Distinguishing Biomechanical Properties of Intrinsic and Extrinsic Human Wrist Ligaments

Abstract

Two intrinsic (scapholunate and lunotriquetral) and two extrinsic (radiolunate and radiocapitate) wrist ligaments were studied at high and low elongation rates (1 and 100 mm/min). Statistically significant differences among all four ligaments were noted for the viscoelastic and elastic components of stress versus strain for the fully recoverable strain and early permanent deformation stress for all ligaments. Intrinsic ligaments became permanently deformed at statistically significantly higher strain levels than the extrinsic ligaments and accept larger permanent deformation at strain levels below evident fiber failure. Ultimate strength data demonstrated significant rate dependency for stress and strain for all ligaments. Intrinsic ligaments failed statistically greater stress and strain levels than the extrinsic group. Some clinical implications of these findings are discussed.

Viscoelastic constitutive law in large deformations

“…Few experimental studies have been conducted in this field. Nevertheless, the effect of the strain rate on the stress-strain curves has been demonstrated with anterior cruciate ligament (Kennedy et al, 1976), tendons (Haut, 1983;Sanjeevi, 1982), intrinsic and extrinsic wrist ligament (Nowalk and Logan, 1991), incisor periodontal ligament (Chiba and Komatsu, 1993), and inferior glenohumeral ligament (Ticker et al, 1996).…”

Measurements of Cross-Sectional Areas in Selected Human Wrist-Joint Ligaments

“…These data are significantly higher than our data (table l ). Nowak and Logan [6] find average CSAs of 8.0 mm" for the RSC and 11.0 mm2 for the RLTp. using about the same micrometer and an average of ten specimens.…”

“…The differences may partly be explained by the division of the ligaments from the joint. Nowak and Logan [6] take only the ulnar part of the ligament that is called the RSC in our study; they dis card the part running to the scaphoid and a smaller area is the result. These authors do take measurements in the mid dle portions of the ligament, like we have done.…”

“…in order to assess the CSAs of these ligaments, it is necessary to define before hand in which way this complex of fiber bundles is divided into individual ligaments. This has not been done in the studies offering CSAs of some carpal ligaments [5][6][7], so that comparisons are difficult to make.…”

Development and Validation of a Computational Model for Investigation of Wrist Biomechanics

“…3,6,25,30 Ligament stiffness values for carpal ligaments were assigned from published experimental data, 8,24,31 or from previous computational models in the literature 5,7,16,35 ranging from 40 to 350 N/mm ( Table 1). All carpometacarpal and intermetacarpal ligaments represented in the model were assumed to have a stiffness of 100 N/mm.…”