFCC and soft tissue. Bone was defined as a uniform tissue that did not break. With the carpals and radius constrained, the rotation axis was set at the center of the ulnar head and a force was applied to move the ulnar head in pronation and supination. Under these boundary conditions, the behavior of the TFCC was extracted as a moving image. The average value of the maximum principal stress for each component of the TFCC was extracted and graphed. Results: In the supinated position, the maximum principal stress was found on the palmar side of the TFCC (eg, on the tension side). In pronation, the maximum principal stress was found on the dorsal side. Conclusions: This study clearly showed the 3-dimensional structure of the TFCC and analyzed its stress distribution under load. In supination, mean values of the maximum principal stress were greater on the palmar fibers than the dorsal fibers. In pronation, mean maximum principal stress was greater on the dorsal fibers than the palmar fibers. Clinical relevance: Knowing the distribution of stresses in the TFCC is an important factor in developing treatment strategies for a pathologic TFCC.