Application of Raman scattering to the measurement of ligament tension

Abstract

More marginal results and complications occur as a result of knee ligament surgery than of other common surgical procedure. Long-term success rates of anterior cruciate ligament reconstruction range between 75 and 90%. The goal of knee surgery is to restore the normal kinematics of the knee. If the tension is too high, the range of motion of the joint is restricted, resulting in abnormal stresses on the articular cartilage and the meniscuses, and interfering with the revascularization of the graft. The use of Raman spectroscopy for the measurement of tension in ligaments and tendons is described. Measurements of the Raman spectrum demonstrate that the Raman frequencies shift with applied tension.

Molecular analysis of the destruction of articular joint tissues by Raman spectroscopy

“…These assignments were used as references for identifying variations in collagen backbone or fibers orientation, under tension conditions, that support RS application for determining tension in ligaments and tendons [79,80]. Later, this technology was suggested to monitor mechanical properties of ligaments, such as tensile stress, during knee surgery, promoting better ligament fixation, by setting a proper tension in a repaired or grafted tissue, contributing to a normal kinematics of the knee [81]. Moreover, analysis of supraspinatus tendon enthesis spectra led to the identification of a mineralization gradient associated to mineral crystallinity across the tendon-bone insertion site [82][83][84].…”

Raman Spectroscopy of Soft Musculoskeletal Tissues

“…A preliminary study by Winchester et al indicates that unpolarized Raman spectroscopy can monitor tensile and compressive forces in the collagen chain. 52 They used a custom-built Raman system with free-standing optics to examine mink and rabbit ligament. Because the composition of ligament is similar to that of tendon, its Raman spectrum is similar to a tendon spectrum.…”

Raman Spectroscopy Methods to Characterize the Mechanical Response of Soft Biomaterials

“…One popular method to analyze the mechanical response of biomaterials to an applied load is Raman piezo-spectroscopy, which correlates the shift in a specific spectral peak position to the magnitude of applied or residual stress in the material . Piezo-spectroscopy has been effectively used on hard biomaterials (e.g., bone and teeth) that exhibit detectable peak shifts to applied loads. − However, for soft biomaterials (with modulus < 1 GPa), peak shifts under applied loads are negligible. , Hence, the determination of local stress is not currently possible for soft biomaterials such as ligaments or synthesized hydrogel scaffolds with low stiffness such as collagen or fibrin hydrogels. Because the sensitivities of Raman peaks associated with molecular vibrations to mechanical deformation, Raman piezo-spectroscopy cannot be applied uniformly across all biomaterials under mechanical deformation.…”

“…Because the sensitivities of Raman peaks associated with molecular vibrations to mechanical deformation, Raman piezo-spectroscopy cannot be applied uniformly across all biomaterials under mechanical deformation. Figure compares the observed peak shift sensitivity under mechanical stress to Young’s modulus for various biomaterials that have been studied using μRS. − The dashed line indicates the limit of the piezo-spectroscopy below which peak shifts are not currently detectable. While local stress magnitude may not be determined in these low-stiffness biomaterials, μRS can still be effectively used to determine local structural changes in these materials after mechanical deformation.…”